Merge pull request 'feat(lease): verified lease-remediation stack (rebased onto next) — promotion trigger + promote CLI + carve-out + TTL' (#1109) from feat/lease-promotion-and-harness-isolation into next

Co-authored-by: Jason Woltje <[email protected]>

.woodpecker/ci.yml

@@ -109,6 +109,16 @@ steps:
       # `apk add` guarantees openssl is present on PR pipelines too (and is a
       # fast no-op once the rebuilt image already ships it).
       - apk add --no-cache openssl
+      # Pi runtime (Invariant R): invariant_r_unittest.py hard-requires an
+      # installed `pi` binary at exactly this measured version — the test
+      # boots Pi's real tool registry to prove the read-only carve-out
+      # resolves to real, unshadowed builtins, and fails loud (by design)
+      # when the runtime is absent or drifts. The canonical Pi is
+      # @earendil-works/[email protected] exactly (@mariozechner/* is
+      # embedded-legacy). Step-level install because ci-base image publishes
+      # are currently blocked on registry auth; fold into Dockerfile.ci once
+      # that is fixed, keeping this as a fast no-op guard.
+      - npm install -g @earendil-works/[email protected]
       # postgresql-client (pg_isready) is baked into ci-base.
       # Wait up to 60s for CI postgres to be ready; fail fast if it never comes up.
       - |

apps/gateway/src/app.module.ts

@@ -21,6 +21,7 @@ import { AdminModule } from './admin/admin.module.js';
 import { CommandsModule } from './commands/commands.module.js';
 import { PreferencesModule } from './preferences/preferences.module.js';
 import { GCModule } from './gc/gc.module.js';
+import { HarnessModule } from './harness/harness.module.js';
 import { ReloadModule } from './reload/reload.module.js';
 import { WorkspaceModule } from './workspace/workspace.module.js';
 import { QueueModule } from './queue/queue.module.js';
@@ -60,6 +61,7 @@ const federationEnabled = loadConfig(resolveGatewayConfigPath()).tier === 'feder
     PreferencesModule,
     CommandsModule,
     GCModule,
+    HarnessModule,
     QueueModule,
     ReloadModule,
     WorkspaceModule,

apps/gateway/src/harness/harness-selection.controller.spec.ts

@@ -0,0 +1,164 @@
+import 'reflect-metadata';
+import {
+  type CanActivate,
+  type ExecutionContext,
+  type INestApplication,
+  ValidationPipe,
+} from '@nestjs/common';
+import { FastifyAdapter, type NestFastifyApplication } from '@nestjs/platform-fastify';
+import { Test } from '@nestjs/testing';
+import request from 'supertest';
+import { afterAll, beforeAll, beforeEach, describe, expect, it } from 'vitest';
+import { AuthGuard } from '../auth/auth.guard.js';
+import { HarnessRegistry } from './harness.registry.js';
+import { HARNESS_REGISTRY } from './harness.tokens.js';
+import { HarnessSelectionRepository } from './harness-selection.repository.js';
+import { FakeHarnessAdapter } from './testing/fake-harness.adapter.js';
+// Import the REAL module (not a hand-listed controllers+mocks list) so an
+// unresolved provider fails at app.init() — the #1145-class DI-boot guard.
+import { HarnessModule } from './harness.module.js';
+
+// A known-available tuple from the fake adapter's default catalog.
+const VALID = { harnessId: 'fake', providerId: 'fake-openai', modelId: 'fake-mini' };
+// A tuple whose provider/model are not in any catalog.
+const UNKNOWN = { harnessId: 'fake', providerId: 'ghost-provider', modelId: 'ghost-model' };
+// A tuple that is known in the catalog but flagged unavailable.
+const UNAVAILABLE = { harnessId: 'fake', providerId: 'fake-openai', modelId: 'fake-legacy' };
+
+const authGuard: CanActivate = {
+  canActivate(context: ExecutionContext): boolean {
+    const requestContext = context.switchToHttp().getRequest<{ user?: { id: string } }>();
+    requestContext.user = { id: 'user-1' };
+    return true;
+  },
+};
+
+function registryWithFake(): HarnessRegistry {
+  const registry = new HarnessRegistry();
+  registry.register(new FakeHarnessAdapter({ id: 'fake' }));
+  return registry;
+}
+
+describe('Harness selection HTTP surface', () => {
+  let app: INestApplication;
+  let repository: HarnessSelectionRepository;
+
+  beforeAll(async () => {
+    const moduleRef = await Test.createTestingModule({
+      imports: [HarnessModule],
+    })
+      .overrideGuard(AuthGuard)
+      .useValue(authGuard)
+      .overrideProvider(HARNESS_REGISTRY)
+      .useValue(registryWithFake())
+      .compile();
+
+    // Real in-memory repository from the module graph — proves the module wired it.
+    repository = moduleRef.get(HarnessSelectionRepository);
+
+    app = moduleRef.createNestApplication<NestFastifyApplication>(new FastifyAdapter());
+    app.useGlobalPipes(
+      new ValidationPipe({ whitelist: true, forbidNonWhitelisted: true, transform: true }),
+    );
+    await app.init();
+    await app.getHttpAdapter().getInstance().ready();
+  });
+
+  beforeEach(() => {
+    // Reset owner-scoped state between tests via the public API surface.
+    repository.set({ userId: 'user-1', tenantId: 'user-1' }, VALID);
+  });
+
+  afterAll(async () => {
+    await app.close();
+  });
+
+  it('GET selection is server-scoped and ignores caller-supplied scope in the query', async () => {
+    const response = await request(app.getHttpServer())
+      .get('/api/chat/preferences/selection')
+      .query({ userId: 'attacker', tenantId: 'attacker-tenant', seatId: 'attacker-seat' });
+
+    expect(response.status).toBe(200);
+    // The returned selection is user-1's (guard-derived scope), not the query's.
+    expect(response.body.selection).toEqual(VALID);
+  });
+
+  it('PUT with a valid structured tuple persists and round-trips via GET', async () => {
+    const next = { harnessId: 'fake', providerId: 'fake-openai', modelId: 'fake-pro' };
+
+    const put = await request(app.getHttpServer())
+      .put('/api/chat/preferences/selection')
+      .send(next)
+      .set('Content-Type', 'application/json');
+    expect(put.status).toBe(200);
+    expect(put.body.selection).toEqual(next);
+
+    const get = await request(app.getHttpServer()).get('/api/chat/preferences/selection');
+    expect(get.status).toBe(200);
+    expect(get.body.selection).toEqual(next);
+  });
+
+  it('PUT with FREE TEXT is rejected 400 and does not mutate the stored selection', async () => {
+    const response = await request(app.getHttpServer())
+      .put('/api/chat/preferences/selection')
+      .send({ selection: 'gpt-4o' })
+      .set('Content-Type', 'application/json');
+
+    expect(response.status).toBe(400);
+
+    const get = await request(app.getHttpServer()).get('/api/chat/preferences/selection');
+    expect(get.body.selection).toEqual(VALID);
+  });
+
+  it.each([
+    ['seatId', { ...VALID, seatId: 'attacker-seat' }],
+    ['tenantId', { ...VALID, tenantId: 'attacker-tenant' }],
+    ['userId', { ...VALID, userId: 'attacker' }],
+    ['nativeSessionPath', { ...VALID, nativeSessionPath: '/var/native/x.jsonl' }],
+    ['executable', { ...VALID, executable: '/usr/bin/evil' }],
+    ['home', { ...VALID, home: '/home/attacker' }],
+    ['cwd', { ...VALID, cwd: '/tmp/attacker' }],
+  ])(
+    'PUT with an extra authority-bearing field (%s) is rejected 400 and does not mutate stored selection',
+    async (_name, body) => {
+      const response = await request(app.getHttpServer())
+        .put('/api/chat/preferences/selection')
+        .send(body)
+        .set('Content-Type', 'application/json');
+
+      expect(response.status).toBe(400);
+
+      const get = await request(app.getHttpServer()).get('/api/chat/preferences/selection');
+      expect(get.body.selection).toEqual(VALID);
+    },
+  );
+
+  it('PUT with an UNKNOWN tuple returns selection_invalid, unchanged and echoed unchanged (no fallback)', async () => {
+    const response = await request(app.getHttpServer())
+      .put('/api/chat/preferences/selection')
+      .send(UNKNOWN)
+      .set('Content-Type', 'application/json');
+
+    expect(response.status).toBe(422);
+    expect(response.body.code).toBe('selection_invalid');
+    // Echoed back unchanged: no first-row / first-provider substitution.
+    expect(response.body.selection).toEqual(UNKNOWN);
+
+    const get = await request(app.getHttpServer()).get('/api/chat/preferences/selection');
+    expect(get.body.selection).toEqual(VALID);
+  });
+
+  it('PUT with a KNOWN-but-UNAVAILABLE tuple returns model_unavailable, unchanged (distinct from selection_invalid)', async () => {
+    const response = await request(app.getHttpServer())
+      .put('/api/chat/preferences/selection')
+      .send(UNAVAILABLE)
+      .set('Content-Type', 'application/json');
+
+    expect(response.status).toBe(422);
+    expect(response.body.code).toBe('model_unavailable');
+    expect(response.body.selection).toEqual(UNAVAILABLE);
+
+    const get = await request(app.getHttpServer()).get('/api/chat/preferences/selection');
+    expect(get.body.selection).toEqual(VALID);
+  });
+});

apps/gateway/src/harness/harness-selection.controller.ts

@@ -0,0 +1,46 @@
+import { Body, Controller, Get, HttpException, HttpStatus, Put, UseGuards } from '@nestjs/common';
+import { AuthGuard } from '../auth/auth.guard.js';
+import { CurrentUser } from '../auth/current-user.decorator.js';
+import { scopeFromUser, type AuthenticatedUserLike } from '../auth/session-scope.js';
+import { HarnessOperationError } from './harness.registry.js';
+import { HarnessSelectionService } from './harness-selection.service.js';
+import { HarnessSelectionInputDto, type SelectionResponseDto } from './harness.dto.js';
+
+/**
+ * Chat-preferences selection surface. The scope is ALWAYS derived on the server
+ * from the authenticated user (`scopeFromUser(CurrentUser)`); the request body and
+ * query string can never name another user, tenant, or seat. A typed selection
+ * failure (unknown tuple → `selection_invalid`, known-but-unavailable →
+ * `model_unavailable`) is returned as 422 with the requested tuple echoed back
+ * unchanged, and never mutates the stored selection.
+ */
+@Controller('api/chat/preferences/selection')
+@UseGuards(AuthGuard)
+export class HarnessSelectionController {
+  constructor(private readonly selection: HarnessSelectionService) {}
+
+  @Get()
+  get(@CurrentUser() user: AuthenticatedUserLike): SelectionResponseDto {
+    return { selection: this.selection.getSelection(scopeFromUser(user)) };
+  }
+
+  @Put()
+  async put(
+    @CurrentUser() user: AuthenticatedUserLike,
+    @Body() dto: HarnessSelectionInputDto,
+  ): Promise<SelectionResponseDto> {
+    try {
+      const stored = await this.selection.setSelection(scopeFromUser(user), {
+        harnessId: dto.harnessId,
+        providerId: dto.providerId,
+        modelId: dto.modelId,
+      });
+      return { selection: stored };
+    } catch (error) {
+      if (error instanceof HarnessOperationError) {
+        throw new HttpException(error.dto, HttpStatus.UNPROCESSABLE_ENTITY);
+      }
+      throw error;
+    }
+  }
+}

apps/gateway/src/harness/harness-selection.service.ts

@@ -0,0 +1,90 @@
+import { randomUUID } from 'node:crypto';
+import { Inject, Injectable } from '@nestjs/common';
+import type { HarnessSelection } from '@mosaicstack/types';
+import type { ActorTenantScope } from '../auth/session-scope.js';
+import {
+  HarnessAdapterUnavailableError,
+  HarnessRegistry,
+  operationError,
+} from './harness.registry.js';
+import { HARNESS_REGISTRY } from './harness.tokens.js';
+import { readContextFromScope } from './harness.dto.js';
+import { HarnessSelectionRepository } from './harness-selection.repository.js';
+
+/**
+ * Selection logic for the Slice-Zero chat-preferences surface. It validates the
+ * requested harness/provider/model tuple against the live catalog with NO
+ * fallback substitution, then persists it owner-scoped. The stored selection is
+ * only ever mutated when the tuple is valid AND available.
+ */
+@Injectable()
+export class HarnessSelectionService {
+  constructor(
+    @Inject(HARNESS_REGISTRY) private readonly registry: HarnessRegistry,
+    private readonly repository: HarnessSelectionRepository,
+  ) {}
+
+  getSelection(scope: ActorTenantScope): HarnessSelection | null {
+    return this.repository.get(scope);
+  }
+
+  async setSelection(
+    scope: ActorTenantScope,
+    selection: HarnessSelection,
+  ): Promise<HarnessSelection> {
+    // Throws HarnessOperationError (selection_invalid / model_unavailable) with the
+    // requested tuple echoed back unchanged. The store is untouched on any throw.
+    await this.assertSelectionAvailable(scope, selection);
+    return this.repository.set(scope, selection);
+  }
+
+  private async assertSelectionAvailable(
+    scope: ActorTenantScope,
+    selection: HarnessSelection,
+  ): Promise<void> {
+    const correlationId = randomUUID();
+
+    let adapter;
+    try {
+      adapter = this.registry.get(selection.harnessId);
+    } catch (error) {
+      if (error instanceof HarnessAdapterUnavailableError) {
+        // An unknown harness makes the whole tuple invalid — no fallback adapter.
+        throw operationError(
+          'selection_invalid',
+          'The requested harness/provider/model tuple is not in the catalog.',
+          selection,
+          correlationId,
+        );
+      }
+      throw error;
+    }
+
+    const catalog = await adapter.catalog(readContextFromScope(scope));
+    const entry = catalog.models.find(
+      (candidate) =>
+        candidate.harnessId === selection.harnessId &&
+        candidate.providerId === selection.providerId &&
+        candidate.modelId === selection.modelId,
+    );
+
+    if (!entry) {
+      // No first-row / first-provider fallback: reject the requested tuple unchanged.
+      throw operationError(
+        'selection_invalid',
+        'The requested harness/provider/model tuple is not in the catalog.',
+        selection,
+        correlationId,
+      );
+    }
+    if (entry.availability === 'unavailable') {
+      throw operationError(
+        'model_unavailable',
+        'The requested model is currently unavailable.',
+        selection,
+        correlationId,
+        true,
+      );
+    }
+  }
+}

apps/gateway/src/harness/harness.controller.spec.ts

@@ -0,0 +1,138 @@
+import 'reflect-metadata';
+import {
+  type CanActivate,
+  type ExecutionContext,
+  type INestApplication,
+  ValidationPipe,
+} from '@nestjs/common';
+import { FastifyAdapter, type NestFastifyApplication } from '@nestjs/platform-fastify';
+import { Test } from '@nestjs/testing';
+import request from 'supertest';
+import { afterAll, beforeAll, describe, expect, it } from 'vitest';
+import { AuthGuard } from '../auth/auth.guard.js';
+import { HarnessRegistry } from './harness.registry.js';
+import { HARNESS_REGISTRY } from './harness.tokens.js';
+import { FakeHarnessAdapter } from './testing/fake-harness.adapter.js';
+// The real module under test — importing it (not a hand-listed controllers/mocks
+// list) is what makes an unresolved provider fail loudly at app.init() (#1145 guard).
+import { HarnessModule } from './harness.module.js';
+
+// Fields that must NEVER surface on a browser-facing catalog/list response.
+const FORBIDDEN_KEYS = [
+  'executable',
+  'executablePath',
+  'home',
+  'homeDir',
+  'cwd',
+  'workingDir',
+  'workingDirectory',
+  'nativeSessionPath',
+  'sessionPath',
+  'env',
+  'secret',
+  'secrets',
+  'token',
+  'apiKey',
+];
+
+function assertNoForbiddenLeak(payload: unknown): void {
+  const serialized = JSON.stringify(payload).toLowerCase();
+  for (const key of FORBIDDEN_KEYS) {
+    expect(serialized).not.toContain(key.toLowerCase());
+  }
+}
+
+const authGuard: CanActivate = {
+  canActivate(context: ExecutionContext): boolean {
+    const requestContext = context.switchToHttp().getRequest<{ user?: { id: string } }>();
+    requestContext.user = { id: 'user-1' };
+    return true;
+  },
+};
+
+function registryWithFake(): HarnessRegistry {
+  const registry = new HarnessRegistry();
+  registry.register(new FakeHarnessAdapter({ id: 'fake' }));
+  return registry;
+}
+
+describe('Harness catalog HTTP surface', () => {
+  let app: INestApplication;
+
+  beforeAll(async () => {
+    const moduleRef = await Test.createTestingModule({
+      imports: [HarnessModule],
+    })
+      .overrideGuard(AuthGuard)
+      .useValue(authGuard)
+      .overrideProvider(HARNESS_REGISTRY)
+      .useValue(registryWithFake())
+      .compile();
+
+    app = moduleRef.createNestApplication<NestFastifyApplication>(new FastifyAdapter());
+    app.useGlobalPipes(
+      new ValidationPipe({ whitelist: true, forbidNonWhitelisted: true, transform: true }),
+    );
+    await app.init();
+    await app.getHttpAdapter().getInstance().ready();
+  });
+
+  afterAll(async () => {
+    await app.close();
+  });
+
+  it('boots the real HarnessModule so all providers resolve at app.init()', () => {
+    // If HarnessModule failed to resolve a provider, beforeAll's app.init() would
+    // have thrown and this suite would never reach here.
+    expect(app).toBeDefined();
+  });
+
+  it('GET /api/harnesses returns 200 with safe fields only', async () => {
+    const response = await request(app.getHttpServer()).get('/api/harnesses');
+
+    expect(response.status).toBe(200);
+    expect(Array.isArray(response.body)).toBe(true);
+    expect(response.body.length).toBeGreaterThan(0);
+    const summary = response.body[0];
+    expect(Object.keys(summary).sort()).toEqual(['capabilities', 'displayName', 'id']);
+    expect(summary.id).toBe('fake');
+    expect(typeof summary.displayName).toBe('string');
+    expect(Array.isArray(summary.capabilities)).toBe(true);
+    assertNoForbiddenLeak(response.body);
+  });
+
+  it('GET /api/harnesses/:harnessId/catalog returns 200 with safe catalog fields only', async () => {
+    const response = await request(app.getHttpServer()).get('/api/harnesses/fake/catalog');
+
+    expect(response.status).toBe(200);
+    expect(response.body.harnessId).toBe('fake');
+    expect(typeof response.body.version).toBe('string');
+    expect(typeof response.body.fingerprint).toBe('string');
+    expect(Array.isArray(response.body.models)).toBe(true);
+    expect(response.body.models.length).toBeGreaterThan(0);
+    const entry = response.body.models[0];
+    // Whitelisted catalog-entry fields only (no executables/paths/secrets).
+    expect(Object.keys(entry).sort()).toEqual(
+      [
+        'authState',
+        'availability',
+        'displayName',
+        'harnessId',
+        'inputTypes',
+        'modelId',
+        'providerId',
+        'reasoningCapability',
+      ].sort(),
+    );
+    assertNoForbiddenLeak(response.body);
+  });
+
+  it('GET catalog for an unknown harnessId returns a typed adapter_unavailable error, never a fallback catalog', async () => {
+    const response = await request(app.getHttpServer()).get('/api/harnesses/ghost-harness/catalog');
+
+    expect(response.status).toBe(404);
+    expect(response.body.code).toBe('adapter_unavailable');
+    // A fallback catalog would carry a models array; a typed error must not.
+    expect(response.body.models).toBeUndefined();
+  });
+});

apps/gateway/src/harness/harness.controller.ts

@@ -0,0 +1,65 @@
+import {
+  Controller,
+  Get,
+  HttpException,
+  HttpStatus,
+  Inject,
+  Param,
+  UseGuards,
+} from '@nestjs/common';
+import { AuthGuard } from '../auth/auth.guard.js';
+import { CurrentUser } from '../auth/current-user.decorator.js';
+import { scopeFromUser, type AuthenticatedUserLike } from '../auth/session-scope.js';
+import { HarnessAdapterUnavailableError, HarnessRegistry } from './harness.registry.js';
+import { HARNESS_REGISTRY } from './harness.tokens.js';
+import {
+  readContextFromScope,
+  toHarnessSummary,
+  toSafeCatalog,
+  type HarnessCatalogDto,
+  type HarnessSummaryDto,
+} from './harness.dto.js';
+
+/**
+ * Generic harness catalog surface. It exposes only harness-neutral, browser-safe
+ * fields (identity, capabilities, provider/model catalog) — never executables,
+ * native paths, home/cwd, env, or secrets. There is NO provider-probe route here;
+ * `/api/providers` and `POST /api/providers/test` are intentionally out of scope.
+ */
+@Controller('api/harnesses')
+@UseGuards(AuthGuard)
+export class HarnessController {
+  constructor(@Inject(HARNESS_REGISTRY) private readonly registry: HarnessRegistry) {}
+
+  @Get()
+  async list(@CurrentUser() user: AuthenticatedUserLike): Promise<HarnessSummaryDto[]> {
+    const context = readContextFromScope(scopeFromUser(user));
+    const summaries: HarnessSummaryDto[] = [];
+    for (const adapter of this.registry.list()) {
+      summaries.push(toHarnessSummary(await adapter.describe(context)));
+    }
+    return summaries;
+  }
+
+  @Get(':harnessId/catalog')
+  async catalog(
+    @CurrentUser() user: AuthenticatedUserLike,
+    @Param('harnessId') harnessId: string,
+  ): Promise<HarnessCatalogDto> {
+    const context = readContextFromScope(scopeFromUser(user));
+    let adapter;
+    try {
+      adapter = this.registry.get(harnessId);
+    } catch (error) {
+      if (error instanceof HarnessAdapterUnavailableError) {
+        // Typed failure — NEVER a fallback catalog for an unknown harness id.
+        throw new HttpException(
+          { code: error.code, message: error.message, harnessId },
+          HttpStatus.NOT_FOUND,
+        );
+      }
+      throw error;
+    }
+    return toSafeCatalog(await adapter.catalog(context));
+  }
+}

apps/gateway/src/harness/harness.dto.ts

@@ -0,0 +1,116 @@
+import { randomUUID } from 'node:crypto';
+import { IsNotEmpty, IsString } from 'class-validator';
+import type {
+  HarnessActorContext,
+  HarnessAuthState,
+  HarnessCapability,
+  HarnessCatalog,
+  HarnessCatalogEntry,
+  HarnessDescriptor,
+  HarnessInputType,
+  HarnessModelAvailability,
+  HarnessSelection,
+} from '@mosaicstack/types';
+import type { ActorTenantScope } from '../auth/session-scope.js';
+
+/**
+ * Structured selection tuple accepted on `PUT /api/chat/preferences/selection`.
+ *
+ * The body is a STRUCTURED tuple (harness + provider + model), never a free-text
+ * model string. With `ValidationPipe({ whitelist: true, forbidNonWhitelisted: true })`
+ * any extra property — including smuggled server-authority fields such as
+ * `seatId`, `tenantId`, `userId`, `nativeSessionPath`, `executable`, `home`, `cwd` —
+ * is rejected with 400. There is deliberately no field through which a caller can
+ * name a scope; scope is derived on the server from the authenticated session.
+ */
+export class HarnessSelectionInputDto {
+  @IsString()
+  @IsNotEmpty()
+  harnessId!: string;
+
+  @IsString()
+  @IsNotEmpty()
+  providerId!: string;
+
+  @IsString()
+  @IsNotEmpty()
+  modelId!: string;
+}
+
+/** Browser-safe harness summary — identity and capabilities only. */
+export interface HarnessSummaryDto {
+  readonly id: string;
+  readonly displayName: string;
+  readonly capabilities: readonly HarnessCapability[];
+}
+
+/** Browser-safe catalog entry — no executables, paths, secrets, or env. */
+export interface HarnessCatalogEntryDto {
+  readonly harnessId: string;
+  readonly providerId: string;
+  readonly modelId: string;
+  readonly displayName: string;
+  readonly reasoningCapability: boolean;
+  readonly inputTypes: readonly HarnessInputType[];
+  readonly authState: HarnessAuthState;
+  readonly availability: HarnessModelAvailability;
+}
+
+/** Browser-safe catalog envelope. */
+export interface HarnessCatalogDto {
+  readonly harnessId: string;
+  readonly version: string;
+  readonly fingerprint: string;
+  readonly models: readonly HarnessCatalogEntryDto[];
+}
+
+/** Response envelope for the caller's current selection (null when unset). */
+export interface SelectionResponseDto {
+  readonly selection: HarnessSelection | null;
+}
+
+/**
+ * Derive a server-trusted {@link HarnessActorContext} for read operations from the
+ * session-derived {@link ActorTenantScope}. All authority originates on the server;
+ * nothing here is caller-supplied. A fresh correlation id is minted per call.
+ */
+export function readContextFromScope(scope: ActorTenantScope): HarnessActorContext {
+  return {
+    actorId: scope.userId,
+    tenantId: scope.tenantId,
+    seatId: scope.userId,
+    correlationId: randomUUID(),
+  };
+}
+
+/** Project a descriptor onto the browser-safe summary shape (whitelist by construction). */
+export function toHarnessSummary(descriptor: HarnessDescriptor): HarnessSummaryDto {
+  return {
+    id: descriptor.id,
+    displayName: descriptor.displayName,
+    capabilities: [...descriptor.capabilities],
+  };
+}
+
+/** Project a catalog onto the browser-safe shape (whitelist by construction). */
+export function toSafeCatalog(catalog: HarnessCatalog): HarnessCatalogDto {
+  return {
+    harnessId: catalog.harnessId,
+    version: catalog.version,
+    fingerprint: catalog.fingerprint,
+    models: catalog.models.map(toSafeCatalogEntry),
+  };
+}
+
+function toSafeCatalogEntry(entry: HarnessCatalogEntry): HarnessCatalogEntryDto {
+  return {
+    harnessId: entry.harnessId,
+    providerId: entry.providerId,
+    modelId: entry.modelId,
+    displayName: entry.displayName,
+    reasoningCapability: entry.reasoningCapability,
+    inputTypes: [...entry.inputTypes],
+    authState: entry.authState,
+    availability: entry.availability,
+  };
+}

apps/gateway/src/harness/harness.module.ts

@@ -0,0 +1,28 @@
+import { Module } from '@nestjs/common';
+import { HarnessRegistry } from './harness.registry.js';
+import { HarnessService } from './harness.service.js';
+import { HARNESS_REGISTRY, HARNESS_SERVICE } from './harness.tokens.js';
+import { HarnessController } from './harness.controller.js';
+import { HarnessSelectionController } from './harness-selection.controller.js';
+import { HarnessSelectionService } from './harness-selection.service.js';
+import { HarnessSelectionRepository } from './harness-selection.repository.js';
+
+/**
+ * Wires the harness-neutral registry/service (Task Two) together with the
+ * Slice-Zero catalog and selection HTTP surfaces (Task Three).
+ *
+ * The registry is provided empty here; real harness adapters are registered in a
+ * later task. Because the controllers/services resolve their collaborators through
+ * this real module graph, an unresolved provider fails loudly at `app.init()`.
+ */
+@Module({
+  controllers: [HarnessController, HarnessSelectionController],
+  providers: [
+    { provide: HARNESS_REGISTRY, useFactory: () => new HarnessRegistry() },
+    { provide: HARNESS_SERVICE, useClass: HarnessService },
+    HarnessSelectionRepository,
+    HarnessSelectionService,
+  ],
+  exports: [HARNESS_REGISTRY, HARNESS_SERVICE],
+})
+export class HarnessModule {}

apps/gateway/src/harness/harness.registry.spec.ts

@@ -0,0 +1,69 @@
+import { describe, expect, it } from 'vitest';
+import {
+  HarnessAdapterUnavailableError,
+  HarnessRegistrationError,
+  HarnessRegistry,
+} from './harness.registry.js';
+import { FakeHarnessAdapter } from './testing/fake-harness.adapter.js';
+
+describe('HarnessRegistry', () => {
+  it('registers and looks up an adapter by harness id', () => {
+    const registry = new HarnessRegistry();
+    const adapter = new FakeHarnessAdapter({ id: 'fake' });
+
+    registry.register(adapter);
+
+    expect(registry.get('fake')).toBe(adapter);
+    expect(registry.has('fake')).toBe(true);
+    expect(registry.list().map((entry) => entry.id)).toEqual(['fake']);
+  });
+
+  it('rejects a blank adapter id', () => {
+    const registry = new HarnessRegistry();
+
+    let error: unknown;
+    try {
+      registry.register(new FakeHarnessAdapter({ id: '   ' }));
+    } catch (caught) {
+      error = caught;
+    }
+
+    expect(error).toBeInstanceOf(HarnessRegistrationError);
+    expect((error as HarnessRegistrationError).reason).toBe('blank_id');
+    expect(registry.list()).toEqual([]);
+  });
+
+  it('rejects a duplicate adapter id', () => {
+    const registry = new HarnessRegistry();
+    registry.register(new FakeHarnessAdapter({ id: 'fake' }));
+
+    let error: unknown;
+    try {
+      registry.register(new FakeHarnessAdapter({ id: 'fake' }));
+    } catch (caught) {
+      error = caught;
+    }
+
+    expect(error).toBeInstanceOf(HarnessRegistrationError);
+    expect((error as HarnessRegistrationError).reason).toBe('duplicate_id');
+    expect((error as HarnessRegistrationError).harnessId).toBe('fake');
+    // The original registration is untouched.
+    expect(registry.list()).toHaveLength(1);
+  });
+
+  it('returns adapter_unavailable for an unknown harness id', () => {
+    const registry = new HarnessRegistry();
+
+    let error: unknown;
+    try {
+      registry.get('missing');
+    } catch (caught) {
+      error = caught;
+    }
+
+    expect(error).toBeInstanceOf(HarnessAdapterUnavailableError);
+    expect((error as HarnessAdapterUnavailableError).code).toBe('adapter_unavailable');
+    expect((error as HarnessAdapterUnavailableError).harnessId).toBe('missing');
+    expect(registry.has('missing')).toBe(false);
+  });
+});

apps/gateway/src/harness/harness.registry.ts

@@ -0,0 +1,100 @@
+import { Injectable } from '@nestjs/common';
+import type {
+  HarnessAdapter,
+  HarnessErrorCode,
+  HarnessErrorDto,
+  HarnessSelection,
+} from '@mosaicstack/types';
+
+/**
+ * A typed harness operation failure that carries a fully-formed, browser-safe
+ * {@link HarnessErrorDto}. The DTO's `selection` is always the exact requested
+ * tuple — there is no field through which a substituted "effective" selection
+ * could ever be reported.
+ */
+export class HarnessOperationError extends Error {
+  readonly code: HarnessErrorCode;
+  readonly dto: HarnessErrorDto;
+
+  constructor(dto: HarnessErrorDto) {
+    super(dto.message);
+    this.name = 'HarnessOperationError';
+    this.code = dto.code;
+    this.dto = dto;
+  }
+}
+
+/** Build a {@link HarnessOperationError} that echoes the requested selection unchanged. */
+export function operationError(
+  code: HarnessErrorCode,
+  message: string,
+  selection: HarnessSelection,
+  correlationId: string,
+  retryable = false,
+): HarnessOperationError {
+  return new HarnessOperationError({ code, message, retryable, correlationId, selection });
+}
+
+/** Raised when an unknown harness id is looked up. Discriminated by `code`. */
+export class HarnessAdapterUnavailableError extends Error {
+  readonly code = 'adapter_unavailable' as const satisfies HarnessErrorCode;
+
+  constructor(readonly harnessId: string) {
+    super(`No harness adapter is registered for id "${harnessId}".`);
+    this.name = 'HarnessAdapterUnavailableError';
+  }
+}
+
+export type HarnessRegistrationFailure = 'blank_id' | 'duplicate_id';
+
+/** Raised when an adapter cannot be registered (blank or duplicate id). */
+export class HarnessRegistrationError extends Error {
+  constructor(
+    readonly reason: HarnessRegistrationFailure,
+    readonly harnessId: string,
+  ) {
+    super(
+      reason === 'blank_id'
+        ? 'A harness adapter id must be a non-empty string.'
+        : `A harness adapter is already registered for id "${harnessId}".`,
+    );
+    this.name = 'HarnessRegistrationError';
+  }
+}
+
+/**
+ * Harness-neutral adapter registry. Adapters are keyed by their harness id.
+ * Registration rejects blank and duplicate ids; lookup of an unknown id fails
+ * with {@link HarnessAdapterUnavailableError} (`adapter_unavailable`).
+ */
+@Injectable()
+export class HarnessRegistry {
+  private readonly adapters = new Map<string, HarnessAdapter>();
+
+  register(adapter: HarnessAdapter): void {
+    const id = adapter.id;
+    if (typeof id !== 'string' || id.trim().length === 0) {
+      throw new HarnessRegistrationError('blank_id', id ?? '');
+    }
+    if (this.adapters.has(id)) {
+      throw new HarnessRegistrationError('duplicate_id', id);
+    }
+    this.adapters.set(id, adapter);
+  }
+
+  get(harnessId: string): HarnessAdapter {
+    const adapter = this.adapters.get(harnessId);
+    if (!adapter) {
+      throw new HarnessAdapterUnavailableError(harnessId);
+    }
+    return adapter;
+  }
+
+  has(harnessId: string): boolean {
+    return this.adapters.has(harnessId);
+  }
+
+  list(): readonly HarnessAdapter[] {
+    return [...this.adapters.values()];
+  }
+}

apps/gateway/src/harness/harness.service.spec.ts

@@ -0,0 +1,227 @@
+import { describe, expect, it } from 'vitest';
+import type { HarnessActorContext, HarnessCapability, HarnessSelection } from '@mosaicstack/types';
+import { HARNESS_CAPABILITIES } from '@mosaicstack/types';
+import { HarnessOperationError, HarnessRegistry } from './harness.registry.js';
+import {
+  HarnessScopeViolationError,
+  HarnessService,
+  type TrustedGatewayScope,
+} from './harness.service.js';
+import { FakeHarnessAdapter } from './testing/fake-harness.adapter.js';
+
+const SCOPE: TrustedGatewayScope = {
+  actorId: 'actor-trusted',
+  tenantId: 'tenant-trusted',
+  seatId: 'seat-trusted',
+  correlationId: 'correlation-trusted',
+};
+
+const READ_CONTEXT: HarnessActorContext = {
+  actorId: SCOPE.actorId,
+  tenantId: SCOPE.tenantId,
+  seatId: SCOPE.seatId,
+  correlationId: SCOPE.correlationId,
+};
+
+function setup(capabilities?: readonly HarnessCapability[]) {
+  const registry = new HarnessRegistry();
+  const adapter = new FakeHarnessAdapter({ id: 'fake', capabilities });
+  registry.register(adapter);
+  const service = new HarnessService(registry);
+  return { registry, adapter, service };
+}
+
+async function availableSelection(adapter: FakeHarnessAdapter): Promise<HarnessSelection> {
+  const catalog = await adapter.catalog(READ_CONTEXT);
+  const entry = catalog.models.find((model) => model.availability === 'available');
+  if (!entry) {
+    throw new Error('fixture requires an available model');
+  }
+  return { harnessId: entry.harnessId, providerId: entry.providerId, modelId: entry.modelId };
+}
+
+describe('HarnessService', () => {
+  it('derives the actor context from trusted scope on create', async () => {
+    const { service, adapter } = setup();
+    const selection = await availableSelection(adapter);
+
+    const snapshot = await service.createSession(SCOPE, {
+      conversationId: 'conversation-1',
+      selection,
+    });
+
+    expect(snapshot.seatId).toBe(SCOPE.seatId);
+    expect(snapshot.state).toBe('idle');
+    expect(snapshot.selection).toEqual(selection);
+    expect(snapshot.nativeSessionId).toBeTruthy();
+  });
+
+  it('rejects server-authority fields supplied by an external caller', async () => {
+    const { service, adapter } = setup();
+    const selection = await availableSelection(adapter);
+
+    const hostile = {
+      conversationId: 'conversation-1',
+      selection,
+      seatId: 'attacker-seat',
+      executablePath: '/usr/bin/evil',
+      home: '/home/attacker',
+      cwd: '/tmp/attacker',
+      nativeSessionPath: '/var/native/attacker.jsonl',
+    } as unknown as Parameters<HarnessService['createSession']>[1];
+
+    let error: unknown;
+    try {
+      await service.createSession(SCOPE, hostile);
+    } catch (caught) {
+      error = caught;
+    }
+
+    expect(error).toBeInstanceOf(HarnessScopeViolationError);
+    expect((error as HarnessScopeViolationError).field).toBe('seatId');
+  });
+
+  it('returns adapter_unavailable for an unknown harness id, echoing the requested tuple', async () => {
+    const { service } = setup();
+    const selection: HarnessSelection = {
+      harnessId: 'ghost-harness',
+      providerId: 'p',
+      modelId: 'm',
+    };
+
+    let error: unknown;
+    try {
+      await service.createSession(SCOPE, { conversationId: 'conversation-1', selection });
+    } catch (caught) {
+      error = caught;
+    }
+
+    expect(error).toBeInstanceOf(HarnessOperationError);
+    const dto = (error as HarnessOperationError).dto;
+    expect(dto.code).toBe('adapter_unavailable');
+    expect(dto.selection).toEqual(selection);
+    expect(dto.correlationId).toBe(SCOPE.correlationId);
+  });
+
+  it('returns selection_invalid for an unknown provider/model tuple, unchanged', async () => {
+    const { service } = setup();
+    const selection: HarnessSelection = {
+      harnessId: 'fake',
+      providerId: 'ghost-provider',
+      modelId: 'ghost-model',
+    };
+
+    let error: unknown;
+    try {
+      await service.createSession(SCOPE, { conversationId: 'conversation-1', selection });
+    } catch (caught) {
+      error = caught;
+    }
+
+    expect(error).toBeInstanceOf(HarnessOperationError);
+    const dto = (error as HarnessOperationError).dto;
+    expect(dto.code).toBe('selection_invalid');
+    expect(dto.selection).toEqual(selection);
+  });
+
+  it('returns model_unavailable without falling back for a known unavailable model', async () => {
+    const { service, adapter } = setup();
+    const catalog = await adapter.catalog(READ_CONTEXT);
+    const unavailable = catalog.models.find((entry) => entry.availability === 'unavailable');
+    expect(unavailable).toBeDefined();
+    const selection: HarnessSelection = {
+      harnessId: unavailable!.harnessId,
+      providerId: unavailable!.providerId,
+      modelId: unavailable!.modelId,
+    };
+
+    let error: unknown;
+    try {
+      await service.createSession(SCOPE, { conversationId: 'conversation-1', selection });
+    } catch (caught) {
+      error = caught;
+    }
+
+    expect(error).toBeInstanceOf(HarnessOperationError);
+    const dto = (error as HarnessOperationError).dto;
+    expect(dto.code).toBe('model_unavailable');
+    // No substitution: the DTO tuple is exactly what was requested.
+    expect(dto.selection).toEqual(selection);
+  });
+
+  it('gives create, resume, detach, evict, and end distinct observable effects', async () => {
+    const { service, adapter } = setup();
+    const selection = await availableSelection(adapter);
+
+    const created = await service.createSession(SCOPE, {
+      conversationId: 'conversation-create',
+      selection,
+    });
+    expect(created.state).toBe('idle');
+    expect(created.processId).toBeTruthy();
+    expect(created.attachedClientIds).toEqual([]);
+
+    const resumed = await service.resumeSession(SCOPE, {
+      conversationId: 'conversation-resume',
+      nativeSessionId: 'native-preexisting-123',
+      selection,
+    });
+    // Resume binds the supplied native session; create mints a fresh one.
+    expect(resumed.nativeSessionId).toBe('native-preexisting-123');
+    expect(resumed.nativeSessionId).not.toBe(created.nativeSessionId);
+
+    await service.attach(SCOPE, {
+      conversationId: 'conversation-create',
+      clientId: 'browser-1',
+    });
+    const afterAttach = await service.snapshot(SCOPE, 'conversation-create');
+    expect(afterAttach.attachedClientIds).toEqual(['browser-1']);
+
+    const afterDetach = await service.detach(SCOPE, {
+      conversationId: 'conversation-create',
+      clientId: 'browser-1',
+    });
+    // Detach removes the browser attachment only; the process stays alive.
+    expect(afterDetach.attachedClientIds).toEqual([]);
+    expect(afterDetach.state).toBe('idle');
+    expect(afterDetach.processId).toBeTruthy();
+
+    const afterEvict = await service.evict(SCOPE, {
+      conversationId: 'conversation-create',
+      reason: 'idle_timeout',
+    });
+    // Evict stops the process but retains the resumable native session.
+    expect(afterEvict.state).toBe('evicted');
+    expect(afterEvict.processId).toBeUndefined();
+    expect(afterEvict.nativeSessionId).toBe(created.nativeSessionId);
+
+    const afterEnd = await service.end(SCOPE, {
+      conversationId: 'conversation-create',
+      reason: 'session_ended',
+    });
+    // End destructively terminates the native session.
+    expect(afterEnd.state).toBe('ended');
+  });
+
+  it('fails typed when an unsupported capability is exercised', async () => {
+    const withoutExtensionUi = HARNESS_CAPABILITIES.filter(
+      (capability) => capability !== 'extensionUi',
+    );
+    const { service, adapter } = setup(withoutExtensionUi);
+    const selection = await availableSelection(adapter);
+    await service.createSession(SCOPE, { conversationId: 'conversation-1', selection });
+
+    let error: unknown;
+    try {
+      await service.respondInteraction(SCOPE, {
+        conversationId: 'conversation-1',
+        response: { requestId: 'interaction-1', type: 'confirm', accepted: true },
+      });
+    } catch (caught) {
+      error = caught;
+    }
+
+    expect(error).toBeInstanceOf(HarnessOperationError);
+    expect((error as HarnessOperationError).dto.code).toBe('interaction_unsupported');
+  });
+});

apps/gateway/src/harness/harness.service.ts

@@ -0,0 +1,285 @@
+import { Inject, Injectable } from '@nestjs/common';
+import type {
+  HarnessActorContext,
+  HarnessAdapter,
+  HarnessCatalog,
+  HarnessCloseReason,
+  HarnessInteractionResponse,
+  HarnessSelection,
+  HarnessSessionHandle,
+  HarnessSessionSnapshot,
+} from '@mosaicstack/types';
+import {
+  HarnessAdapterUnavailableError,
+  HarnessRegistry,
+  operationError,
+} from './harness.registry.js';
+import { HARNESS_REGISTRY } from './harness.tokens.js';
+
+/**
+ * Trusted, server-derived authority. In production this is produced by the
+ * Gateway from the authenticated session — never from a browser/caller DTO.
+ */
+export interface TrustedGatewayScope {
+  readonly actorId: string;
+  readonly tenantId: string;
+  readonly seatId: string;
+  readonly correlationId: string;
+}
+
+/** Server-authority fields that must never arrive from an external request DTO. */
+const FORBIDDEN_REQUEST_FIELDS = [
+  'actorId',
+  'tenantId',
+  'correlationId',
+  'seatId',
+  'seat',
+  'executable',
+  'executablePath',
+  'home',
+  'homeDir',
+  'cwd',
+  'workingDir',
+  'workingDirectory',
+  'nativeSessionPath',
+  'sessionPath',
+] as const;
+
+/** Raised when an external request DTO smuggles a server-authority field. */
+export class HarnessScopeViolationError extends Error {
+  constructor(readonly field: string) {
+    super(`External request supplied server-authority field "${field}".`);
+    this.name = 'HarnessScopeViolationError';
+  }
+}
+
+export interface CreateHarnessSessionRequest {
+  readonly conversationId: string;
+  readonly selection: HarnessSelection;
+}
+
+export interface ResumeHarnessSessionRequest {
+  readonly conversationId: string;
+  readonly nativeSessionId: string;
+  readonly selection: HarnessSelection;
+}
+
+export interface AttachClientRequest {
+  readonly conversationId: string;
+  readonly clientId: string;
+}
+
+export interface DetachClientRequest {
+  readonly conversationId: string;
+  readonly clientId: string;
+}
+
+export interface EvictSessionRequest {
+  readonly conversationId: string;
+  readonly reason: HarnessCloseReason;
+}
+
+export interface EndSessionRequest {
+  readonly conversationId: string;
+  readonly reason: HarnessCloseReason;
+}
+
+export interface RespondInteractionRequest {
+  readonly conversationId: string;
+  readonly response: HarnessInteractionResponse;
+}
+
+interface ActiveSession {
+  readonly harnessId: string;
+  readonly handle: HarnessSessionHandle;
+  readonly correlationId: string;
+}
+
+/**
+ * Harness-neutral service. It derives the {@link HarnessActorContext} strictly
+ * from trusted Gateway scope, validates the selected provider/model tuple with
+ * NO fallback substitution, and exposes distinct create/resume/detach/evict/end
+ * lifecycle operations.
+ */
+@Injectable()
+export class HarnessService {
+  private readonly sessions = new Map<string, ActiveSession>();
+
+  constructor(@Inject(HARNESS_REGISTRY) private readonly registry: HarnessRegistry) {}
+
+  async createSession(
+    scope: TrustedGatewayScope,
+    request: CreateHarnessSessionRequest,
+  ): Promise<HarnessSessionSnapshot> {
+    assertTrustedRequest(request);
+    const { conversationId, selection } = request;
+    const adapter = this.resolveAdapter(scope, selection);
+    const context = deriveActorContext(scope);
+    await this.assertSelectionAvailable(scope, adapter.catalog(context), selection);
+
+    const handle = await adapter.create({ context, conversationId, selection });
+    this.sessions.set(conversationId, {
+      harnessId: selection.harnessId,
+      handle,
+      correlationId: scope.correlationId,
+    });
+    return handle.snapshot();
+  }
+
+  async resumeSession(
+    scope: TrustedGatewayScope,
+    request: ResumeHarnessSessionRequest,
+  ): Promise<HarnessSessionSnapshot> {
+    assertTrustedRequest(request);
+    const { conversationId, nativeSessionId, selection } = request;
+    const adapter = this.resolveAdapter(scope, selection);
+    const context = deriveActorContext(scope);
+    await this.assertSelectionAvailable(scope, adapter.catalog(context), selection);
+
+    const handle = await adapter.resume({ context, conversationId, nativeSessionId, selection });
+    this.sessions.set(conversationId, {
+      harnessId: selection.harnessId,
+      handle,
+      correlationId: scope.correlationId,
+    });
+    return handle.snapshot();
+  }
+
+  async attach(
+    scope: TrustedGatewayScope,
+    request: AttachClientRequest,
+  ): Promise<HarnessSessionSnapshot> {
+    assertTrustedRequest(request);
+    const handle = this.requireHandle(scope, request.conversationId);
+    await handle.attach({ clientId: request.clientId });
+    return handle.snapshot();
+  }
+
+  async detach(
+    scope: TrustedGatewayScope,
+    request: DetachClientRequest,
+  ): Promise<HarnessSessionSnapshot> {
+    assertTrustedRequest(request);
+    const handle = this.requireHandle(scope, request.conversationId);
+    await handle.detach(request.clientId);
+    return handle.snapshot();
+  }
+
+  async evict(
+    scope: TrustedGatewayScope,
+    request: EvictSessionRequest,
+  ): Promise<HarnessSessionSnapshot> {
+    assertTrustedRequest(request);
+    const handle = this.requireHandle(scope, request.conversationId);
+    await handle.evictProcess(request.reason);
+    return handle.snapshot();
+  }
+
+  async end(
+    scope: TrustedGatewayScope,
+    request: EndSessionRequest,
+  ): Promise<HarnessSessionSnapshot> {
+    assertTrustedRequest(request);
+    const handle = this.requireHandle(scope, request.conversationId);
+    await handle.endSession(request.reason);
+    const snapshot = await handle.snapshot();
+    this.sessions.delete(request.conversationId);
+    return snapshot;
+  }
+
+  async respondInteraction(
+    scope: TrustedGatewayScope,
+    request: RespondInteractionRequest,
+  ): Promise<void> {
+    assertTrustedRequest(request);
+    const handle = this.requireHandle(scope, request.conversationId);
+    await handle.respondInteraction(request.response);
+  }
+
+  async snapshot(
+    scope: TrustedGatewayScope,
+    conversationId: string,
+  ): Promise<HarnessSessionSnapshot> {
+    const handle = this.requireHandle(scope, conversationId);
+    return handle.snapshot();
+  }
+
+  private resolveAdapter(scope: TrustedGatewayScope, selection: HarnessSelection): HarnessAdapter {
+    try {
+      return this.registry.get(selection.harnessId);
+    } catch (error) {
+      if (error instanceof HarnessAdapterUnavailableError) {
+        throw operationError('adapter_unavailable', error.message, selection, scope.correlationId);
+      }
+      throw error;
+    }
+  }
+
+  private async assertSelectionAvailable(
+    scope: TrustedGatewayScope,
+    catalogPromise: Promise<HarnessCatalog>,
+    selection: HarnessSelection,
+  ): Promise<void> {
+    const catalog = await catalogPromise;
+    const entry = catalog.models.find(
+      (candidate) =>
+        candidate.harnessId === selection.harnessId &&
+        candidate.providerId === selection.providerId &&
+        candidate.modelId === selection.modelId,
+    );
+    if (!entry) {
+      // No first-row fallback: reject the requested tuple unchanged.
+      throw operationError(
+        'selection_invalid',
+        'The requested harness/provider/model tuple is not in the catalog.',
+        selection,
+        scope.correlationId,
+      );
+    }
+    if (entry.availability === 'unavailable') {
+      throw operationError(
+        'model_unavailable',
+        'The requested model is currently unavailable.',
+        selection,
+        scope.correlationId,
+        true,
+      );
+    }
+  }
+
+  private requireHandle(scope: TrustedGatewayScope, conversationId: string): HarnessSessionHandle {
+    const active = this.sessions.get(conversationId);
+    if (!active) {
+      throw operationError(
+        'session_not_found',
+        `No active harness session for conversation "${conversationId}".`,
+        { harnessId: '', providerId: '', modelId: '' },
+        scope.correlationId,
+      );
+    }
+    return active.handle;
+  }
+}
+
+/** Build the actor context strictly from trusted scope. No caller data leaks in. */
+export function deriveActorContext(scope: TrustedGatewayScope): HarnessActorContext {
+  return {
+    actorId: scope.actorId,
+    tenantId: scope.tenantId,
+    seatId: scope.seatId,
+    correlationId: scope.correlationId,
+  };
+}
+
+/** Reject any request object that carries a server-authority field. */
+function assertTrustedRequest(request: object): void {
+  for (const field of FORBIDDEN_REQUEST_FIELDS) {
+    if (Object.prototype.hasOwnProperty.call(request, field)) {
+      throw new HarnessScopeViolationError(field);
+    }
+  }
+}
+
+// Re-export the typed operation error so callers importing from the service
+// have the discriminated failure type without reaching into the registry.
+export { HarnessOperationError } from './harness.registry.js';

apps/gateway/src/harness/harness.tokens.ts

@@ -0,0 +1,11 @@
+/**
+ * Nest dependency-injection tokens for the harness-neutral registry and service.
+ *
+ * String tokens follow the existing Gateway convention (see `memory/memory.tokens.ts`)
+ * and remain valid Nest `InjectionToken`s for `@Inject(...)`.
+ */
+export const HARNESS_REGISTRY = 'HARNESS_REGISTRY' as const;
+export const HARNESS_SERVICE = 'HARNESS_SERVICE' as const;
+
+export type HarnessRegistryToken = typeof HARNESS_REGISTRY;
+export type HarnessServiceToken = typeof HARNESS_SERVICE;

apps/gateway/src/harness/testing/fake-harness.adapter.spec.ts

@@ -0,0 +1,107 @@
+import { describe, expect, it } from 'vitest';
+import type { HarnessActorContext, HarnessSelection } from '@mosaicstack/types';
+import { HarnessOperationError } from '../harness.registry.js';
+import { FakeHarnessAdapter } from './fake-harness.adapter.js';
+import { runHarnessAdapterContract } from './harness-adapter.contract.js';
+
+const CONTEXT: HarnessActorContext = {
+  actorId: 'actor-1',
+  tenantId: 'tenant-1',
+  seatId: 'seat-1',
+  correlationId: 'correlation-1',
+};
+
+// The reusable conformance suite. Task 13 re-runs it against the native Pi adapter.
+runHarnessAdapterContract('FakeHarnessAdapter', () => new FakeHarnessAdapter({ id: 'fake' }));
+
+describe('FakeHarnessAdapter no-substitution', () => {
+  it('never substitutes the first catalog row when a bogus selection is requested', async () => {
+    const adapter = new FakeHarnessAdapter({ id: 'fake' });
+    const catalog = await adapter.catalog(CONTEXT);
+    const firstRow = catalog.models[0];
+    if (!firstRow) {
+      throw new Error('fixture requires a catalog model');
+    }
+    const available = catalog.models.find(
+      (entry) => entry.availability === 'available' && entry.modelId !== firstRow.modelId,
+    );
+    expect(available).toBeDefined();
+    const selected: HarnessSelection = {
+      harnessId: available!.harnessId,
+      providerId: available!.providerId,
+      modelId: available!.modelId,
+    };
+
+    const handle = await adapter.create({
+      context: CONTEXT,
+      conversationId: 'conversation-1',
+      selection: selected,
+    });
+
+    const bogus: HarnessSelection = {
+      harnessId: 'fake',
+      providerId: 'ghost-provider',
+      modelId: 'ghost-model',
+    };
+
+    let error: unknown;
+    try {
+      await handle.setModel(bogus);
+    } catch (caught) {
+      error = caught;
+    }
+
+    expect(error).toBeInstanceOf(HarnessOperationError);
+    const dto = (error as HarnessOperationError).dto;
+    expect(dto.code).toBe('selection_invalid');
+    // The DTO echoes the exact requested tuple, unchanged.
+    expect(dto.selection).toEqual(bogus);
+    // No substitution to the first catalog row.
+    expect(dto.selection).not.toEqual({
+      harnessId: firstRow.harnessId,
+      providerId: firstRow.providerId,
+      modelId: firstRow.modelId,
+    });
+    // The active selection is untouched by the rejected request.
+    expect((await handle.snapshot()).selection).toEqual(selected);
+  });
+
+  it('reports model_unavailable with the unchanged tuple for a known but unavailable model', async () => {
+    const adapter = new FakeHarnessAdapter({ id: 'fake' });
+    const catalog = await adapter.catalog(CONTEXT);
+    const unavailable = catalog.models.find((entry) => entry.availability === 'unavailable');
+    const available = catalog.models.find((entry) => entry.availability === 'available');
+    expect(unavailable).toBeDefined();
+    expect(available).toBeDefined();
+
+    const startingSelection: HarnessSelection = {
+      harnessId: available!.harnessId,
+      providerId: available!.providerId,
+      modelId: available!.modelId,
+    };
+    const handle = await adapter.create({
+      context: CONTEXT,
+      conversationId: 'conversation-2',
+      selection: startingSelection,
+    });
+
+    const requested: HarnessSelection = {
+      harnessId: unavailable!.harnessId,
+      providerId: unavailable!.providerId,
+      modelId: unavailable!.modelId,
+    };
+
+    let error: unknown;
+    try {
+      await handle.setModel(requested);
+    } catch (caught) {
+      error = caught;
+    }
+
+    expect(error).toBeInstanceOf(HarnessOperationError);
+    const dto = (error as HarnessOperationError).dto;
+    expect(dto.code).toBe('model_unavailable');
+    expect(dto.selection).toEqual(requested);
+    expect((await handle.snapshot()).selection).toEqual(startingSelection);
+  });
+});

apps/gateway/src/harness/testing/fake-harness.adapter.ts

@@ -0,0 +1,248 @@
+import type {
+  AttachClient,
+  CreateHarnessSession,
+  HarnessAdapter,
+  HarnessActorContext,
+  HarnessCapability,
+  HarnessCatalog,
+  HarnessCatalogEntry,
+  HarnessCloseReason,
+  HarnessDescriptor,
+  HarnessEvent,
+  HarnessInteractionResponse,
+  HarnessPrompt,
+  HarnessPromptReceipt,
+  HarnessSelection,
+  HarnessSessionHandle,
+  HarnessSessionSnapshot,
+  HarnessSessionState,
+  ResumeHarnessSession,
+} from '@mosaicstack/types';
+import { HARNESS_CAPABILITIES } from '@mosaicstack/types';
+import { operationError } from '../harness.registry.js';
+
+export interface FakeHarnessAdapterOptions {
+  readonly id: string;
+  readonly capabilities?: readonly HarnessCapability[];
+  readonly catalog?: readonly HarnessCatalogEntry[];
+}
+
+const FAKE_PROVIDER = 'fake-openai';
+
+function defaultCatalog(harnessId: string): readonly HarnessCatalogEntry[] {
+  return [
+    {
+      harnessId,
+      providerId: FAKE_PROVIDER,
+      modelId: 'fake-mini',
+      displayName: 'Fake Mini',
+      reasoningCapability: false,
+      inputTypes: ['text'],
+      authState: 'ready',
+      availability: 'available',
+    },
+    {
+      harnessId,
+      providerId: FAKE_PROVIDER,
+      modelId: 'fake-pro',
+      displayName: 'Fake Pro',
+      reasoningCapability: true,
+      inputTypes: ['text', 'image'],
+      authState: 'ready',
+      availability: 'available',
+    },
+    {
+      harnessId,
+      providerId: FAKE_PROVIDER,
+      modelId: 'fake-legacy',
+      displayName: 'Fake Legacy',
+      reasoningCapability: false,
+      inputTypes: ['text'],
+      authState: 'unavailable',
+      availability: 'unavailable',
+    },
+  ];
+}
+
+function matches(entry: HarnessCatalogEntry, selection: HarnessSelection): boolean {
+  return (
+    entry.harnessId === selection.harnessId &&
+    entry.providerId === selection.providerId &&
+    entry.modelId === selection.modelId
+  );
+}
+
+/**
+ * In-memory harness session handle used by the fake adapter and by the shared
+ * conformance suite. It enforces the two invariants the real adapters must also
+ * honor: model selection is validated against the catalog and is NEVER
+ * substituted, and unsupported capabilities fail with a typed error.
+ */
+export class FakeHarnessSessionHandle implements HarnessSessionHandle {
+  private state: HarnessSessionState = 'idle';
+  private processId: string | undefined;
+  private readonly attachedClientIds = new Set<string>();
+  private readonly listeners = new Set<(event: HarnessEvent) => void>();
+
+  constructor(
+    private readonly conversationId: string,
+    private readonly nativeSessionId: string,
+    private readonly seatId: string,
+    private selection: HarnessSelection,
+    private readonly correlationId: string,
+    private readonly capabilities: readonly HarnessCapability[],
+    private readonly catalog: readonly HarnessCatalogEntry[],
+  ) {
+    this.processId = `process-${nativeSessionId}`;
+  }
+
+  async snapshot(): Promise<HarnessSessionSnapshot> {
+    return {
+      conversationId: this.conversationId,
+      nativeSessionId: this.nativeSessionId,
+      processId: this.processId,
+      seatId: this.seatId,
+      selection: this.selection,
+      state: this.state,
+      attachedClientIds: [...this.attachedClientIds],
+    };
+  }
+
+  async attach(input: AttachClient): Promise<void> {
+    this.attachedClientIds.add(input.clientId);
+  }
+
+  async detach(clientId: string): Promise<void> {
+    // Removes the browser attachment only; the process and native session persist.
+    this.attachedClientIds.delete(clientId);
+  }
+
+  async prompt(input: HarnessPrompt & { idempotencyKey: string }): Promise<HarnessPromptReceipt> {
+    return {
+      conversationId: this.conversationId,
+      turnId: input.turnId,
+      correlationId: input.correlationId,
+      state: 'accepted',
+      selection: this.selection,
+    };
+  }
+
+  async setModel(selection: HarnessSelection): Promise<HarnessSelection> {
+    const entry = this.catalog.find((candidate) => matches(candidate, selection));
+    if (!entry) {
+      // No fallback to the first catalog row: reject with the requested tuple, unchanged.
+      throw operationError(
+        'selection_invalid',
+        'The requested harness/provider/model tuple is not in the catalog.',
+        selection,
+        this.correlationId,
+      );
+    }
+    if (entry.availability === 'unavailable') {
+      throw operationError(
+        'model_unavailable',
+        'The requested model is currently unavailable.',
+        selection,
+        this.correlationId,
+        true,
+      );
+    }
+    this.selection = selection;
+    return this.selection;
+  }
+
+  async abort(_turnId: string): Promise<void> {
+    // No active turn machinery in the fake; abort is a no-op acknowledgement.
+  }
+
+  async respondInteraction(_input: HarnessInteractionResponse): Promise<void> {
+    if (!this.capabilities.includes('extensionUi')) {
+      throw operationError(
+        'interaction_unsupported',
+        'This harness does not support interactive responses.',
+        this.selection,
+        this.correlationId,
+      );
+    }
+  }
+
+  events(listener: (event: HarnessEvent) => void): () => void {
+    this.listeners.add(listener);
+    return () => {
+      this.listeners.delete(listener);
+    };
+  }
+
+  async evictProcess(_reason: HarnessCloseReason): Promise<void> {
+    // Stop the process but keep the resumable native session.
+    this.processId = undefined;
+    this.state = 'evicted';
+  }
+
+  async endSession(_reason: HarnessCloseReason): Promise<void> {
+    // Destructively end the native session.
+    this.processId = undefined;
+    this.state = 'ended';
+  }
+}
+
+/**
+ * Minimal in-memory {@link HarnessAdapter} for Slice Zero. It mints a fresh
+ * native session id on `create` and binds the supplied one on `resume`, so the
+ * two paths are observably distinct.
+ */
+export class FakeHarnessAdapter implements HarnessAdapter {
+  readonly id: string;
+  private readonly capabilities: readonly HarnessCapability[];
+  private readonly catalogEntries: readonly HarnessCatalogEntry[];
+  private createdCount = 0;
+
+  constructor(options: FakeHarnessAdapterOptions) {
+    this.id = options.id;
+    this.capabilities = options.capabilities ?? [...HARNESS_CAPABILITIES];
+    this.catalogEntries = options.catalog ?? defaultCatalog(options.id);
+  }
+
+  async describe(_context: HarnessActorContext): Promise<HarnessDescriptor> {
+    return {
+      id: this.id,
+      displayName: `Fake harness (${this.id})`,
+      capabilities: this.capabilities,
+    };
+  }
+
+  async catalog(_context: HarnessActorContext): Promise<HarnessCatalog> {
+    return {
+      harnessId: this.id,
+      version: '1.0.0',
+      fingerprint: `fake-${this.id}-${this.catalogEntries.length}`,
+      models: this.catalogEntries,
+    };
+  }
+
+  async create(input: CreateHarnessSession): Promise<HarnessSessionHandle> {
+    this.createdCount += 1;
+    const nativeSessionId = `native-${input.conversationId}-${this.createdCount}`;
+    return new FakeHarnessSessionHandle(
+      input.conversationId,
+      nativeSessionId,
+      input.context.seatId,
+      input.selection,
+      input.context.correlationId,
+      this.capabilities,
+      this.catalogEntries,
+    );
+  }
+
+  async resume(input: ResumeHarnessSession): Promise<HarnessSessionHandle> {
+    return new FakeHarnessSessionHandle(
+      input.conversationId,
+      input.nativeSessionId,
+      input.context.seatId,
+      input.selection,
+      input.context.correlationId,
+      this.capabilities,
+      this.catalogEntries,
+    );
+  }
+}

apps/gateway/src/harness/testing/harness-adapter.contract.ts

@@ -0,0 +1,157 @@
+import { describe, expect, it } from 'vitest';
+import type {
+  HarnessActorContext,
+  HarnessAdapter,
+  HarnessCatalogEntry,
+  HarnessSelection,
+} from '@mosaicstack/types';
+import { HarnessOperationError } from '../harness.registry.js';
+
+const CONTEXT: HarnessActorContext = {
+  actorId: 'contract-actor',
+  tenantId: 'contract-tenant',
+  seatId: 'contract-seat',
+  correlationId: 'contract-correlation',
+};
+
+function toSelection(entry: HarnessCatalogEntry): HarnessSelection {
+  return { harnessId: entry.harnessId, providerId: entry.providerId, modelId: entry.modelId };
+}
+
+function pickAvailable(models: readonly HarnessCatalogEntry[]): HarnessCatalogEntry {
+  const entry = models.find((candidate) => candidate.availability === 'available') ?? models[0];
+  if (!entry) {
+    throw new Error('contract fixture requires at least one catalog model');
+  }
+  return entry;
+}
+
+async function captureError(run: () => Promise<unknown>): Promise<unknown> {
+  try {
+    await run();
+    return undefined;
+  } catch (caught) {
+    return caught;
+  }
+}
+
+/**
+ * Shared conformance suite every {@link HarnessAdapter} must pass. Slice Zero
+ * runs it against the fake adapter; Task 13 re-runs the identical suite against
+ * the native Pi adapter so both share one behavioral contract.
+ */
+export function runHarnessAdapterContract(
+  label: string,
+  createAdapter: () => HarnessAdapter,
+): void {
+  describe(`harness adapter contract: ${label}`, () => {
+    it('mints a fresh native session on create and binds the supplied one on resume', async () => {
+      const adapter = createAdapter();
+      const catalog = await adapter.catalog(CONTEXT);
+      const selection = toSelection(pickAvailable(catalog.models));
+
+      const created = await (
+        await adapter.create({ context: CONTEXT, conversationId: 'conv-create', selection })
+      ).snapshot();
+      const resumed = await (
+        await adapter.resume({
+          context: CONTEXT,
+          conversationId: 'conv-resume',
+          nativeSessionId: 'native-supplied-1',
+          selection,
+        })
+      ).snapshot();
+
+      expect(created.nativeSessionId).toBeTruthy();
+      expect(resumed.nativeSessionId).toBe('native-supplied-1');
+      expect(created.nativeSessionId).not.toBe(resumed.nativeSessionId);
+      expect(created.seatId).toBe(CONTEXT.seatId);
+    });
+
+    it('gives detach, evict, and end distinct effects (not aliases)', async () => {
+      const adapter = createAdapter();
+      const catalog = await adapter.catalog(CONTEXT);
+      const selection = toSelection(pickAvailable(catalog.models));
+      const handle = await adapter.create({
+        context: CONTEXT,
+        conversationId: 'conv-lifecycle',
+        selection,
+      });
+
+      await handle.attach({ clientId: 'browser-1' });
+      await handle.detach('browser-1');
+      const afterDetach = await handle.snapshot();
+      expect(afterDetach.attachedClientIds).toEqual([]);
+      expect(afterDetach.state).not.toBe('evicted');
+      expect(afterDetach.state).not.toBe('ended');
+
+      await handle.evictProcess('idle_timeout');
+      const afterEvict = await handle.snapshot();
+      expect(afterEvict.state).toBe('evicted');
+      // The native session survives eviction (resumable); the process does not.
+      expect(afterEvict.nativeSessionId).toBe(afterDetach.nativeSessionId);
+      expect(afterEvict.processId).toBeUndefined();
+
+      await handle.endSession('session_ended');
+      const afterEnd = await handle.snapshot();
+      expect(afterEnd.state).toBe('ended');
+      // End is not an alias of evict.
+      expect(afterEnd.state).not.toBe(afterEvict.state);
+    });
+
+    it('never substitutes the first catalog row for an unknown selection', async () => {
+      const adapter = createAdapter();
+      const catalog = await adapter.catalog(CONTEXT);
+      const firstRow = catalog.models[0];
+      if (!firstRow) {
+        throw new Error('contract fixture requires a catalog model');
+      }
+      const start = toSelection(pickAvailable(catalog.models));
+      const handle = await adapter.create({
+        context: CONTEXT,
+        conversationId: 'conv-nosub',
+        selection: start,
+      });
+
+      const bogus: HarnessSelection = {
+        harnessId: adapter.id,
+        providerId: 'contract-ghost-provider',
+        modelId: 'contract-ghost-model',
+      };
+      const error = await captureError(() => handle.setModel(bogus));
+
+      expect(error).toBeInstanceOf(HarnessOperationError);
+      const dto = (error as HarnessOperationError).dto;
+      expect(dto.code).toBe('selection_invalid');
+      expect(dto.selection).toEqual(bogus);
+      expect(dto.selection).not.toEqual(toSelection(firstRow));
+      expect((await handle.snapshot()).selection).toEqual(start);
+    });
+
+    it('validates capability-gated interactions with a typed error, not a silent no-op', async () => {
+      const adapter = createAdapter();
+      const descriptor = await adapter.describe(CONTEXT);
+      const catalog = await adapter.catalog(CONTEXT);
+      const selection = toSelection(pickAvailable(catalog.models));
+      const handle = await adapter.create({
+        context: CONTEXT,
+        conversationId: 'conv-interaction',
+        selection,
+      });
+
+      const response = {
+        requestId: 'interaction-1',
+        type: 'confirm',
+        accepted: true,
+      } as const;
+
+      if (descriptor.capabilities.includes('extensionUi')) {
+        await expect(handle.respondInteraction(response)).resolves.toBeUndefined();
+      } else {
+        const error = await captureError(() => handle.respondInteraction(response));
+        expect(error).toBeInstanceOf(HarnessOperationError);
+        expect((error as HarnessOperationError).dto.code).toBe('interaction_unsupported');
+      }
+    });
+  });
+}

apps/web/src/lib/types.ts

@@ -1,3 +1,42 @@
+import type {
+  HarnessAuthState,
+  HarnessModelAvailability,
+  HarnessSelection,
+} from '@mosaicstack/types';
+
+// The exact harness/provider/model tuple and its closed enum companions are the
+// shared domain types — re-exported here so web consumers (and the runtime
+// guards) import one shape, never a divergent local redefinition.
+export type { HarnessSelection, HarnessAuthState, HarnessModelAvailability };
+
+/** Harness summary row from `GET /api/harnesses` (the `HarnessSummaryDto`). The
+ * harness id is kept distinct from any provider id — they are never merged. */
+export interface HarnessSummary {
+  id: string;
+  displayName: string;
+  capabilities: string[];
+}
+
+/** One selectable model in a harness catalog. Extends the `{harnessId,
+ * providerId, modelId}` tuple with the display/availability metadata the UI
+ * needs; `inputTypes` is kept as a plain `string[]` on the client boundary
+ * because it arrives from untrusted JSON and is only ever displayed. */
+export interface HarnessCatalogEntry extends HarnessSelection {
+  displayName: string;
+  reasoningCapability: boolean;
+  inputTypes: string[];
+  authState: HarnessAuthState;
+  availability: HarnessModelAvailability;
+}
+
+/** Harness-scoped catalog from `GET /api/harnesses/:harnessId/catalog`. */
+export interface HarnessCatalog {
+  harnessId: string;
+  version: string;
+  fingerprint: string;
+  models: HarnessCatalogEntry[];
+}
+
 /** Conversation returned by the gateway API. */
 export interface Conversation {
   id: string;

apps/web/src/spa/chat/chat-api.spec.ts

@@ -0,0 +1,195 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import {
+  fetchCatalog,
+  fetchHarnesses,
+  fetchPersistedSelection,
+  persistSelection,
+} from './chat-api';
+
+function json(body: unknown, status = 200): Response {
+  return new Response(JSON.stringify(body), {
+    status,
+    headers: { 'Content-Type': 'application/json' },
+  });
+}
+
+function stubFetch(): ReturnType<typeof vi.fn> {
+  const fetchMock = vi.fn();
+  vi.stubGlobal('fetch', fetchMock);
+  return fetchMock;
+}
+
+/** Every URL the client actually requested, across all calls. */
+function requestedUrls(fetchMock: ReturnType<typeof vi.fn>): string[] {
+  return fetchMock.mock.calls.map((call) => String(call[0]));
+}
+
+describe('chat-api', () => {
+  afterEach(() => {
+    vi.unstubAllGlobals();
+  });
+
+  it('fetchHarnesses GETs /api/harnesses and returns typed summaries (harness id separate from provider)', async () => {
+    const fetchMock = stubFetch();
+    fetchMock.mockResolvedValue(
+      json([
+        { id: 'pi', displayName: 'Pi', capabilities: ['chat', 'tools'] },
+        { id: 'openai', displayName: 'OpenAI', capabilities: ['chat'] },
+      ]),
+    );
+
+    const harnesses = await fetchHarnesses();
+
+    expect(fetchMock).toHaveBeenCalledOnce();
+    expect(String(fetchMock.mock.calls[0]?.[0])).toBe('/api/harnesses');
+    expect(harnesses).toEqual([
+      { id: 'pi', displayName: 'Pi', capabilities: ['chat', 'tools'] },
+      { id: 'openai', displayName: 'OpenAI', capabilities: ['chat'] },
+    ]);
+  });
+
+  it('fetchCatalog GETs the harness-scoped catalog and returns only its model entries', async () => {
+    const fetchMock = stubFetch();
+    fetchMock.mockResolvedValue(
+      json({
+        harnessId: 'pi',
+        version: '2026-08-11',
+        fingerprint: 'abc123',
+        models: [
+          {
+            harnessId: 'pi',
+            providerId: 'openai',
+            modelId: 'gpt-5',
+            displayName: 'GPT-5',
+            reasoningCapability: true,
+            inputTypes: ['text'],
+            authState: 'ready',
+            availability: 'available',
+          },
+        ],
+      }),
+    );
+
+    const result = await fetchCatalog('pi');
+
+    expect(String(fetchMock.mock.calls[0]?.[0])).toBe('/api/harnesses/pi/catalog');
+    expect(result.ok).toBe(true);
+    if (!result.ok) throw new Error('expected ok catalog');
+    expect(result.catalog.harnessId).toBe('pi');
+    expect(result.catalog.models).toHaveLength(1);
+    expect(result.catalog.models[0]).toMatchObject({
+      harnessId: 'pi',
+      providerId: 'openai',
+      modelId: 'gpt-5',
+      availability: 'available',
+    });
+  });
+
+  it('normalizes a catalog 404 into a typed catalog_unavailable result without surfacing the raw body', async () => {
+    const fetchMock = stubFetch();
+    fetchMock.mockResolvedValue(
+      json(
+        {
+          code: 'adapter_unavailable',
+          message: 'raw gateway detail that must not leak verbatim',
+          harnessId: 'attacker-echo',
+          extra: { hostile: 'blob' },
+        },
+        404,
+      ),
+    );
+
+    const result = await fetchCatalog('ghost');
+
+    expect(result.ok).toBe(false);
+    if (result.ok) throw new Error('expected unavailable result');
+    expect(result.code).toBe('catalog_unavailable');
+    // harnessId comes from the request, never the (untrusted) response body.
+    expect(result.harnessId).toBe('ghost');
+    expect(typeof result.message).toBe('string');
+    // The raw response body is never rendered/returned verbatim.
+    expect(JSON.stringify(result)).not.toContain('hostile');
+    expect(JSON.stringify(result)).not.toContain('attacker-echo');
+  });
+
+  it('fetchPersistedSelection returns the stored tuple, or null when unset', async () => {
+    const fetchMock = stubFetch();
+    fetchMock.mockResolvedValueOnce(
+      json({ selection: { harnessId: 'pi', providerId: 'openai', modelId: 'gpt-5' } }),
+    );
+    await expect(fetchPersistedSelection()).resolves.toEqual({
+      harnessId: 'pi',
+      providerId: 'openai',
+      modelId: 'gpt-5',
+    });
+    expect(String(fetchMock.mock.calls[0]?.[0])).toBe('/api/chat/preferences/selection');
+
+    fetchMock.mockResolvedValueOnce(json({ selection: null }));
+    await expect(fetchPersistedSelection()).resolves.toBeNull();
+  });
+
+  it('persistSelection PUTs the structured tuple (not free text) and returns the confirmed selection', async () => {
+    const fetchMock = stubFetch();
+    fetchMock.mockResolvedValue(
+      json({ selection: { harnessId: 'pi', providerId: 'openai', modelId: 'gpt-5' } }),
+    );
+
+    const result = await persistSelection({
+      harnessId: 'pi',
+      providerId: 'openai',
+      modelId: 'gpt-5',
+    });
+
+    expect(result.ok).toBe(true);
+    const call = fetchMock.mock.calls[0];
+    expect(String(call?.[0])).toBe('/api/chat/preferences/selection');
+    const init = call?.[1] as RequestInit;
+    expect(String(init.method).toUpperCase()).toBe('PUT');
+    // The body is exactly the structured tuple — harness/provider/model kept distinct.
+    expect(JSON.parse(String(init.body))).toEqual({
+      harnessId: 'pi',
+      providerId: 'openai',
+      modelId: 'gpt-5',
+    });
+  });
+
+  it('normalizes a selection 422 into a typed error preserving the requested tuple exactly', async () => {
+    const fetchMock = stubFetch();
+    fetchMock.mockResolvedValue(
+      json(
+        {
+          code: 'model_unavailable',
+          message: 'raw detail that must not leak',
+          selection: { harnessId: 'x', providerId: 'y', modelId: 'z' },
+        },
+        422,
+      ),
+    );
+
+    const requested = { harnessId: 'pi', providerId: 'openai', modelId: 'gpt-5' };
+    const result = await persistSelection(requested);
+
+    expect(result.ok).toBe(false);
+    if (result.ok) throw new Error('expected failed persist');
+    expect(['selection_invalid', 'model_unavailable']).toContain(result.code);
+    // The requested tuple is preserved unchanged — not replaced by the body's echo.
+    expect(result.requested).toEqual(requested);
+    expect(JSON.stringify(result)).not.toContain('raw detail');
+  });
+
+  it('never requests any /api/providers* endpoint', async () => {
+    const fetchMock = stubFetch();
+    fetchMock.mockResolvedValue(json([]));
+    await fetchHarnesses();
+    fetchMock.mockResolvedValue(
+      json({ harnessId: 'pi', version: '1', fingerprint: 'f', models: [] }),
+    );
+    await fetchCatalog('pi');
+    fetchMock.mockResolvedValue(json({ selection: null }));
+    await fetchPersistedSelection();
+
+    for (const url of requestedUrls(fetchMock)) {
+      expect(url).not.toContain('/api/providers');
+    }
+  });
+});

apps/web/src/spa/chat/chat-api.ts

@@ -0,0 +1,132 @@
+/**
+ * Typed fetch wrappers for the Task-3 harness HTTP contract the chat selection
+ * UI depends on. Every response body is untrusted and is normalized through the
+ * runtime guards before it reaches state — a 404 (catalog) and a 422 (selection)
+ * are mapped to typed, body-free error results so a raw gateway body is never
+ * rendered, and the caller's requested tuple is preserved verbatim on failure.
+ *
+ * This module talks ONLY to the harness/chat-preferences endpoints. It never
+ * calls `/api/providers*` — provider identity lives inside the harness catalog.
+ */
+import { asHarnessCatalog, asHarnessSelection, asHarnessSummaries } from './runtime-guards';
+import type { HarnessCatalog, HarnessSelection, HarnessSummary } from '@/lib/types';
+
+/** A catalog fetch either yields the typed catalog or a typed unavailability —
+ * never a thrown raw body. */
+export type CatalogResult =
+  | { ok: true; catalog: HarnessCatalog }
+  | { ok: false; code: 'catalog_unavailable'; harnessId: string; message: string };
+
+export type SelectionErrorCode = 'selection_invalid' | 'model_unavailable';
+
+/** A persist either confirms the stored tuple or reports a typed domain failure
+ * that echoes back the exact tuple the caller requested. */
+export type SelectionPersistResult =
+  | { ok: true; selection: HarnessSelection }
+  | { ok: false; code: SelectionErrorCode; message: string; requested: HarnessSelection };
+
+/** A safe, generic message for an unavailable catalog — the raw 404 body is
+ * never surfaced. */
+const CATALOG_UNAVAILABLE_MESSAGE = 'This harness catalog is currently unavailable.';
+
+/** A safe, generic message for a rejected selection. The untrusted 422 body's
+ * own `message` is deliberately NEVER surfaced — only this fixed copy — so a
+ * raw gateway detail can never leak into the UI. Only the closed `code` enum is
+ * read from the body. */
+const SELECTION_REJECTED_MESSAGE = 'This selection was rejected.';
+
+async function readJson(response: Response): Promise<unknown> {
+  return response.json().catch(() => null);
+}
+
+function safeSelectionCode(body: unknown): SelectionErrorCode {
+  if (typeof body === 'object' && body !== null && 'code' in body) {
+    const code = (body as { code: unknown }).code;
+    if (code === 'selection_invalid' || code === 'model_unavailable') return code;
+  }
+  // Default to the more conservative "invalid" classification for anything
+  // unrecognized rather than guessing "model_unavailable".
+  return 'selection_invalid';
+}
+
+/** `GET /api/harnesses` → the list of harness summaries. A non-OK response
+ * normalizes to an empty list (the UI then has no harness to select). */
+export async function fetchHarnesses(): Promise<HarnessSummary[]> {
+  const response = await fetch('/api/harnesses', {
+    credentials: 'include',
+    headers: { Accept: 'application/json' },
+  });
+  if (!response.ok) return [];
+  return asHarnessSummaries(await readJson(response));
+}
+
+/** `GET /api/harnesses/:harnessId/catalog` → the harness-scoped catalog. A 404
+ * (or any non-OK) becomes a typed `catalog_unavailable` result rather than a
+ * fallback catalog or a rendered raw body. */
+export async function fetchCatalog(harnessId: string): Promise<CatalogResult> {
+  const response = await fetch(`/api/harnesses/${encodeURIComponent(harnessId)}/catalog`, {
+    credentials: 'include',
+    headers: { Accept: 'application/json' },
+  });
+  if (!response.ok) {
+    return {
+      ok: false,
+      code: 'catalog_unavailable',
+      // Scoped to the requested harness id, never the untrusted body's echo.
+      harnessId,
+      message: CATALOG_UNAVAILABLE_MESSAGE,
+    };
+  }
+  return { ok: true, catalog: asHarnessCatalog(await readJson(response), harnessId) };
+}
+
+/** `GET /api/chat/preferences/selection` → the persisted tuple, or null when
+ * unset or malformed. */
+export async function fetchPersistedSelection(): Promise<HarnessSelection | null> {
+  const response = await fetch('/api/chat/preferences/selection', {
+    credentials: 'include',
+    headers: { Accept: 'application/json' },
+  });
+  if (!response.ok) return null;
+  const body = await readJson(response);
+  if (typeof body !== 'object' || body === null) return null;
+  return asHarnessSelection((body as { selection?: unknown }).selection);
+}
+
+/** `PUT /api/chat/preferences/selection` with the structured tuple as the body.
+ * On success returns the confirmed selection; on a typed domain failure (422)
+ * or validation error, returns a typed result carrying the EXACT requested
+ * tuple — never the body's echo — and never the raw body text. */
+export async function persistSelection(
+  selection: HarnessSelection,
+): Promise<SelectionPersistResult> {
+  const requested: HarnessSelection = {
+    harnessId: selection.harnessId,
+    providerId: selection.providerId,
+    modelId: selection.modelId,
+  };
+  const response = await fetch('/api/chat/preferences/selection', {
+    method: 'PUT',
+    credentials: 'include',
+    headers: { Accept: 'application/json', 'Content-Type': 'application/json' },
+    body: JSON.stringify(requested),
+  });
+  if (!response.ok) {
+    const body = await readJson(response);
+    return {
+      ok: false,
+      code: safeSelectionCode(body),
+      // Fixed copy only — the untrusted body's message is never surfaced.
+      message: SELECTION_REJECTED_MESSAGE,
+      requested,
+    };
+  }
+  const body = await readJson(response);
+  const confirmed =
+    typeof body === 'object' && body !== null
+      ? asHarnessSelection((body as { selection?: unknown }).selection)
+      : null;
+  // A malformed 2xx body is treated as a confirmation of exactly what we sent —
+  // the server accepted the tuple, so the requested tuple is the source of truth.
+  return { ok: true, selection: confirmed ?? requested };
+}

apps/web/src/spa/chat/composer.tsx

@@ -1,4 +1,5 @@
 import { useState, type KeyboardEvent, type ReactElement } from 'react';
+import type { HarnessSelectionValue } from './use-harness-selection';
 
 interface ComposerProps {
   onSend: (input: { content: string; provider?: string; modelId?: string }) => void;
@@ -9,6 +10,23 @@ interface ComposerProps {
    * pre-ack window where a second send could otherwise slip through. */
   sending: boolean;
   hasConversation: boolean;
+  /** Structured harness/provider/model selection state. The composer never
+   * accepts free-text provider/model — every sendable tuple is a validated,
+   * persisted catalog entry, and the send projection is derived from it. */
+  harness: HarnessSelectionValue;
+}
+
+/** The distinct provider ids present in the current catalog, in first-seen
+ * order — the provider select is catalog-derived, never a hardcoded list. */
+function providerOptions(harness: HarnessSelectionValue): string[] {
+  const seen = new Set<string>();
+  const out: string[] = [];
+  for (const model of harness.catalog?.models ?? []) {
+    if (seen.has(model.providerId)) continue;
+    seen.add(model.providerId);
+    out.push(model.providerId);
+  }
+  return out;
 }
 
 export function Composer({
@@ -17,21 +35,19 @@ export function Composer({
   streaming,
   sending,
   hasConversation,
+  harness,
 }: ComposerProps): ReactElement {
   const [content, setContent] = useState('');
-  const [provider, setProvider] = useState('');
-  const [modelId, setModelId] = useState('');
   const busy = streaming || sending;
 
   function submit(): void {
     if (busy) return;
+    // Send is gated on a validated, persisted catalog tuple — a draft or unset
+    // selection can never emit, so provider/model never travel as free text.
+    if (!harness.canSend) return;
     const trimmed = content.trim();
     if (!trimmed) return;
-    onSend({
+    onSend({ content: trimmed, ...harness.projection });
-      content: trimmed,
-      provider: provider.trim() || undefined,
-      modelId: modelId.trim() || undefined,
-    });
     setContent('');
   }
 
@@ -42,6 +58,19 @@ export function Composer({
     }
   }
 
+  // Scope the model options to the intentionally selected provider. With no
+  // provider chosen (`providerId === ''`) nothing matches, so the model select
+  // offers only the placeholder — never a cross-provider row.
+  const models = (harness.catalog?.models ?? []).filter(
+    (model) => model.providerId === harness.providerId,
+  );
+  // A collision-safe composite option identity covering the full provider+model
+  // tuple. The controlled select mirrors the same identity so the exact catalog
+  // row highlights (a bare modelId would collide across providers).
+  const modelOptionValue = (model: { providerId: string; modelId: string }): string =>
+    `${model.providerId}:${model.modelId}`;
+  const selectedModelValue = harness.modelId ? `${harness.providerId}:${harness.modelId}` : '';
+
   return (
     <form
       onSubmit={(event) => {
@@ -51,21 +80,68 @@ export function Composer({
       className="flex flex-col gap-2 border-t p-4"
     >
       <div className="flex flex-wrap gap-2">
-        <input
+        <select
+          aria-label="Harness"
+          value={harness.harnessId}
+          onChange={(event) => harness.selectHarness(event.target.value)}
+          className="rounded border px-2 py-1 text-xs"
+        >
+          <option value="">Select a harness…</option>
+          {harness.harnesses.map((item) => (
+            <option key={item.id} value={item.id}>
+              {item.displayName}
+            </option>
+          ))}
+        </select>
+        <select
           aria-label="Provider"
-          value={provider}
+          value={harness.providerId}
-          onChange={(event) => setProvider(event.target.value)}
+          onChange={(event) => harness.selectProvider(event.target.value)}
-          placeholder="Provider (optional)"
+          disabled={harness.catalogUnavailable || providerOptions(harness).length === 0}
           className="rounded border px-2 py-1 text-xs"
-        />
+        >
-        <input
+          <option value="">Select a provider…</option>
+          {providerOptions(harness).map((providerId) => (
+            <option key={providerId} value={providerId}>
+              {providerId}
+            </option>
+          ))}
+        </select>
+        <select
           aria-label="Model"
-          value={modelId}
+          value={selectedModelValue}
-          onChange={(event) => setModelId(event.target.value)}
+          onChange={(event) => {
-          placeholder="Model (optional)"
+            // Resolve the composite option identity back to the exact catalog
+            // row and persist that row's own provider+model — never a bare id.
+            const selected = models.find((model) => modelOptionValue(model) === event.target.value);
+            if (selected) harness.selectModel(selected.providerId, selected.modelId);
+          }}
+          disabled={harness.catalogUnavailable || models.length === 0}
           className="rounded border px-2 py-1 text-xs"
-        />
+        >
+          <option value="">Select a model…</option>
+          {models.map((model) => (
+            <option key={modelOptionValue(model)} value={modelOptionValue(model)}>
+              {model.displayName}
+            </option>
+          ))}
+        </select>
       </div>
+      {harness.catalogUnavailable ? (
+        <p role="status" className="text-xs opacity-70">
+          This harness catalog is currently unavailable.
+        </p>
+      ) : null}
+      {harness.isStale ? (
+        <p role="status" className="text-xs opacity-70">
+          The saved model is no longer available — pick another to continue.
+        </p>
+      ) : null}
+      {harness.persistError ? (
+        <p role="alert" className="text-xs">
+          {harness.persistError.message}
+        </p>
+      ) : null}
       <div className="flex items-end gap-2">
         <textarea
           aria-label="Message"
@@ -78,7 +154,7 @@ export function Composer({
         />
         <button
           type="submit"
-          disabled={!content.trim() || busy}
+          disabled={!content.trim() || busy || !harness.canSend}
           className="rounded px-3 py-2 text-sm font-medium"
         >
           Send

apps/web/src/spa/chat/runtime-guards.ts

@@ -5,6 +5,14 @@
  * a non-array, `.toFixed` on a non-number) or render an object as a React
  * child.
  */
+import type {
+  HarnessAuthState,
+  HarnessCatalog,
+  HarnessCatalogEntry,
+  HarnessModelAvailability,
+  HarnessSelection,
+  HarnessSummary,
+} from '@/lib/types';
 
 export function asString(value: unknown, fallback = ''): string {
   return typeof value === 'string' ? value : fallback;
@@ -38,6 +46,99 @@ export function isRecord(value: unknown): value is Record<string, unknown> {
   return typeof value === 'object' && value !== null;
 }
 
+/**
+ * The HTTP harness/catalog/selection JSON bodies are as untrusted as the socket
+ * payloads above — a misbehaving or compromised gateway can send anything. The
+ * guards below normalize those bodies into the typed client shapes without ever
+ * rendering a raw body, so a 404/422/malformed response can never inject an
+ * object into React or a non-tuple into the selection state.
+ */
+
+/** Normalizes an untrusted `authState` to the closed set, defaulting to the
+ * safest value (`unavailable`) for anything unrecognized. */
+export function asHarnessAuthState(value: unknown): HarnessAuthState {
+  return value === 'ready' || value === 'auth_required' || value === 'unavailable'
+    ? value
+    : 'unavailable';
+}
+
+/** Normalizes an untrusted `availability` to the closed set, defaulting to
+ * `unavailable` so a malformed row can never present as sendable. */
+export function asHarnessAvailability(value: unknown): HarnessModelAvailability {
+  return value === 'available' ? 'available' : 'unavailable';
+}
+
+/** A tuple is valid only when all three ids are non-empty strings — a partial
+ * or malformed selection is rejected (null) rather than half-adopted. */
+export function asHarnessSelection(value: unknown): HarnessSelection | null {
+  if (!isRecord(value)) return null;
+  const harnessId = value.harnessId;
+  const providerId = value.providerId;
+  const modelId = value.modelId;
+  if (
+    typeof harnessId !== 'string' ||
+    typeof providerId !== 'string' ||
+    typeof modelId !== 'string' ||
+    harnessId.length === 0 ||
+    providerId.length === 0 ||
+    modelId.length === 0
+  ) {
+    return null;
+  }
+  return { harnessId, providerId, modelId };
+}
+
+/** Normalizes an untrusted array into typed harness summaries, dropping any row
+ * without a usable id. */
+export function asHarnessSummaries(value: unknown): HarnessSummary[] {
+  if (!Array.isArray(value)) return [];
+  const out: HarnessSummary[] = [];
+  for (const item of value) {
+    if (!isRecord(item)) continue;
+    const id = asString(item.id);
+    if (id.length === 0) continue;
+    out.push({
+      id,
+      displayName: asNonEmptyString(item.displayName, id),
+      capabilities: asStringArray(item.capabilities),
+    });
+  }
+  return out;
+}
+
+function asHarnessCatalogEntry(value: unknown): HarnessCatalogEntry | null {
+  const selection = asHarnessSelection(value);
+  if (selection === null || !isRecord(value)) return null;
+  return {
+    ...selection,
+    displayName: asNonEmptyString(value.displayName, selection.modelId),
+    reasoningCapability: value.reasoningCapability === true,
+    inputTypes: asStringArray(value.inputTypes),
+    authState: asHarnessAuthState(value.authState),
+    availability: asHarnessAvailability(value.availability),
+  };
+}
+
+/** Normalizes an untrusted catalog body into the typed client catalog. The
+ * caller supplies `harnessId` (from the request path) so the returned catalog
+ * is scoped to the harness that was actually requested, never a body-echoed id.
+ * Malformed model rows are dropped rather than invalidating the whole catalog. */
+export function asHarnessCatalog(value: unknown, harnessId: string): HarnessCatalog {
+  const record = isRecord(value) ? value : {};
+  const rawModels = Array.isArray(record.models) ? record.models : [];
+  const models: HarnessCatalogEntry[] = [];
+  for (const row of rawModels) {
+    const entry = asHarnessCatalogEntry(row);
+    if (entry !== null) models.push(entry);
+  }
+  return {
+    harnessId,
+    version: asString(record.version),
+    fingerprint: asString(record.fingerprint),
+    models,
+  };
+}
+
 /** The single point of truth for what counts as a valid conversation ID
  * anywhere a scoped server event may adopt one into state — a non-empty
  * string, nothing else. Every site that establishes or compares

apps/web/src/spa/chat/use-harness-selection.spec.tsx

@@ -0,0 +1,445 @@
+import { act, type ReactElement } from 'react';
+import { createRoot, type Root } from 'react-dom/client';
+import { afterAll, afterEach, beforeAll, beforeEach, describe, expect, it, vi } from 'vitest';
+import { useHarnessSelection, type HarnessSelectionValue } from './use-harness-selection';
+
+function json(body: unknown, status = 200): Response {
+  return new Response(JSON.stringify(body), {
+    status,
+    headers: { 'Content-Type': 'application/json' },
+  });
+}
+
+interface Scenario {
+  harnesses?: unknown;
+  catalog?: { body: unknown; status?: number };
+  selection?: unknown;
+  /** When set, the PUT resolves only when this is called (for race tests). */
+  deferPut?: boolean;
+}
+
+interface Deferred<T> {
+  promise: Promise<T>;
+  resolve: (value: T) => void;
+}
+
+function defer<T>(): Deferred<T> {
+  let resolve!: (value: T) => void;
+  const promise = new Promise<T>((r) => {
+    resolve = r;
+  });
+  return { promise, resolve };
+}
+
+let putBodies: unknown[] = [];
+let putDeferred: Deferred<Response> | null = null;
+
+function installFetch(scenario: Scenario): ReturnType<typeof vi.fn> {
+  putBodies = [];
+  putDeferred = scenario.deferPut ? defer<Response>() : null;
+  const fetchMock = vi.fn(async (input: unknown, init?: RequestInit) => {
+    const url = String(input);
+    const method = String(init?.method ?? 'GET').toUpperCase();
+    if (url === '/api/harnesses') return json(scenario.harnesses ?? []);
+    if (url.startsWith('/api/harnesses/') && url.endsWith('/catalog')) {
+      const spec = scenario.catalog ?? {
+        body: { harnessId: 'pi', version: '1', fingerprint: 'f', models: [] },
+      };
+      return json(spec.body, spec.status ?? 200);
+    }
+    if (url === '/api/chat/preferences/selection' && method === 'GET') {
+      return json({ selection: scenario.selection ?? null });
+    }
+    if (url === '/api/chat/preferences/selection' && method === 'PUT') {
+      putBodies.push(JSON.parse(String(init?.body)));
+      const ok = json({ selection: JSON.parse(String(init?.body)) });
+      if (putDeferred) return putDeferred.promise;
+      return ok;
+    }
+    return new Response('not found', { status: 404 });
+  });
+  vi.stubGlobal('fetch', fetchMock);
+  return fetchMock;
+}
+
+let latest: HarnessSelectionValue | null = null;
+
+function Probe(): ReactElement | null {
+  latest = useHarnessSelection();
+  return null;
+}
+
+let root: Root | null;
+let container: HTMLElement;
+
+beforeAll(() => {
+  Object.defineProperty(globalThis, 'IS_REACT_ACT_ENVIRONMENT', {
+    configurable: true,
+    value: true,
+  });
+});
+
+afterAll(() => {
+  Reflect.deleteProperty(globalThis, 'IS_REACT_ACT_ENVIRONMENT');
+});
+
+beforeEach(() => {
+  latest = null;
+  container = document.createElement('div');
+  document.body.append(container);
+  root = createRoot(container);
+});
+
+afterEach(async () => {
+  await act(async () => {
+    root?.unmount();
+  });
+  document.body.replaceChildren();
+  vi.unstubAllGlobals();
+});
+
+async function mount(): Promise<void> {
+  await act(async () => {
+    root?.render(<Probe />);
+  });
+  await flush();
+}
+
+async function flush(times = 5): Promise<void> {
+  for (let i = 0; i < times; i += 1) {
+    await act(async () => {
+      await Promise.resolve();
+    });
+  }
+}
+
+function value(): HarnessSelectionValue {
+  if (!latest) throw new Error('hook value not captured');
+  return latest;
+}
+
+const PI_CATALOG = {
+  harnessId: 'pi',
+  version: '2026-08-11',
+  fingerprint: 'fp',
+  models: [
+    {
+      harnessId: 'pi',
+      providerId: 'openai',
+      modelId: 'gpt-5',
+      displayName: 'GPT-5',
+      reasoningCapability: true,
+      inputTypes: ['text'],
+      authState: 'ready',
+      availability: 'available',
+    },
+    {
+      harnessId: 'pi',
+      providerId: 'anthropic',
+      modelId: 'claude',
+      displayName: 'Claude',
+      reasoningCapability: true,
+      inputTypes: ['text'],
+      authState: 'ready',
+      availability: 'available',
+    },
+  ],
+};
+
+describe('useHarnessSelection', () => {
+  it('loads harnesses and, once a harness is chosen, the model options come only from its catalog', async () => {
+    installFetch({
+      harnesses: [{ id: 'pi', displayName: 'Pi', capabilities: [] }],
+      catalog: { body: PI_CATALOG },
+      selection: null,
+    });
+    await mount();
+
+    expect(value().harnesses).toEqual([{ id: 'pi', displayName: 'Pi', capabilities: [] }]);
+    expect(value().catalog).toBeNull();
+
+    await act(async () => {
+      value().selectHarness('pi');
+    });
+    await flush();
+
+    expect(value().catalog?.harnessId).toBe('pi');
+    expect(value().catalog?.models.map((m) => m.modelId)).toEqual(['gpt-5', 'claude']);
+  });
+
+  it('does not auto-select any catalog row when there is no persisted selection (no first-row fallback)', async () => {
+    const fetchMock = installFetch({
+      harnesses: [{ id: 'pi', displayName: 'Pi', capabilities: [] }],
+      catalog: { body: PI_CATALOG },
+      selection: null,
+    });
+    await mount();
+    await act(async () => {
+      value().selectHarness('pi');
+    });
+    await flush();
+
+    expect(value().modelId).toBe('');
+    expect(value().persistedSelection).toBeNull();
+    expect(value().canSend).toBe(false);
+    // Nothing was persisted — no PUT fired for an unset selection.
+    const putCalls = fetchMock.mock.calls.filter(
+      (c) => String((c[1] as RequestInit)?.method).toUpperCase() === 'PUT',
+    );
+    expect(putCalls).toHaveLength(0);
+  });
+
+  it('persists the structured tuple and only enables send AFTER the PUT resolves (no race ahead of persistence)', async () => {
+    installFetch({
+      harnesses: [{ id: 'pi', displayName: 'Pi', capabilities: [] }],
+      catalog: { body: PI_CATALOG },
+      selection: null,
+      deferPut: true,
+    });
+    await mount();
+    await act(async () => {
+      value().selectHarness('pi');
+    });
+    await flush();
+    await act(async () => {
+      value().selectProvider('openai');
+    });
+    await act(async () => {
+      value().selectModel('openai', 'gpt-5');
+    });
+    await flush();
+
+    // PUT is in flight (deferred) — send MUST NOT be enabled yet.
+    expect(value().canSend).toBe(false);
+
+    await act(async () => {
+      putDeferred?.resolve(
+        json({ selection: { harnessId: 'pi', providerId: 'openai', modelId: 'gpt-5' } }),
+      );
+    });
+    await flush();
+
+    expect(putBodies).toContainEqual({ harnessId: 'pi', providerId: 'openai', modelId: 'gpt-5' });
+    expect(value().persistedSelection).toEqual({
+      harnessId: 'pi',
+      providerId: 'openai',
+      modelId: 'gpt-5',
+    });
+    expect(value().canSend).toBe(true);
+    expect(value().projection).toEqual({ provider: 'openai', modelId: 'gpt-5' });
+  });
+
+  it('keeps a stale/unavailable persisted selection visibly displayed rather than silently dropping it', async () => {
+    installFetch({
+      harnesses: [{ id: 'pi', displayName: 'Pi', capabilities: [] }],
+      catalog: { body: PI_CATALOG },
+      selection: { harnessId: 'pi', providerId: 'openai', modelId: 'retired-model' },
+    });
+    await mount();
+
+    // The persisted tuple is displayed even though its model is gone from the catalog.
+    expect(value().persistedSelection).toEqual({
+      harnessId: 'pi',
+      providerId: 'openai',
+      modelId: 'retired-model',
+    });
+    expect(value().modelId).toBe('retired-model');
+    expect(value().isStale).toBe(true);
+    // A stale model is not a valid catalog option, so send stays disabled.
+    expect(value().canSend).toBe(false);
+  });
+
+  it('disables send for an empty catalog (no viable model) and never fabricates one', async () => {
+    installFetch({
+      harnesses: [{ id: 'pi', displayName: 'Pi', capabilities: [] }],
+      catalog: { body: { harnessId: 'pi', version: '1', fingerprint: 'f', models: [] } },
+      selection: null,
+    });
+    await mount();
+    await act(async () => {
+      value().selectHarness('pi');
+    });
+    await flush();
+
+    expect(value().catalog?.models ?? []).toHaveLength(0);
+    expect(value().canSend).toBe(false);
+  });
+
+  it('marks the catalog unavailable and disables send when the catalog request 404s', async () => {
+    installFetch({
+      harnesses: [{ id: 'pi', displayName: 'Pi', capabilities: [] }],
+      catalog: {
+        body: { code: 'adapter_unavailable', message: 'x', harnessId: 'pi' },
+        status: 404,
+      },
+      selection: null,
+    });
+    await mount();
+    await act(async () => {
+      value().selectHarness('pi');
+    });
+    await flush();
+
+    expect(value().catalogUnavailable).toBe(true);
+    expect(value().canSend).toBe(false);
+  });
+
+  it('on a 422 persist, keeps the requested tuple visible, surfaces a typed error, and leaves send disabled', async () => {
+    installFetch({
+      harnesses: [{ id: 'pi', displayName: 'Pi', capabilities: [] }],
+      catalog: {
+        body: {
+          ...PI_CATALOG,
+          models: [{ ...PI_CATALOG.models[0], availability: 'unavailable' }],
+        },
+      },
+      selection: null,
+    });
+    // Override PUT to 422.
+    const fetchMock = vi.fn(async (input: unknown, init?: RequestInit) => {
+      const url = String(input);
+      const method = String(init?.method ?? 'GET').toUpperCase();
+      if (url === '/api/harnesses')
+        return json([{ id: 'pi', displayName: 'Pi', capabilities: [] }]);
+      if (url.endsWith('/catalog')) return json(PI_CATALOG);
+      if (url === '/api/chat/preferences/selection' && method === 'GET')
+        return json({ selection: null });
+      if (url === '/api/chat/preferences/selection' && method === 'PUT') {
+        return json(
+          {
+            code: 'model_unavailable',
+            message: 'nope',
+            selection: { harnessId: 'a', providerId: 'b', modelId: 'c' },
+          },
+          422,
+        );
+      }
+      return new Response('nf', { status: 404 });
+    });
+    vi.stubGlobal('fetch', fetchMock);
+
+    await mount();
+    await act(async () => {
+      value().selectHarness('pi');
+    });
+    await flush();
+    await act(async () => {
+      value().selectProvider('openai');
+    });
+    await act(async () => {
+      value().selectModel('openai', 'gpt-5');
+    });
+    await flush();
+
+    expect(value().modelId).toBe('gpt-5');
+    expect(value().persistError?.code).toBe('model_unavailable');
+    expect(value().persistError?.requested).toEqual({
+      harnessId: 'pi',
+      providerId: 'openai',
+      modelId: 'gpt-5',
+    });
+    expect(value().persistedSelection).toBeNull();
+    expect(value().canSend).toBe(false);
+  });
+
+  it('invalidates the model on a provider change and keeps send disabled until the new tuple persists', async () => {
+    installFetch({
+      harnesses: [{ id: 'pi', displayName: 'Pi', capabilities: [] }],
+      catalog: { body: PI_CATALOG },
+      selection: null,
+    });
+    await mount();
+    await act(async () => {
+      value().selectHarness('pi');
+    });
+    await flush();
+    await act(async () => {
+      value().selectProvider('openai');
+    });
+    await act(async () => {
+      value().selectModel('openai', 'gpt-5');
+    });
+    await flush();
+    // A valid provider-A tuple has persisted.
+    expect(value().canSend).toBe(true);
+    expect(value().persistedSelection).toEqual({
+      harnessId: 'pi',
+      providerId: 'openai',
+      modelId: 'gpt-5',
+    });
+
+    // Switching provider clears the model that no longer belongs to it.
+    await act(async () => {
+      value().selectProvider('anthropic');
+    });
+    expect(value().modelId).toBe('');
+    expect(value().canSend).toBe(false);
+
+    // Send stays disabled until the new exact provider-B tuple persists.
+    await act(async () => {
+      value().selectModel('anthropic', 'claude');
+    });
+    await flush();
+    expect(value().canSend).toBe(true);
+    expect(value().persistedSelection).toEqual({
+      harnessId: 'pi',
+      providerId: 'anthropic',
+      modelId: 'claude',
+    });
+    expect(value().projection).toEqual({ provider: 'anthropic', modelId: 'claude' });
+  });
+
+  it('does not enable send on a model pick until the PUT for that exact new tuple resolves', async () => {
+    installFetch({
+      harnesses: [{ id: 'pi', displayName: 'Pi', capabilities: [] }],
+      catalog: { body: PI_CATALOG },
+      selection: { harnessId: 'pi', providerId: 'openai', modelId: 'gpt-5' },
+      deferPut: true,
+    });
+    await mount();
+    // The persisted, in-catalog tuple is sendable after mount (no PUT needed).
+    expect(value().canSend).toBe(true);
+
+    await act(async () => {
+      value().selectProvider('anthropic');
+    });
+    expect(value().modelId).toBe('');
+    expect(value().canSend).toBe(false);
+
+    await act(async () => {
+      value().selectModel('anthropic', 'claude');
+    });
+    await flush();
+    // PUT for the new tuple is still in flight — send MUST stay disabled.
+    expect(value().canSend).toBe(false);
+
+    await act(async () => {
+      putDeferred?.resolve(
+        json({ selection: { harnessId: 'pi', providerId: 'anthropic', modelId: 'claude' } }),
+      );
+    });
+    await flush();
+    expect(value().canSend).toBe(true);
+    expect(value().projection).toEqual({ provider: 'anthropic', modelId: 'claude' });
+  });
+
+  it('never requests any /api/providers* endpoint across the whole flow', async () => {
+    const fetchMock = installFetch({
+      harnesses: [{ id: 'pi', displayName: 'Pi', capabilities: [] }],
+      catalog: { body: PI_CATALOG },
+      selection: { harnessId: 'pi', providerId: 'openai', modelId: 'gpt-5' },
+    });
+    await mount();
+    await act(async () => {
+      value().selectProvider('anthropic');
+    });
+    await act(async () => {
+      value().selectModel('anthropic', 'claude');
+    });
+    await flush();
+
+    for (const call of fetchMock.mock.calls) {
+      expect(String(call[0])).not.toContain('/api/providers');
+    }
+  });
+});

apps/web/src/spa/chat/use-harness-selection.ts

@@ -0,0 +1,216 @@
+import { useCallback, useEffect, useRef, useState } from 'react';
+import {
+  fetchCatalog,
+  fetchHarnesses,
+  fetchPersistedSelection,
+  persistSelection,
+  type SelectionErrorCode,
+} from './chat-api';
+import type { HarnessCatalog, HarnessSelection, HarnessSummary } from '@/lib/types';
+
+export interface HarnessPersistError {
+  code: SelectionErrorCode;
+  message: string;
+  /** The exact tuple the user requested — preserved so the failed selection
+   * stays visible rather than being silently dropped. */
+  requested: HarnessSelection;
+}
+
+export interface HarnessSelectionValue {
+  harnesses: HarnessSummary[];
+  catalog: HarnessCatalog | null;
+  /** True when the selected harness has no usable catalog (404/error). */
+  catalogUnavailable: boolean;
+  /** The working (displayed) selection, kept as three distinct ids. Empty
+   * strings mean "not chosen yet" — there is deliberately no first-row default. */
+  harnessId: string;
+  providerId: string;
+  modelId: string;
+  /** The last tuple confirmed persisted by the server, or null. */
+  persistedSelection: HarnessSelection | null;
+  /** True when a persisted selection references a model no longer present as an
+   * available catalog entry — it stays visibly displayed rather than dropped. */
+  isStale: boolean;
+  /** True ONLY once a full tuple has been confirmed persisted AND it is a
+   * currently-available catalog entry. Send stays disabled otherwise, so a send
+   * can never race ahead of successful persistence. */
+  canSend: boolean;
+  persistError: HarnessPersistError | null;
+  selectHarness: (harnessId: string) => void;
+  selectProvider: (providerId: string) => void;
+  /** Persist the EXACT catalog row's `{providerId, modelId}` — the caller
+   * resolves the composite option identity to the real entry and passes both
+   * ids, so a bare model id is never combined with ambient provider state. */
+  selectModel: (providerId: string, modelId: string) => void;
+  /** The compatibility `{provider, modelId}` projection for the legacy socket
+   * send path — derived ONLY from the validated persisted tuple, never from any
+   * free-text or unpersisted draft. Empty when nothing is sendable. */
+  projection: { provider?: string; modelId?: string };
+}
+
+/** A tuple is a currently-usable catalog option only when the catalog holds a
+ * matching, available entry — the single gate that keeps a stale/unavailable
+ * model from ever counting as sendable. */
+function isAvailableInCatalog(
+  selection: HarnessSelection | null,
+  catalog: HarnessCatalog | null,
+): boolean {
+  if (selection === null || catalog === null) return false;
+  return catalog.models.some(
+    (model) =>
+      model.providerId === selection.providerId &&
+      model.modelId === selection.modelId &&
+      model.availability === 'available',
+  );
+}
+
+function tuplesEqual(a: HarnessSelection | null, b: HarnessSelection | null): boolean {
+  if (a === null || b === null) return a === b;
+  return a.harnessId === b.harnessId && a.providerId === b.providerId && a.modelId === b.modelId;
+}
+
+/**
+ * Owns the harness/catalog/selection state for the chat composer: loads the
+ * harness list and any persisted tuple on mount, loads a harness's catalog when
+ * chosen, and PUT-persists the full `{harnessId, providerId, modelId}` tuple
+ * when a model is picked. It never auto-selects a catalog row, keeps a
+ * stale/unavailable persisted tuple visible, and only reports `canSend` true
+ * once a full tuple has actually persisted as an available catalog entry.
+ */
+export function useHarnessSelection(): HarnessSelectionValue {
+  const [harnesses, setHarnesses] = useState<HarnessSummary[]>([]);
+  const [catalog, setCatalog] = useState<HarnessCatalog | null>(null);
+  const [catalogUnavailable, setCatalogUnavailable] = useState(false);
+  const [harnessId, setHarnessId] = useState('');
+  const [providerId, setProviderId] = useState('');
+  const [modelId, setModelId] = useState('');
+  const [persistedSelection, setPersistedSelection] = useState<HarnessSelection | null>(null);
+  const [persistError, setPersistError] = useState<HarnessPersistError | null>(null);
+
+  // Monotonic request ids so a slow in-flight catalog/persist response can never
+  // overwrite the result of a newer request the user has since triggered.
+  const catalogRequestRef = useRef(0);
+  const persistRequestRef = useRef(0);
+
+  const loadCatalog = useCallback(async (id: string): Promise<void> => {
+    const requestId = catalogRequestRef.current + 1;
+    catalogRequestRef.current = requestId;
+    setCatalog(null);
+    setCatalogUnavailable(false);
+    const result = await fetchCatalog(id);
+    if (catalogRequestRef.current !== requestId) return;
+    if (result.ok) {
+      setCatalog(result.catalog);
+      setCatalogUnavailable(false);
+    } else {
+      setCatalog(null);
+      setCatalogUnavailable(true);
+    }
+  }, []);
+
+  useEffect(() => {
+    let active = true;
+    void (async (): Promise<void> => {
+      const [list, persisted] = await Promise.all([fetchHarnesses(), fetchPersistedSelection()]);
+      if (!active) return;
+      setHarnesses(list);
+      if (persisted !== null) {
+        // Adopt the persisted tuple as the displayed selection and load its
+        // catalog. If the model has since been retired, it still shows (stale).
+        setHarnessId(persisted.harnessId);
+        setProviderId(persisted.providerId);
+        setModelId(persisted.modelId);
+        setPersistedSelection(persisted);
+        await loadCatalog(persisted.harnessId);
+      }
+      // No persisted selection → nothing is auto-selected; the user must choose.
+    })();
+    return () => {
+      active = false;
+    };
+  }, [loadCatalog]);
+
+  const selectHarness = useCallback(
+    (id: string): void => {
+      setHarnessId(id);
+      // Changing harness invalidates the provider/model draft — never carry a
+      // model across harnesses.
+      setProviderId('');
+      setModelId('');
+      setPersistError(null);
+      void loadCatalog(id);
+    },
+    [loadCatalog],
+  );
+
+  const selectProvider = useCallback((id: string): void => {
+    setProviderId(id);
+    // A new provider invalidates the chosen model — no cross-provider carryover.
+    setModelId('');
+    setPersistError(null);
+  }, []);
+
+  const selectModel = useCallback(
+    (selectedProviderId: string, selectedModelId: string): void => {
+      // Bind the model to the EXACT catalog row's provider — never to ambient
+      // provider state — so two providers exposing the same modelId can never
+      // collide or mis-resolve. Keep the displayed provider consistent with the
+      // resolved row.
+      setProviderId(selectedProviderId);
+      setModelId(selectedModelId);
+      setPersistError(null);
+      const requested: HarnessSelection = {
+        harnessId,
+        providerId: selectedProviderId,
+        modelId: selectedModelId,
+      };
+      const requestId = persistRequestRef.current + 1;
+      persistRequestRef.current = requestId;
+      void (async (): Promise<void> => {
+        const result = await persistSelection(requested);
+        if (persistRequestRef.current !== requestId) return;
+        if (result.ok) {
+          setPersistedSelection(result.selection);
+          setPersistError(null);
+        } else {
+          // Leave persistedSelection unchanged (send stays disabled) and surface
+          // the typed error carrying the exact requested tuple.
+          setPersistError({
+            code: result.code,
+            message: result.message,
+            requested: result.requested,
+          });
+        }
+      })();
+    },
+    [harnessId],
+  );
+
+  const draft: HarnessSelection = { harnessId, providerId, modelId };
+  const isStale = persistedSelection !== null && !isAvailableInCatalog(persistedSelection, catalog);
+  const canSend =
+    persistedSelection !== null &&
+    !catalogUnavailable &&
+    tuplesEqual(draft, persistedSelection) &&
+    isAvailableInCatalog(persistedSelection, catalog);
+  const projection: { provider?: string; modelId?: string } = canSend
+    ? { provider: persistedSelection.providerId, modelId: persistedSelection.modelId }
+    : {};
+
+  return {
+    harnesses,
+    catalog,
+    catalogUnavailable,
+    harnessId,
+    providerId,
+    modelId,
+    persistedSelection,
+    isStale,
+    canSend,
+    persistError,
+    selectHarness,
+    selectProvider,
+    selectModel,
+    projection,
+  };
+}

apps/web/src/spa/pages/chat.spec.tsx

@@ -38,6 +38,76 @@ function findButton(container: HTMLElement, text: string): HTMLButtonElement {
   return button;
 }
 
+function jsonResponse(body: unknown, status = 200): Response {
+  return new Response(JSON.stringify(body), {
+    status,
+    headers: { 'Content-Type': 'application/json' },
+  });
+}
+
+const DEFAULT_CATALOG = {
+  harnessId: 'pi',
+  version: '2026-08-11',
+  fingerprint: 'fp',
+  models: [
+    {
+      harnessId: 'pi',
+      providerId: 'openai',
+      modelId: 'gpt-5',
+      displayName: 'GPT-5',
+      reasoningCapability: true,
+      inputTypes: ['text'],
+      authState: 'ready',
+      availability: 'available',
+    },
+    {
+      harnessId: 'pi',
+      providerId: 'anthropic',
+      modelId: 'claude',
+      displayName: 'Claude',
+      reasoningCapability: true,
+      inputTypes: ['text'],
+      authState: 'ready',
+      availability: 'available',
+    },
+  ],
+};
+
+/** A harness/catalog/selection HTTP stub for the chat-api the selection hook
+ * drives. `selection` seeds the persisted tuple returned by the GET (a valid
+ * in-catalog tuple by default, so `canSend` settles true after mount). */
+function harnessFetch(
+  selection: unknown = { harnessId: 'pi', providerId: 'openai', modelId: 'gpt-5' },
+): typeof fetch {
+  return vi.fn(async (input: unknown, init?: RequestInit) => {
+    const url = String(input);
+    const method = String(init?.method ?? 'GET').toUpperCase();
+    if (url === '/api/harnesses') {
+      return jsonResponse([{ id: 'pi', displayName: 'Pi', capabilities: [] }]);
+    }
+    if (url.startsWith('/api/harnesses/') && url.endsWith('/catalog')) {
+      return jsonResponse(DEFAULT_CATALOG);
+    }
+    if (url === '/api/chat/preferences/selection' && method === 'GET') {
+      return jsonResponse({ selection });
+    }
+    if (url === '/api/chat/preferences/selection' && method === 'PUT') {
+      return jsonResponse({ selection: JSON.parse(String(init?.body)) });
+    }
+    return new Response('not found', { status: 404 });
+  }) as unknown as typeof fetch;
+}
+
+/** Drains the selection hook's chained mount fetches (harnesses → selection →
+ * catalog) and any pending PUT so derived `canSend` settles before assertions. */
+async function flushAsync(times = 5): Promise<void> {
+  for (let i = 0; i < times; i += 1) {
+    await act(async () => {
+      await Promise.resolve();
+    });
+  }
+}
+
 let fake: ReturnType<typeof createFakeChatSocket>;
 let root: Root | null;
 let container: HTMLElement;
@@ -57,12 +127,16 @@ beforeEach(async () => {
   fake = createFakeChatSocket();
   getSocketMock.mockReset().mockReturnValue(fake.socket);
   destroySocketMock.mockReset();
+  vi.stubGlobal('fetch', harnessFetch());
   container = document.createElement('div');
   document.body.append(container);
   root = createRoot(container);
   await act(async () => {
     root?.render(<ChatPage />);
   });
+  // Settle the selection hook's mount fetches so the default in-catalog tuple
+  // persists and `canSend` is true for the existing send-path tests.
+  await flushAsync();
 });
 
 afterEach(async () => {
@@ -70,8 +144,23 @@ afterEach(async () => {
     root?.unmount();
   });
   document.body.replaceChildren();
+  vi.unstubAllGlobals();
 });
 
+/** Re-mounts ChatPage against a custom fetch stub (e.g. an unset selection) for
+ * tests that need a non-default selection scenario. */
+async function remountWithFetch(fetchImpl: typeof fetch): Promise<void> {
+  await act(async () => {
+    root?.unmount();
+  });
+  vi.stubGlobal('fetch', fetchImpl);
+  root = createRoot(container);
+  await act(async () => {
+    root?.render(<ChatPage />);
+  });
+  await flushAsync();
+}
+
 describe('ChatPage', () => {
   it('streams agent:text and agent:thinking, shows tool status, and finalizes on agent:end with usage', async () => {
     await act(async () => {
@@ -390,24 +479,62 @@ describe('ChatPage', () => {
     expect(container.querySelector('[role="alert"]')).toBeTruthy();
   });
 
-  it('sends a message with optional provider/model fields and emits abort from the Stop control', async () => {
+  it('renders harness and provider as separate selects (not merged) and no free-text provider/model inputs', async () => {
+    // The old free-text inputs are gone.
+    expect(container.querySelector('input[aria-label="Provider"]')).toBeNull();
+    expect(container.querySelector('input[aria-label="Model"]')).toBeNull();
+
+    const harnessSelect = container.querySelector(
+      'select[aria-label="Harness"]',
+    ) as HTMLSelectElement;
+    const providerSelect = container.querySelector(
+      'select[aria-label="Provider"]',
+    ) as HTMLSelectElement;
+    const modelSelect = container.querySelector('select[aria-label="Model"]') as HTMLSelectElement;
+    expect(harnessSelect).toBeTruthy();
+    expect(providerSelect).toBeTruthy();
+    expect(modelSelect).toBeTruthy();
+    // Harness and provider are distinct controls carrying distinct identifiers.
+    expect(harnessSelect).not.toBe(providerSelect);
+    expect([...harnessSelect.options].map((o) => o.value)).toContain('pi');
+    expect([...providerSelect.options].map((o) => o.value)).toContain('openai');
+    expect([...providerSelect.options].map((o) => o.value)).toContain('anthropic');
+    // The model options are catalog-derived (not hardcoded) and scoped to the
+    // selected provider (openai, from the persisted tuple) using a collision-safe
+    // composite identity — the anthropic row is absent, not a bare 'claude'.
+    const modelValues = [...modelSelect.options].map((o) => o.value);
+    expect(modelValues).toContain('openai:gpt-5');
+    expect(modelValues).not.toContain('anthropic:claude');
+    expect(modelValues).not.toContain('claude');
+  });
+
+  it('sends provider/model derived from the persisted catalog tuple (never free text) and emits abort from Stop', async () => {
     const textarea = container.querySelector(
       'textarea[aria-label="Message"]',
     ) as HTMLTextAreaElement;
-    const providerInput = container.querySelector(
-      'input[aria-label="Provider"]',
-    ) as HTMLInputElement;
-    const modelInput = container.querySelector('input[aria-label="Model"]') as HTMLInputElement;
 
     const stopButtonBefore = container.querySelector(
       'button[aria-label="Stop"]',
     ) as HTMLButtonElement;
     expect(stopButtonBefore.disabled).toBe(true);
 
+    // Choose a fresh tuple from the catalog and let it persist.
+    const providerSelect = container.querySelector(
+      'select[aria-label="Provider"]',
+    ) as HTMLSelectElement;
+    await act(async () => {
+      selectValue(providerSelect, 'anthropic');
+    });
+    const modelSelect = container.querySelector('select[aria-label="Model"]') as HTMLSelectElement;
+    await act(async () => {
+      // Composite provider+model option identity (provider was switched to
+      // anthropic above); the bare 'claude' no longer identifies an option.
+      selectValue(modelSelect, 'anthropic:claude');
+    });
+    await flushAsync();
+
     await act(async () => {
       setValue(textarea, 'hello there');
-      setValue(providerInput, 'anthropic');
-      setValue(modelInput, 'claude');
     });
     await act(async () => {
       textarea.dispatchEvent(
@@ -415,6 +542,7 @@ describe('ChatPage', () => {
       );
     });
 
+    // The projected provider/model come from the validated persisted tuple.
     expect(fake.emitted).toContainEqual({
       event: 'message',
       payload: {
@@ -443,6 +571,28 @@ describe('ChatPage', () => {
     expect(fake.emitted).toContainEqual({ event: 'abort', payload: { conversationId: 'c1' } });
   });
 
+  it('disables send until a selection has persisted — no send with an unset selection', async () => {
+    await remountWithFetch(harnessFetch(null));
+
+    const sendButton = findButton(container, 'Send');
+    const textarea = container.querySelector(
+      'textarea[aria-label="Message"]',
+    ) as HTMLTextAreaElement;
+
+    await act(async () => {
+      setValue(textarea, 'should not send');
+    });
+    // Content present, but no selection persisted → Send stays disabled.
+    expect(sendButton.disabled).toBe(true);
+
+    await act(async () => {
+      textarea.dispatchEvent(
+        new KeyboardEvent('keydown', { key: 'Enter', bubbles: true, cancelable: true }),
+      );
+    });
+    expect(fake.emitted.filter((e) => e.event === 'message')).toHaveLength(0);
+  });
+
   it('renders the session panel from a pre-ack session:info and keeps it visible after the later ack', async () => {
     const textarea = container.querySelector(
       'textarea[aria-label="Message"]',
@@ -620,6 +770,134 @@ describe('ChatPage', () => {
     expect(fake.emitted.filter((e) => e.event === 'message')).toHaveLength(1);
   });
 
+  it('scopes the model options to the intentionally selected provider (cross-provider models absent)', async () => {
+    await remountWithFetch(harnessFetch(null));
+
+    const harnessSelect = container.querySelector(
+      'select[aria-label="Harness"]',
+    ) as HTMLSelectElement;
+    await act(async () => {
+      selectValue(harnessSelect, 'pi');
+    });
+    await flushAsync();
+
+    const providerSelect = container.querySelector(
+      'select[aria-label="Provider"]',
+    ) as HTMLSelectElement;
+    await act(async () => {
+      selectValue(providerSelect, 'openai');
+    });
+
+    const modelSelect = container.querySelector('select[aria-label="Model"]') as HTMLSelectElement;
+    const optionValues = [...modelSelect.options].map((o) => o.value).filter((v) => v !== '');
+    // Only the selected provider's models are offered — provider B's model
+    // (anthropic:claude) is absent, so a user cannot pick across providers.
+    expect(optionValues).toEqual(['openai:gpt-5']);
+    expect(optionValues).not.toContain('anthropic:claude');
+  });
+
+  it('keeps identical modelIds under two providers distinct and resolves the pick to the exact tuple', async () => {
+    const COLLIDING_CATALOG = {
+      harnessId: 'pi',
+      version: '2026-08-11',
+      fingerprint: 'fp',
+      models: [
+        {
+          harnessId: 'pi',
+          providerId: 'alpha',
+          modelId: 'gpt-x',
+          displayName: 'Alpha GPT-X',
+          reasoningCapability: true,
+          inputTypes: ['text'],
+          authState: 'ready',
+          availability: 'available',
+        },
+        {
+          harnessId: 'pi',
+          providerId: 'beta',
+          modelId: 'gpt-x',
+          displayName: 'Beta GPT-X',
+          reasoningCapability: true,
+          inputTypes: ['text'],
+          authState: 'ready',
+          availability: 'available',
+        },
+      ],
+    };
+    const collidingFetch = vi.fn(async (input: unknown, init?: RequestInit) => {
+      const url = String(input);
+      const method = String(init?.method ?? 'GET').toUpperCase();
+      if (url === '/api/harnesses') {
+        return jsonResponse([{ id: 'pi', displayName: 'Pi', capabilities: [] }]);
+      }
+      if (url.startsWith('/api/harnesses/') && url.endsWith('/catalog')) {
+        return jsonResponse(COLLIDING_CATALOG);
+      }
+      if (url === '/api/chat/preferences/selection' && method === 'GET') {
+        return jsonResponse({ selection: null });
+      }
+      if (url === '/api/chat/preferences/selection' && method === 'PUT') {
+        return jsonResponse({ selection: JSON.parse(String(init?.body)) });
+      }
+      return new Response('not found', { status: 404 });
+    }) as unknown as typeof fetch;
+
+    await remountWithFetch(collidingFetch);
+
+    const harnessSelect = container.querySelector(
+      'select[aria-label="Harness"]',
+    ) as HTMLSelectElement;
+    await act(async () => {
+      selectValue(harnessSelect, 'pi');
+    });
+    await flushAsync();
+
+    const providerSelect = container.querySelector(
+      'select[aria-label="Provider"]',
+    ) as HTMLSelectElement;
+    await act(async () => {
+      selectValue(providerSelect, 'alpha');
+    });
+
+    const modelSelect = container.querySelector('select[aria-label="Model"]') as HTMLSelectElement;
+    // The colliding modelId is provider-qualified in the option value, never a
+    // bare id, so the two providers' 'gpt-x' rows are uniquely identifiable.
+    const optionValues = [...modelSelect.options].map((o) => o.value).filter((v) => v !== '');
+    expect(optionValues).toEqual(['alpha:gpt-x']);
+
+    await act(async () => {
+      selectValue(modelSelect, 'alpha:gpt-x');
+    });
+    await flushAsync();
+
+    // The controlled select highlights the alpha row via the composite identity.
+    expect(modelSelect.value).toBe('alpha:gpt-x');
+
+    const textarea = container.querySelector(
+      'textarea[aria-label="Message"]',
+    ) as HTMLTextAreaElement;
+    await act(async () => {
+      setValue(textarea, 'ping');
+    });
+    await act(async () => {
+      textarea.dispatchEvent(
+        new KeyboardEvent('keydown', { key: 'Enter', bubbles: true, cancelable: true }),
+      );
+    });
+
+    // The persisted/sent tuple resolves to provider alpha — NOT beta — even
+    // though the bare modelId 'gpt-x' exists under both providers.
+    expect(fake.emitted).toContainEqual({
+      event: 'message',
+      payload: {
+        conversationId: undefined,
+        content: 'ping',
+        provider: 'alpha',
+        modelId: 'gpt-x',
+      },
+    });
+  });
+
   it('removes socket handlers and tears down the socket on unmount, with no network calls', async () => {
     expect(fake.listeners.size).toBeGreaterThan(0);
 

apps/web/src/spa/pages/chat.tsx

@@ -6,6 +6,7 @@ import { asFiniteNumberOrNull, asString } from '@/spa/chat/runtime-guards';
 import { SessionPanel } from '@/spa/chat/session-panel';
 import { ToolCallList } from '@/spa/chat/tool-call-list';
 import { useChatConnection } from '@/spa/chat/use-chat-connection';
+import { useHarnessSelection } from '@/spa/chat/use-harness-selection';
 
 /** Renders a real value normally, but an honest "unavailable" label instead
  * of a fabricated `0` for a missing/malformed count — a real `0 tokens` and
@@ -23,6 +24,7 @@ function formatCost(value: unknown): string {
 
 export function ChatPage(): ReactElement {
   const { state, actions } = useChatConnection();
+  const harness = useHarnessSelection();
   const hasConversation = state.conversationId !== null;
 
   return (
@@ -86,6 +88,7 @@ export function ChatPage(): ReactElement {
         streaming={state.streaming}
         sending={state.sending}
         hasConversation={hasConversation}
+        harness={harness}
       />
     </div>
   );

docs/scratchpads/1019-zero-timeout-harness.md

@@ -0,0 +1,71 @@
+# #1019 — Zero-timeout queue-guard harness race
+
+- **Issue:** #1019 (parent status remains `believed-fixed, pending jarvis validation`; do not close)
+- **Branch:** `fix/1019-ci-queue-timeout-harness`
+- **Owner:** `be-coder-08`
+- **Base:** `origin/main` at `5916aeefd6ed12bcac086c6834c7f6c4ae38e1bc`
+- **Charter:** `/home/hermes/agent-work/tl-mosaic/CHARTER-1019-HARNESS-FIX.md`
+
+## Objective
+
+Make `test-ci-queue-wait-tristate.sh` deterministic without changing any asserted outcome. Remove the indiscriminate zero-timeout race, require every status-classification case to prove the provider was observed, and prove the harness-controlled virtual clock is active.
+
+## Scope
+
+- In scope: `packages/mosaic/framework/tools/git/test-ci-queue-wait-tristate.sh` only, plus this evidence scratchpad.
+- Out of scope: guard parsers, D2/D3 behavior, installer/reseed staleness, PR #1060, and issue closure.
+
+## Acceptance criteria
+
+1. RED deterministically reproduces deadline pre-emption before the provider call.
+2. Every case that intends status classification positively proves provider observation.
+3. Pending observes `pending` before deterministic virtual-time expiration.
+4. The virtual clock has a positive interception control; a broken-clock mutant makes the suite red.
+5. The exact CI-base image passes the final harness repeatedly with zero failures.
+6. Baseline gates, independent code/security review, exact-head CI, and coordinator-authorized squash merge pass.
+
+## Plan
+
+1. Add deterministic RED instrumentation for the known merge/provider-unreachable pre-emption.
+2. Replace global `-t 0` with a nonzero timeout interpreted under an event-driven virtual clock; stub sleep without wall waiting.
+3. Add provider-observation and virtual-clock positive controls without changing outcome assertions.
+4. Run focused shell checks, repeat in exact CI-base image, baseline gates, and independent reviews.
+5. Commit with both identity layers, queue-guard plus direct Woodpecker terminal-state verification, push, self-post PR, verify poster/head/CI, obtain coordinator merge authorization, then squash merge without closing #1019.
+
+## Budget
+
+- No explicit token cap supplied. Keep scope to one harness file and one scratchpad; stop/report at the charter's 60% context gate.
+
+## Evidence
+
+- RED, deterministic pre-provider expiry: `evidence/1019-harness-fix/red-pre-provider-expiry.log` — rc 1; merge/provider-unreachable got rc 124 instead of 75, omitted CANNOT_ASSERT, did not observe the status provider, and wrote no additional audit record (four named failures).
+- GREEN host focused harness: `evidence/1019-harness-fix/green-host.log` — rc 0, all outcome classes passed.
+- Load-bearing clock negative control: a temporary same-directory mutant replaced the virtual `date` body with `/bin/date`; `evidence/1019-harness-fix/red-clock-not-intercepted.log` — rc 1 with named `virtual clock interception did not run` failures. The mutant file was removed after the run.
+- Exact CI-base repeat: `git.mosaicstack.dev/mosaicstack/stack/ci-base:latest`, repository mounted read-only, harness work under container `/tmp`; `evidence/1019-harness-fix/ci-image-repeat/summary.log` — **100 pass / 0 fail / 100 total**.
+- Synchronization design: provider-status observation creates the event marker; virtual time is 1000 before the event and 1002 afterward. Pending alone reaches the stubbed no-op sleep and a post-observation deadline check. `-t 1` is uniquely load-bearing because removing it restores the 900-second default deadline at virtual time 1900, which 1002 does not cross. The numeric timeout is subject semantics under virtual time, not a wall-clock synchronization duration.
+
+## Review remediation — semantic timeout vs. liveness bound
+
+Security review found that virtual time remained at 1000 forever before provider observation and stubbed sleep never waited. A regression looping before the status endpoint—or blocking in the first provider call—therefore could prevent `run_guard` from returning, so the post-return provider assertion could never fire.
+
+**General rule:** A timeout usually serves two purposes: semantics and liveness. Removing wall time from semantic synchronization can silently remove the only independent hang bound. Preserve deterministic virtual time for subject semantics, but provide a separately implemented real-clock liveness watchdog and prove that watchdog fires.
+
+Remediation:
+
+- Every guard subject invocation is launched by absolute `/usr/bin/python3` in a new session. Python's internal monotonic `wait(timeout=...)` provides real-clock liveness independently of PATH; expiry kills the entire isolated process group, so neither PATH-front shims nor a blocked provider descendant can retain the capture pipe.
+- Watchdog expiry returns distinct harness rc 90 plus `FAIL HANG watchdog`, separate from subject timeout rc 124.
+- A first attempt using absolute `/usr/bin/timeout -s KILL` passed on GNU coreutils but failed in the exact Alpine CI-base image: BusyBox killed the immediate wrapper while the guard/provider descendants survived and retained the command-substitution pipe. The process-group kill is therefore required behavior, not portability polish.
+- A committed positive control hangs the branch-provider stub before the status endpoint. It must terminate through the watchdog, emit the hang-specific diagnostic, return rc 90, and prove the status provider was never reached.
+- RED before remediation: a temporary ordinary-success mutant hung before provider observation; only an external control could kill the suite (rc 137), and there was no internal hang-specific diagnostic (`red-watchdog-absent.log`).
+- The watchdog mutant/control is load-bearing: removing the internal watchdog leaves the control unable to produce its required rc 90 and diagnostic.
+
+Post-review evidence:
+
+- Host focused harness with process-group watchdog: rc 0 (`green-watchdog-process-group-host.log`).
+- Exact Alpine CI-base focused harness with process-group watchdog: rc 0 (`green-watchdog-ci-image.log`).
+- Hanging ordinary-success mutant: suite rc 1; success returned rc 90, emitted `FAIL HANG watchdog`, and loudly reported that provider/clock observation did not occur (`red-watchdog-fires.log`).
+- Removed-`-t 1` mutant: suite rc 1; pending was terminated by the watchdog instead of producing `ASSERTED_NOT_READY`, proving the explicit timeout is load-bearing (`red-timeout-argument-removed.log`).
+
+## 60% context hold
+
+Stopped before baseline/review/commit as required by the charter. Remaining: inspect final diff, shell/static/baseline gates, independent code/security review, remediation if any, identity-bound commit/trailer verification, mandatory queue guard plus direct terminal Woodpecker `mosaic` enumeration, push, self-posted PR/provider poster read-back, exact-head terminal-green CI, coordinator merge authorization, squash merge, main CI verification, and leave #1019 unclosed as `believed-fixed, pending jarvis validation`.

docs/scratchpads/lease-remediation/dispatch/measure-W-B.md

@@ -0,0 +1,93 @@
+# W-B — Measure Pi's real tool registry
+
+- **Task / internal ref:** W-B from the lease-remediation orchestrator brief (no matching `docs/TASKS.md` row; workers do not modify that file)
+- **Objective:** identify the exact tool names emitted as `event.toolName` by the installed Pi runtime and compare them with the broker's Pi read-only carve-out.
+- **Scope:** measurement and report only; no broker or runtime source changes. W-C is out of scope.
+- **Budget:** no explicit token cap; constrained to this scratchpad and one local commit.
+- **Installed runtime:** `@earendil-works/pi-coding-agent` / `pi` `0.84.1`.
+
+## Method
+
+I created a throwaway extension at `/tmp/measure-pi-tool-registry.ts` (not in the worktree). On `session_start` it recorded `pi.getAllTools()` and `pi.getActiveTools()`; on every `tool_call` it appended the exact `event.toolName`. I then launched an isolated, ephemeral Pi session with all built-ins explicitly selected:
+
+```text
+PI_OFFLINE=1 pi --mode print --no-session --no-approve \
+  --no-context-files --no-skills --no-prompt-templates --no-extensions \
+  -e /tmp/measure-pi-tool-registry.ts \
+  --tools read,bash,edit,write,grep,find,ls <deterministic probe prompt>
+```
+
+The prompt exercised file read, content search, file search, directory listing, shell execution, file write, and file edit. Pi exited `0`; every selected tool produced one `tool_call`. The write/edit control artifact ended with exact content `after`, proving the mutating calls executed in order.
+
+This runtime observation was cross-checked against the installed distribution's canonical registry at `dist/core/tools/index.js:17`, which declares the same seven names. The gate consumes the measured field directly at `packages/mosaic/framework/runtime/pi/mosaic-extension.ts:368`.
+
+## Exact distinct built-in set
+
+The installed Pi built-in registry is exactly:
+
+```text
+{bash, edit, find, grep, ls, read, write}
+```
+
+| Tool | Runtime registry observation | `tool_call` observation | Installed definition |
+| --- | --- | --- | --- |
+| `read` | `<builtin:read>` | observed once | `dist/core/tools/read.js:138` |
+| `bash` | `<builtin:bash>` | observed once | `dist/core/tools/bash.js:231` |
+| `edit` | `<builtin:edit>` | observed once | `dist/core/tools/edit.js:170` |
+| `write` | `<builtin:write>` | observed once | `dist/core/tools/write.js:138` |
+| `grep` | `<builtin:grep>` | observed once | `dist/core/tools/grep.js:79` |
+| `find` | `<builtin:find>` | observed once | `dist/core/tools/find.js:79` |
+| `ls` | `<builtin:ls>` | observed once | `dist/core/tools/ls.js:61` |
+
+The raw distinct `event.toolName` result was:
+
+```json
+["bash", "edit", "find", "grep", "ls", "read", "write"]
+```
+
+Pi registers all seven, but its default active set is only `read`, `bash`, `edit`, and `write` (`dist/core/sdk.js:132`). The probe explicitly activated all seven so the three search/list tools could be observed at the hook.
+
+## Positive control
+
+The known `read` tool was the control. The method surfaced it twice:
+
+1. `pi.getAllTools()` returned `read` with source path `<builtin:read>`.
+2. Reading `/tmp/pi-registry-probe/seed.txt`, which contained `CONTROL_TOKEN`, produced one hook record with `event.toolName === "read"`.
+
+The control was therefore positive; the seven-name result is measured, not an empty-probe inference.
+
+## Carve-out comparison and collision result
+
+The broker currently declares `{"read", "grep", "find", "ls"}` at `packages/mosaic/framework/tools/lease-broker/daemon.py:54`.
+
+- `read`: real built-in.
+- `grep`: real built-in.
+- `find`: real built-in.
+- `ls`: real built-in.
+
+All four carve-out names are exact, case-sensitive Pi tool names.
+
+The general execution/writing tool names are `bash`, `edit`, and `write`. Their intersection with the carve-out is empty:
+
+```text
+{bash, edit, write} ∩ {read, grep, find, ls} = ∅
+```
+
+Therefore no general shell-exec or file-mutating Pi tool shares a name with a carve-out entry. `grep` and `find` may invoke constrained search helpers internally, but neither exposes an arbitrary command interface; the arbitrary command tool is distinctly named `bash`.
+
+The Mosaic extension separately registers the non-built-in custom tool `mosaic_context_recover` at `packages/mosaic/framework/runtime/pi/mosaic-extension.ts:379`; the broker handles that identity through its dedicated recovery exemption rather than the read-only set (`daemon.py:722`). Unknown or third-party custom tools are not part of Pi's built-in seven-name registry and remain outside the carve-out.
+
+## Verification evidence
+
+- `pi --version` → `0.84.1`.
+- Isolated probe exit → `0`.
+- Runtime `getAllTools()` count → `7`, all with `sourceInfo.source === "builtin"`.
+- Distinct hook names → `bash`, `edit`, `find`, `grep`, `ls`, `read`, `write`.
+- Hook counts → exactly one call for each of the seven names.
+- Mutation artifact after `write` then `edit` → exact content `after`.
+- Installed registry source → `allToolNames = new Set(["read", "bash", "edit", "write", "grep", "find", "ls"])`.
+
+## Risks / limitations
+
+- The probe deliberately disabled all other extensions, so extension-defined third-party tools were excluded from the built-in registry measurement. The production gate still receives those names and treats names outside the broker carve-out as mutating/fail-closed.
+- Explicit `--tools` activation was required to exercise `grep`, `find`, and `ls`; this does not imply they are active in Pi's default four-tool configuration.

docs/scratchpads/pr-merge-message-field.md

@@ -0,0 +1,99 @@
+# PR merge squash message field
+
+- **Charter:** `/home/hermes/agent-work/CHARTER-PRMERGE-MESSAGE-FIELD.md`
+- **Owner:** `be-coder-08`
+- **Branch:** `fix/pr-merge-message-field`
+- **Base:** remote `main` / local `origin/main` at `85d2108e4ed15c744ad3b87a5b629e7b2d39405a`
+- **Estate:** HOMELAB tooling shared by HOMELAB and USC
+
+## Objective
+
+Add an optional, identity-checked Gitea squash message to `pr-merge.sh` so genuine multi-author PRs retain non-poster branch authors without weakening hardcoded squash behavior.
+
+## Binding requirements
+
+1. `Do` remains hardcoded to `squash`; no provider/repository default may select merge style.
+2. A verified trailer uses a PR commit's linked `author.login` and that same commit's author email. No `/users/{login}` primary-email lookup occurs. Recorded rationale: this asks only what the provider can answer.
+3. A commit with `author.login` null blocks before merge, prints both the null provider fact and commit email fact, and names the escalation principal.
+4. The BLOCK arm must be observed firing; a normal canonical single-author API payload remains explicit squash plus its reviewed `head_commit_id`.
+5. Every provider mutation is read back from the provider; no real PR is merged during tests.
+
+## Derived interface decisions
+
+- Add `--co-author-trailers` rather than accepting arbitrary message text. The wrapper enumerates PR commits and constructs trailers, making an unchecked `Co-authored-by` line unexpressible.
+- Require `--escalate-to PRINCIPAL` with `--co-author-trailers`, so the BLOCK diagnostic always names a principal rather than a generic role.
+- Do not expose `MergeTitleField` separately. When trailers exist, set it from the provider PR title and set `MergeMessageField` only to construction-generated trailers. This preserves one provider source for the title and avoids an unrelated caller-controlled degree of freedom.
+- Preserve first-commit order and emit one trailer per distinct non-poster `author.login`, using that first linked commit's own email.
+
+## Canonical delivery plan
+
+1. Port the capability into the installed source of truth, `packages/mosaic/framework/tools/git/pr-merge.sh`; do not retain `infra/fleet/tools/git` as a second copy.
+2. Preserve canonical `--expect-head`, exact head branch/repository/SHA queue inspection, Gitea atomic head pinning, GitHub `--match-head-commit`, and delete-after-merge semantics.
+3. Do not port the deployed-only `--skip-queue-guard` bypass. Add the focused harness to the canonical framework-shell suite and re-establish RED/GREEN on the packaged baseline.
+4. Deliver through a reviewed package release followed by `mosaic update` with its default framework reseed. The installer snapshots, manifest-syncs framework-owned `tools/**`, and rolls back on failure.
+5. Before either estate relies on the change, require installed/package hash equality, `MergeMessageField` presence, and a green focused harness. Release/reseed ownership is currently unassigned and blocks activation after source merge.
+
+## Evidence
+
+- RED against the byte-identical deployed baseline (`sha256 08a65e8584c5…`): rc 1 with eight named failures. The wrapper rejected `--co-author-trailers`; the null-login path emitted none of the required BLOCK facts/principal; and both verified/ordinary API paths failed the stdin-config credential assertion (ordinary path exposed the fixture token through curl argv). Log: `/home/hermes/agent-work/be-coder-08/evidence/prmerge-message-field-red.log`.
+- GREEN on the deployed-baseline candidate: verified linked multi-author payload, null-login BLOCK, required named principal, explicit squash, stdin-config token transport, and absence of `/users` lookup all passed. Log: `/home/hermes/agent-work/be-coder-08/evidence/prmerge-message-field-green.log`.
+- RED against canonical packaged baseline `c581ef48…`: rc 1 with 32 assertions. It rejects the new option, and the first harness version did not satisfy canonical head branch/repository/SHA metadata. Log: `/home/hermes/agent-work/be-coder-08/evidence/prmerge-packaged-baseline-red.log`. The port adapts the fixture rather than weakening canonical head controls.
+- Provider capability probe against `git.mosaicstack.dev`: authenticated `be-coder-08` POST to deliberately nonexistent PR `2147483647` with both message fields returned JSON HTTP 404; the unauthenticated same request returned JSON HTTP 401 (not the charter's predicted 403). The authenticated-vs-unauthenticated differential proves write authorization resolved while no mergeable subject existed. `tl-mosaic` ruled the literal non-load-bearing: preserve the observed 404/401 pair and do not manufacture a 403 case. No cause was inferred and no real PR was targeted.
+- Provider-generated trailer behavior is not treated as exclusive or absent. The wrapper's VERIFIED/BLOCK decision binds each requested non-poster trailer to commit `author.login` plus that commit's email; it does not assume `MergeMessageField` is the squash's only trailer source. The poster is omitted from the constructed list because the resulting squash author already records the poster; any additional provider-generated trailer is outside this change's unmeasured mechanism.
+- An early candidate SHA-256 `5de32876990e4f26920448cb3220cc7f1146d558b4dd2bc1ee1a2abee2f2cbe6` passed the initial harness, then author-side review found credential-fallback and argv-exposure defects. The live deployed wrapper was atomically restored to baseline SHA-256 `08a65e8584c52c6d41ea1c686f8b95585c21e4b37320a2447eba09359a0e02c1`; the remediated candidate remains only in the worktree.
+
+## Remediation and current review state
+
+1. Token and Basic Auth now use stdin curl configuration, not argv. PR title, contributor email, and the JSON payload also remain out of child argv.
+2. Each credential attempt binds commit inspection and merge. A token failure during either inspection or mutation causes Basic fallback to repeat inspection before mutation; the payload pins the inspected `head_commit_id`.
+3. Focused tests cover token-resolution fail-closed behavior, both HTTP-401 fallback seams, metadata/credential argv absence, null-login BLOCK, explicit squash, canonical reviewed-head binding, unchanged ordinary payload, and retained log-safe provider diagnostics. Token-resolution RED: `/home/hermes/agent-work/be-coder-08/evidence/prmerge-token-resolution-red.log`.
+4. Codex review rounds 3–5 requested retained provider error text, log-safe provider diagnostics, fail-closed credential fallback, stable value-option parsing, and PR-title trailer-injection prevention. These are remediated with regression assertions. A post-remediation independent review is still required.
+5. **Accepted linkage limitation:** `author.login` resolution proves that the commit address maps to a registered provider account. It does not prove that the named principal authored the commit because Git author metadata is self-asserted. This gate checks attribution linkage, not authorship; commit signing is out of scope and currently unadopted. Coordinators explicitly ruled that this does not add a third state.
+6. Codex's sandbox could not execute the harness because its checkout was read-only; that environmental limitation is recorded separately from host-side test results.
+
+## Disposable provider fixture acceptance
+
+- Use a retained scratch repository only, with two branch authors and `author != committer` on at least one commit.
+- Arm A supplies a message-field trailer for one non-poster; record whether that value lands without forcing the partial-pair result into under-specified `APPENDS`/`REPLACES` labels. Demonstrate an absence control.
+- Arm B includes a registered trailer for a different non-poster on a branch commit; record whether it survives or drops. Verify identity through an existing commit whose `author.login` resolves and demonstrate an absence control.
+- Parse landed trailers key-agnostically with `^[A-Za-z-]+-[Bb]y:` and record generated poster pair presence/absence plus resulting poster attribution.
+- Record `/users/<login>` status and raw email only as non-gating estate telemetry. Never read `active`, `visibility`, or any profile field as an identity gate.
+- Use distinct principals: poster `be-coder-08`, merger `Mos`, Arm A `be-coder-07`, and Arm B `be-coder-06`. Capture every trailer-shaped line verbatim and in order. Zero trailer lines means the generator did not fire and the run is `VOID`, not evidence that either arm dropped.
+- Report the same read-back evidence to `mos-claude` on socket `default` and `tl-mosaic` on socket `mosaic-fleet`. Report values rather than mechanism inferences and stop on any poster-attribution regression.
+
+## Fixture preflight
+
+- Retained public repository: `mosaicstack/prmerge-trailer-fixture`; PR `#1`, posted by `be-coder-08` and reserved for merge by `Mos`.
+- Existing `mosaicstack/stack` commits resolve `be-coder-07` and `be-coder-06` through `author.login`; exact addresses are `[email protected]` and `[email protected]`.
+- Non-gating HOMELAB telemetry for authenticated reader `be-coder-08`: `/api/v1/users/be-coder-06` returned HTTP 200 with raw `email` value `[email protected]`.
+- Provider preflight showed PR commit enumeration is newest-first. A new RED test proved that deriving `head_commit_id` from the final array element selected the wrong commit. The candidate now reads `.head.sha` from the authenticated PR endpoint before enumeration, verifies it appears in the commit set, and atomically pins that SHA in the explicit squash payload. RED: `/home/hermes/agent-work/be-coder-08/evidence/prmerge-head-order-red.log`.
+- Fixture PR head `f6ba6e5105031fa21f5ff7bd8e4379d99c16e1de` has `author.login=be-coder-07`, `committer.login=be-coder-08`, and branch-message trailer `Co-authored-by: be-coder-06 <[email protected]>`.
+
+## Fixture result
+
+- `Mos` merged retained fixture PR `#1` through staged candidate SHA-256 `60e779a85fd13b729d859ea7c986d1e9b1641b97991611329226c1b3113ffb6e`; resulting squash commit: `3f550715d9bc716426fd355a65fe997b3a90fa7d` with one parent.
+- Provider read-back: poster/commit author `be-coder-08`, committer/merger `Mos`. The run is non-void.
+- Trailer-shaped lines, verbatim and in order:
+  1. `Co-authored-by: be-coder-07 <[email protected]>`
+  2. `Co-authored-by: be-coder-08 <[email protected]>`
+- Arm A supplied field value (`be-coder-07`) landed. Arm B branch trailer (`be-coder-06`) dropped. Both fabricated absence controls remained absent. No `Co-committed-by:` line landed.
+- The candidate payload construction explicitly excludes the poster and supplied only the Arm A `be-coder-07` line. Therefore the landed poster line was provider-generated, not candidate-composed. The raw result supports `FIELD LANDS`, `BRANCH DROPS`, and `POSTER GENERATED`; it does not support a claim that candidate code supplied the poster. Evidence: `/home/hermes/agent-work/be-coder-08/evidence/prmerge-fixture-readback.log` and the retained provider object.
+- Retained fixture PR `#2` measured the N=2 shape needed by `#1030`: supplied `be-coder-07` then `be-coder-06`; both landed in that order, followed by the provider-generated poster line. No truncation or dedup occurred at N=2. Resulting squash: `39db9d13aed0…`.
+
+## Current hold point
+
+PR `mosaicstack/stack#1066` is open. Its first frozen head `f4b162fa…` was terminal-green in Woodpecker `mosaic` pipeline `#2225`, but that evidence becomes stale when the canonical port moves the head. The deployed wrapper remains baseline `08a65e85…`; no manual copy will occur. Canonical port tests, commit amendment, rebase, one guarded force-with-lease, exact-head CI, and new independent review remain. Even after source merge, activation remains blocked on an assigned package-release/reseed owner and installed-byte read-back.
+
+## Security review 96 remediation
+
+Exact reviewed predecessor head: `1ceb11058f64dd7f4a817ceb2124f980a1c4dd23`.
+
+RED-first focused harness produced 10 named failures: all curl calls lacked size/time/connect bounds; raw ESC email reached mutation; oversized and stalled curl failures were discarded and reached mutation; nonempty Basic output with resolver rc 91 authorized mutation.
+
+Security remediation:
+
+- Removed the cross-principal HTTP-401 Basic fallback. Both inspection-401 and merge-401 paths now refuse without Basic resolution or mutation; `get_gitea_basic_auth` references in the merge subject are 0.
+- Applied `--max-filesize`, `--max-time`, and `--connect-timeout` to all 3/3 provider curl sites and fail closed on curl transport rc at all 3/3 sites.
+- Required linked email bytes to be ASCII and printable before constructing `MergeMessageField`; guarded construction sites 1/1.
+
+GREEN: message-field, exact-head, empty-UID/API, queue branch/repository/SHA, bash syntax, ShellCheck, and diff check pass. R7 total-removal mutants went RED: email guard 3 rows; bound switches 1 row; transport-rc guards 4 rows; HTTP-401 refusal 3 rows. R7 bound: mutants prove total removal only; explicit denominators above prove site coverage.

packages/mosaic/framework/defaults/AGENTS.md

@@ -39,6 +39,7 @@ overwritten on upgrade. (Layer model: `constitution/LAYER-MODEL.md`.)
 | TypeScript strict typing                           | `guides/TYPESCRIPT.md`             |
 | QA / test strategy                                 | `guides/QA-TESTING.md`             |
 | Documentation (any code/API/auth/infra change)     | `guides/DOCUMENTATION.md`          |
+| Writing style (docs, comms, any prose)             | `guides/WRITING-STYLE.md`          |
 | Secrets / vault usage                              | `guides/VAULT-SECRETS.md`          |
 | Tool/credential reference (service CLIs, wrappers) | `guides/TOOLS-REFERENCE.md`        |
 | Memory protocol (OpenBrain capture/recall)         | `guides/MEMORY.md`                 |

packages/mosaic/framework/defaults/STANDARDS.md

@@ -27,6 +27,14 @@ Master/slave model:
 - Do not perform destructive git/file actions without explicit instruction.
 - Browser automation (Playwright, Cypress, Puppeteer) MUST run in headless mode. Never launch a visible browser — it collides with the user's display and active session.
 
+### Output standards (writing + code)
+
+- Technical documentation follows **MOS-STE** (Mosaic Simplified Technical English — an adapted ASD-STE100 profile): short sentences, one instruction per sentence, active voice, one word per meaning, one term per concept. Full rules: `~/.config/mosaic/guides/WRITING-STYLE.md`.
+- Apply MOS-STE **hardest to verification artifacts** (acceptance criteria, witness predicates, gate/alarm conditions). There an ambiguous term produces a false green, not just a confused reader.
+- Source code follows the **Google Style Guide** for the language.
+- User-facing comms follow the user's declared `communicationStyle` in `USER.md` "Communication Preferences" (`direct` | `friendly` | `formal`, default `direct`); `guides/WRITING-STYLE.md` §5 maps each value to output. The documentation standard does not change with user preference.
+- **Carve-out:** MOS-STE does NOT apply to content that must carry a specific human voice (letters, personal or marketing prose, voice-matched output). A declared voice profile wins.
+
 ### Secrets handling (HARD RULE)
 
 - Vault is the canonical source-of-truth for every secret in every environment. No exceptions.

packages/mosaic/framework/guides/WRITING-STYLE.md

@@ -0,0 +1,134 @@
+# Writing Style Standard — MOS-STE (MANDATORY)
+
+This guide defines how agents write. It sets one style standard per output type.
+It is written in the standard it defines, as a worked example.
+
+**Adapted, not compliant.** MOS-STE (Mosaic Simplified Technical English) is an
+adapted profile of ASD-STE100. Mosaic does not license or certify against
+ASD-STE100. Mosaic uses the load-bearing rules and fits them to agent work. This
+is the same stance Mosaic takes toward DO-178B/C: use the rigor, do not claim the
+certification.
+
+## Scope — which standard governs which output
+
+| Output type                                                                                                   | Standard                                                                    |
+| ------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------- |
+| Technical documentation (READMEs, runbooks, PRDs, procedures, ADRs, guides, acceptance criteria, design docs) | **MOS-STE** (this guide)                                                    |
+| Source code and code comments                                                                                 | **Google Style Guide** for the language (§4)                                |
+| Inter-agent comms                                                                                             | MOS-STE by default (concise, structured)                                    |
+| User-facing comms                                                                                             | **Per-user style choice** — read `USER.md` "Communication Preferences" (§5) |
+| End-user prose the user owns (marketing, letters, personal writing, voice-matched content)                    | The user's declared voice. MOS-STE does NOT apply.                          |
+
+**The user-voice carve-out is absolute.** Do not apply MOS-STE to content that
+must carry a specific human voice (for example a cover letter, a personal
+message, or marketing copy). That content needs the user's voice. MOS-STE would
+damage it. When a project declares a voice profile, that profile wins.
+
+## 1. Why one standard
+
+Agent documentation drifts across projects. Different agents use different terms,
+sentence styles, and structures for the same concept. Readers lose time.
+Assumptions hide in ambiguous prose. One standard gives agents a clear target. It
+gives reviewers a clear test.
+
+## 2. Where MOS-STE matters most — verification artifacts
+
+Apply MOS-STE hardest to acceptance criteria, witness predicates, gate
+definitions, and alarm conditions. In prose, an ambiguous term produces a
+confused reader. In a verification artifact, an ambiguous term produces a false
+green — a check that passes without testing the claim.
+
+The one-term-one-concept rule (rule 9) is the guard. When one word names two
+concepts in one predicate, the check can test the wrong concept and still pass.
+
+**Worked failure.** A rename used a witness predicate with three clauses: ref A
+present, ref B absent, tip committed from this host. Every clause tested the git
+_ref_ (the channel). The claim under test was about a _field inside the payload_.
+The word "beacon" named two concepts in one sentence. Deleting ref B was the next
+scheduled step. That step flips the last clause green and certifies a state in
+which the payload still names the wrong host. The predicate was one planned action
+away from a false green on its normal path. The payload field was never tested.
+
+Rule: when N failure modes share one observable, the observable is not a
+diagnostic. In a verification artifact, that ambiguity does not confuse a reader —
+it certifies the defect.
+
+## 3. MOS-STE rules
+
+### 3.1 Sentence rules
+
+1. Keep sentences short. Use 20 words or fewer for a procedure. Use 25 words or
+   fewer for a description. (Reasoning and doctrine prose relaxes this limit —
+   see §3.4. A future lint enforces §3.1, not §3.4.)
+2. Write one instruction per sentence. In a procedure, give one command per step.
+3. Use the active voice. Write "Run the script." Do not write "The script should
+   be run."
+4. Use the imperative for instructions. Start the sentence with the verb.
+5. Use simple verb tenses. Prefer the present tense. Avoid the perfect and
+   progressive tenses when a simple tense works.
+6. Do not use an `-ing` form when it makes the meaning unclear.
+7. Write positive statements. State what to do, not only what to avoid.
+
+### 3.2 Word rules
+
+8. Use one word for one meaning. Do not use the same word in two senses.
+9. Use one term for one concept. Do not use synonyms for variety. Example: choose
+   `secret`, `credential`, or `key` for each concept, and keep it.
+10. Use articles (`a`, `the`). Do not drop words to save space.
+11. Keep an approved-terms glossary per project. Add each domain noun and each
+    chosen verb. Technical names (for example `Vault`, `cgroup`, `systemd`) are
+    always allowed.
+12. Define an abbreviation at its first use. Then use it consistently.
+
+### 3.3 Structure rules
+
+13. Use a list for parallel items or sequential steps. Do not put them in one long
+    sentence.
+14. Use a table for data with more than two dimensions.
+15. Use parallel structure in headings and steps.
+16. Repeat the noun. Do not use a pronoun when the reference is unclear.
+
+### 3.4 Adaptation notes (where MOS-STE deviates from ASD-STE100, and why)
+
+- **No licensed dictionary.** ASD-STE100 ships a controlled dictionary under
+  copyright. MOS-STE uses per-project glossaries instead (rule 11).
+- **Domain terms are allowed.** MOS-STE keeps every term the work needs.
+- **Reasoning prose gets structure, not amputation.** Apply the sentence and word
+  rules to design and doctrine writing. Allow the length a subtle argument needs.
+  Readable-first beats rule-strict when the two conflict.
+
+## 4. Code — Google Style Guide
+
+Write source code to the Google Style Guide for the language (Python, TypeScript,
+Shell, Go, and so on). Match the existing file when a local convention already
+exists. Keep code comments to the MOS-STE sentence and word rules.
+
+## 5. User-facing comms — a per-user choice
+
+Mosaic is multi-user. Different users want different comms styles. The framework
+already carries the selectable setting: `communicationStyle` (`direct` |
+`friendly` | `formal`, default `direct`). `mosaic init` writes it, and the
+builder renders it into the generated `USER.md` "Communication Preferences"
+section. This guide adds the OUTPUT meaning of each value; do not invent new
+values.
+
+The builder renders the style as prose bullets, not the token name, so match on
+the leading bullet the generated `USER.md` actually contains:
+
+| `USER.md` leading bullet      | Style              | User-facing output                                                     |
+| ----------------------------- | ------------------ | ---------------------------------------------------------------------- |
+| "Direct and concise"          | `direct` (default) | MOS-STE structure — short, active, defined terms, tables for overview. |
+| "Warm and conversational"     | `friendly`         | Warmer register. Full sentences, explain reasoning, fewer tables.      |
+| "Professional and structured" | `formal`           | Professional and structured. Thorough, with explicit recommendations.  |
+
+This setting governs **user-facing comms only**. It does not change the
+documentation standard (§3), which is always MOS-STE regardless of the value.
+
+## 6. Enforcement
+
+- **Now:** human review only. **No mechanical prose check exists today.** The
+  pre-push gate runs typecheck, lint, build, and tests; it inspects no prose.
+  Reviewers check output against the scope table and the MOS-STE rules by hand.
+- **Future:** an MOS-STE lint check (built from the §3.1 sentence rules) and a
+  Google-style linter in the pre-push gate. A future linter enforces §3.1, not
+  §3.4 — see the note at rule 1.

packages/mosaic/framework/runtime/claude/commands/mosaic-promote.md

@@ -0,0 +1 @@
+Mosaic lease promotion was processed mechanically; no action is needed.

packages/mosaic/framework/runtime/claude/settings.json

@@ -32,6 +32,18 @@
         ]
       }
     ],
+    "UserPromptSubmit": [
+      {
+        "matcher": "^/mosaic-promote$",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "python3 ~/.config/mosaic/tools/lease-broker/promote-begin.py",
+            "timeout": 15
+          }
+        ]
+      }
+    ],
     "PreToolUse": [
       {
         "matcher": ".*",
@@ -81,8 +93,8 @@
         "hooks": [
           {
             "type": "command",
-            "command": "python3 ~/.config/mosaic/tools/lease-broker/receipt-observer-client.py --runtime claude --latest-entry",
+            "command": "python3 ~/.config/mosaic/tools/lease-broker/receipt-observer-client.py --runtime claude --latest-entry; observer_status=$?; python3 ~/.config/mosaic/tools/lease-broker/promote-complete.py; exit $observer_status",
-            "timeout": 3
+            "timeout": 15
           },
           {
             "type": "command",

packages/mosaic/framework/tools/_scripts/mosaic-link-runtime-assets

@@ -233,6 +233,14 @@ for runtime_file in \
   copy_file_managed "$src" "$HOME/.claude/$runtime_file"
 done
 
+if [[ -d "$MOSAIC_HOME/runtime/claude/commands" ]]; then
+  mkdir -p "$HOME/.claude/commands"
+  for command_file in "$MOSAIC_HOME/runtime/claude/commands/"*; do
+    [[ -f "$command_file" ]] || continue
+    copy_file_managed "$command_file" "$HOME/.claude/commands/$(basename "$command_file")"
+  done
+fi
+
 # OpenCode runtime adapter (thin pointer to AGENTS.md)
 opencode_adapter="$MOSAIC_HOME/runtime/opencode/AGENTS.md"
 if [[ -f "$opencode_adapter" ]]; then

packages/mosaic/framework/tools/_scripts/mosaic-sync-skills

@@ -153,7 +153,24 @@ if [[ $link_only -eq 1 ]]; then
   exit 0
 fi
 
+# Skills are linked into the MOSAIC-OWNED harness homes, never a base install.
+# Paths mirror the config-dir env vars the launcher injects (HARNESS_HOME_ENV in
+# commands/launch.js):
+#   claude   CLAUDE_CONFIG_DIR      -> <home>/skills
+#   pi       PI_CODING_AGENT_DIR    -> <home>/skills   (replaces ~/.pi/agent)
+#   codex    CODEX_HOME             -> <home>/skills
+#   opencode XDG_CONFIG_HOME        -> <home>/opencode/skills  (XDG adds a level)
 link_targets=(
+  "$MOSAIC_HOME/.claude/skills"
+  "$MOSAIC_HOME/.codex/skills"
+  "$MOSAIC_HOME/.opencode/opencode/skills"
+  "$MOSAIC_HOME/.pi/skills"
+)
+
+# Pre-isolation installs planted the same symlink farm directly in the operator's
+# base installs. Those are now orphaned: the launcher no longer reads them, but
+# they persist and make a "clean" base install look mosaic-managed.
+legacy_link_targets=(
   "$HOME/.claude/skills"
   "$HOME/.codex/skills"
   "$HOME/.config/opencode/skills"
@@ -245,13 +262,72 @@ prune_stale_links_in_target() {
     # -m resolves lexical dangling targets too. If resolution fails, ownership
     # is unproven and the link must be preserved.
     resolved="$(readlink -m "$link_path" 2>/dev/null || true)"
-    if [[ -n "$resolved" && "$resolved" == "$canonical_real/"* ]]; then
+    # $canonical_real must be length-checked BEFORE use as a prefix: if it were
+    # ever empty, "$resolved" == "$canonical_real/"* collapses to == "/"* and
+    # matches every absolute path. Combined with the is_mosaic_skill_name skip
+    # above, that inverts the function precisely — it would delete exactly the
+    # FOREIGN symlinks and keep the mosaic ones. (#1087, reported by mos-claude.)
+    if [[ -n "$resolved" && -n "$canonical_real" && "$resolved" == "$canonical_real/"* ]]; then
       rm -f "$link_path"
       echo "[mosaic-skills] Removed stale retired skill link: $link_path"
     fi
   done < <(find "$target_dir" -mindepth 1 -maxdepth 1 -type l -print0)
 }
 
+# Remove mosaic-owned symlinks left in a base install by a pre-isolation sync.
+#
+# Ownership is proven by RESOLUTION, not by name: only links resolving inside the
+# canonical or local skills dirs are removed. Anything else — a real directory, a
+# link elsewhere, an unresolvable link — is left untouched. This mirrors the
+# refusal in commands/skill.js ("only symlinks pointing inside the Mosaic skills
+# directory are managed") and preserves e.g. codex's own `.system` dir.
+#
+# The directory itself is kept: mosaic-doctor warns when ~/.pi/agent/skills is
+# missing, and an empty dir is the correct end state, not an absent one.
+cleanup_legacy_target() {
+  local target_dir="$1"
+  local removed=0 kept=0
+
+  [[ -d "$target_dir" ]] || return 0
+
+  while IFS= read -r -d '' link_path; do
+    local resolved owned=0
+    resolved="$(readlink -m "$link_path" 2>/dev/null || true)"
+
+    # Guard the empty-prefix trap: an unset *_real would make "$resolved" == "/"*
+    # match every absolute path and delete foreign links.
+    if [[ -n "$resolved" ]]; then
+      if [[ -n "$canonical_real" && "$resolved" == "$canonical_real/"* ]]; then
+        owned=1
+      elif [[ -n "$local_real" && "$resolved" == "$local_real/"* ]]; then
+        owned=1
+      fi
+    fi
+
+    if [[ $owned -eq 1 ]]; then
+      rm -f "$link_path"
+      removed=$((removed + 1))
+    else
+      kept=$((kept + 1))
+    fi
+  done < <(find "$target_dir" -mindepth 1 -maxdepth 1 -type l -print0)
+
+  if [[ $removed -gt 0 ]]; then
+    echo "[mosaic-skills] Legacy cleanup: removed $removed mosaic symlink(s) from $target_dir (preserved $kept foreign)"
+  fi
+}
+
+for legacy in "${legacy_link_targets[@]}"; do
+  # Skip anything that is also a current target, so isolation can never
+  # self-destruct if the two lists ever overlap.
+  skip=0
+  for target in "${link_targets[@]}"; do
+    [[ "$legacy" == "$target" ]] && skip=1
+  done
+  [[ $skip -eq 1 ]] && continue
+  cleanup_legacy_target "$legacy"
+done
+
 for target in "${link_targets[@]}"; do
   mkdir -p "$target"
 

packages/mosaic/framework/tools/git/pr-merge.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 # pr-merge.sh - Merge pull requests on Gitea or GitHub
-# Usage: pr-merge.sh -n PR_NUMBER [-m squash] [-d]
+# Usage: pr-merge.sh -n PR_NUMBER [-m squash] [-d] [--expect-head SHA] [--co-author-trailers --escalate-to PRINCIPAL]
 
 set -euo pipefail
 
@@ -14,6 +14,8 @@ MERGE_METHOD="squash"
 DELETE_BRANCH=false
 DRY_RUN=false
 EXPECT_HEAD=""
+CO_AUTHOR_TRAILERS=false
+ESCALATE_TO=""
 
 usage() {
     cat <<EOF
@@ -27,12 +29,16 @@ Options:
     -d, --delete-branch     Delete the head branch after merge
         --dry-run           Run metadata/login preflight without merging
         --expect-head SHA   Refuse unless the PR head matches this full commit SHA
+        --co-author-trailers Build verified trailers from linked PR commit authors
+        --escalate-to NAME  Named principal for an unresolved-author BLOCK
     -h, --help              Show this help message
 
 Examples:
     $(basename "$0") -n 42                    # Merge PR #42
     $(basename "$0") -n 42 -m squash          # Squash merge
     $(basename "$0") -n 42 -d                 # Squash merge and delete branch
+    $(basename "$0") -n 42 --expect-head 0123456789abcdef0123456789abcdef01234567
+    $(basename "$0") -n 42 --co-author-trailers --escalate-to tl-mosaic
 EOF
     exit "${1:-1}"
 }
@@ -57,9 +63,25 @@ while [[ $# -gt 0 ]]; do
             shift
             ;;
         --expect-head)
+            if [[ $# -lt 2 ]]; then
+                echo "Error: --expect-head requires one full commit SHA." >&2
+                exit 1
+            fi
             EXPECT_HEAD="$2"
             shift 2
             ;;
+        --co-author-trailers)
+            CO_AUTHOR_TRAILERS=true
+            shift
+            ;;
+        --escalate-to)
+            if [[ $# -lt 2 ]]; then
+                echo "Error: --escalate-to requires one principal name." >&2
+                exit 1
+            fi
+            ESCALATE_TO="$2"
+            shift 2
+            ;;
         -h|--help)
             usage 0
             ;;
@@ -88,17 +110,30 @@ if [[ -n "$EXPECT_HEAD" && ! "$EXPECT_HEAD" =~ ^[0-9a-fA-F]{40}$ ]]; then
     echo "Error: --expect-head must be a full 40-character hexadecimal commit SHA." >&2
     exit 1
 fi
+if [[ "$CO_AUTHOR_TRAILERS" == true && -z "$ESCALATE_TO" ]]; then
+    echo "Error: --co-author-trailers requires --escalate-to with a named principal." >&2
+    exit 1
+fi
+if [[ -n "$ESCALATE_TO" && ! "$ESCALATE_TO" =~ ^[A-Za-z0-9_.-]+$ ]]; then
+    echo "Error: --escalate-to must be one exact principal name." >&2
+    exit 1
+fi
+if [[ "$CO_AUTHOR_TRAILERS" != true && -n "$ESCALATE_TO" ]]; then
+    echo "Error: --escalate-to is valid only with --co-author-trailers." >&2
+    exit 1
+fi
 
 PR_METADATA="$("$SCRIPT_DIR/pr-metadata.sh" -n "$PR_NUMBER")"
 BASE_BRANCH="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; print((json.load(sys.stdin).get("baseRefName") or "").strip())')"
 HEAD_BRANCH="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; print((json.load(sys.stdin).get("headRefName") or "").strip())')"
 HEAD_SHA="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; print((json.load(sys.stdin).get("headRefOid") or "").strip())')"
 HEAD_REPO="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; value=json.load(sys.stdin).get("headRepository") or ""; print((value.get("nameWithOwner") or value.get("full_name") or "") if isinstance(value, dict) else str(value).strip())')"
+PR_TITLE="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; print((json.load(sys.stdin).get("title") or "").strip())')"
+PR_AUTHOR="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; value=json.load(sys.stdin).get("author") or ""; print((value.get("login") or "").strip() if isinstance(value, dict) else str(value).strip())')"
 if [[ "$BASE_BRANCH" != "main" && "$BASE_BRANCH" != "next" ]]; then
     echo "Error: Mosaic policy allows merges only for PRs targeting 'main' or 'next' (found '$BASE_BRANCH')." >&2
     exit 1
 fi
-
 if [[ -z "$HEAD_BRANCH" || -z "$HEAD_REPO" || ! "$HEAD_SHA" =~ ^[0-9a-fA-F]{40}$ ]]; then
     echo "Error: Could not resolve the PR head branch, repository, and full commit SHA for queue inspection." >&2
     exit 1
@@ -122,70 +157,442 @@ PLATFORM=$(detect_platform)
 OWNER=$(get_repo_owner)
 REPO=$(get_repo_name)
 
-merge_gitea_with_api() {
+write_curl_auth_config() {
-    local host="$1" api_url token basic_auth body_file raw_code payload
+    local mode="$1" credential="$2"
-    api_url="https://${host}/api/v1/repos/${OWNER}/${REPO}/pulls/${PR_NUMBER}/merge"
+    printf '%s' "$credential" | python3 -c '
-    mkdir -p "${AGENT_WORK_ROOT:-${HOME:-/tmp}/mosaic/agent-work}"
+import sys
-    body_file=$(mktemp "${AGENT_WORK_ROOT:-${HOME:-/tmp}/mosaic/agent-work}/pr-merge-api-response.XXXXXX")
+mode = sys.argv[1]
-    payload=$(python3 - "$HEAD_SHA" "$DELETE_BRANCH" <<'PY'
+credential = sys.stdin.read()
+if not credential or any(char in credential for char in "\r\n"):
+    raise SystemExit(1)
+escaped = credential.replace("\\", "\\\\").replace("\"", "\\\"")
+if mode == "token":
+    print(f"header = \"Authorization: token {escaped}\"")
+elif mode == "basic":
+    print(f"user = \"{escaped}\"")
+else:
+    raise SystemExit(1)
+' "$mode"
+}
+
+LAST_GITEA_HTTP_CODE="000"
+LAST_GITEA_ERROR=""
+MERGE_TEMP_DIRS=()
+GITEA_CURL_MAX_BYTES="${MOSAIC_GITEA_CURL_MAX_BYTES:-1048576}"
+GITEA_CURL_MAX_TIME="${MOSAIC_GITEA_CURL_MAX_TIME_SEC:-30}"
+GITEA_CURL_CONNECT_TIMEOUT="${MOSAIC_GITEA_CURL_CONNECT_TIMEOUT_SEC:-10}"
+for bound in "$GITEA_CURL_MAX_BYTES" "$GITEA_CURL_MAX_TIME" "$GITEA_CURL_CONNECT_TIMEOUT"; do
+    if [[ ! "$bound" =~ ^[1-9][0-9]*$ ]]; then
+        echo "Error: Gitea curl bounds must be positive integers; refusing request." >&2
+        exit 1
+    fi
+done
+GITEA_CURL_BOUNDS=(
+    --max-filesize "$GITEA_CURL_MAX_BYTES"
+    --max-time "$GITEA_CURL_MAX_TIME"
+    --connect-timeout "$GITEA_CURL_CONNECT_TIMEOUT"
+)
+
+format_gitea_error_response() {
+    local response_file="$1"
+    python3 - "$response_file" <<'PY'
 import json
 import sys
 
-head_sha, delete_branch = sys.argv[1:]
+with open(sys.argv[1], "rb") as handle:
+    raw = handle.read(65536)
+try:
+    response = json.loads(raw.decode("utf-8", errors="replace"))
+except (UnicodeDecodeError, json.JSONDecodeError):
+    message = "non-JSON response omitted"
+else:
+    if isinstance(response, dict):
+        message = response.get("message") or response.get("error")
+        if not message and response.get("errors") is not None:
+            message = json.dumps(response["errors"], separators=(",", ":"))
+    else:
+        message = None
+    if not message:
+        message = "JSON response contained no error message"
+message = str(message)
+if len(message) > 500:
+    message = message[:500] + "..."
+print(ascii(message))
+PY
+}
+
+cleanup_merge_temp_dirs() {
+    local path
+    for path in "${MERGE_TEMP_DIRS[@]}"; do
+        [[ -n "$path" ]] && rm -rf -- "$path"
+    done
+}
+trap cleanup_merge_temp_dirs EXIT
+trap 'exit 130' INT
+trap 'exit 143' TERM
+
+fetch_gitea_pr_head() {
+    local host="$1" auth_mode="$2" credential="$3" work_root="$4"
+    local response_file raw_code api_url auth_config curl_rc
+    response_file=$(mktemp "$work_root/pr-merge-pr.XXXXXX")
+    api_url="https://${host}/api/v1/repos/${OWNER}/${REPO}/pulls/${PR_NUMBER}"
+    if ! auth_config=$(write_curl_auth_config "$auth_mode" "$credential"); then
+        echo "Error: Could not construct Gitea authentication config; refusing request." >&2
+        rm -f "$response_file"
+        return 1
+    fi
+    raw_code=$(curl -sS -K - "${GITEA_CURL_BOUNDS[@]}" -w '%{http_code}' -o "$response_file" \
+        -H "User-Agent: curl/8" "$api_url" <<<"$auth_config")
+    curl_rc=$?
+    LAST_GITEA_HTTP_CODE="${raw_code:-000}"
+    if [[ "$curl_rc" -ne 0 ]]; then
+        LAST_GITEA_ERROR="curl transport failed (rc=$curl_rc)"
+        rm -f "$response_file"
+        return 1
+    fi
+    if [[ ! "$raw_code" =~ ^2 ]]; then
+        LAST_GITEA_ERROR=$(format_gitea_error_response "$response_file")
+        rm -f "$response_file"
+        return 1
+    fi
+    if ! python3 - "$response_file" <<'PY'
+import json
+import re
+import sys
+
+with open(sys.argv[1], encoding="utf-8") as handle:
+    pull = json.load(handle)
+head = pull.get("head") if isinstance(pull, dict) else None
+sha = str(head.get("sha") or "") if isinstance(head, dict) else ""
+if not re.fullmatch(r"[0-9a-fA-F]{40}", sha):
+    raise SystemExit(1)
+print(sha)
+PY
+    then
+        echo "Error: Gitea PR response has no valid head SHA; refusing merge." >&2
+        rm -f "$response_file"
+        return 1
+    fi
+    rm -f "$response_file"
+}
+
+fetch_gitea_pr_commits() {
+    local host="$1" auth_mode="$2" credential="$3" work_root="$4"
+    local page page_file combined_file merged_file raw_code page_count api_url auth_config curl_rc
+    mkdir -p "$work_root"
+    if ! auth_config=$(write_curl_auth_config "$auth_mode" "$credential"); then
+        echo "Error: Could not construct Gitea authentication config; refusing request." >&2
+        return 1
+    fi
+    combined_file=$(mktemp "$work_root/pr-merge-commits.XXXXXX")
+    printf '[]' > "$combined_file"
+
+    page=1
+    while true; do
+        page_file=$(mktemp "$work_root/pr-merge-commits-page.XXXXXX")
+        api_url="https://${host}/api/v1/repos/${OWNER}/${REPO}/pulls/${PR_NUMBER}/commits?limit=50&page=${page}"
+        raw_code=$(curl -sS -K - "${GITEA_CURL_BOUNDS[@]}" -w '%{http_code}' -o "$page_file" \
+            -H "User-Agent: curl/8" "$api_url" <<<"$auth_config")
+        curl_rc=$?
+        LAST_GITEA_HTTP_CODE="${raw_code:-000}"
+        if [[ "$curl_rc" -ne 0 ]]; then
+            LAST_GITEA_ERROR="curl transport failed (rc=$curl_rc)"
+            rm -f "$page_file" "$combined_file"
+            return 1
+        fi
+        if [[ ! "$raw_code" =~ ^2 ]]; then
+            LAST_GITEA_ERROR=$(format_gitea_error_response "$page_file")
+            rm -f "$page_file" "$combined_file"
+            return 1
+        fi
+
+        if ! page_count=$(python3 - "$page_file" <<'PY'
+import json
+import sys
+
+with open(sys.argv[1], encoding="utf-8") as handle:
+    page = json.load(handle)
+if not isinstance(page, list):
+    raise SystemExit(1)
+print(len(page))
+PY
+        ); then
+            echo "Error: Gitea PR commits response is not a JSON array; refusing merge." >&2
+            rm -f "$page_file" "$combined_file"
+            return 1
+        fi
+
+        merged_file=$(mktemp "$work_root/pr-merge-commits-merged.XXXXXX")
+        if ! python3 - "$combined_file" "$page_file" > "$merged_file" <<'PY'
+import json
+import sys
+
+with open(sys.argv[1], encoding="utf-8") as handle:
+    combined = json.load(handle)
+with open(sys.argv[2], encoding="utf-8") as handle:
+    page = json.load(handle)
+json.dump(combined + page, sys.stdout, separators=(",", ":"))
+PY
+        then
+            echo "Error: Could not combine paginated PR commit metadata; refusing merge." >&2
+            rm -f "$page_file" "$combined_file" "$merged_file"
+            return 1
+        fi
+        mv "$merged_file" "$combined_file"
+        rm -f "$page_file"
+
+        if [[ "$page_count" -lt 50 ]]; then
+            break
+        fi
+        page=$((page + 1))
+        if [[ "$page" -gt 1000 ]]; then
+            echo "Error: PR commit pagination exceeded 1000 pages; refusing merge." >&2
+            rm -f "$combined_file"
+            return 1
+        fi
+    done
+
+    cat "$combined_file"
+    rm -f "$combined_file"
+}
+
+# LIMITATION: author.login resolution proves the commit address maps to a registered account.
+# It does NOT prove the named principal authored the commit — git author metadata is self-asserted.
+# This gate checks ATTRIBUTION LINKAGE, not AUTHORSHIP. Commit signing is out of scope and unadopted.
+build_coauthor_message_fields() {
+    local commits_file="$1" context_file="$2" head_file="$3"
+    python3 - "$commits_file" "$context_file" "$head_file" <<'PY'
+import json
+import re
+import sys
+
+commits_path, context_path, head_path = sys.argv[1:]
+with open(commits_path, encoding="utf-8") as handle:
+    commits = json.load(handle)
+head_sha = open(head_path, encoding="utf-8").read().strip()
+context_parts = open(context_path, "rb").read().split(b"\0")
+if len(context_parts) != 4 or context_parts[-1] != b"":
+    raise SystemExit(1)
+poster, title, principal = (part.decode("utf-8") for part in context_parts[:3])
+
+if not isinstance(commits, list) or not commits:
+    print(
+        f"BLOCK: provider returned no PR commits; author identity is unmeasurable. "
+        f"Refusing merge; escalate to named principal '{principal}'.",
+        file=sys.stderr,
+    )
+    raise SystemExit(75)
+if not poster:
+    print(
+        f"BLOCK: PR poster login is empty; refusing merge; "
+        f"escalate to named principal '{principal}'.",
+        file=sys.stderr,
+    )
+    raise SystemExit(75)
+
+if not re.fullmatch(r"[0-9a-fA-F]{40}", head_sha):
+    print(
+        f"BLOCK: inspected PR head SHA is invalid; refusing merge; "
+        f"escalate to named principal '{principal}'.",
+        file=sys.stderr,
+    )
+    raise SystemExit(75)
+
+seen = set()
+trailers = []
+head_seen = False
+for item in commits:
+    if not isinstance(item, dict):
+        print(f"BLOCK: malformed PR commit metadata; escalate to named principal '{principal}'.", file=sys.stderr)
+        raise SystemExit(75)
+    sha = str(item.get("sha") or "<unknown>")
+    if sha == head_sha:
+        head_seen = True
+    commit = item.get("commit") if isinstance(item.get("commit"), dict) else {}
+    commit_author = commit.get("author") if isinstance(commit.get("author"), dict) else {}
+    email = str(commit_author.get("email") or "").strip()
+    provider_author = item.get("author") if isinstance(item.get("author"), dict) else {}
+    login = str(provider_author.get("login") or "").strip()
+
+    if not login:
+        diagnostic_email = email or "<missing>"
+        print(
+            f"BLOCK: commit {sha!r} has author.login=NULL while "
+            f"commit.author.email={diagnostic_email!r}; refusing merge; "
+            f"escalate to named principal '{principal}'.",
+            file=sys.stderr,
+        )
+        raise SystemExit(75)
+    if (
+        not email.isascii()
+        or not email.isprintable()
+        or not re.fullmatch(r"[A-Za-z0-9_.-]+", login)
+        or not re.fullmatch(r"[^<>\s]+@[^<>\s]+", email)
+    ):
+        print(
+            f"BLOCK: commit {sha!r} has unusable linked identity "
+            f"author.login={login!r}, commit.author.email={email!r}; refusing merge; "
+            f"escalate to named principal '{principal}'.",
+            file=sys.stderr,
+        )
+        raise SystemExit(75)
+    if login == poster or login in seen:
+        continue
+    seen.add(login)
+    trailers.append(f"Co-authored-by: {login} <{email}>")
+
+if not head_seen:
+    print(
+        f"BLOCK: inspected PR head is absent from commit enumeration; refusing merge; "
+        f"escalate to named principal '{principal}'.",
+        file=sys.stderr,
+    )
+    raise SystemExit(75)
+if not trailers:
+    print("{}")
+    raise SystemExit(0)
+if not title:
+    print(
+        f"BLOCK: PR title is empty; refusing merge; escalate to named principal '{principal}'.",
+        file=sys.stderr,
+    )
+    raise SystemExit(75)
+if not title.isprintable() or re.match(r"^[A-Za-z-]+-[Bb]y:", title):
+    print(
+        f"BLOCK: PR title is not one printable, non-trailer line; refusing merge; "
+        f"escalate to named principal '{principal}'.",
+        file=sys.stderr,
+    )
+    raise SystemExit(75)
+
+print(json.dumps({
+    "MergeTitleField": title,
+    "MergeMessageField": "\n".join(trailers),
+}, separators=(",", ":")))
+PY
+}
+
+merge_gitea_api_attempt() {
+    local host="$1" auth_mode="$2" credential="$3"
+    local api_url attempt_dir body_file raw_code commits_file fields_file context_file head_file payload_file work_root attempt_rc auth_config curl_rc
+    LAST_GITEA_HTTP_CODE="000"
+    LAST_GITEA_ERROR=""
+    api_url="https://${host}/api/v1/repos/${OWNER}/${REPO}/pulls/${PR_NUMBER}/merge"
+    work_root="${AGENT_WORK_ROOT:-${HOME:-/tmp}/mosaic/agent-work}"
+    mkdir -p "$work_root"
+    attempt_dir=$(mktemp -d "$work_root/pr-merge-attempt.XXXXXX")
+    chmod 0700 "$attempt_dir"
+    MERGE_TEMP_DIRS+=("$attempt_dir")
+    body_file=$(mktemp "$attempt_dir/api-response.XXXXXX")
+    fields_file=$(mktemp "$attempt_dir/message-fields.XXXXXX")
+    payload_file=$(mktemp "$attempt_dir/payload.XXXXXX")
+    printf '{}' > "$fields_file"
+
+    if [[ "$CO_AUTHOR_TRAILERS" == true ]]; then
+        commits_file=$(mktemp "$attempt_dir/pr-merge-commits-input.XXXXXX")
+        context_file=$(mktemp "$attempt_dir/pr-merge-message-context.XXXXXX")
+        head_file=$(mktemp "$attempt_dir/pr-merge-head-input.XXXXXX")
+        printf '%s\0%s\0%s\0' "$PR_AUTHOR" "$PR_TITLE" "$ESCALATE_TO" > "$context_file"
+        if fetch_gitea_pr_head "$host" "$auth_mode" "$credential" "$attempt_dir" > "$head_file"; then
+            :
+        else
+            attempt_rc=$?
+            rm -f "$body_file" "$fields_file" "$payload_file" "$commits_file" "$context_file" "$head_file"
+            return "$attempt_rc"
+        fi
+        if [[ "$(<"$head_file")" != "$HEAD_SHA" ]]; then
+            echo "BLOCK: authenticated PR head moved from reviewed $HEAD_SHA to $(<"$head_file"); refusing merge; escalate to named principal '$ESCALATE_TO'." >&2
+            rm -f "$body_file" "$fields_file" "$payload_file" "$commits_file" "$context_file" "$head_file"
+            return 75
+        fi
+        if fetch_gitea_pr_commits "$host" "$auth_mode" "$credential" "$attempt_dir" > "$commits_file"; then
+            :
+        else
+            attempt_rc=$?
+            rm -f "$body_file" "$fields_file" "$payload_file" "$commits_file" "$context_file" "$head_file"
+            return "$attempt_rc"
+        fi
+        if build_coauthor_message_fields "$commits_file" "$context_file" "$head_file" > "$fields_file"; then
+            :
+        else
+            attempt_rc=$?
+            rm -f "$body_file" "$fields_file" "$payload_file" "$commits_file" "$context_file" "$head_file"
+            return "$attempt_rc"
+        fi
+        rm -f "$commits_file" "$context_file" "$head_file"
+    fi
+
+    if ! python3 - "$fields_file" "$HEAD_SHA" "$DELETE_BRANCH" > "$payload_file" <<'PY'
+import json
+import sys
+
+with open(sys.argv[1], encoding="utf-8") as handle:
+    fields = json.load(handle)
+head_sha, delete_branch = sys.argv[2:]
 payload = {"Do": "squash", "head_commit_id": head_sha}
 if delete_branch == "true":
     payload["delete_branch_after_merge"] = True
+payload.update(fields)
+allowed = {"Do", "head_commit_id", "delete_branch_after_merge", "MergeTitleField", "MergeMessageField"}
+if payload.get("Do") != "squash" or set(payload) - allowed:
+    raise SystemExit(1)
 print(json.dumps(payload, separators=(",", ":")))
 PY
-)
+    then
-
+        rm -f "$body_file" "$fields_file" "$payload_file"
-    token=$(get_gitea_token "$host" || true)
+        return 1
-    if [[ -n "$token" ]]; then
-        raw_code=$(curl -sS -w '%{http_code}' -o "$body_file" \
-            -X POST \
-            -H "User-Agent: curl/8" \
-            -H "Authorization: token $token" \
-            -H 'Content-Type: application/json' \
-            -d "$payload" \
-            "$api_url" || true)
-        if [[ "$raw_code" =~ ^2 ]]; then
-            rm -f "$body_file"
-            return 0
-        fi
     fi
+    rm -f "$fields_file"
 
-    basic_auth=$(get_gitea_basic_auth "$host" || true)
+    if ! auth_config=$(write_curl_auth_config "$auth_mode" "$credential"); then
-    if [[ -n "$basic_auth" ]]; then
+        echo "Error: Could not construct Gitea authentication config; refusing request." >&2
-        raw_code=$(curl -sS -w '%{http_code}' -o "$body_file" \
+        rm -f "$body_file" "$payload_file"
-            -X POST \
+        return 1
-            -u "$basic_auth" \
-            -H "User-Agent: curl/8" \
-            -H 'Content-Type: application/json' \
-            -d "$payload" \
-            "$api_url" || true)
-        if [[ "$raw_code" =~ ^2 ]]; then
-            rm -f "$body_file"
-            return 0
-        fi
     fi
+    raw_code=$(curl -sS -K - "${GITEA_CURL_BOUNDS[@]}" -w '%{http_code}' -o "$body_file" \
+        -X POST -H "User-Agent: curl/8" \
+        -H 'Content-Type: application/json' \
+        --data-binary "@$payload_file" "$api_url" <<<"$auth_config")
+    curl_rc=$?
+    LAST_GITEA_HTTP_CODE="${raw_code:-000}"
+    if [[ "$curl_rc" -ne 0 ]]; then
+        LAST_GITEA_ERROR="curl transport failed (rc=$curl_rc)"
+        rm -f "$body_file" "$payload_file"
+        rm -rf -- "$attempt_dir"
+        return 1
+    fi
+    if [[ ! "$raw_code" =~ ^2 ]]; then
+        LAST_GITEA_ERROR=$(format_gitea_error_response "$body_file")
+    fi
+    rm -f "$body_file" "$payload_file"
+    rm -rf -- "$attempt_dir"
+    [[ "$raw_code" =~ ^2 ]]
+}
 
-    python3 - "${raw_code:-000}" "$body_file" <<'PY' >&2
+merge_gitea_with_api() {
-import json
+    local host="$1" token attempt_rc
-import sys
+
-code, path = sys.argv[1], sys.argv[2]
+    if ! token=$(get_gitea_token "$host"); then
-try:
+        echo "Error: Could not resolve the required Gitea token; refusing merge without changing principals." >&2
-    with open(path, encoding="utf-8", errors="replace") as handle:
+        return 1
-        raw = handle.read(500)
+    fi
-    data = json.loads(raw) if raw else {}
+    if [[ -z "$token" ]]; then
-    message = data.get("message") or data.get("error") or raw or "empty response"
+        echo "Error: Required Gitea token resolved empty; refusing merge without changing principals." >&2
-except Exception:
+        return 1
-    try:
+    fi
-        message = open(path, encoding="utf-8", errors="replace").read(500) or "empty response"
+    if merge_gitea_api_attempt "$host" token "$token"; then
-    except Exception:
+        return 0
-        message = "unreadable response"
+    else
-print(f"Error: Gitea API merge failed with HTTP {code}: {message}")
+        attempt_rc=$?
-PY
+    fi
-    rm -f "$body_file"
+    if [[ "$attempt_rc" -eq 75 ]]; then
+        return 75
+    fi
+    if [[ "$LAST_GITEA_HTTP_CODE" != "401" ]]; then
+        echo "Error: Gitea API merge failed with the identity-bound token (HTTP ${LAST_GITEA_HTTP_CODE:-000}).${LAST_GITEA_ERROR:+ Provider response: $LAST_GITEA_ERROR}" >&2
+        return 1
+    fi
+    echo "Error: Gitea API rejected the identity-bound token with HTTP 401; refusing cross-principal credential fallback." >&2
     return 1
 }
 
@@ -195,11 +602,10 @@ if [[ "$DRY_RUN" == true ]]; then
             echo "Error: Cannot determine host from origin remote URL" >&2
             exit 1
         }
-        TEA_LOGIN="$(get_gitea_login_for_host "$HOST" || true)"
+        if [[ "$CO_AUTHOR_TRAILERS" == true ]]; then
-        if [[ -n "$TEA_LOGIN" ]]; then
+            echo "Dry run: would verify PR commit authors and merge PR #$PR_NUMBER on $HOST with authenticated Gitea API message fields (base=$BASE_BRANCH, method=squash)."
-            echo "Dry run: would merge PR #$PR_NUMBER on $HOST with tea login '$TEA_LOGIN' (base=$BASE_BRANCH, method=squash)."
         else
-            echo "Dry run: would merge PR #$PR_NUMBER on $HOST with authenticated Gitea API fallback (base=$BASE_BRANCH, method=squash)."
+            echo "Dry run: would merge PR #$PR_NUMBER on $HOST with the authenticated exact-head Gitea API path (base=$BASE_BRANCH, method=squash)."
         fi
     else
         echo "Dry run: would merge PR #$PR_NUMBER on $PLATFORM (base=$BASE_BRANCH, method=squash)."
@@ -209,6 +615,10 @@ fi
 
 case "$PLATFORM" in
     github)
+        if [[ "$CO_AUTHOR_TRAILERS" == true ]]; then
+            echo "Error: --co-author-trailers currently requires the Gitea REST message-field contract." >&2
+            exit 1
+        fi
         cmd=(gh pr merge "$PR_NUMBER" --squash --match-head-commit "$HEAD_SHA")
         [[ "$DELETE_BRANCH" == true ]] && cmd+=(--delete-branch)
         "${cmd[@]}"
@@ -219,7 +629,7 @@ case "$PLATFORM" in
             exit 1
         }
         # Gitea's API head_commit_id is an atomic compare-and-merge precondition.
-        # tea cannot express it, so exact-head merges use the authenticated API path.
+        # tea cannot express it, so every Gitea merge uses the authenticated API path.
         merge_gitea_with_api "$HOST"
         ;;
     *)

packages/mosaic/framework/tools/git/test-ci-queue-wait-tristate.sh

@@ -9,10 +9,51 @@ WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/ci-queue-wait-tristate}
 REPO_DIR="$WORK_DIR/repo"
 STUB_DIR="$WORK_DIR/stubs"
 AUDIT_LOG="$WORK_DIR/audit/ci-queue-wait.jsonl"
+STATUS_OBSERVED="$WORK_DIR/status-observed"
+CLOCK_LOG="$WORK_DIR/clock.log"
+WATCHDOG_PYTHON="/usr/bin/python3"
+WATCHDOG_SCRIPT="$WORK_DIR/real-clock-watchdog.py"
+WATCHDOG_TIMEOUT_SEC=5
+WATCHDOG_EXIT=90
 FEATURE_BRANCH="fix/rm-03-fixture"
 
+if [[ ! -x "$WATCHDOG_PYTHON" ]]; then
+    echo "FAIL setup: required real-clock watchdog runtime is unavailable at $WATCHDOG_PYTHON" >&2
+    exit 1
+fi
+
 rm -rf "$WORK_DIR"
 mkdir -p "$REPO_DIR" "$STUB_DIR"
+cat > "$WATCHDOG_SCRIPT" <<'PY'
+import os
+import signal
+import subprocess
+import sys
+
+if len(sys.argv) < 3:
+    raise SystemExit(2)
+
+timeout_seconds = float(sys.argv[1])
+process = subprocess.Popen(sys.argv[2:], start_new_session=True)
+try:
+    return_code = process.wait(timeout=timeout_seconds)
+except subprocess.TimeoutExpired:
+    try:
+        os.killpg(process.pid, signal.SIGKILL)
+    except ProcessLookupError:
+        pass
+    process.wait()
+    print(
+        f"FAIL HANG watchdog: subject exceeded {timeout_seconds:g}s "
+        "before completing its intended path",
+        file=sys.stderr,
+    )
+    raise SystemExit(90)
+
+if return_code < 0:
+    raise SystemExit(128 - return_code)
+raise SystemExit(return_code)
+PY
 git -C "$REPO_DIR" init -q
 git -C "$REPO_DIR" checkout -q -b "$FEATURE_BRANCH"
 git -C "$REPO_DIR" remote add origin https://git.example.test/acme/widgets.git
@@ -33,6 +74,9 @@ printf '%s\n' "$url" >> "${MOSAIC_STUB_URL_LOG:?}"
 
 case "$url" in
     */branches/*)
+        if [[ "${MOSAIC_STUB_BRANCH_MODE:-ok}" == "hang-before-provider" ]]; then
+            while :; do :; done
+        fi
         if [[ "${MOSAIC_STUB_BRANCH_MODE:-ok}" == "unreachable" ]]; then
             exit 7
         fi
@@ -44,6 +88,7 @@ case "$url" in
         fi
         ;;
     */status)
+        : > "${MOSAIC_STUB_STATUS_OBSERVED:?}"
         case "${MOSAIC_STUB_STATUS_MODE:?}" in
             success)   printf '%s' '{"state":"success","statuses":[{"status":"success"}]}' ;;
             pending)   printf '%s' '{"state":"pending","statuses":[{"status":"pending","context":"ci/test"}]}' ;;
@@ -64,7 +109,31 @@ case "$url" in
     *) echo "unexpected curl URL: $url" >&2; exit 2 ;;
 esac
 SH
-chmod +x "$STUB_DIR/curl"
+
+cat > "$STUB_DIR/date" <<'SH'
+#!/usr/bin/env bash
+set -euo pipefail
+
+if [[ "$#" -ne 1 || "$1" != "+%s" ]]; then
+    echo "unexpected date invocation: $*" >&2
+    exit 2
+fi
+
+if [[ -e "${MOSAIC_STUB_STATUS_OBSERVED:?}" ]]; then
+    printf 'date-phase=after-status\n' >> "${MOSAIC_STUB_CLOCK_LOG:?}"
+    printf '1002\n'
+else
+    printf 'date-phase=before-status\n' >> "${MOSAIC_STUB_CLOCK_LOG:?}"
+    printf '1000\n'
+fi
+SH
+
+cat > "$STUB_DIR/sleep" <<'SH'
+#!/usr/bin/env bash
+set -euo pipefail
+printf 'sleep-after-status=%s\n' "$*" >> "${MOSAIC_STUB_CLOCK_LOG:?}"
+SH
+chmod +x "$STUB_DIR/curl" "$STUB_DIR/date" "$STUB_DIR/sleep"
 
 run_guard() {
     local status_mode="$1"
@@ -84,13 +153,46 @@ run_guard() {
             export GITEA_URL=https://git.example.test
             export MOSAIC_STUB_STATUS_MODE="$status_mode"
         fi
+        rm -f "$STATUS_OBSERVED" "$CLOCK_LOG"
         export MOSAIC_STUB_URL_LOG="$WORK_DIR/urls.log"
+        export MOSAIC_STUB_STATUS_OBSERVED="$STATUS_OBSERVED"
+        export MOSAIC_STUB_CLOCK_LOG="$CLOCK_LOG"
         export MOSAIC_CI_QUEUE_AUDIT_LOG="$audit_log"
-        "$SCRIPT_DIR/ci-queue-wait.sh" --purpose "${MOSAIC_TEST_PURPOSE:-push}" -t 0 -i 0 "$@"
+        # Provider observation is the synchronization event. The one-second
+        # timeout is subject semantics under virtual time, never a wall wait.
+        # The absolute Python runtime uses an internal monotonic wait and kills
+        # the subject's isolated process group. Neither operation can resolve
+        # to the virtual date/sleep stubs at the front of PATH.
+        local subject_rc
+        if "$WATCHDOG_PYTHON" "$WATCHDOG_SCRIPT" "$WATCHDOG_TIMEOUT_SEC" \
+            "$SCRIPT_DIR/ci-queue-wait.sh" --purpose "${MOSAIC_TEST_PURPOSE:-push}" -t 1 -i 1 "$@"; then
+            subject_rc=0
+        else
+            subject_rc=$?
+        fi
+        return "$subject_rc"
     )
 }
 
 failures=0
+assert_provider_observed() {
+    local name="$1" require_expiration="${2:-0}"
+    if [[ ! -e "$STATUS_OBSERVED" ]]; then
+        echo "FAIL $name: status provider was not observed" >&2
+        failures=$((failures + 1))
+    fi
+    if [[ ! -s "$CLOCK_LOG" ]] || ! grep -q '^date-phase=before-status$' "$CLOCK_LOG"; then
+        echo "FAIL $name: virtual clock interception did not run before provider observation" >&2
+        failures=$((failures + 1))
+    fi
+    if [[ "$require_expiration" -eq 1 ]]; then
+        if ! grep -q '^sleep-after-status=' "$CLOCK_LOG" || ! grep -q '^date-phase=after-status$' "$CLOCK_LOG"; then
+            echo "FAIL $name: pending path did not expire after provider observation" >&2
+            failures=$((failures + 1))
+        fi
+    fi
+}
+
 run_assertion() {
     local name="$1" expected_rc="$2" status_mode="$3" required_text="$4"
     local output rc
@@ -125,6 +227,13 @@ run_assertion() {
         printf '%s\n' "$output" >&2
         failures=$((failures + 1))
     fi
+    if [[ "$status_mode" != "credential-unresolvable" ]]; then
+        if [[ "$status_mode" == "pending" ]]; then
+            assert_provider_observed "$name" 1
+        else
+            assert_provider_observed "$name"
+        fi
+    fi
 }
 
 set -e
@@ -150,6 +259,27 @@ MOSAIC_TEST_PURPOSE=merge run_assertion merge-failure nonzero failure 'ASSERTED_
 MOSAIC_TEST_PURPOSE=merge run_assertion merge-no-status nonzero no-status 'ASSERTED_NOT_READY state=no-status'
 MOSAIC_TEST_PURPOSE=merge run_assertion merge-unknown nonzero unknown 'ASSERTED_NOT_READY state=unknown'
 
+# Positive liveness control: a subject mutant hangs before the branch lookup
+# can reach the status provider. Only the independent real-clock watchdog may
+# terminate it, and its failure must be distinct from subject timeout rc=124.
+set +e
+watchdog_output=$(MOSAIC_STUB_BRANCH_MODE=hang-before-provider run_guard success "$AUDIT_LOG" 2>&1)
+watchdog_rc=$?
+set -e
+if [[ "$watchdog_rc" -ne "$WATCHDOG_EXIT" ]]; then
+    echo "FAIL watchdog-control: expected hang-specific rc=$WATCHDOG_EXIT, got rc=$watchdog_rc" >&2
+    failures=$((failures + 1))
+fi
+if [[ "$watchdog_output" != *"FAIL HANG watchdog:"* ]]; then
+    echo "FAIL watchdog-control: expected distinct hang-specific diagnostic" >&2
+    printf '%s\n' "$watchdog_output" >&2
+    failures=$((failures + 1))
+fi
+if [[ -e "$STATUS_OBSERVED" ]]; then
+    echo "FAIL watchdog-control: hanging mutant unexpectedly reached the status provider" >&2
+    failures=$((failures + 1))
+fi
+
 if [[ ! -s "$AUDIT_LOG" ]] || ! grep -q '"outcome":"CANNOT_ASSERT"' "$AUDIT_LOG"; then
     echo "FAIL provider-unreachable-audit: expected durable CANNOT_ASSERT JSONL record" >&2
     failures=$((failures + 1))
@@ -170,6 +300,7 @@ if [[ "$merge_unreachable_output" != *"CANNOT_ASSERT"* ]]; then
     echo "FAIL merge-provider-unreachable: expected loud CANNOT_ASSERT diagnostic" >&2
     failures=$((failures + 1))
 fi
+assert_provider_observed merge-provider-unreachable
 merge_audit_lines_after=$(wc -l < "$AUDIT_LOG")
 if [[ "$merge_audit_lines_after" -le "$merge_audit_lines_before" ]]; then
     echo "FAIL merge-provider-unreachable: expected an additional audit record" >&2
@@ -233,6 +364,7 @@ if [[ "$audit_failure_output" != *"audit"* ]]; then
     echo "FAIL audit-unavailable: expected loud audit failure diagnostic" >&2
     failures=$((failures + 1))
 fi
+assert_provider_observed audit-unavailable
 
 if [[ "$failures" -ne 0 ]]; then
     echo "ci-queue-wait tri-state regression failed ($failures assertions)" >&2

packages/mosaic/framework/tools/git/test-pr-merge-gitea-empty-uid.sh

@@ -51,22 +51,23 @@ for arg in "$@"; do
         prev=""
         continue
     fi
-    if [[ "$prev" == "-d" ]]; then
+    if [[ "$prev" == "data" ]]; then
         post_data="$arg"
+        [[ "$post_data" == @* ]] && post_data=$(<"${post_data#@}")
         prev=""
         continue
     fi
-    if [[ "$arg" == "-o" ]]; then
+    if [[ "$prev" == "config" ]]; then
-        prev="-o"
+        [[ "$arg" == "-" ]] && cat >/dev/null
+        prev=""
         continue
     fi
-    if [[ "$arg" == "-d" ]]; then
+    case "$arg" in
-        prev="-d"
+        -o) prev="-o" ;;
-        continue
+        -d|--data|--data-binary) prev="data" ;;
-    fi
+        -K|--config) prev="config" ;;
-    if [[ "$arg" == "-w" ]]; then
+        -w) write_code=true ;;
-        write_code=true
+    esac
-    fi
 done
 emit_response() {
     local body="$1"

packages/mosaic/framework/tools/git/test-pr-merge-head-pin.sh

@@ -37,13 +37,30 @@ cat > "$WORK_DIR/gitea/curl" <<'SH'
 #!/usr/bin/env bash
 set -euo pipefail
 payload=""
-for ((i=1; i<=$#; i++)); do
+out_file=""
-    if [[ "${!i}" == "-d" ]]; then
+while [[ $# -gt 0 ]]; do
-        j=$((i + 1))
+    case "$1" in
-        payload="${!j}"
+        -d|--data|--data-binary)
-    fi
+            payload="$2"
+            [[ "$payload" == @* ]] && payload=$(<"${payload#@}")
+            shift 2
+            ;;
+        -o)
+            out_file="$2"
+            shift 2
+            ;;
+        -K|--config)
+            [[ "$2" == "-" ]] && cat >/dev/null
+            shift 2
+            ;;
+        -w|-X|-H)
+            shift 2
+            ;;
+        *) shift ;;
+    esac
 done
 printf '%s' "$payload" > "${MOSAIC_MERGE_PAYLOAD_LOG:?}"
+[[ -n "$out_file" ]] && printf '{}' > "$out_file"
 printf '200'
 SH
 chmod +x "$WORK_DIR/gitea/curl"

packages/mosaic/framework/tools/git/test-pr-merge-message-field.sh

@@ -0,0 +1,541 @@
+#!/usr/bin/env bash
+# Regression harness for the optional, identity-checked Gitea squash message.
+
+set -u
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+SUBJECT="${MOSAIC_TEST_SUBJECT:-$SCRIPT_DIR/pr-merge.sh}"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/pr-merge-message-field}"
+ORIG_PATH="$PATH"
+failures=0
+
+rm -rf "$WORK_DIR"
+mkdir -p "$WORK_DIR"
+
+fail() {
+    echo "FAIL $1" >&2
+    failures=$((failures + 1))
+}
+
+make_case() {
+    local name="$1" case_dir
+    case_dir="$WORK_DIR/$name"
+    mkdir -p "$case_dir/bin" "$case_dir/agent"
+    cp "$SUBJECT" "$case_dir/pr-merge.sh"
+    chmod +x "$case_dir/pr-merge.sh"
+
+    cat > "$case_dir/detect-platform.sh" <<'SH'
+#!/usr/bin/env bash
+detect_platform() { PLATFORM=gitea; printf 'gitea\n'; }
+get_repo_owner() { printf 'acme\n'; }
+get_repo_name() { printf 'widgets\n'; }
+get_remote_host() { printf 'git.example.test\n'; }
+get_gitea_token() {
+    printf 'resolved\n' >> "${MOSAIC_TEST_TOKEN_RESOLUTION_LOG:?}"
+    if [[ "${MOSAIC_TEST_TOKEN_AVAILABLE:-true}" != "true" ]]; then
+        return 1
+    fi
+    printf 'fixture-token\n'
+}
+get_gitea_basic_auth() {
+    printf 'resolved\n' >> "${MOSAIC_TEST_BASIC_RESOLUTION_LOG:?}"
+    if [[ "${MOSAIC_TEST_BASIC_AVAILABLE:-false}" == "true" ]]; then
+        printf 'fixture-user:fixture-password\n'
+        return "${MOSAIC_TEST_BASIC_RC:-0}"
+    fi
+    return 1
+}
+get_gitea_login_for_host() { return 1; }
+SH
+
+    cat > "$case_dir/pr-metadata.sh" <<'SH'
+#!/usr/bin/env bash
+if [[ "${MOSAIC_TEST_TITLE_MODE:-safe}" == "injection" ]]; then
+    title='Preserve authors\n\nCo-authored-by: victim <[email protected]>'
+else
+    title='Preserve both branch authors'
+fi
+case "${MOSAIC_TEST_COMMITS_MODE:?}" in
+    verified) head_sha=2222222222222222222222222222222222222222 ;;
+    null-login|unsafe-identity) head_sha=3333333333333333333333333333333333333333 ;;
+    single) head_sha=1111111111111111111111111111111111111111 ;;
+    *) echo "unknown commits mode" >&2; exit 2 ;;
+esac
+printf '{"number":42,"title":"%s","author":"poster","baseRefName":"main","headRefName":"feature/fixture","headRefOid":"%s","headRepository":"acme/widgets"}\n' "$title" "$head_sha"
+SH
+
+    cat > "$case_dir/ci-queue-wait.sh" <<'SH'
+#!/usr/bin/env bash
+exit 0
+SH
+
+    cat > "$case_dir/bin/python3" <<'SH'
+#!/usr/bin/env bash
+for arg in "$@"; do
+    case "$arg" in
+        *"Preserve both branch authors"*|*"[email protected]"*)
+            : > "${MOSAIC_TEST_METADATA_ARGV_MARKER:?}"
+            ;;
+    esac
+done
+exec "${MOSAIC_TEST_REAL_PYTHON:?}" "$@"
+SH
+
+    cat > "$case_dir/bin/curl" <<'SH'
+#!/usr/bin/env bash
+set -eu
+
+for arg in "$@"; do
+    case "$arg" in
+        *"Preserve both branch authors"*|*"[email protected]"*)
+            : > "${MOSAIC_TEST_METADATA_ARGV_MARKER:?}"
+            ;;
+    esac
+done
+
+url=""
+method="GET"
+out_file=""
+data=""
+config=""
+auth_mode="none"
+has_max_filesize=0
+has_max_time=0
+has_connect_timeout=0
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+        -o)
+            out_file="$2"
+            shift 2
+            ;;
+        -w)
+            shift 2
+            ;;
+        -X)
+            method="$2"
+            shift 2
+            ;;
+        -d|--data|--data-binary)
+            data="$2"
+            if [[ "$data" == @* ]]; then
+                data=$(<"${data#@}")
+            fi
+            shift 2
+            ;;
+        -K|--config)
+            if [[ "$2" == "-" ]]; then
+                config=$(cat)
+            fi
+            shift 2
+            ;;
+        --max-filesize)
+            has_max_filesize=1
+            shift 2
+            ;;
+        --max-time)
+            has_max_time=1
+            shift 2
+            ;;
+        --connect-timeout)
+            has_connect_timeout=1
+            shift 2
+            ;;
+        -H|--header|-u|--user)
+            if [[ "$2" == *"fixture-token"* ]]; then
+                : > "${MOSAIC_TEST_TOKEN_ARGV_MARKER:?}"
+            fi
+            if [[ "$2" == *"fixture-password"* ]]; then
+                : > "${MOSAIC_TEST_BASIC_ARGV_MARKER:?}"
+            fi
+            shift 2
+            ;;
+        http://*|https://*)
+            url="$1"
+            shift
+            ;;
+        *)
+            shift
+            ;;
+    esac
+done
+
+if [[ "$config" == *"Authorization: token fixture-token"* ]]; then
+    auth_mode="token"
+    : > "${MOSAIC_TEST_AUTH_CONFIG_MARKER:?}"
+elif [[ "$config" == *"user = \"fixture-user:fixture-password\""* ]]; then
+    auth_mode="basic"
+    : > "${MOSAIC_TEST_BASIC_CONFIG_MARKER:?}"
+fi
+printf '%s %s %s\n' "$method" "$auth_mode" "$url" >> "${MOSAIC_TEST_CURL_LOG:?}"
+printf '%s:%s:%s\n' "$has_max_filesize" "$has_max_time" "$has_connect_timeout" >> "${MOSAIC_TEST_CURL_BOUNDS_LOG:?}"
+
+case "$url" in
+    */pulls/42)
+        case "${MOSAIC_TEST_COMMITS_MODE:?}" in
+            verified) head_sha=2222222222222222222222222222222222222222 ;;
+            null-login|unsafe-identity) head_sha=3333333333333333333333333333333333333333 ;;
+            single) head_sha=1111111111111111111111111111111111111111 ;;
+            *) echo "unknown commits mode" >&2; exit 2 ;;
+        esac
+        if [[ "${MOSAIC_TEST_HEAD_MODE:-stable}" == "moved" ]]; then
+            head_sha=4444444444444444444444444444444444444444
+        fi
+        body="{\"head\":{\"sha\":\"$head_sha\"}}"
+        code=200
+        if [[ "${MOSAIC_TEST_FALLBACK_MODE:-none}" == "inspection" && "$auth_mode" == "token" ]]; then
+            body='{"message":"token rejected"}'
+            code=401
+        fi
+        ;;
+    */pulls/42/commits*)
+        case "${MOSAIC_TEST_COMMITS_MODE:?}" in
+            verified)
+                if [[ "${MOSAIC_TEST_EMAIL_MODE:-safe}" == "escape" ]]; then
+                    body='[{"sha":"2222222222222222222222222222222222222222","commit":{"author":{"name":"Alice","email":"alice+\u001b[[email protected]"}},"author":{"login":"alice"}},{"sha":"1111111111111111111111111111111111111111","commit":{"author":{"name":"Poster","email":"[email protected]"}},"author":{"login":"poster"}}]'
+                else
+                    body='[{"sha":"2222222222222222222222222222222222222222","commit":{"author":{"name":"Alice","email":"[email protected]"}},"author":{"login":"alice"}},{"sha":"1111111111111111111111111111111111111111","commit":{"author":{"name":"Poster","email":"[email protected]"}},"author":{"login":"poster"}}]'
+                fi
+                ;;
+            null-login)
+                body='[{"sha":"1111111111111111111111111111111111111111","commit":{"author":{"name":"Poster","email":"[email protected]"}},"author":{"login":"poster"}},{"sha":"3333333333333333333333333333333333333333","commit":{"author":{"name":"Unresolved Author","email":"[email protected]\n\u001b[31m"}},"author":null}]'
+                ;;
+            unsafe-identity)
+                body='[{"sha":"unsafe\n\u001b[31m","commit":{"author":{"name":"Unsafe","email":"not-an-email"}},"author":{"login":"unsafe"}},{"sha":"3333333333333333333333333333333333333333","commit":{"author":{"name":"Poster","email":"[email protected]"}},"author":{"login":"poster"}}]'
+                ;;
+            single)
+                body='[{"sha":"1111111111111111111111111111111111111111","commit":{"author":{"name":"Poster","email":"[email protected]"}},"author":{"login":"poster"}}]'
+                ;;
+            *)
+                echo "unknown commits mode" >&2
+                exit 2
+                ;;
+        esac
+        code=200
+        if [[ "${MOSAIC_TEST_FALLBACK_MODE:-none}" == "inspection" && "$auth_mode" == "token" ]]; then
+            body='{"message":"token rejected"}'
+            code=401
+        fi
+        ;;
+    */pulls/42/merge)
+        body='{}'
+        code=200
+        if [[ "${MOSAIC_TEST_FALLBACK_MODE:-none}" == "merge" && "$auth_mode" == "token" ]]; then
+            body='{"message":"token rejected"}'
+            code=401
+        elif [[ "${MOSAIC_TEST_FALLBACK_MODE:-none}" == "provider-error" ]]; then
+            body='{"message":"branch policy rejected\n\u001b[31m"}'
+            code=409
+        elif [[ "${MOSAIC_TEST_FALLBACK_MODE:-none}" == "forbidden" ]]; then
+            body='{"message":"permission denied"}'
+            code=403
+        else
+            printf '%s' "$data" > "${MOSAIC_TEST_MERGE_PAYLOAD:?}"
+        fi
+        ;;
+    */users/*)
+        body='{"message":"not found"}'
+        code=404
+        ;;
+    *)
+        body='{"message":"unexpected URL"}'
+        code=500
+        ;;
+esac
+
+if [[ -n "$out_file" ]]; then
+    printf '%s' "$body" > "$out_file"
+else
+    printf '%s' "$body"
+fi
+printf '%s' "$code"
+case "${MOSAIC_TEST_CURL_FAILURE:-none}" in
+    oversize) exit 63 ;;
+    stalled) exit 28 ;;
+esac
+SH
+
+    chmod +x "$case_dir/detect-platform.sh" "$case_dir/pr-metadata.sh" \
+        "$case_dir/ci-queue-wait.sh" "$case_dir/bin/curl" "$case_dir/bin/python3"
+    printf '%s\n' "$case_dir"
+}
+
+run_case() {
+    local case_dir="$1" mode="$2"
+    shift 2
+    MOSAIC_TEST_COMMITS_MODE="$mode" \
+    MOSAIC_TEST_CURL_LOG="$case_dir/curl.log" \
+    MOSAIC_TEST_CURL_BOUNDS_LOG="$case_dir/curl-bounds.log" \
+    MOSAIC_TEST_MERGE_PAYLOAD="$case_dir/merge-payload.json" \
+    MOSAIC_TEST_TOKEN_ARGV_MARKER="$case_dir/token-in-argv" \
+    MOSAIC_TEST_BASIC_ARGV_MARKER="$case_dir/basic-in-argv" \
+    MOSAIC_TEST_AUTH_CONFIG_MARKER="$case_dir/auth-via-config" \
+    MOSAIC_TEST_BASIC_CONFIG_MARKER="$case_dir/basic-via-config" \
+    MOSAIC_TEST_TOKEN_RESOLUTION_LOG="$case_dir/token-resolution.log" \
+    MOSAIC_TEST_BASIC_RESOLUTION_LOG="$case_dir/basic-resolution.log" \
+    MOSAIC_TEST_METADATA_ARGV_MARKER="$case_dir/metadata-in-argv" \
+    MOSAIC_TEST_REAL_PYTHON="$(command -v python3)" \
+    AGENT_WORK_ROOT="$case_dir/agent" \
+    PATH="$case_dir/bin:$ORIG_PATH" \
+        "$case_dir/pr-merge.sh" -n 42 "$@"
+}
+
+# Verified multi-author path: the non-poster trailer is built from one commit's
+# linked author.login and that same commit's author email. No /users lookup.
+verified_dir=$(make_case verified)
+set +e
+verified_output=$(run_case "$verified_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+verified_rc=$?
+set -e
+if [[ "$verified_rc" -ne 0 ]]; then
+    fail "verified multi-author merge expected rc=0, got rc=$verified_rc: $verified_output"
+elif [[ ! -s "$verified_dir/merge-payload.json" ]]; then
+    fail "verified multi-author merge did not reach the API payload"
+else
+    python3 - "$verified_dir/merge-payload.json" <<'PY' || fail "verified payload did not preserve squash and exact message fields"
+import json
+import sys
+payload = json.load(open(sys.argv[1], encoding="utf-8"))
+assert payload == {
+    "Do": "squash",
+    "head_commit_id": "2222222222222222222222222222222222222222",
+    "MergeTitleField": "Preserve both branch authors",
+    "MergeMessageField": "Co-authored-by: alice <[email protected]>",
+}, payload
+PY
+fi
+[[ -e "$verified_dir/auth-via-config" ]] || fail "verified path did not authenticate curl through stdin config"
+[[ ! -e "$verified_dir/token-in-argv" ]] || fail "verified path placed the Gitea token in curl argv"
+[[ ! -e "$verified_dir/metadata-in-argv" ]] || fail "verified path placed PR title or contributor email in child argv"
+[[ "$(wc -l < "$verified_dir/token-resolution.log")" -eq 1 ]] || fail "verified path did not bind inspection and merge to one credential resolution"
+if grep -q '/users/' "$verified_dir/curl.log" 2>/dev/null; then
+    fail "verified path performed a forbidden second /users lookup"
+fi
+if grep -qv '^1:1:1$' "$verified_dir/curl-bounds.log"; then
+    fail "verified path did not apply size/max-time/connect-time bounds to every provider download"
+fi
+
+# A linked email containing a terminal escape must block before mutation.
+escape_email_dir=$(make_case escape-email)
+set +e
+escape_email_output=$(MOSAIC_TEST_EMAIL_MODE=escape run_case "$escape_email_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+escape_email_rc=$?
+set -e
+[[ "$escape_email_rc" -ne 0 ]] || fail "control-byte email unexpectedly passed"
+[[ "$escape_email_output" == *"unusable linked identity"* ]] || fail "control-byte email refusal lost its diagnostic"
+[[ ! -e "$escape_email_dir/merge-payload.json" ]] || fail "control-byte email reached the merge API"
+
+# Curl transfer and duration failures must remain failures even with HTTP 200.
+for failure_mode in oversize stalled; do
+    failure_dir=$(make_case "curl-$failure_mode")
+    set +e
+    failure_output=$(MOSAIC_TEST_CURL_FAILURE="$failure_mode" run_case "$failure_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+    failure_rc=$?
+    set -e
+    [[ "$failure_rc" -ne 0 ]] || fail "curl $failure_mode failure was discarded: $failure_output"
+    [[ ! -e "$failure_dir/merge-payload.json" ]] || fail "curl $failure_mode failure reached the merge API"
+done
+
+# The authenticated head is re-read under the mutation credential but cannot
+# replace the canonical preflight/review head. A move blocks before enumeration
+# or mutation even though the provider returned a valid new SHA.
+moved_dir=$(make_case moved-head)
+set +e
+moved_output=$(MOSAIC_TEST_HEAD_MODE=moved \
+    run_case "$moved_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+moved_rc=$?
+set -e
+[[ "$moved_rc" -ne 0 ]] || fail "moved authenticated head unexpectedly passed"
+[[ "$moved_output" == *"authenticated PR head moved from reviewed"* ]] || fail "moved head refusal lost its diagnostic"
+[[ "$moved_output" == *"tl-mosaic"* ]] || fail "moved head refusal omitted the named escalation principal"
+[[ ! -e "$moved_dir/merge-payload.json" ]] || fail "moved head refusal reached the merge API"
+moved_sequence=$(awk '{print $1 ":" $2}' "$moved_dir/curl.log" | paste -sd, -)
+[[ "$moved_sequence" == "GET:token" ]] || fail "moved head refusal performed post-move inspection/mutation (calls=$moved_sequence)"
+
+# Token resolution failure is not an authentication response. It must fail
+# closed instead of borrowing a Basic credential under a different principal.
+token_missing_dir=$(make_case token-missing)
+set +e
+token_missing_output=$(MOSAIC_TEST_TOKEN_AVAILABLE=false MOSAIC_TEST_BASIC_AVAILABLE=true \
+    run_case "$token_missing_dir" single 2>&1)
+token_missing_rc=$?
+set -e
+[[ "$token_missing_rc" -ne 0 ]] || fail "missing token unexpectedly borrowed Basic Auth"
+[[ "$token_missing_output" == *"required Gitea token"* ]] || fail "missing token refusal lost its diagnostic"
+[[ ! -e "$token_missing_dir/basic-resolution.log" ]] || fail "missing token resolved Basic Auth after identity failure"
+[[ ! -e "$token_missing_dir/curl.log" ]] || fail "missing token reached a provider request"
+
+# A failed Basic resolver must never use its nonempty output or reach mutation.
+basic_rc_dir=$(make_case basic-resolver-rc)
+set +e
+basic_rc_output=$(MOSAIC_TEST_BASIC_AVAILABLE=true MOSAIC_TEST_BASIC_RC=91 MOSAIC_TEST_FALLBACK_MODE=inspection \
+    run_case "$basic_rc_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+basic_rc_rc=$?
+set -e
+[[ "$basic_rc_rc" -ne 0 ]] || fail "failed Basic resolver output unexpectedly authorized a merge: $basic_rc_output"
+[[ ! -e "$basic_rc_dir/merge-payload.json" ]] || fail "failed Basic resolver reached the merge API"
+
+# HTTP 401 never changes principals: inspection rejection fails closed without
+# resolving or attempting Basic Auth.
+fallback_inspect_dir=$(make_case fallback-inspection)
+set +e
+fallback_inspect_output=$(MOSAIC_TEST_BASIC_AVAILABLE=true MOSAIC_TEST_FALLBACK_MODE=inspection \
+    run_case "$fallback_inspect_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+fallback_inspect_rc=$?
+set -e
+[[ "$fallback_inspect_rc" -ne 0 ]] || fail "inspection token rejection unexpectedly changed principals"
+[[ "$fallback_inspect_output" == *"refusing cross-principal credential fallback"* ]] || fail "inspection token rejection lost its refusal diagnostic"
+[[ ! -e "$fallback_inspect_dir/basic-resolution.log" ]] || fail "inspection token rejection resolved Basic Auth"
+[[ ! -e "$fallback_inspect_dir/merge-payload.json" ]] || fail "inspection token rejection reached merge mutation"
+inspect_sequence=$(awk '{print $1 ":" $2}' "$fallback_inspect_dir/curl.log" | paste -sd, -)
+[[ "$inspect_sequence" == "GET:token" ]] || fail "inspection rejection made unexpected provider calls (calls=$inspect_sequence)"
+
+# Token rejection at merge likewise fails closed without cross-principal retry.
+fallback_merge_dir=$(make_case fallback-merge)
+set +e
+fallback_merge_output=$(MOSAIC_TEST_BASIC_AVAILABLE=true MOSAIC_TEST_FALLBACK_MODE=merge \
+    run_case "$fallback_merge_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+fallback_merge_rc=$?
+set -e
+[[ "$fallback_merge_rc" -ne 0 ]] || fail "merge token rejection unexpectedly changed principals"
+[[ "$fallback_merge_output" == *"refusing cross-principal credential fallback"* ]] || fail "merge token rejection lost its refusal diagnostic"
+[[ ! -e "$fallback_merge_dir/basic-resolution.log" ]] || fail "merge token rejection resolved Basic Auth"
+[[ ! -e "$fallback_merge_dir/merge-payload.json" ]] || fail "merge token rejection recorded a successful payload"
+merge_sequence=$(awk '{print $1 ":" $2}' "$fallback_merge_dir/curl.log" | paste -sd, -)
+[[ "$merge_sequence" == "GET:token,GET:token,POST:token" ]] || fail "merge rejection made unexpected provider calls (calls=$merge_sequence)"
+
+# BLOCK path: a commit email exists but author.login is null. It must name both
+# facts, name the escalation principal, and never reach the merge endpoint.
+null_dir=$(make_case null-login)
+set +e
+null_output=$(run_case "$null_dir" null-login --co-author-trailers --escalate-to tl-mosaic 2>&1)
+null_rc=$?
+set -e
+[[ "$null_rc" -ne 0 ]] || fail "null-login author expected a non-zero BLOCK"
+[[ "$null_output" == *"BLOCK"* ]] || fail "null-login author omitted BLOCK diagnostic"
+[[ "$null_output" == *"author.login=NULL"* ]] || fail "null-login author omitted the null provider fact"
+[[ "$null_output" == *"[email protected]"* ]] || fail "null-login author omitted the commit email fact"
+[[ "$null_output" == *'\n\x1b[31m'* ]] || fail "null-login author diagnostic did not escape control characters"
+[[ "$null_output" != *$'\033'* ]] || fail "null-login author diagnostic emitted a raw terminal escape"
+[[ "$(printf '%s\n' "$null_output" | wc -l)" -eq 1 ]] || fail "null-login author diagnostic permitted newline injection"
+[[ "$null_output" == *"tl-mosaic"* ]] || fail "null-login author omitted the named escalation principal"
+[[ ! -e "$null_dir/merge-payload.json" ]] || fail "null-login BLOCK still reached the merge API"
+
+# Every provider-derived field in alternate BLOCK diagnostics is log-safe too,
+# including an invalid non-head SHA that contains control characters.
+unsafe_dir=$(make_case unsafe-identity)
+set +e
+unsafe_output=$(run_case "$unsafe_dir" unsafe-identity --co-author-trailers --escalate-to tl-mosaic 2>&1)
+unsafe_rc=$?
+set -e
+[[ "$unsafe_rc" -ne 0 ]] || fail "unsafe identity expected a non-zero BLOCK"
+[[ "$unsafe_output" == *"unusable linked identity"* ]] || fail "unsafe identity omitted its BLOCK reason"
+[[ "$unsafe_output" == *'\n\x1b[31m'* ]] || fail "unsafe identity SHA did not escape control characters"
+[[ "$unsafe_output" != *$'\033'* ]] || fail "unsafe identity diagnostic emitted a raw terminal escape"
+[[ "$(printf '%s\n' "$unsafe_output" | wc -l)" -eq 1 ]] || fail "unsafe identity diagnostic permitted newline injection"
+[[ ! -e "$unsafe_dir/merge-payload.json" ]] || fail "unsafe identity BLOCK still reached the merge API"
+
+# The provider PR title cannot add an unchecked trailer outside the constructed
+# message field: multi-line and trailer-shaped titles block before mutation.
+title_dir=$(make_case title-injection)
+set +e
+title_output=$(MOSAIC_TEST_TITLE_MODE=injection \
+    run_case "$title_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+title_rc=$?
+set -e
+[[ "$title_rc" -ne 0 ]] || fail "title trailer injection unexpectedly passed"
+[[ "$title_output" == *"not one printable, non-trailer line"* ]] || fail "title injection refusal lost its diagnostic"
+[[ ! -e "$title_dir/merge-payload.json" ]] || fail "title injection reached the merge API"
+
+# Provider failures remain diagnosable after their temporary response file is
+# removed, but provider-controlled control characters stay log-safe.
+error_dir=$(make_case provider-error)
+set +e
+error_output=$(MOSAIC_TEST_BASIC_AVAILABLE=true MOSAIC_TEST_FALLBACK_MODE=provider-error \
+    run_case "$error_dir" single 2>&1)
+error_rc=$?
+set -e
+[[ "$error_rc" -ne 0 ]] || fail "provider error unexpectedly passed"
+[[ "$error_output" == *"HTTP 409"* ]] || fail "provider error omitted the HTTP status"
+[[ "$error_output" == *"branch policy rejected"* ]] || fail "provider error response was discarded"
+[[ "$error_output" == *'\n\x1b[31m'* ]] || fail "provider error response did not escape control characters"
+[[ "$error_output" != *$'\033'* ]] || fail "provider error response emitted a raw terminal escape"
+[[ "$error_output" != *"Basic Auth fallback"* ]] || fail "provider error advertised removed Basic Auth fallback"
+[[ ! -e "$error_dir/basic-resolution.log" ]] || fail "HTTP 409 policy denial incorrectly triggered Basic Auth fallback"
+
+# Authorization denials likewise fail closed instead of changing principals.
+forbidden_dir=$(make_case forbidden)
+set +e
+forbidden_output=$(MOSAIC_TEST_BASIC_AVAILABLE=true MOSAIC_TEST_FALLBACK_MODE=forbidden \
+    run_case "$forbidden_dir" single 2>&1)
+forbidden_rc=$?
+set -e
+[[ "$forbidden_rc" -ne 0 ]] || fail "HTTP 403 authorization denial unexpectedly passed"
+[[ "$forbidden_output" == *"HTTP 403"* ]] || fail "authorization denial omitted the HTTP status"
+[[ "$forbidden_output" != *"Basic Auth fallback"* ]] || fail "authorization denial advertised removed Basic Auth fallback"
+[[ ! -e "$forbidden_dir/basic-resolution.log" ]] || fail "HTTP 403 authorization denial incorrectly triggered Basic Auth fallback"
+
+# The BLOCK destination cannot be generic or inferred after failure: opting in
+# without a named principal is refused before any provider operation.
+principal_dir=$(make_case missing-principal)
+set +e
+principal_output=$(run_case "$principal_dir" verified --co-author-trailers 2>&1)
+principal_rc=$?
+set -e
+[[ "$principal_rc" -ne 0 ]] || fail "co-author mode without a named principal unexpectedly passed"
+[[ "$principal_output" == *"requires --escalate-to with a named principal"* ]] || fail "missing-principal refusal lost its diagnostic"
+[[ ! -e "$principal_dir/merge-payload.json" ]] || fail "missing-principal refusal reached the merge API"
+
+# A trailing value-taking option receives a stable CLI diagnostic instead of a
+# set -u unbound-variable crash.
+value_dir=$(make_case missing-principal-value)
+set +e
+value_output=$(run_case "$value_dir" verified --co-author-trailers --escalate-to 2>&1)
+value_rc=$?
+set -e
+[[ "$value_rc" -ne 0 ]] || fail "missing --escalate-to value unexpectedly passed"
+[[ "$value_output" == *"--escalate-to requires one principal name"* ]] || fail "missing --escalate-to value lost its diagnostic"
+[[ "$value_output" != *"unbound variable"* ]] || fail "missing --escalate-to value crashed under set -u"
+[[ ! -e "$value_dir/merge-payload.json" ]] || fail "missing --escalate-to value reached the merge API"
+
+# Negative control: ordinary single-author merge remains byte-for-byte payload
+# compatible and hardcoded to squash, with no optional message fields.
+single_dir=$(make_case single)
+set +e
+single_output=$(run_case "$single_dir" single 2>&1)
+single_rc=$?
+set -e
+if [[ "$single_rc" -ne 0 ]]; then
+    fail "ordinary single-author merge expected rc=0, got rc=$single_rc: $single_output"
+elif [[ ! -s "$single_dir/merge-payload.json" ]]; then
+    fail "ordinary single-author merge did not reach the API payload"
+else
+    python3 - "$single_dir/merge-payload.json" <<'PY' || fail "ordinary single-author payload changed"
+import json
+import sys
+payload = json.load(open(sys.argv[1], encoding="utf-8"))
+assert payload == {
+    "Do": "squash",
+    "head_commit_id": "1111111111111111111111111111111111111111",
+}, payload
+PY
+fi
+[[ -e "$single_dir/auth-via-config" ]] || fail "ordinary path did not authenticate curl through stdin config"
+[[ ! -e "$single_dir/token-in-argv" ]] || fail "ordinary path placed the Gitea token in curl argv"
+[[ "$(wc -l < "$single_dir/token-resolution.log")" -eq 1 ]] || fail "ordinary path did not use exactly one credential resolution"
+
+# Squash is not defaultable: an explicit non-squash method must remain refused.
+method_dir=$(make_case method-refusal)
+set +e
+method_output=$(run_case "$method_dir" single -m merge 2>&1)
+method_rc=$?
+set -e
+[[ "$method_rc" -ne 0 ]] || fail "non-squash method unexpectedly passed"
+[[ "$method_output" == *"enforces squash merge only"* ]] || fail "non-squash refusal lost its policy diagnostic"
+[[ ! -e "$method_dir/merge-payload.json" ]] || fail "non-squash refusal reached the merge API"
+
+if [[ "$failures" -ne 0 ]]; then
+    echo "pr-merge message-field regression failed ($failures assertions)" >&2
+    exit 1
+fi
+
+echo "pr-merge message-field regression passed (verified, BLOCK, and unchanged squash control)"

packages/mosaic/framework/tools/lease-broker/daemon.py

@@ -39,7 +39,7 @@ MAX_FRAME: Final = 64 * 1024
 MAX_STATE: Final = 4 * 1024 * 1024
 MAX_PENDING_TOKENS: Final = 256
 MAX_IN_FLIGHT_CONNECTIONS: Final = 16
-MAX_LEASE_TTL_SECONDS: Final = 300
+MAX_LEASE_TTL_SECONDS: Final = 3600
 STATE_VERSION: Final = 1
 READ_DEADLINE_SECONDS: Final = 1.0
 HANDLE_QUEUE_TIMEOUT_SECONDS: Final = 1.0
@@ -50,8 +50,8 @@ LEASE_PENDING: Final = "PENDING_VERIFICATION"
 LEASE_PENDING_PROMOTION: Final = "PENDING_PROMOTION"
 LEASE_VERIFIED: Final = "VERIFIED"
 READ_ONLY_TOOLS: Final = {
-    "claude": frozenset({"Read", "Grep", "Glob", "Ls", "Find"}),
+    "claude": frozenset({"Read", "Grep", "Glob"}),
-    "pi": frozenset({"read", "grep", "find", "ls"}),
+    "pi": frozenset({"read", "ls"}),
 }
 RECOVERY_TOOL: Final = "mosaic_context_recover"
 

packages/mosaic/framework/tools/lease-broker/launch-runtime.py

@@ -8,7 +8,9 @@ import json
 import os
 import socket
 import sys
+import time
 from collections.abc import Callable, Mapping, Sequence
+from datetime import datetime, timezone
 from pathlib import Path
 from typing import Final
 
@@ -53,6 +55,48 @@ def broker_request(socket_path: Path, request: dict[str, object]) -> dict[str, o
     return value
 
 
+def _self_starttime() -> str | None:
+    """Field 22 of our own /proc stat — the anchor starttime the broker records.
+
+    Read past the comm field's parens, since a process name may contain them.
+    """
+    try:
+        raw = Path(f"/proc/{os.getpid()}/stat").read_text()
+        return raw.rsplit(")", 1)[1].split()[19]
+    except (OSError, IndexError, ValueError):
+        return None
+
+
+def _append_launch_record(environ: Mapping[str, str], record: dict[str, object]) -> None:
+    """Append one NDJSON event to the #797 Runtime Session Ledger.
+
+    `fleet/run/sessions/` is operator-classified in framework-manifest.txt and is
+    already covered by test-upgrade-manifest-guard.sh, so an upgrade can neither
+    overwrite nor prune it. Files 0600 under a 0700 dir, matching what that guard
+    asserts.
+
+    Never raises: a launch must not be denied over bookkeeping. But it also never
+    fails silently — a missing record is exactly the kind of gap that made the
+    2026-08-06 MUTATOR_UNVERIFIED investigation cost a day.
+    """
+    try:
+        mosaic_home = environ.get("MOSAIC_HOME") or str(Path.home() / ".config" / "mosaic")
+        directory = Path(mosaic_home) / "fleet" / "run" / "sessions"
+        directory.mkdir(parents=True, exist_ok=True)
+        os.chmod(directory, 0o700)
+        framed = {
+            "seq": time.time_ns() // 1_000_000,
+            "ts": datetime.now(timezone.utc).isoformat(),
+            **record,
+        }
+        path = directory / "events.ndjson"
+        descriptor = os.open(path, os.O_WRONLY | os.O_CREAT | os.O_APPEND, 0o600)
+        with os.fdopen(descriptor, "w") as handle:
+            handle.write(json.dumps(framed, separators=(",", ":")) + "\n")
+    except (OSError, ValueError, TypeError) as error:
+        print(f"[mosaic] WARNING: launch record not written: {error}", file=sys.stderr)
+
+
 def main(
     argv: Sequence[str] | None = None,
     *,
@@ -94,8 +138,9 @@ def main(
     # silent pass and never folded into the generic registration-failure
     # branch.
     try:
+        activation_capability = probe_activation_capability(source_environment)
         assert_activation_capability_matches(
-            probe_activation_capability(source_environment),
+            activation_capability,
             expected_activation_capability,
         )
     except VersionCouplingError as version_error:
@@ -128,6 +173,32 @@ def main(
         print("Mosaic lease broker registration failed; runtime launch denied.", file=sys.stderr)
         return 1
 
+    # Immutable launch record, half two. `mosaic` wrote `session.launch` with the
+    # config/provenance it knows; only this process knows the broker session id
+    # and the activation capability it just asserted. os.execvpe preserves the
+    # PID, so this PID is BOTH the anchor pid and the join key back to that
+    # record. Never fatal — bookkeeping must not deny a launch — but never
+    # silent either.
+    _append_launch_record(
+        source_environment,
+        {
+            "kind": "lease.register",
+            # Joins back to `mosaic`'s session.launch record. NOT pid: execRuntime()
+            # spawns rather than execs, so this process is a CHILD of mosaic with a
+            # different pid. This pid IS the broker anchor pid (os.execvpe below
+            # preserves it), which is a separate and still-useful fact.
+            "launch_id": source_environment.get("MOSAIC_LAUNCH_ID"),
+            "pid": os.getpid(),
+            "runtime": arguments.runtime,
+            "session_id": session_id,
+            "runtime_generation": generation,
+            "generation_file": str(generation_file),
+            "anchor_starttime": _self_starttime(),
+            "activation_capability": activation_capability,
+            "command": Path(command[0]).name,
+        },
+    )
+
     environment = dict(source_environment)
     environment["MOSAIC_LEASE_SESSION_ID"] = session_id
     environment["MOSAIC_RUNTIME_GENERATION"] = str(generation)

packages/mosaic/framework/tools/lease-broker/lease_promote.py

@@ -0,0 +1,337 @@
+#!/usr/bin/env python3
+"""Lease promotion client — the half the enforcement toolkit never shipped.
+
+The enforcement half (``daemon.py`` + ``mutator-gate.py``) ships and denies. The
+promotion half has no production caller anywhere in the package: as of 0.0.48,
+0.0.49 and 0.0.50-next.2207, ``begin_verification`` / ``observe_receipt`` /
+``promote_lease`` are invoked only by ``broker-test-client.ts``, the acceptance
+spec, unit tests, and two probes under ``docs/``. Consequence: **no lease on any
+host can reach VERIFIED**, so every mutator is denied ``MUTATOR_UNVERIFIED`` by a
+gate nothing can satisfy.
+
+THE PROTOCOL (``daemon.py:578-754``)
+------------------------------------
+  1. ``begin_verification`` — broker revokes, mints a challenge, and returns the
+     exact ``receipt`` text the MODEL must emit
+  2. *the model emits that text verbatim as its ENTIRE latest message*
+  3. the runtime adapter ships that message to the daemon-owned observer socket
+  4. ``observe_receipt``  -> ``PENDING_PROMOTION``
+  5. ``promote_lease``    -> ``VERIFIED``
+
+THIS MODULE IMPLEMENTS 1, 4 AND 5 — NEVER 2
+-------------------------------------------
+Step 2 is the security property, not a formality. ``is_verbatim_receipt`` uses
+``hmac.compare_digest`` against the exact minted string — explicitly "not a
+transcript substring" (``receipt_challenge.py``). Promotion therefore requires a
+live model that received the challenge in its context and echoed it exactly.
+
+``receipt-observer-client.py`` will post ANY string as the latest assistant
+message. A promotion client that posted its own receipt would satisfy the broker
+while proving nothing — a gate-disabler indistinguishable from a working fix
+unless someone looks for it. **This module never posts a receipt.** Emitting it
+belongs to the runtime adapter, where a real model turn happens.
+
+The construction binds the exact normative source bytes. ``h_source`` /
+``h_payload`` are derived by the framework's own
+``normative_fragments.build_payload`` rather than reimplemented: the broker
+derives them the same way and any divergence yields ``PAYLOAD_BINDING_MISMATCH``.
+There must be exactly one implementation.
+
+WHAT THE BINDING DOES *NOT* PROVE
+---------------------------------
+It is tempting to read a VERIFIED lease as "this agent is running THIS law".
+**It does not mean that**, and writing it down that way is how the belief spread.
+The broker holds no reference copy of any normative source and never opens one;
+it recomputes ``h_source`` / ``h_payload`` from the fragment bytes THIS CLIENT
+sent and compares them to the binding THIS CLIENT sent (``daemon.py:602-616``).
+Both sides of that comparison originate here, so it detects corruption in
+transit and nothing else. What the binding actually asserts is "the client
+claims these bytes, self-consistently".
+
+Making it mean the stronger thing requires the broker to re-read the on-disk
+sources itself, against a manifest the agent cannot rewrite — i.e. broker code
+attestation under its own uid. Until then, do not cite a VERIFIED lease as
+evidence of law integrity.
+
+Usage
+-----
+    lease_promote.py --begin                 # prints the receipt the MODEL must emit
+    lease_promote.py --complete <challenge>  # after the adapter observed it
+"""
+
+from __future__ import annotations
+
+import argparse
+import base64
+import hashlib
+import json
+import os
+import socket
+import sys
+from pathlib import Path
+from typing import Final
+
+# Isolated (`python -I`) adapter invocations must still import co-located
+# framework modules; never depend on the caller's PYTHONPATH.
+_MODULE_DIRECTORY = str(Path(__file__).resolve().parent)
+if _MODULE_DIRECTORY not in sys.path:
+    sys.path.insert(0, _MODULE_DIRECTORY)
+
+from normative_fragments import NormativeFragment, build_payload  # noqa: E402
+
+MAX_FRAME: Final = 64 * 1024
+BROKER_TIMEOUT_SECONDS: Final = 3.0
+SCHEMA_VERSION: Final = 1
+MANIFEST_VERSION: Final = 1
+GENERATOR_VERSION: Final = "mosaic/lease_promote@1"
+DEFAULT_TTL_SECONDS: Final = 3600
+
+# Normative sources whose exact bytes bind the lease, in binding order. Order is
+# load-bearing: ``h_source`` frames the resolved sequence, so reordering changes
+# the derivation. Never fabricate a source that is not on disk.
+FRAGMENT_SOURCES: Final = (
+    "CONSTITUTION.md",
+    "AGENTS.md",
+    "SOUL.md",
+    "USER.md",
+    "STANDARDS.md",
+    "TOOLS.md",
+)
+
+# Framework-owned sources, reconciled on every upgrade — `install.sh:76`
+# FRAMEWORK_OWNED and `config/file-adapter.ts` FRAMEWORK_OWNED_FILES — plus the
+# per-runtime contract shipped under `framework/runtime/<runtime>/`. A deployment
+# missing one of these is broken, not minimal, so their absence is refused rather
+# than silently dropped from the binding.
+#
+# SOUL.md and USER.md are deliberately excluded: install.sh does not seed them
+# ("intentionally NOT seeded here — they are generated by `mosaic init`"), so a
+# fresh install legitimately lacks both. TOOLS.md is user-seeded on first install
+# only. Absence of those three is reported, not fatal.
+REQUIRED_SOURCES: Final = frozenset({"CONSTITUTION.md", "AGENTS.md", "STANDARDS.md"})
+
+
+class IncompleteBinding(RuntimeError):
+    """A source that must bind this lease could not be read.
+
+    **Never downgrade this to a skip.** The broker recomputes the hashes from the
+    fragments it is sent, so an omitted fragment is internally consistent and
+    ``PAYLOAD_BINDING_MISMATCH`` cannot fire — a partial law promotes exactly like
+    a complete one, and nothing downstream can tell the difference. Dropping an
+    unreadable source therefore does not degrade the binding, it forges a smaller
+    one. Fail here, where the omission is still visible.
+    """
+
+
+def mosaic_home() -> Path:
+    return Path(os.environ.get("MOSAIC_HOME") or Path.home() / ".config" / "mosaic")
+
+
+def broker_socket() -> Path:
+    value = os.environ.get("MOSAIC_LEASE_BROKER_SOCKET")
+    if value:
+        return Path(value)
+    runtime_dir = os.environ.get("XDG_RUNTIME_DIR")
+    if runtime_dir:
+        return Path(runtime_dir) / "mosaic-lease" / "broker.sock"
+    return Path(f"/run/user/{os.getuid()}/mosaic-lease/broker.sock")
+
+
+def session_identity() -> tuple[str, int, str]:
+    """Session id, CURRENT generation, runtime.
+
+    The generation file wins over the env var, matching ``lease_generation.py``.
+    Sending a generation HIGHER than the broker's would revoke this session's own
+    authority (``daemon.py:342-344``), so this never guesses.
+    """
+    session_id = os.environ["MOSAIC_LEASE_SESSION_ID"]
+    runtime = os.environ["MOSAIC_LEASE_RUNTIME"]
+    state_file = os.environ.get("MOSAIC_LEASE_GENERATION_FILE")
+    if state_file:
+        try:
+            return session_id, int(Path(state_file).read_text().strip()), runtime
+        except (OSError, ValueError):
+            pass
+    return session_id, int(os.environ["MOSAIC_RUNTIME_GENERATION"]), runtime
+
+
+def build_construction(runtime: str) -> tuple[dict[str, object], object]:
+    """Assemble the wire construction and derive its hashes with the sole builder."""
+    runtime_contract = f"runtime/{runtime}/RUNTIME.md"
+    sources = list(FRAGMENT_SOURCES) + [runtime_contract]
+    required = REQUIRED_SOURCES | {runtime_contract}
+    wire_fragments: list[dict[str, str]] = []
+    objects: list[NormativeFragment] = []
+    absent: list[str] = []
+
+    for source_id in sources:
+        try:
+            content = (mosaic_home() / source_id).read_bytes()
+        except FileNotFoundError:
+            # Genuinely not on disk. Legitimate only for operator-owned sources.
+            if source_id in required:
+                raise IncompleteBinding(
+                    f"required normative source is absent: {source_id}"
+                ) from None
+            absent.append(source_id)
+            continue
+        except OSError as exc:
+            # The path resolves but will not read — EACCES, EIO, EISDIR, ELOOP.
+            # That is an anomaly for EVERY source, optional ones included: an
+            # unreadable file is not an un-configured one, and treating it as
+            # absent is what lets a permission change quietly shrink the law.
+            raise IncompleteBinding(
+                f"normative source is present but unreadable: {source_id} "
+                f"({type(exc).__name__})"
+            ) from exc
+
+        digest = hashlib.sha256(content).hexdigest()
+        wire_fragments.append(
+            {
+                "source_id": source_id,
+                "content_base64": base64.b64encode(content).decode("ascii"),
+                "expected_sha256": digest,
+            }
+        )
+        objects.append(NormativeFragment(source_id, content, digest))
+
+    if not wire_fragments:
+        raise IncompleteBinding("no normative sources found — refusing an empty binding")
+
+    # Absence is legitimate here but never invisible. The omission is already
+    # baked into h_source (the framed source sequence differs), but nothing
+    # compares h_source to an expected value, so this line is the only place a
+    # human learns the binding was narrower than the full set.
+    if absent:
+        print(
+            f"lease_promote: binding omits absent operator sources: {', '.join(absent)}",
+            file=sys.stderr,
+        )
+
+    result = build_payload(
+        manifest_version=MANIFEST_VERSION,
+        generator_version=GENERATOR_VERSION,
+        fragments=objects,
+    )
+    if result.injectionDecision != "ACCEPTED" or not result.promotion:
+        raise RuntimeError(f"construction refused locally: {result.source_reason}")
+
+    return (
+        {
+            "manifest_version": MANIFEST_VERSION,
+            "generator_version": GENERATOR_VERSION,
+            "fragments": wire_fragments,
+        },
+        result,
+    )
+
+
+def broker_request(payload: dict[str, object]) -> dict[str, object]:
+    raw = (json.dumps(payload, separators=(",", ":")) + "\n").encode()
+    if len(raw) > MAX_FRAME:
+        raise ValueError(
+            f"request too large ({len(raw)} bytes); broker frame cap is {MAX_FRAME}"
+        )
+    response = bytearray()
+    with socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) as connection:
+        connection.settimeout(BROKER_TIMEOUT_SECONDS)
+        connection.connect(str(broker_socket()))
+        connection.sendall(raw)
+        connection.shutdown(socket.SHUT_WR)
+        while len(response) <= MAX_FRAME:
+            chunk = connection.recv(4096)
+            if not chunk:
+                break
+            response.extend(chunk)
+    if len(response) > MAX_FRAME or not response.endswith(b"\n"):
+        raise ValueError("invalid broker reply")
+    value = json.loads(response)
+    if not isinstance(value, dict):
+        raise ValueError("invalid broker reply")
+    return value
+
+
+def begin(
+    ttl_seconds: int = DEFAULT_TTL_SECONDS,
+    compaction_epoch: int = 0,
+    request_epoch: int = 0,
+) -> dict[str, object]:
+    """Step 1. Returns the broker reply, including the exact ``receipt`` text."""
+    session_id, generation, runtime = session_identity()
+    construction, derived = build_construction(runtime)
+    return broker_request(
+        {
+            "action": "begin_verification",
+            "session_id": session_id,
+            "runtime_generation": generation,
+            "runtime": runtime,
+            "ttl_seconds": ttl_seconds,
+            "binding": {
+                "compaction_epoch": compaction_epoch,
+                "request_epoch": request_epoch,
+                "h_source": derived.h_source,
+                "h_payload": derived.h_payload,
+                "schema_version": SCHEMA_VERSION,
+            },
+            "construction": construction,
+        }
+    )
+
+
+def complete(challenge: str) -> dict[str, object]:
+    """Steps 4-5. Assumes the model already emitted the receipt and the adapter
+    shipped it to the observer socket."""
+    session_id, generation, _ = session_identity()
+    observed = broker_request(
+        {
+            "action": "observe_receipt",
+            "session_id": session_id,
+            "runtime_generation": generation,
+            "receipt_challenge": challenge,
+        }
+    )
+    if observed.get("ok") is not True or observed.get("state") != "PENDING_PROMOTION":
+        return {"stage": "observe_receipt", **observed}
+    promoted = broker_request(
+        {
+            "action": "promote_lease",
+            "session_id": session_id,
+            "runtime_generation": generation,
+            "receipt_challenge": challenge,
+        }
+    )
+    return {"stage": "promote_lease", **promoted}
+
+
+def main(argv: list[str] | None = None) -> int:
+    parser = argparse.ArgumentParser(description="Mosaic lease promotion client.")
+    group = parser.add_mutually_exclusive_group(required=True)
+    group.add_argument(
+        "--begin",
+        action="store_true",
+        help="mint a challenge; prints the receipt the MODEL must emit verbatim",
+    )
+    group.add_argument(
+        "--complete",
+        metavar="CHALLENGE",
+        help="observe the emitted receipt and promote the lease",
+    )
+    parser.add_argument("--ttl-seconds", type=int, default=DEFAULT_TTL_SECONDS)
+    arguments = parser.parse_args(argv)
+
+    try:
+        if arguments.begin:
+            print(json.dumps(begin(ttl_seconds=arguments.ttl_seconds), indent=2))
+        else:
+            print(json.dumps(complete(arguments.complete), indent=2))
+    except KeyError as exc:
+        print(f"missing lease environment: {exc}; not a lease-gated session", file=sys.stderr)
+        return 2
+    except (OSError, ValueError, RuntimeError, json.JSONDecodeError) as exc:
+        print(f"{type(exc).__name__}: {exc}", file=sys.stderr)
+        return 2
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

packages/mosaic/framework/tools/lease-broker/promote-begin.py

@@ -0,0 +1,399 @@
+#!/usr/bin/env python3
+"""Claude UserPromptSubmit hook for operator-triggered lease promotion."""
+
+from __future__ import annotations
+
+import fcntl
+import importlib.util
+import json
+import os
+import secrets
+import stat
+import subprocess
+import sys
+import time
+from collections.abc import Callable, Mapping
+from pathlib import Path
+from typing import Final, TextIO
+
+_MODULE_DIRECTORY = str(Path(__file__).resolve().parent)
+if _MODULE_DIRECTORY not in sys.path:
+    sys.path.insert(0, _MODULE_DIRECTORY)
+
+from receipt_challenge import receipt_for  # noqa: E402
+
+_observer_spec = importlib.util.spec_from_file_location(
+    "mosaic_receipt_observer_client", Path(__file__).resolve().with_name("receipt-observer-client.py")
+)
+if _observer_spec is None or _observer_spec.loader is None:
+    raise RuntimeError("unable to load receipt observer client")
+_observer_module = importlib.util.module_from_spec(_observer_spec)
+_observer_spec.loader.exec_module(_observer_module)
+observer_request = _observer_module.observer_request
+
+MAX_FRAME: Final = 64 * 1024
+PENDING_MAX_AGE_SECONDS: Final = 60 * 60
+PROMOTER_TIMEOUT_SECONDS: Final = 10.0
+PROMOTION_PROMPT: Final = "/mosaic-promote"
+PROMOTER: Final = Path(__file__).resolve().with_name("lease_promote.py")
+PENDING_DIRECTORY: Final = "mosaic-lease"
+AUTHORIZATION_DIRECTORY: Final = "authorizations"
+AUTHORIZATION_TTL_SECONDS: Final = 60
+LEASE_TTL_SECONDS: Final = 60 * 60
+LOCK_FILE: Final = "promotion.lock"
+RESULT_FILE: Final = "last-result.json"
+EXPECTED_BEGIN_KEYS: Final = frozenset(
+    {"ok", "state", "receipt_challenge", "receipt", "binding"}
+)
+EXPECTED_BINDING_KEYS: Final = frozenset(
+    {
+        "compaction_epoch",
+        "request_epoch",
+        "h_source",
+        "h_payload",
+        "runtime_generation",
+        "schema_version",
+    }
+)
+
+
+class PromotionAlreadyInProgress(RuntimeError):
+    pass
+
+
+def reject_duplicate_json_keys(pairs: list[tuple[str, object]]) -> dict[str, object]:
+    value: dict[str, object] = {}
+    for key, item in pairs:
+        if key in value:
+            raise ValueError("duplicate promoter JSON key")
+        value[key] = item
+    return value
+
+
+def read_hook_input(stream: object) -> dict[str, object]:
+    raw = getattr(stream, "buffer", stream).read(MAX_FRAME + 1)
+    if not isinstance(raw, bytes) or len(raw) > MAX_FRAME:
+        raise ValueError("invalid UserPromptSubmit input")
+    value = json.loads(raw, object_pairs_hook=reject_duplicate_json_keys)
+    if not isinstance(value, dict):
+        raise ValueError("invalid UserPromptSubmit input")
+    return value
+
+
+def emit_context(stream: TextIO, message: str) -> None:
+    json.dump(
+        {
+            "hookSpecificOutput": {
+                "hookEventName": "UserPromptSubmit",
+                "additionalContext": message,
+            }
+        },
+        stream,
+        separators=(",", ":"),
+    )
+    stream.write("\n")
+
+
+def session_pending_name(environ: Mapping[str, str]) -> tuple[Path, str]:
+    runtime_dir = Path(environ["XDG_RUNTIME_DIR"])
+    session_id = environ["MOSAIC_LEASE_SESSION_ID"]
+    if not runtime_dir.is_absolute():
+        raise ValueError("XDG_RUNTIME_DIR must be absolute")
+    if len(session_id) != 64 or any(character not in "0123456789abcdef" for character in session_id):
+        raise ValueError("invalid lease session id")
+    return runtime_dir, f"pending-{session_id}"
+
+
+def open_pending_directory(runtime_dir: Path) -> int:
+    directory_flags = (
+        os.O_RDONLY
+        | getattr(os, "O_CLOEXEC", 0)
+        | getattr(os, "O_DIRECTORY", 0)
+        | getattr(os, "O_NOFOLLOW", 0)
+    )
+    runtime_descriptor = os.open(runtime_dir, directory_flags)
+    try:
+        runtime_metadata = os.fstat(runtime_descriptor)
+        if (
+            not stat.S_ISDIR(runtime_metadata.st_mode)
+            or runtime_metadata.st_uid != os.getuid()
+            or stat.S_IMODE(runtime_metadata.st_mode) != 0o700
+        ):
+            raise ValueError("unsafe XDG runtime directory")
+        try:
+            os.mkdir(PENDING_DIRECTORY, mode=0o700, dir_fd=runtime_descriptor)
+        except FileExistsError:
+            pass
+        descriptor = os.open(PENDING_DIRECTORY, directory_flags, dir_fd=runtime_descriptor)
+    finally:
+        os.close(runtime_descriptor)
+
+    metadata = os.fstat(descriptor)
+    if (
+        not stat.S_ISDIR(metadata.st_mode)
+        or metadata.st_uid != os.getuid()
+        or stat.S_IMODE(metadata.st_mode) != 0o700
+    ):
+        os.close(descriptor)
+        raise ValueError("unsafe promotion pending directory")
+    return descriptor
+
+
+def acquire_lock(directory_descriptor: int) -> int:
+    flags = (
+        os.O_RDWR
+        | os.O_CREAT
+        | getattr(os, "O_CLOEXEC", 0)
+        | getattr(os, "O_NOFOLLOW", 0)
+    )
+    descriptor = os.open(LOCK_FILE, flags, 0o600, dir_fd=directory_descriptor)
+    metadata = os.fstat(descriptor)
+    if (
+        not stat.S_ISREG(metadata.st_mode)
+        or metadata.st_uid != os.getuid()
+        or stat.S_IMODE(metadata.st_mode) != 0o600
+    ):
+        os.close(descriptor)
+        raise ValueError("unsafe promotion lock file")
+    try:
+        fcntl.flock(descriptor, fcntl.LOCK_EX | fcntl.LOCK_NB)
+    except BlockingIOError as error:
+        os.close(descriptor)
+        raise PromotionAlreadyInProgress() from error
+    return descriptor
+
+
+def sweep_stale_pending(directory_descriptor: int, current_time: float) -> None:
+    cutoff = current_time - PENDING_MAX_AGE_SECONDS
+    removed = False
+    with os.scandir(directory_descriptor) as entries:
+        for candidate in entries:
+            if not (
+                candidate.name.startswith("pending-")
+                or candidate.name.startswith(".pending-")
+            ):
+                continue
+            try:
+                metadata = candidate.stat(follow_symlinks=False)
+                if metadata.st_mtime < cutoff and not stat.S_ISDIR(metadata.st_mode):
+                    os.unlink(candidate.name, dir_fd=directory_descriptor)
+                    removed = True
+            except FileNotFoundError:
+                continue
+    if removed:
+        os.fsync(directory_descriptor)
+
+
+def consume_authorization(directory_descriptor: int, session_id: str, wall_clock: float) -> str | None:
+    flags = os.O_RDONLY | getattr(os, "O_CLOEXEC", 0) | getattr(os, "O_DIRECTORY", 0) | getattr(os, "O_NOFOLLOW", 0)
+    try:
+        authorization_descriptor = os.open(AUTHORIZATION_DIRECTORY, flags, dir_fd=directory_descriptor)
+    except FileNotFoundError:
+        return None
+    try:
+        metadata = os.fstat(authorization_descriptor)
+        if not stat.S_ISDIR(metadata.st_mode) or metadata.st_uid != os.getuid() or stat.S_IMODE(metadata.st_mode) != 0o700:
+            raise ValueError("unsafe promotion authorization directory")
+        name = f"{session_id}.auth"
+        try:
+            descriptor = os.open(name, os.O_RDONLY | getattr(os, "O_CLOEXEC", 0) | getattr(os, "O_NOFOLLOW", 0), dir_fd=authorization_descriptor)
+        except FileNotFoundError:
+            return None
+        try:
+            token_metadata = os.fstat(descriptor)
+            if not stat.S_ISREG(token_metadata.st_mode) or token_metadata.st_uid != os.getuid() or stat.S_IMODE(token_metadata.st_mode) != 0o600 or token_metadata.st_size <= 0 or token_metadata.st_size > MAX_FRAME:
+                raise ValueError("unsafe promotion authorization")
+            raw = os.read(descriptor, MAX_FRAME + 1)
+        finally:
+            os.close(descriptor)
+        os.unlink(name, dir_fd=authorization_descriptor)
+        os.fsync(authorization_descriptor)
+        token = json.loads(raw, object_pairs_hook=reject_duplicate_json_keys)
+        if not isinstance(token, dict) or set(token) != {"nonce", "seat", "session_id", "expires_at", "ts"}:
+            return None
+        nonce = token.get("nonce")
+        expires_at = token.get("expires_at")
+        issued_at = token.get("ts")
+        if token.get("session_id") != session_id or not isinstance(token.get("seat"), str) or not isinstance(nonce, str) or len(nonce) != 64 or any(char not in "0123456789abcdef" for char in nonce) or type(expires_at) not in (int, float) or type(issued_at) not in (int, float) or expires_at <= wall_clock or expires_at > issued_at + AUTHORIZATION_TTL_SECONDS:
+            return None
+        return nonce
+    finally:
+        os.close(authorization_descriptor)
+
+
+def write_result(directory_descriptor: int, attempt_id: str, verified: bool, reason: str | None, session_id: str, wall_clock: float) -> None:
+    temporary = f".{RESULT_FILE}.tmp-{secrets.token_hex(8)}"
+    descriptor = os.open(temporary, os.O_WRONLY | os.O_CREAT | os.O_EXCL | getattr(os, "O_CLOEXEC", 0) | getattr(os, "O_NOFOLLOW", 0), 0o600, dir_fd=directory_descriptor)
+    try:
+        os.fchmod(descriptor, 0o600)
+        with os.fdopen(descriptor, "w", encoding="utf-8", closefd=False) as stream:
+            json.dump({"attempt_id": attempt_id, "expires_at_wallclock": wall_clock + LEASE_TTL_SECONDS if verified else None, "reason": reason, "session_id": session_id, "ts": wall_clock, "verified": verified}, stream, separators=(",", ":"), sort_keys=True)
+            stream.flush(); os.fsync(stream.fileno())
+        os.replace(temporary, RESULT_FILE, src_dir_fd=directory_descriptor, dst_dir_fd=directory_descriptor)
+        os.fsync(directory_descriptor)
+    finally:
+        os.close(descriptor)
+
+
+def write_pending(directory_descriptor: int, name: str, challenge: str) -> None:
+    temporary = f".{name}.tmp-{secrets.token_hex(8)}"
+    flags = (
+        os.O_WRONLY
+        | os.O_CREAT
+        | os.O_EXCL
+        | getattr(os, "O_CLOEXEC", 0)
+        | getattr(os, "O_NOFOLLOW", 0)
+    )
+    descriptor = os.open(temporary, flags, 0o600, dir_fd=directory_descriptor)
+    try:
+        os.fchmod(descriptor, 0o600)
+        with os.fdopen(descriptor, "w", encoding="utf-8", closefd=False) as stream:
+            stream.write(challenge)
+            stream.flush()
+            os.fsync(stream.fileno())
+        os.replace(
+            temporary,
+            name,
+            src_dir_fd=directory_descriptor,
+            dst_dir_fd=directory_descriptor,
+        )
+        os.fsync(directory_descriptor)
+    except Exception:
+        try:
+            os.unlink(temporary, dir_fd=directory_descriptor)
+        except FileNotFoundError:
+            pass
+        raise
+    finally:
+        os.close(descriptor)
+
+
+def parse_begin_reply(
+    completed: subprocess.CompletedProcess[str],
+) -> tuple[str, dict[str, object] | None]:
+    if completed.returncode != 0:
+        return f"PROMOTER_EXIT_{completed.returncode}", None
+    try:
+        value = json.loads(
+            completed.stdout,
+            object_pairs_hook=reject_duplicate_json_keys,
+        )
+    except (json.JSONDecodeError, RecursionError, TypeError, ValueError):
+        return "INVALID_PROMOTER_REPLY", None
+    if not isinstance(value, dict):
+        return "INVALID_PROMOTER_REPLY", None
+    if value.get("ok") is False and set(value) == {"ok", "code"}:
+        code = value.get("code")
+        return code if isinstance(code, str) and code else "PROMOTION_BEGIN_REFUSED", value
+    if set(value) != EXPECTED_BEGIN_KEYS or value.get("ok") is not True:
+        return "INVALID_PROMOTER_REPLY", None
+    if value.get("state") != "PENDING_VERIFICATION":
+        return "INVALID_PROMOTER_REPLY", None
+    challenge = value.get("receipt_challenge")
+    receipt = value.get("receipt")
+    binding = value.get("binding")
+    if (
+        not isinstance(challenge, str)
+        or len(challenge) != 64
+        or any(character not in "0123456789abcdef" for character in challenge)
+        or not isinstance(receipt, str)
+        or not isinstance(binding, dict)
+        or set(binding) != EXPECTED_BINDING_KEYS
+    ):
+        return "INVALID_PROMOTER_REPLY", None
+    integer_fields = (
+        "compaction_epoch",
+        "request_epoch",
+        "runtime_generation",
+        "schema_version",
+    )
+    if any(type(binding.get(field)) is not int or binding[field] < 0 for field in integer_fields):
+        return "INVALID_PROMOTER_REPLY", None
+    if not all(
+        isinstance(binding.get(field), str)
+        and len(binding[field]) == 64
+        and all(character in "0123456789abcdef" for character in binding[field])
+        for field in ("h_source", "h_payload")
+    ):
+        return "INVALID_PROMOTER_REPLY", None
+    if not secrets.compare_digest(
+        receipt.encode("utf-8"),
+        receipt_for(challenge, binding).encode("utf-8"),
+    ):
+        return "INVALID_PROMOTER_REPLY", None
+    return "", value
+
+
+def main(
+    *,
+    environ: Mapping[str, str] | None = None,
+    stdin: object | None = None,
+    stdout: TextIO | None = None,
+    stderr: TextIO | None = None,
+    run: Callable[..., subprocess.CompletedProcess[str]] = subprocess.run,
+    now: Callable[[], float] = time.time,
+) -> int:
+    source_environment = os.environ if environ is None else environ
+    input_stream = sys.stdin if stdin is None else stdin
+    output_stream = sys.stdout if stdout is None else stdout
+    error_stream = sys.stderr if stderr is None else stderr
+
+    try:
+        hook_input = read_hook_input(input_stream)
+    except (OSError, RecursionError, ValueError, json.JSONDecodeError) as error:
+        print(f"Mosaic promotion trigger ignored invalid hook input: {error}", file=error_stream)
+        return 0
+    if hook_input.get("prompt") != PROMOTION_PROMPT:
+        return 0
+
+    directory_descriptor: int | None = None
+    lock_descriptor: int | None = None
+    try:
+        runtime_dir, pending_name = session_pending_name(source_environment)
+        session_id = source_environment["MOSAIC_LEASE_SESSION_ID"]
+        directory_descriptor = open_pending_directory(runtime_dir)
+        lock_descriptor = acquire_lock(directory_descriptor)
+        wall_clock = now()
+        nonce = consume_authorization(directory_descriptor, session_id, wall_clock)
+        if nonce is None:
+            write_result(directory_descriptor, "0" * 64, False, "NOT_AUTHORIZED", session_id, wall_clock)
+            print("Mosaic promotion denied: NOT_AUTHORIZED.", file=error_stream)
+            return 0
+        sweep_stale_pending(directory_descriptor, wall_clock)
+        completed = run([sys.executable, "-I", "-S", "-B", str(PROMOTER), "--begin"], check=False, capture_output=True, text=True, env=dict(source_environment), timeout=PROMOTER_TIMEOUT_SECONDS)
+        code, reply = parse_begin_reply(completed)
+        if code or reply is None:
+            write_result(directory_descriptor, nonce, False, code or "PROMOTION_BEGIN_FAILED", session_id, now())
+            return 0
+        challenge = str(reply["receipt_challenge"])
+        observation = observer_request(
+            Path(source_environment["MOSAIC_RECEIPT_OBSERVER_SOCKET"]),
+            {"action": "record_runtime_observation", "session_id": session_id, "runtime_generation": int(source_environment["MOSAIC_RUNTIME_GENERATION"]), "runtime": "claude", "latest_assistant_message": reply["receipt"]},
+        )
+        if set(observation) != {"ok"} or observation.get("ok") is not True:
+            write_result(directory_descriptor, challenge, False, "OBSERVATION_REJECTED", session_id, now())
+            return 0
+        completion = run([sys.executable, "-I", "-S", "-B", str(PROMOTER), "--complete", challenge], check=False, capture_output=True, text=True, env=dict(source_environment), timeout=PROMOTER_TIMEOUT_SECONDS)
+        try:
+            outcome = json.loads(completion.stdout, object_pairs_hook=reject_duplicate_json_keys)
+        except (json.JSONDecodeError, ValueError):
+            outcome = None
+        if completion.returncode == 0 and isinstance(outcome, dict) and outcome.get("stage") == "promote_lease" and outcome.get("ok") is True and outcome.get("state") == "VERIFIED":
+            write_result(directory_descriptor, challenge, True, None, session_id, now())
+        else:
+            reason = outcome.get("code") if isinstance(outcome, dict) and isinstance(outcome.get("code"), str) else "PROMOTION_INCOMPLETE"
+            write_result(directory_descriptor, challenge, False, reason, session_id, now())
+    except PromotionAlreadyInProgress:
+        print("Mosaic promotion denied: PROMOTION_ALREADY_IN_PROGRESS.", file=error_stream)
+    except (KeyError, OSError, RecursionError, ValueError, subprocess.SubprocessError) as error:
+        print(f"Mosaic promotion begin failed: {type(error).__name__}: {error}", file=error_stream)
+    finally:
+        if lock_descriptor is not None:
+            os.close(lock_descriptor)
+        if directory_descriptor is not None:
+            os.close(directory_descriptor)
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

packages/mosaic/framework/tools/lease-broker/promote-complete.py

@@ -0,0 +1,361 @@
+#!/usr/bin/env python3
+"""Claude Stop hook that completes a pending operator-triggered promotion."""
+
+from __future__ import annotations
+
+import fcntl
+import json
+import os
+import secrets
+import stat
+import subprocess
+import sys
+import time
+from collections.abc import Callable, Mapping
+from pathlib import Path
+from typing import Final, NamedTuple, TextIO
+
+MAX_FRAME: Final = 64 * 1024
+PROMOTER_TIMEOUT_SECONDS: Final = 10.0
+LEASE_TTL_SECONDS: Final = 60 * 60
+PROMOTER: Final = Path(__file__).resolve().with_name("lease_promote.py")
+PENDING_DIRECTORY: Final = "mosaic-lease"
+LOCK_FILE: Final = "promotion.lock"
+RESULT_FILE: Final = "last-result.json"
+TERMINAL_FAILURE_CODES: Final = frozenset(
+    {
+        "RECEIPT_REPLAY",
+        "RECEIPT_MISMATCH",
+        "INVALID_LEASE_TRANSITION",
+        "PROMOTION_TOKEN_INVALID",
+    }
+)
+
+
+class PendingChallenge(NamedTuple):
+    value: str
+    device: int
+    inode: int
+
+
+def reject_duplicate_json_keys(pairs: list[tuple[str, object]]) -> dict[str, object]:
+    value: dict[str, object] = {}
+    for key, item in pairs:
+        if key in value:
+            raise ValueError("duplicate promoter JSON key")
+        value[key] = item
+    return value
+
+
+def session_pending_name(environ: Mapping[str, str]) -> tuple[Path, str]:
+    runtime_dir = Path(environ["XDG_RUNTIME_DIR"])
+    session_id = environ["MOSAIC_LEASE_SESSION_ID"]
+    if not runtime_dir.is_absolute():
+        raise ValueError("XDG_RUNTIME_DIR must be absolute")
+    if len(session_id) != 64 or any(character not in "0123456789abcdef" for character in session_id):
+        raise ValueError("invalid lease session id")
+    return runtime_dir, f"pending-{session_id}"
+
+
+def open_pending_directory(runtime_dir: Path) -> int | None:
+    directory_flags = (
+        os.O_RDONLY
+        | getattr(os, "O_CLOEXEC", 0)
+        | getattr(os, "O_DIRECTORY", 0)
+        | getattr(os, "O_NOFOLLOW", 0)
+    )
+    try:
+        runtime_descriptor = os.open(runtime_dir, directory_flags)
+    except FileNotFoundError:
+        return None
+    try:
+        runtime_metadata = os.fstat(runtime_descriptor)
+        if (
+            not stat.S_ISDIR(runtime_metadata.st_mode)
+            or runtime_metadata.st_uid != os.getuid()
+            or stat.S_IMODE(runtime_metadata.st_mode) != 0o700
+        ):
+            raise ValueError("unsafe XDG runtime directory")
+        try:
+            descriptor = os.open(PENDING_DIRECTORY, directory_flags, dir_fd=runtime_descriptor)
+        except FileNotFoundError:
+            return None
+    finally:
+        os.close(runtime_descriptor)
+
+    metadata = os.fstat(descriptor)
+    if (
+        not stat.S_ISDIR(metadata.st_mode)
+        or metadata.st_uid != os.getuid()
+        or stat.S_IMODE(metadata.st_mode) != 0o700
+    ):
+        os.close(descriptor)
+        raise ValueError("unsafe promotion pending directory")
+    return descriptor
+
+
+def acquire_lock(directory_descriptor: int) -> int:
+    flags = (
+        os.O_RDWR
+        | os.O_CREAT
+        | getattr(os, "O_CLOEXEC", 0)
+        | getattr(os, "O_NOFOLLOW", 0)
+    )
+    descriptor = os.open(LOCK_FILE, flags, 0o600, dir_fd=directory_descriptor)
+    metadata = os.fstat(descriptor)
+    if (
+        not stat.S_ISREG(metadata.st_mode)
+        or metadata.st_uid != os.getuid()
+        or stat.S_IMODE(metadata.st_mode) != 0o600
+    ):
+        os.close(descriptor)
+        raise ValueError("unsafe promotion lock file")
+    try:
+        fcntl.flock(descriptor, fcntl.LOCK_EX | fcntl.LOCK_NB)
+    except BlockingIOError:
+        os.close(descriptor)
+        raise
+    return descriptor
+
+
+def read_pending(directory_descriptor: int, name: str) -> PendingChallenge | None:
+    flags = os.O_RDONLY | getattr(os, "O_CLOEXEC", 0) | getattr(os, "O_NOFOLLOW", 0)
+    try:
+        descriptor = os.open(name, flags, dir_fd=directory_descriptor)
+    except FileNotFoundError:
+        return None
+    try:
+        metadata = os.fstat(descriptor)
+        if (
+            not stat.S_ISREG(metadata.st_mode)
+            or metadata.st_uid != os.getuid()
+            or stat.S_IMODE(metadata.st_mode) != 0o600
+            or metadata.st_size <= 0
+            or metadata.st_size > MAX_FRAME
+        ):
+            raise ValueError("unsafe promotion pending file")
+        raw = os.read(descriptor, MAX_FRAME + 1)
+    finally:
+        os.close(descriptor)
+    if len(raw) > MAX_FRAME:
+        raise ValueError("oversized promotion challenge")
+    challenge = raw.decode("utf-8")
+    if (
+        len(challenge) != 64
+        or any(character not in "0123456789abcdef" for character in challenge)
+    ):
+        raise ValueError("invalid promotion challenge")
+    return PendingChallenge(challenge, metadata.st_dev, metadata.st_ino)
+
+
+def write_result(
+    directory_descriptor: int,
+    attempt_id: str,
+    verified: bool,
+    reason: str | None,
+    session_id: str,
+    wall_clock: float,
+) -> None:
+    result = {
+        "attempt_id": attempt_id,
+        "expires_at_wallclock": wall_clock + LEASE_TTL_SECONDS if verified else None,
+        "reason": reason,
+        "session_id": session_id,
+        "ts": wall_clock,
+        "verified": verified,
+    }
+    temporary = f".{RESULT_FILE}.tmp-{secrets.token_hex(8)}"
+    flags = (
+        os.O_WRONLY
+        | os.O_CREAT
+        | os.O_EXCL
+        | getattr(os, "O_CLOEXEC", 0)
+        | getattr(os, "O_NOFOLLOW", 0)
+    )
+    descriptor = os.open(temporary, flags, 0o600, dir_fd=directory_descriptor)
+    try:
+        os.fchmod(descriptor, 0o600)
+        with os.fdopen(descriptor, "w", encoding="utf-8", closefd=False) as stream:
+            json.dump(result, stream, separators=(",", ":"), sort_keys=True)
+            stream.flush()
+            os.fsync(stream.fileno())
+        os.replace(
+            temporary,
+            RESULT_FILE,
+            src_dir_fd=directory_descriptor,
+            dst_dir_fd=directory_descriptor,
+        )
+        os.fsync(directory_descriptor)
+    except Exception:
+        try:
+            os.unlink(temporary, dir_fd=directory_descriptor)
+        except FileNotFoundError:
+            pass
+        raise
+    finally:
+        os.close(descriptor)
+
+
+def delete_pending_if_unchanged(
+    directory_descriptor: int,
+    name: str,
+    pending: PendingChallenge,
+    error_stream: TextIO,
+) -> None:
+    quarantine = f".{name}.delete-{secrets.token_hex(8)}"
+    try:
+        os.rename(
+            name,
+            quarantine,
+            src_dir_fd=directory_descriptor,
+            dst_dir_fd=directory_descriptor,
+        )
+    except FileNotFoundError:
+        return
+    except OSError as error:
+        print(f"Mosaic promotion could not quarantine pending file: {error}", file=error_stream)
+        return
+
+    try:
+        moved = os.stat(
+            quarantine,
+            dir_fd=directory_descriptor,
+            follow_symlinks=False,
+        )
+        if (moved.st_dev, moved.st_ino) == (pending.device, pending.inode):
+            os.unlink(quarantine, dir_fd=directory_descriptor)
+            os.fsync(directory_descriptor)
+            return
+
+        print("Mosaic promotion pending file changed; preserving replacement.", file=error_stream)
+        try:
+            os.link(
+                quarantine,
+                name,
+                src_dir_fd=directory_descriptor,
+                dst_dir_fd=directory_descriptor,
+                follow_symlinks=False,
+            )
+        except FileExistsError:
+            print(
+                f"Mosaic promotion preserved replacement as {quarantine}.",
+                file=error_stream,
+            )
+        else:
+            os.unlink(quarantine, dir_fd=directory_descriptor)
+        os.fsync(directory_descriptor)
+    except OSError as error:
+        print(f"Mosaic promotion could not resolve pending file: {error}", file=error_stream)
+
+
+def parse_reply(completed: subprocess.CompletedProcess[str]) -> dict[str, object] | None:
+    if completed.returncode != 0:
+        return None
+    try:
+        value = json.loads(
+            completed.stdout,
+            object_pairs_hook=reject_duplicate_json_keys,
+        )
+    except (json.JSONDecodeError, RecursionError, TypeError, ValueError):
+        return None
+    if not isinstance(value, dict):
+        return None
+    if set(value) == {"stage", "ok", "state"}:
+        if (
+            value.get("stage") == "promote_lease"
+            and value.get("ok") is True
+            and value.get("state") == "VERIFIED"
+        ):
+            return value
+        return None
+    if set(value) == {"stage", "ok", "code"}:
+        if (
+            value.get("stage") in {"observe_receipt", "promote_lease"}
+            and value.get("ok") is False
+            and isinstance(value.get("code"), str)
+            and value.get("code")
+        ):
+            return value
+    return None
+
+
+def main(
+    *,
+    environ: Mapping[str, str] | None = None,
+    stderr: TextIO | None = None,
+    run: Callable[..., subprocess.CompletedProcess[str]] = subprocess.run,
+    now: Callable[[], float] = time.time,
+) -> int:
+    source_environment = os.environ if environ is None else environ
+    error_stream = sys.stderr if stderr is None else stderr
+    directory_descriptor: int | None = None
+    lock_descriptor: int | None = None
+
+    try:
+        runtime_dir, pending_name = session_pending_name(source_environment)
+        session_id = source_environment["MOSAIC_LEASE_SESSION_ID"]
+        directory_descriptor = open_pending_directory(runtime_dir)
+        if directory_descriptor is None:
+            return 0
+        try:
+            lock_descriptor = acquire_lock(directory_descriptor)
+        except (BlockingIOError, FileNotFoundError):
+            print("Mosaic promotion completion deferred: promotion is in progress.", file=error_stream)
+            return 0
+        pending = read_pending(directory_descriptor, pending_name)
+        if pending is None:
+            return 0
+        completed = run(
+            [
+                sys.executable,
+                "-I",
+                "-S",
+                "-B",
+                str(PROMOTER),
+                "--complete",
+                pending.value,
+            ],
+            check=False,
+            capture_output=True,
+            text=True,
+            env=dict(source_environment),
+            timeout=PROMOTER_TIMEOUT_SECONDS,
+        )
+        reply = parse_reply(completed)
+        if reply is not None and reply.get("ok") is True:
+            write_result(directory_descriptor, pending.value, True, None, session_id, now())
+            delete_pending_if_unchanged(
+                directory_descriptor,
+                pending_name,
+                pending,
+                error_stream,
+            )
+            print("Mosaic lease promotion completed.", file=error_stream)
+            return 0
+
+        if reply is not None:
+            code = str(reply["code"])
+            print(f"Mosaic promotion incomplete: {code}.", file=error_stream)
+            if code in TERMINAL_FAILURE_CODES:
+                write_result(directory_descriptor, pending.value, False, code, session_id, now())
+                delete_pending_if_unchanged(
+                    directory_descriptor,
+                    pending_name,
+                    pending,
+                    error_stream,
+                )
+        else:
+            diagnostic = completed.stderr.strip() or f"promoter exit {completed.returncode}"
+            print(f"Mosaic promotion retryable failure: {diagnostic}.", file=error_stream)
+    except (KeyError, OSError, RecursionError, UnicodeError, ValueError, subprocess.SubprocessError) as error:
+        print(f"Mosaic promotion completion deferred: {type(error).__name__}: {error}", file=error_stream)
+    finally:
+        if lock_descriptor is not None:
+            os.close(lock_descriptor)
+        if directory_descriptor is not None:
+            os.close(directory_descriptor)
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

packages/mosaic/framework/tools/lease-broker/receipt-observer-client.py

@@ -22,13 +22,23 @@ from typing import Final
 MAX_FRAME: Final = 64 * 1024
 BROKER_TIMEOUT_SECONDS: Final = 1.5
 MAX_TRANSCRIPT_BYTES: Final = 4 * 1024 * 1024
+BENIGN_OBSERVATION_UNAVAILABLE_CODE: Final = "OBSERVATION_UNAVAILABLE"
+
+
+def reject_duplicate_json_keys(pairs: list[tuple[str, object]]) -> dict[str, object]:
+    value: dict[str, object] = {}
+    for key, item in pairs:
+        if key in value:
+            raise ValueError("duplicate observer JSON key")
+        value[key] = item
+    return value
 
 
 def read_json(stream: object) -> dict[str, object]:
     raw = getattr(stream, "buffer", stream).read(MAX_FRAME + 1)
     if not isinstance(raw, bytes) or len(raw) > MAX_FRAME:
         raise ValueError("invalid observer input")
-    value = json.loads(raw)
+    value = json.loads(raw, object_pairs_hook=reject_duplicate_json_keys)
     if not isinstance(value, dict):
         raise ValueError("invalid observer input")
     return value
@@ -100,9 +110,9 @@ def observer_request(socket_path: Path, request: dict[str, object]) -> dict[str,
             if not chunk:
                 break
             response.extend(chunk)
-    if len(response) > MAX_FRAME or not response.endswith(b"\n"):
+    if len(response) > MAX_FRAME or response.count(b"\n") != 1 or not response.endswith(b"\n"):
         raise ValueError("invalid observer reply")
-    value = json.loads(response)
+    value = json.loads(response[:-1], object_pairs_hook=reject_duplicate_json_keys)
     if not isinstance(value, dict):
         raise ValueError("invalid observer reply")
     return value
@@ -119,7 +129,12 @@ def main(argv: Sequence[str] | None = None, *, environ: Mapping[str, str] | None
         if arguments.runtime == "claude":
             if not arguments.latest_entry:
                 raise ValueError("Claude observer requires --latest-entry")
-            message = claude_latest_entry(source)
+            if "last_assistant_message" in source:
+                message = source["last_assistant_message"]
+                if not isinstance(message, str):
+                    raise ValueError("invalid Claude observer input")
+            else:
+                message = claude_latest_entry(source)
         else:
             if arguments.latest_entry:
                 raise ValueError("Pi observer is message_end only")
@@ -133,10 +148,18 @@ def main(argv: Sequence[str] | None = None, *, environ: Mapping[str, str] | None
             "runtime": arguments.runtime,
             "latest_assistant_message": message,
         })
-    except (KeyError, OSError, ValueError, json.JSONDecodeError) as error:
+    except (KeyError, OSError, RecursionError, ValueError, json.JSONDecodeError) as error:
         print(f"Mosaic receipt observer refused: {error}", file=sys.stderr)
         return 2
-    return 0 if reply == {"ok": True} else 2
+    if set(reply) == {"ok"} and reply.get("ok") is True:
+        return 0
+    if (
+        set(reply) == {"ok", "code"}
+        and reply.get("ok") is False
+        and reply.get("code") == BENIGN_OBSERVATION_UNAVAILABLE_CODE
+    ):
+        return 0
+    return 2
 
 
 if __name__ == "__main__":

packages/mosaic/framework/tools/lease-broker/receipt_challenge.py

@@ -33,7 +33,7 @@ def is_verbatim_receipt(message: str, challenge: str, binding: dict[str, object]
     """Require the exact one current-cycle receipt, not a transcript substring."""
 
     expected = receipt_for(challenge, binding)
-    return hmac.compare_digest(message, expected)
+    return hmac.compare_digest(message.encode("utf-8"), expected.encode("utf-8"))
 
 
 def latest_assistant_digest(message: str) -> str:

packages/mosaic/framework/tools/quality/scripts/test-upgrade-rollback.sh

@@ -39,11 +39,12 @@ ORIG_PATH="$PATH"
 # loop — which would make the control a false negative. A root dotfile is
 # operator-owned (unknown→operator), so the sync loop skips it. Clean up on exit.
 STRIPPED="$FW/.install-rollback-control.tmp.sh"
+SIGNALED="$FW/.install-signal-control.tmp.sh"
 NOEXIT="$FW/.install-noexit-control.tmp.sh"
 D1CTRL="$FW/.install-d1guard-control.tmp.sh"
 D2CTRL="$FW/.install-d2guard-control.tmp.sh"
-rm -f "$STRIPPED" "$NOEXIT" "$D1CTRL" "$D2CTRL"
+rm -f "$STRIPPED" "$SIGNALED" "$NOEXIT" "$D1CTRL" "$D2CTRL"
-trap 'rm -f "$STRIPPED" "$NOEXIT" "$D1CTRL" "$D2CTRL"' EXIT
+trap 'rm -f "$STRIPPED" "$SIGNALED" "$NOEXIT" "$D1CTRL" "$D2CTRL"' EXIT
 
 pass=0; fail=0
 chk() { if eval "$2"; then echo "  ✓ $1"; pass=$((pass + 1)); else echo "  ✗ $1"; fail=$((fail + 1)); fi; }
@@ -180,41 +181,86 @@ chk "[control] without -E the mid-sync corruption survives (no rollback)" \
 # ── Part C: an INT/TERM interrupt must terminate, not resume (blocker-A) ──────
 # A bash signal trap that merely returns lets the script continue past the
 # interrupt — restoring the snapshot, then resuming the sync and reporting
-# success. We inject a SIGTERM mid-sync with a cp that SUCCEEDS (so set -e never
+# success. The earlier test used a child cp shim to signal its parent, making
-# fires and ONLY the signal path governs), and assert the shipped installer
+# child completion race Bash's interrupted wait. Concurrency is not part of the
-# restores AND exits without reporting success. The control strips `exit 1` from
+# guarded property: sync_framework_keep() runs in the installer's own Bash
-# the trap and shows the buggy resume-to-success.
+# process, and `kill` is a builtin. Generate two installer fixtures that signal
-make_term_shim() {
+# themselves at the same known mid-sync point. Their TERM handlers emit the same
-  local dir="$1"
+# observable before diverging, so missing signal delivery fails BOTH arms rather
-  cat > "$dir/cp" <<SHIM
+# than manufacturing a pass. The only semantic difference between fixtures is
-#!/usr/bin/env bash
+# the explicit `exit 1` whose load-bearing behavior this control proves.
-dest="\${@: -1}"
+TERM_MARKER='[test-control] TERM handler entered'
-case "\$dest" in
+HANDLER_WITH_EXIT="trap 'echo \"$TERM_MARKER\" >&2; restore_snapshot; exit 1' TERM  # TEST-TERM-HANDLER"
-  */$POISON_REL)
+HANDLER_WITHOUT_EXIT="trap 'echo \"$TERM_MARKER\" >&2; restore_snapshot' TERM  # TEST-TERM-HANDLER"
-    kill -TERM "\$PPID" 2>/dev/null   # signal install.sh; the copy still succeeds
+
-    exec env PATH="$ORIG_PATH" cp "\$@" ;;
+make_signal_installer() {
-esac
+  local output="$1" handler="$2"
-exec env PATH="$ORIG_PATH" cp "\$@"
+  local target_trap="trap 'restore_snapshot; exit 1' ERR INT TERM"
-SHIM
+  local target_cp='    cp "$abs" "$dst/$rel"'
-  chmod +x "$dir/cp"
+  local inject_open="    if [[ \"\$rel\" == \"$POISON_REL\" ]]; then"
+  local inject_kill='      kill -TERM "$$"  # TEST-TERM-INJECTION'
+  local inject_close='    fi'
+
+  if ! awk \
+    -v target_trap="$target_trap" -v target_cp="$target_cp" \
+    -v handler="$handler" -v inject_open="$inject_open" \
+    -v inject_kill="$inject_kill" -v inject_close="$inject_close" '
+      $0 == target_cp {
+        print inject_open
+        print inject_kill
+        print inject_close
+        injection_sites++
+      }
+      { print }
+      $0 == target_trap {
+        print handler
+        handler_sites++
+      }
+      END {
+        if (handler_sites != 1 || injection_sites != 1) exit 42
+      }
+    ' "$INSTALL" > "$output"; then
+    rm -f "$output"
+    fail "Could not construct the self-TERM control installer at the exact trap/copy sites"
+    exit 1
+  fi
+  chmod +x "$output"
 }
 
-# Run one keep-mode upgrade with the SIGTERM shim. Echoes "<exit>\t<out>\t<home>".
+make_signal_installer "$SIGNALED" "$HANDLER_WITH_EXIT"
+make_signal_installer "$NOEXIT" "$HANDLER_WITHOUT_EXIT"
+signal_fixture_ready() {
+  local fixture="$1" expected_handler="$2"
+  [[ "$(grep -cF '# TEST-TERM-INJECTION' "$fixture")" -eq 1 ]] \
+    && [[ "$(grep -cF '# TEST-TERM-HANDLER' "$fixture")" -eq 1 ]] \
+    && grep -Fqx "$expected_handler" "$fixture"
+}
+signaled_fixture_ready() { signal_fixture_ready "$SIGNALED" "$HANDLER_WITH_EXIT"; }
+noexit_fixture_ready() { signal_fixture_ready "$NOEXIT" "$HANDLER_WITHOUT_EXIT"; }
+chk "[signal] shipped fixture has exactly one self-TERM injection and marked handler" \
+  "signaled_fixture_ready"
+chk "[control] no-exit fixture has exactly one self-TERM injection and marked handler" \
+  "noexit_fixture_ready"
+chk "[control] removing the explicit TERM exit changes the fixture" \
+  "! cmp -s '$SIGNALED' '$NOEXIT'"
+
+# Run one keep-mode upgrade whose own shell delivers SIGTERM synchronously at
+# the selected copy. Echoes "<exit>\t<out>\t<home>".
 run_signal_upgrade() {
-  local installer="$1" H OUT SHIM rc
+  local installer="$1" H OUT rc
-  H=$(mktemp -d); OUT=$(mktemp); SHIM=$(mktemp -d)
+  H=$(mktemp -d); OUT=$(mktemp)
   seed_home "$H"
-  make_term_shim "$SHIM"
   set +e
-  PATH="$SHIM:$ORIG_PATH" \
+  PATH="$ORIG_PATH" \
     MOSAIC_HOME="$H" MOSAIC_INSTALL_MODE=keep MOSAIC_SYNC_ONLY=1 bash "$installer" >"$OUT" 2>&1
   rc=$?
   set -e 2>/dev/null || true
-  rm -rf "$SHIM"
   printf '%s\t%s\t%s\n' "$rc" "$OUT" "$H"
 }
 
-IFS=$'\t' read -r rcC OUTC HC < <(run_signal_upgrade "$INSTALL")
+IFS=$'\t' read -r rcC OUTC HC < <(run_signal_upgrade "$SIGNALED")
+chk "[signal] TERM handler observable fires exactly once" \
+  "[ \"\$(grep -cF '$TERM_MARKER' '$OUTC')\" -eq 1 ]"
 chk "[signal] SIGTERM mid-sync aborts non-zero (trap exits, does not resume)" \
   "[ '$rcC' -ne 0 ]"
 chk "[signal] restore_snapshot fires on the interrupt" \
@@ -222,13 +268,13 @@ chk "[signal] restore_snapshot fires on the interrupt" \
 chk "[signal] does NOT resume to report sync success after the interrupt" \
   "! grep -q 'file phase complete' '$OUTC'"
 
-# Control: strip `exit 1` from the signal trap → the handler returns, the script
+IFS=$'\t' read -r rcD OUTD HD < <(run_signal_upgrade "$NOEXIT")
-# resumes past the interrupt and wrongly reports success. In $FW so SOURCE_DIR resolves.
+chk "[control] TERM handler observable fires exactly once" \
-sed "s/trap 'restore_snapshot; exit 1' ERR INT TERM/trap 'restore_snapshot' ERR INT TERM/" \
+  "[ \"\$(grep -cF '$TERM_MARKER' '$OUTD')\" -eq 1 ]"
-  "$INSTALL" > "$NOEXIT"
+chk "[control] without 'exit 1' the handler restores before returning" \
-chk "[control] the exit-strip actually changed the installer" \
+  "grep -q 'restoring previous state from snapshot' '$OUTD'"
-  "! cmp -s '$INSTALL' '$NOEXIT'"
+chk "[control] without 'exit 1' the installer exits zero after resuming" \
-IFS=$'\t' read -r _rcD OUTD HD < <(run_signal_upgrade "$NOEXIT")
+  "[ '$rcD' -eq 0 ]"
 chk "[control] without 'exit 1' the trap resumes and reports sync success (the bug)" \
   "grep -q 'file phase complete' '$OUTD'"
 
@@ -309,10 +355,10 @@ chk "[control] without the D2 recovery line the operator gets no snapshot pointe
 # Reap any snapshot the reset-fail runs left in /tmp (reset failed → never cleaned).
 grep -o '/[^ ]*mosaic-snapshot[^ ]*' "$OUTH" 2>/dev/null | head -1 | while read -r s; do rm -rf "$s"; done
 
-# Cleanup ($STRIPPED / $NOEXIT / $D1CTRL / $D2CTRL are also removed by the EXIT trap).
+# Cleanup (generated installer controls are also removed by the EXIT trap).
 for d in "$HA" "$REFA" "$HB" "$REFB" "$HC" "$HD" "$HE" "$REFE" "$HF" "$REFF" "$HG" "$HH"; do rm -rf "$d"; done
 rm -f "$OUTA" "$OUTB" "$OUTC" "$OUTD" "$OUTE" "$OUTF" "$OUTG" "$OUTH" \
-  "$STRIPPED" "$NOEXIT" "$D1CTRL" "$D2CTRL"
+  "$STRIPPED" "$SIGNALED" "$NOEXIT" "$D1CTRL" "$D2CTRL"
 
 echo
 echo "RESULT: $pass passed, $fail failed"

packages/mosaic/package.json

@@ -25,7 +25,7 @@
     "lint": "eslint src",
     "typecheck": "tsc --noEmit",
     "test": "vitest run --passWithNoTests && pnpm run test:framework-shell",
-    "test:framework-shell": "bash framework/tools/quality/scripts/check-test-enumeration.sh && bash framework/tools/quality/scripts/test-check-test-enumeration.sh && python3 src/lease-broker/daemon_deadline_unittest.py && python3 src/lease-broker/normative_fragments_unittest.py && python3 src/lease-broker/receipt_challenge_unittest.py && python3 src/lease-broker/context_recovery_unittest.py && python3 src/lease-broker/recovery_runtime_unittest.py && python3 src/lease-broker/recovery_b1_adversarial_unittest.py && python3 src/lease-broker/framework_skill_portability_unittest.py && python3 src/mutator-gate/runtime_tools_unittest.py && python3 src/mutator-gate/runtime_launch_guard_unittest.py && python3 src/mutator-gate/version_coupling_unittest.py && python3 framework/tools/lease-broker/check-runtime-launches.py --root ../.. && bash framework/tools/codex/test-pr-diff-context.sh && bash framework/tools/qa/test-deps-preflight.sh && bash framework/tools/git/test-pr-review-gitea-comment.sh && bash framework/tools/git/test-pr-review-repo-host-override.sh && bash framework/tools/git/test-ci-queue-wait-branch-absent.sh && bash framework/tools/git/test-ci-queue-wait-tristate.sh && bash framework/tools/git/test-ci-queue-wait-github-checks.sh && bash framework/tools/git/test-pr-merge-queue-branch.sh && bash framework/tools/git/test-pr-merge-head-pin.sh && bash framework/tools/git/test-git-credential-mosaic.sh && bash framework/tools/git/test-gitea-token-identity.sh && bash framework/tools/woodpecker/test-terminal-green-contract.sh && bash framework/tools/_scripts/test-install-ordering-guard.sh && bash framework/tools/_scripts/test-mosaic-init-rce.sh && bash framework/tools/tmux/agent-send.test.sh && bash framework/tools/wake/test-wake-store-ack.sh && bash framework/tools/wake/test-wake-store-enqueue-race.sh && bash framework/tools/wake/test-wake-digest-hmac.sh && bash framework/tools/wake/test-wake-digest-quarantine.sh && bash framework/tools/wake/test-wake-detector.sh && bash framework/tools/wake/test-wake-fn-oracle.sh && bash framework/tools/wake/test-wake-reconcile.sh && bash framework/tools/wake/test-wake-beacon.sh && bash framework/tools/wake/test-wake-preimage.sh && bash framework/tools/wake/test-wake-install.sh"
+    "test:framework-shell": "bash framework/tools/quality/scripts/check-test-enumeration.sh && bash framework/tools/quality/scripts/test-check-test-enumeration.sh && python3 src/lease-broker/daemon_deadline_unittest.py && python3 src/lease-broker/normative_fragments_unittest.py && python3 src/lease-broker/promotion_binding_unittest.py && python3 src/lease-broker/promotion_trigger_unittest.py && python3 src/lease-broker/receipt_challenge_unittest.py && python3 src/lease-broker/context_recovery_unittest.py && python3 src/lease-broker/recovery_runtime_unittest.py && python3 src/lease-broker/recovery_b1_adversarial_unittest.py && python3 src/lease-broker/receipt_observer_client_unittest.py && python3 src/lease-broker/invariant_r_unittest.py && python3 src/lease-broker/framework_skill_portability_unittest.py && python3 src/mutator-gate/runtime_tools_unittest.py && python3 src/mutator-gate/runtime_launch_guard_unittest.py && python3 src/mutator-gate/version_coupling_unittest.py && python3 framework/tools/lease-broker/check-runtime-launches.py --root ../.. && bash framework/tools/codex/test-pr-diff-context.sh && bash framework/tools/qa/test-deps-preflight.sh && bash framework/tools/git/test-pr-review-gitea-comment.sh && bash framework/tools/git/test-pr-review-repo-host-override.sh && bash framework/tools/git/test-ci-queue-wait-branch-absent.sh && bash framework/tools/git/test-ci-queue-wait-tristate.sh && bash framework/tools/git/test-ci-queue-wait-github-checks.sh && bash framework/tools/git/test-pr-merge-queue-branch.sh && bash framework/tools/git/test-pr-merge-head-pin.sh && bash framework/tools/git/test-pr-merge-message-field.sh && bash framework/tools/git/test-git-credential-mosaic.sh && bash framework/tools/git/test-gitea-token-identity.sh && bash framework/tools/woodpecker/test-terminal-green-contract.sh && bash framework/tools/_scripts/test-install-ordering-guard.sh && bash framework/tools/_scripts/test-mosaic-init-rce.sh && bash framework/tools/tmux/agent-send.test.sh && bash framework/tools/wake/test-wake-store-ack.sh && bash framework/tools/wake/test-wake-store-enqueue-race.sh && bash framework/tools/wake/test-wake-digest-hmac.sh && bash framework/tools/wake/test-wake-digest-quarantine.sh && bash framework/tools/wake/test-wake-detector.sh && bash framework/tools/wake/test-wake-fn-oracle.sh && bash framework/tools/wake/test-wake-reconcile.sh && bash framework/tools/wake/test-wake-beacon.sh && bash framework/tools/wake/test-wake-preimage.sh && bash framework/tools/wake/test-wake-install.sh"
   },
   "dependencies": {
     "@mosaicstack/brain": "workspace:*",

packages/mosaic/src/cli.ts

@@ -15,6 +15,7 @@ import { registerAgentCommand } from './commands/agent.js';
 import { registerInteractionCommand } from './commands/interaction.js';
 import { registerConfigCommand } from './commands/config.js';
 import { registerFleetCommand } from './commands/fleet.js';
+import { registerPromoteCommand } from './commands/promote.js';
 import { registerMissionCommand } from './commands/mission.js';
 import { registerUninstallCommand } from './commands/uninstall.js';
 import { registerRestoreCommand } from './commands/restore.js';
@@ -370,6 +371,7 @@ registerInteractionCommand(program);
 // ─── fleet ─────────────────────────────────────────────────────────────
 
 registerFleetCommand(program);
+registerPromoteCommand(program);
 
 // ─── config ────────────────────────────────────────────────────────────
 

packages/mosaic/src/commands/launch.ts

@@ -14,9 +14,11 @@ import {
   readdirSync,
   realpathSync,
   rmSync,
+  appendFileSync,
 } from 'node:fs';
+import { createHash, randomBytes } from 'node:crypto';
 import { createRequire } from 'node:module';
-import { homedir } from 'node:os';
+import { homedir, hostname } from 'node:os';
 import { join, dirname } from 'node:path';
 import type { Command } from 'commander';
 import {
@@ -42,6 +44,163 @@ const RUNTIME_LABELS: Record<RuntimeName, string> = {
   pi: 'Pi',
 };
 
+// ─── Harness home isolation ──────────────────────────────────────────────────
+// Mosaic-launched runtimes read config from a dedicated home under the mosaic
+// tree — never the operator's base install. A bare `claude` / `pi` therefore
+// keeps its own config AND its own auth, and stays a working break-glass no
+// matter what mosaic does to its own tree.
+//
+// These paths are manifest-UNKNOWN, which resolves to operator ownership
+// (framework-manifest.txt rule 3, #791), so a keep-mode `mosaic update` can
+// neither overwrite nor prune them. Overwrite-mode install still would.
+//
+// opencode has no dedicated config-dir variable and follows XDG, so isolating it
+// sets XDG_CONFIG_HOME for that process tree. That is blunter than the other
+// three: it also relocates XDG lookups for anything opencode spawns.
+const HARNESS_HOME_ENV: Record<RuntimeName, string> = {
+  claude: 'CLAUDE_CONFIG_DIR',
+  pi: 'PI_CODING_AGENT_DIR',
+  codex: 'CODEX_HOME',
+  opencode: 'XDG_CONFIG_HOME',
+};
+
+/** Dedicated mosaic-owned home for a runtime: ~/.config/mosaic/.<runtime> */
+function harnessHome(runtime: RuntimeName): string {
+  return join(MOSAIC_HOME, `.${runtime}`);
+}
+
+/**
+ * Env overlay pointing a runtime at its mosaic-owned home. The directory is
+ * created on demand so a first launch does not fail on a missing path.
+ */
+function harnessEnv(runtime: RuntimeName): Record<string, string> {
+  const key = HARNESS_HOME_ENV[runtime];
+  if (!key) return {};
+  const home = harnessHome(runtime);
+  mkdirSync(home, { recursive: true });
+  return { [key]: home };
+}
+
+// ─── Launch record (immutable provenance) ────────────────────────────────────
+// MANDATORY and MECHANICAL: every launch appends one record of what the agent
+// actually launched with, written before exec. No model involvement, no opt-out.
+//
+// WHY LAUNCH-TIME AND NOT INSPECT-LATER: pi rewrites its own argv to a bare
+// `pi`, so /proc/<pid>/cmdline DESTROYS the launch evidence. That has already
+// produced a confident wrong diagnosis ("this agent bypassed the launcher"),
+// disproved only by the parent process's argv and only because the parent had
+// not yet exited. A record written before exec is the only place this survives.
+//
+// Lands in fleet/run/sessions/ — the #797 Runtime Session Ledger path, already
+// operator-classified in framework-manifest.txt and already covered by
+// test-upgrade-manifest-guard.sh, so an upgrade can neither overwrite nor prune
+// it.
+//
+// CORRELATION is by an explicit MOSAIC_LAUNCH_ID, never by pid: execRuntime()
+// uses spawnSync, so the runtime is a CHILD with a different pid.
+// launch-runtime.py appends the matching `lease.register` event.
+//
+// NEVER records a credential value: env is captured as PRESENT NAMES ONLY, and
+// oversized argv values (the composed system prompt) become a digest + length.
+const LAUNCH_LEDGER_DIR = join(MOSAIC_HOME, 'fleet', 'run', 'sessions');
+
+const CLI_VERSION: string | null = (() => {
+  try {
+    // Resolved RELATIVELY: the package `exports` map does not expose
+    // package.json, so '@mosaicstack/mosaic/package.json' throws
+    // ERR_PACKAGE_PATH_NOT_EXPORTED. Same relative depth from src/ and dist/.
+    return (createRequire(import.meta.url)('../../package.json') as { version: string }).version;
+  } catch {
+    return null;
+  }
+})();
+
+interface NormativeFragmentDigest {
+  source_id: string;
+  sha256: string | null;
+  bytes: number | null;
+  missing?: boolean;
+}
+
+function sha256Of(value: string | Buffer): string {
+  return createHash('sha256').update(value).digest('hex');
+}
+
+/**
+ * Hash the normative sources injected into the agent. This is "what the agent
+ * IS" — and it is the same fragment set the lease broker hashes for promotion,
+ * so an unexpected digest here is a mechanically detectable red flag rather than
+ * a matter of judgement.
+ */
+function normativeFragmentDigests(runtime: RuntimeName): NormativeFragmentDigest[] {
+  const candidates: Array<[string, string]> = [
+    ['CONSTITUTION.md', join(MOSAIC_HOME, 'CONSTITUTION.md')],
+    ['AGENTS.md', join(MOSAIC_HOME, 'AGENTS.md')],
+    ['SOUL.md', join(MOSAIC_HOME, 'SOUL.md')],
+    ['USER.md', join(MOSAIC_HOME, 'USER.md')],
+    ['STANDARDS.md', join(MOSAIC_HOME, 'STANDARDS.md')],
+    ['TOOLS.md', join(MOSAIC_HOME, 'TOOLS.md')],
+    [`runtime/${runtime}/RUNTIME.md`, join(MOSAIC_HOME, 'runtime', runtime, 'RUNTIME.md')],
+  ];
+  return candidates.map(([sourceId, path]) => {
+    try {
+      const bytes = readFileSync(path);
+      return { source_id: sourceId, sha256: sha256Of(bytes), bytes: bytes.length };
+    } catch {
+      return { source_id: sourceId, sha256: null, bytes: null, missing: true };
+    }
+  });
+}
+
+/** argv with oversized values replaced by a digest, so the record stays small
+ * and never inlines injected content verbatim. */
+function redactArgv(argv: string[]): string[] {
+  return argv.map((a) =>
+    typeof a === 'string' && a.length > 256
+      ? `<redacted sha256:${sha256Of(a).slice(0, 16)} bytes:${a.length}>`
+      : a,
+  );
+}
+
+function recordLaunch(runtime: RuntimeName, cliArgs: string[], yolo: boolean): void {
+  try {
+    mkdirSync(LAUNCH_LEDGER_DIR, { recursive: true, mode: 0o700 });
+    // Correlation id for the lease.register half. Set into process.env so it
+    // propagates through every `...process.env` / `...baseEnv` spread below.
+    const launchId = `${Date.now().toString(36)}-${randomBytes(6).toString('hex')}`;
+    process.env['MOSAIC_LAUNCH_ID'] = launchId;
+    const record = {
+      seq: Date.now(),
+      kind: 'session.launch',
+      launch_id: launchId,
+      ts: new Date().toISOString(),
+      host: hostname(),
+      pid: process.pid,
+      runtime,
+      mode: yolo ? 'yolo' : 'normal',
+      cwd: process.cwd(),
+      cli_version: CLI_VERSION,
+      config_home: harnessHome(runtime),
+      config_home_isolated: true,
+      config_home_env: HARNESS_HOME_ENV[runtime] ?? null,
+      argv: redactArgv(cliArgs),
+      normative_fragments: normativeFragmentDigests(runtime),
+      // names only — values are never recorded
+      mosaic_env_present: Object.keys(process.env)
+        .filter((k) => k.startsWith('MOSAIC_'))
+        .sort(),
+    };
+    appendFileSync(join(LAUNCH_LEDGER_DIR, 'events.ndjson'), `${JSON.stringify(record)}\n`, {
+      mode: 0o600,
+    });
+  } catch (err) {
+    // Never block a launch on bookkeeping — but never fail silently either.
+    console.error(
+      `[mosaic] WARNING: launch record not written: ${err instanceof Error ? err.message : String(err)}`,
+    );
+  }
+}
+
 // ─── Pre-flight checks ──────────────────────────────────────────────────────
 
 function checkMosaicHome(): void {
@@ -105,11 +264,11 @@ interface SettingsAudit {
 
 function auditClaudeSettings(): SettingsAudit {
   const warnings: string[] = [];
-  const settingsPath = join(homedir(), '.claude', 'settings.json');
+  const settingsPath = join(harnessHome('claude'), 'settings.json');
   const settings = readJson(settingsPath);
 
   if (!settings) {
-    warnings.push('~/.claude/settings.json not found — hooks and plugins will be missing');
+    warnings.push(`${settingsPath} not found — hooks and plugins will be missing`);
     return { warnings };
   }
 
@@ -561,7 +720,9 @@ function skillRealPath(dir: string): string {
 /** Skill roots Pi auto-discovers natively (no `--skill` needed): its global
  * skills dir and the project-local one relative to the launch cwd. */
 function piNativeSkillRoots(cwd: string = process.cwd()): string[] {
-  return [join(homedir(), '.pi', 'agent', 'skills'), join(cwd, '.pi', 'skills')];
+  // PI_CODING_AGENT_DIR replaces ~/.pi/agent (not ~/.pi), so skills live at
+  // <home>/skills — there is no extra 'agent' segment under the isolated home.
+  return [join(harnessHome('pi'), 'skills'), join(cwd, '.pi', 'skills')];
 }
 
 /** Enumerate skill dirs under a set of roots, deduped by real path. A directory
@@ -764,12 +925,13 @@ function launchRuntime(runtime: RuntimeName, args: string[], yolo: boolean): nev
         cliArgs.push(...args);
       }
       console.log(`[mosaic] Launching ${label}${modeStr}${missionStr}...`);
+      recordLaunch('claude', cliArgs, yolo);
       execLeaseGatedRuntime('claude', cliArgs, process.env, yolo);
       break;
     }
 
     case 'codex': {
-      ensureRuntimeConfig('codex', join(homedir(), '.codex', 'instructions.md'));
+      ensureRuntimeConfig('codex', join(harnessHome('codex'), 'instructions.md'));
       const cliArgs = yolo ? ['--dangerously-bypass-approvals-and-sandbox'] : [];
       if (hasMissionNoArgs) {
         cliArgs.push(missionPrompt);
@@ -777,14 +939,17 @@ function launchRuntime(runtime: RuntimeName, args: string[], yolo: boolean): nev
         cliArgs.push(...args);
       }
       console.log(`[mosaic] Launching ${label}${modeStr}${missionStr}...`);
-      execRuntime('codex', cliArgs);
+      recordLaunch('codex', cliArgs, yolo);
+      execRuntime('codex', cliArgs, { ...process.env, ...harnessEnv('codex') });
       break;
     }
 
     case 'opencode': {
-      ensureRuntimeConfig('opencode', join(homedir(), '.config', 'opencode', 'AGENTS.md'));
+      // opencode follows XDG, so its config resolves to $XDG_CONFIG_HOME/opencode.
+      ensureRuntimeConfig('opencode', join(harnessHome('opencode'), 'opencode', 'AGENTS.md'));
       console.log(`[mosaic] Launching ${label}${modeStr}...`);
-      execRuntime('opencode', args);
+      recordLaunch('opencode', args, yolo);
+      execRuntime('opencode', args, { ...process.env, ...harnessEnv('opencode') });
       break;
     }
 
@@ -799,6 +964,7 @@ function launchRuntime(runtime: RuntimeName, args: string[], yolo: boolean): nev
         cliArgs.push(...args);
       }
       console.log(`[mosaic] Launching ${label}${modeStr}${missionStr}...`);
+      recordLaunch('pi', cliArgs, yolo);
       execLeaseGatedRuntime('pi', cliArgs);
       break;
     }
@@ -835,6 +1001,7 @@ function execLeaseGatedRuntime(
     [launcher, ...dangerousArgs, '--runtime', runtime, '--', runtime, ...args],
     {
       ...baseEnv,
+      ...harnessEnv(runtime),
       MOSAIC_LEASE_BROKER_SOCKET: defaultLeaseBrokerSocket(baseEnv),
       MOSAIC_RUNTIME_GENERATION: baseEnv['MOSAIC_RUNTIME_GENERATION'] ?? '1',
     },

packages/mosaic/src/commands/promote.spec.ts

@@ -0,0 +1,298 @@
+import { Command } from 'commander';
+import { describe, expect, it, vi } from 'vitest';
+import type { FleetRoster } from './fleet.js';
+import { TmuxPromotionTransport } from '../fleet/promotion-transport.js';
+import {
+  promoteSeat,
+  registerPromoteCommand,
+  type PromotionBreadcrumbStore,
+  type PromotionResult,
+  type PromotionTransport,
+} from './promote.js';
+
+const attemptId = 'a'.repeat(64);
+const target = {
+  bundle: 'local',
+  seat: 'claude-seat',
+  sessionId: 'b'.repeat(64),
+};
+
+function transport(): PromotionTransport {
+  return {
+    resolve: vi.fn(async () => target),
+    sendPromotion: vi.fn(async () => {}),
+  };
+}
+
+describe('mosaic promote', () => {
+  it('accepts only a fresh result correlated to this attempt', async () => {
+    const promotionTransport = transport();
+    const store: PromotionBreadcrumbStore = {
+      readAttemptId: vi.fn().mockResolvedValueOnce(null).mockResolvedValue(attemptId),
+      readResult: vi
+        .fn()
+        .mockResolvedValueOnce({
+          attempt_id: 'c'.repeat(64),
+          expires_at_wallclock: 4_600,
+          reason: null,
+          session_id: target.sessionId,
+          ts: 1_001,
+          verified: true,
+        })
+        .mockResolvedValueOnce({
+          attempt_id: attemptId,
+          expires_at_wallclock: 4_600,
+          reason: null,
+          session_id: target.sessionId,
+          ts: 1_001,
+          verified: true,
+        }),
+    };
+
+    const result = await promoteSeat('claude-seat', {
+      clock: () => 1_000,
+      sleep: async () => {},
+      store,
+      timeoutMs: 1,
+      transport: promotionTransport,
+    });
+
+    expect(result).toEqual({
+      bundle: 'local',
+      expiresAtWallclock: 4_600,
+      reason: null,
+      seat: 'claude-seat',
+      sessionId: 'b'.repeat(64),
+      status: 'VERIFIED',
+    });
+    expect(promotionTransport.sendPromotion).toHaveBeenCalledWith(target);
+    expect(store.readResult).toHaveBeenCalledTimes(2);
+  });
+
+  it('accepts a fresh result for this session when completion consumed the pending nonce', async () => {
+    const promotionTransport = transport();
+    let now = 1_000;
+    const store: PromotionBreadcrumbStore = {
+      readAttemptId: vi.fn(async () => null),
+      readResult: vi.fn(async () => ({
+        attempt_id: attemptId,
+        expires_at_wallclock: 4_600,
+        reason: null,
+        session_id: target.sessionId,
+        ts: 1_001,
+        verified: true,
+      })),
+    };
+
+    const result = await promoteSeat('claude-seat', {
+      clock: () => now,
+      sleep: async () => {
+        now += 10;
+      },
+      store,
+      timeoutMs: 10,
+      transport: promotionTransport,
+    });
+
+    expect(result.status).toBe('VERIFIED');
+  });
+
+  it('returns UNVERIFIED within the command bound when a tmux runner wedges', async () => {
+    vi.useFakeTimers();
+    const roster: FleetRoster = {
+      agents: [{ className: 'worker', name: 'claude-seat', runtime: 'claude' }],
+      defaults: { workingDirectory: '~/src' },
+      runtimes: {},
+      tmux: { holderSession: '_holder', socketName: 'mosaic-fleet' },
+      transport: 'tmux',
+      version: 1,
+    };
+    const promotionTransport = new TmuxPromotionTransport({
+      mosaicHome: '/mosaic',
+      rosterLoader: async () => roster,
+      runner: async () => new Promise(() => {}),
+    });
+    const store: PromotionBreadcrumbStore = {
+      readAttemptId: vi.fn(async () => null),
+      readResult: vi.fn(async () => null),
+    };
+
+    try {
+      let observedResult: PromotionResult | undefined;
+      void promoteSeat('claude-seat', {
+        store,
+        transport: promotionTransport,
+      }).then((result) => {
+        observedResult = result;
+      });
+      await vi.advanceTimersByTimeAsync(5_000);
+
+      expect(observedResult).toMatchObject({
+        reason: 'RESOLVE_FAILED: Promotion transport command timed out after 5000ms.',
+        seat: 'claude-seat',
+        status: 'UNVERIFIED',
+      });
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
+  it('prints VERIFIED with the resolved seat, session, bundle, and wall-clock expiry', async () => {
+    const promotionTransport = transport();
+    const store: PromotionBreadcrumbStore = {
+      readAttemptId: vi.fn().mockResolvedValueOnce(null).mockResolvedValue(attemptId),
+      readResult: vi.fn(async () => ({
+        attempt_id: attemptId,
+        expires_at_wallclock: 4_600,
+        reason: null,
+        session_id: target.sessionId,
+        ts: Number.MAX_SAFE_INTEGER,
+        verified: true,
+      })),
+    };
+    const output = vi.spyOn(console, 'log').mockImplementation(() => {});
+    const program = new Command().exitOverride();
+    registerPromoteCommand(program, {
+      mintAuthorization: async () => {},
+      store,
+      transport: promotionTransport,
+    });
+
+    try {
+      await program.parseAsync(['node', 'mosaic', 'promote', 'claude-seat']);
+      expect(output).toHaveBeenCalledWith(
+        `VERIFIED seat=claude-seat session=${target.sessionId} bundle=local expiry=1970-01-01T01:16:40.000Z`,
+      );
+      expect(process.exitCode).not.toBe(1);
+    } finally {
+      output.mockRestore();
+      process.exitCode = undefined;
+    }
+  });
+
+  it('prints UNVERIFIED and exits 1 when delivery fails', async () => {
+    const promotionTransport: PromotionTransport = {
+      resolve: vi.fn(async () => target),
+      sendPromotion: vi.fn(async () => {
+        throw new Error('tmux unavailable');
+      }),
+    };
+    const store: PromotionBreadcrumbStore = {
+      readAttemptId: vi.fn(async () => null),
+      readResult: vi.fn(async () => null),
+    };
+    const output = vi.spyOn(console, 'log').mockImplementation(() => {});
+    const program = new Command().exitOverride();
+    registerPromoteCommand(program, {
+      mintAuthorization: async () => {},
+      store,
+      transport: promotionTransport,
+    });
+
+    try {
+      process.exitCode = undefined;
+      await program.parseAsync(['node', 'mosaic', 'promote', 'claude-seat']);
+      expect(output).toHaveBeenCalledWith(
+        `UNVERIFIED seat=claude-seat session=${target.sessionId} bundle=local expiry=none reason=DELIVERY_FAILED: tmux unavailable`,
+      );
+      expect(process.exitCode).toBe(1);
+    } finally {
+      output.mockRestore();
+      process.exitCode = undefined;
+    }
+  });
+
+  it('rejects a stale result even when its nonce matches', async () => {
+    const promotionTransport = transport();
+    let now = 1_000;
+    const store: PromotionBreadcrumbStore = {
+      readAttemptId: vi.fn().mockResolvedValueOnce(null).mockResolvedValue(attemptId),
+      readResult: vi.fn(async () => ({
+        attempt_id: attemptId,
+        expires_at_wallclock: 4_600,
+        reason: null,
+        session_id: target.sessionId,
+        ts: 1_000,
+        verified: true,
+      })),
+    };
+
+    const result = await promoteSeat('claude-seat', {
+      clock: () => now,
+      sleep: async () => {
+        now += 10;
+      },
+      store,
+      timeoutMs: 10,
+      transport: promotionTransport,
+    });
+
+    expect(result).toEqual({
+      bundle: 'local',
+      expiresAtWallclock: null,
+      reason: 'PROMOTION_TIMEOUT',
+      seat: 'claude-seat',
+      sessionId: 'b'.repeat(64),
+      status: 'UNVERIFIED',
+    });
+  });
+
+  it('does not accept a result for a pending attempt that existed before send', async () => {
+    const promotionTransport = transport();
+    let now = 1_000;
+    const store: PromotionBreadcrumbStore = {
+      readAttemptId: vi.fn(async () => attemptId),
+      readResult: vi.fn(async () => ({
+        attempt_id: attemptId,
+        expires_at_wallclock: 4_600,
+        reason: null,
+        session_id: target.sessionId,
+        ts: 1_001,
+        verified: true,
+      })),
+    };
+
+    const result = await promoteSeat('claude-seat', {
+      clock: () => now,
+      sleep: async () => {
+        now += 10;
+      },
+      store,
+      timeoutMs: 10,
+      transport: promotionTransport,
+    });
+
+    expect(result.status).toBe('UNVERIFIED');
+    expect(store.readResult).not.toHaveBeenCalled();
+  });
+
+  it('returns UNVERIFIED after a bounded timeout without reading stdin', async () => {
+    const promotionTransport = transport();
+    let now = 1_000;
+    const store: PromotionBreadcrumbStore = {
+      readAttemptId: vi.fn(async () => null),
+      readResult: vi.fn(async () => null),
+    };
+
+    const result = await promoteSeat('claude-seat', {
+      clock: () => now,
+      sleep: async () => {
+        now += 10;
+      },
+      store,
+      timeoutMs: 10,
+      transport: promotionTransport,
+    });
+
+    expect(result).toEqual({
+      bundle: 'local',
+      expiresAtWallclock: null,
+      reason: 'PROMOTION_TIMEOUT',
+      seat: 'claude-seat',
+      sessionId: 'b'.repeat(64),
+      status: 'UNVERIFIED',
+    });
+    expect(promotionTransport.sendPromotion).toHaveBeenCalledOnce();
+    expect(store.readResult).toHaveBeenCalledTimes(2);
+  });
+});

packages/mosaic/src/commands/promote.ts

@@ -0,0 +1,369 @@
+import { spawn } from 'node:child_process';
+import { randomBytes } from 'node:crypto';
+import { constants } from 'node:fs';
+import { mkdir, open, rename } from 'node:fs/promises';
+import { join } from 'node:path';
+import type { Command } from 'commander';
+import {
+  TmuxPromotionTransport,
+  type PromotionTarget,
+  type PromotionTransport,
+} from '../fleet/promotion-transport.js';
+
+export type { PromotionTransport } from '../fleet/promotion-transport.js';
+import { resolveFleetPaths, type CommandRunner } from './fleet.js';
+
+const ATTEMPT_ID_PATTERN = /^[a-f0-9]{64}$/;
+const DEFAULT_POLL_INTERVAL_MS = 250;
+const DEFAULT_TIMEOUT_MS = 30_000;
+const SUBPROCESS_TIMEOUT_MS = 4_500;
+const PENDING_DIRECTORY = 'mosaic-lease';
+const AUTHORIZATION_DIRECTORY = 'authorizations';
+const AUTHORIZATION_TTL_SECONDS = 60;
+const RESULT_FILE = 'last-result.json';
+
+export interface PromotionBreadcrumb {
+  attempt_id: string;
+  expires_at_wallclock: number | null;
+  reason: string | null;
+  session_id: string;
+  ts: number;
+  verified: boolean;
+}
+
+export interface PromotionBreadcrumbStore {
+  readAttemptId(sessionId: string): Promise<string | null>;
+  readResult(): Promise<PromotionBreadcrumb | null>;
+}
+
+export interface PromotionResult {
+  bundle: string;
+  expiresAtWallclock: number | null;
+  reason: string | null;
+  seat: string;
+  sessionId: string;
+  status: 'VERIFIED' | 'UNVERIFIED';
+}
+
+export interface PromoteSeatOptions {
+  clock?: () => number;
+  pollIntervalMs?: number;
+  sleep?: (milliseconds: number) => Promise<void>;
+  store: PromotionBreadcrumbStore;
+  target?: PromotionTarget;
+  timeoutMs?: number;
+  transport: PromotionTransport;
+}
+
+export interface PromoteCommandDeps {
+  mintAuthorization?: (target: PromotionTarget) => Promise<void>;
+  mosaicHome?: string;
+  runner?: CommandRunner;
+  store?: PromotionBreadcrumbStore;
+  transport?: PromotionTransport;
+}
+
+/** Private, local result store shared with the in-seat completion hook. */
+export class FilePromotionBreadcrumbStore implements PromotionBreadcrumbStore {
+  constructor(private readonly runtimeDirectory = defaultRuntimeDirectory()) {}
+
+  async readAttemptId(sessionId: string): Promise<string | null> {
+    if (!ATTEMPT_ID_PATTERN.test(sessionId)) return null;
+    const content = await readPrivateFile(
+      join(this.runtimeDirectory, PENDING_DIRECTORY, `pending-${sessionId}`),
+    );
+    const attemptId = content?.trim();
+    return attemptId !== undefined && ATTEMPT_ID_PATTERN.test(attemptId) ? attemptId : null;
+  }
+
+  async readResult(): Promise<PromotionBreadcrumb | null> {
+    const content = await readPrivateFile(
+      join(this.runtimeDirectory, PENDING_DIRECTORY, RESULT_FILE),
+    );
+    if (content === null) return null;
+    try {
+      return parseBreadcrumb(JSON.parse(content) as unknown);
+    } catch {
+      return null;
+    }
+  }
+}
+
+/** Drives one bounded, non-interactive in-seat promotion attempt. */
+export async function promoteSeat(
+  seat: string,
+  options: PromoteSeatOptions,
+): Promise<PromotionResult> {
+  const clock = options.clock ?? wallClockSeconds;
+  const sleep = options.sleep ?? defaultSleep;
+  const timeoutMs = normalizeTimeout(options.timeoutMs);
+  const pollIntervalMs = normalizePollInterval(options.pollIntervalMs);
+  let target: PromotionTarget;
+  try {
+    target = options.target ?? (await options.transport.resolve(seat));
+  } catch (error: unknown) {
+    return unverifiedUnresolvedSeat(seat, `RESOLVE_FAILED: ${errorMessage(error)}`);
+  }
+  const previousAttemptId = await options.store.readAttemptId(target.sessionId);
+  const preSendTimestamp = clock();
+  try {
+    await options.transport.sendPromotion(target);
+  } catch (error: unknown) {
+    return unverified(target, `DELIVERY_FAILED: ${errorMessage(error)}`);
+  }
+
+  const deadline = preSendTimestamp + timeoutMs / 1_000;
+  let attemptId: string | null = null;
+  while (true) {
+    const currentAttemptId = await options.store.readAttemptId(target.sessionId);
+    if (currentAttemptId !== null && currentAttemptId !== previousAttemptId) {
+      attemptId = currentAttemptId;
+    }
+    if (attemptId !== null || previousAttemptId === null) {
+      // Completion can consume a first attempt's nonce before this poll observes it.
+      // In that branch, correlation degrades to session_id + fresh timestamp, which
+      // is acceptable for this 0600, same-UID local trust boundary.
+      const breadcrumb = await options.store.readResult();
+      if (
+        breadcrumb !== null &&
+        breadcrumb.session_id === target.sessionId &&
+        (attemptId === null || breadcrumb.attempt_id === attemptId) &&
+        breadcrumb.ts > preSendTimestamp
+      ) {
+        return {
+          bundle: target.bundle,
+          expiresAtWallclock: breadcrumb.expires_at_wallclock,
+          reason: breadcrumb.reason,
+          seat: target.seat,
+          sessionId: target.sessionId,
+          status: breadcrumb.verified ? 'VERIFIED' : 'UNVERIFIED',
+        };
+      }
+    }
+    if (clock() >= deadline) return unverified(target, 'PROMOTION_TIMEOUT');
+    await sleep(Math.min(pollIntervalMs, Math.max(0, deadline - clock()) * 1_000));
+  }
+}
+
+export function registerPromoteCommand(program: Command, deps: PromoteCommandDeps = {}): void {
+  const mosaicHome = deps.mosaicHome ?? resolveFleetPaths().mosaicHome;
+  const transport =
+    deps.transport ?? new TmuxPromotionTransport({ mosaicHome, runner: deps.runner ?? runCommand });
+  const store = deps.store ?? new FilePromotionBreadcrumbStore();
+
+  program
+    .command('promote <seat>')
+    .description('Promote a Claude fleet seat and report the correlated lease result')
+    .option(
+      '--timeout <ms>',
+      `Bounded result wait in milliseconds (default: ${DEFAULT_TIMEOUT_MS})`,
+    )
+    .action(async (seat: string, opts: { timeout?: string }) => {
+      if (
+        process.env['MOSAIC_LEASE_SESSION_ID'] !== undefined &&
+        deps.mintAuthorization === undefined
+      ) {
+        console.error('mosaic promote must run outside a lease-gated seat.');
+        process.exitCode = 1;
+        return;
+      }
+      let target: PromotionTarget;
+      try {
+        target = await transport.resolve(seat);
+        await (deps.mintAuthorization ?? mintAuthorization)(target);
+      } catch (error: unknown) {
+        console.error(`mosaic promote authorization failed: ${errorMessage(error)}`);
+        process.exitCode = 1;
+        return;
+      }
+      const result = await promoteSeat(seat, {
+        store,
+        target,
+        timeoutMs: parseOptionTimeout(opts.timeout),
+        transport,
+      });
+      const expiry =
+        result.expiresAtWallclock === null
+          ? 'none'
+          : new Date(result.expiresAtWallclock * 1_000).toISOString();
+      const reason = result.reason === null ? '' : ` reason=${result.reason}`;
+      console.log(
+        `${result.status} seat=${result.seat} session=${result.sessionId} bundle=${result.bundle} expiry=${expiry}${reason}`,
+      );
+      if (result.status === 'UNVERIFIED') process.exitCode = 1;
+    });
+}
+
+async function mintAuthorization(target: PromotionTarget): Promise<void> {
+  const directory = join(defaultRuntimeDirectory(), PENDING_DIRECTORY, AUTHORIZATION_DIRECTORY);
+  await mkdir(directory, { mode: 0o700, recursive: true });
+  const token = {
+    expires_at: wallClockSeconds() + AUTHORIZATION_TTL_SECONDS,
+    nonce: randomBytes(32).toString('hex'),
+    seat: target.seat,
+    session_id: target.sessionId,
+    ts: wallClockSeconds(),
+  };
+  const destination = join(directory, `${target.sessionId}.auth`);
+  const temporary = join(directory, `.${target.sessionId}.${randomBytes(8).toString('hex')}.tmp`);
+  const handle = await open(
+    temporary,
+    constants.O_WRONLY | constants.O_CREAT | constants.O_EXCL,
+    0o600,
+  );
+  try {
+    await handle.chmod(0o600);
+    await handle.writeFile(JSON.stringify(token));
+    await handle.sync();
+  } finally {
+    await handle.close();
+  }
+  await rename(temporary, destination);
+}
+
+function defaultRuntimeDirectory(): string {
+  const configured = process.env['XDG_RUNTIME_DIR'];
+  if (configured) return configured;
+  const uid = typeof process.getuid === 'function' ? process.getuid() : 0;
+  return `/run/user/${uid}`;
+}
+
+async function readPrivateFile(path: string): Promise<string | null> {
+  let handle: Awaited<ReturnType<typeof open>>;
+  try {
+    handle = await open(path, constants.O_RDONLY | constants.O_NOFOLLOW);
+  } catch {
+    return null;
+  }
+  try {
+    const metadata = await handle.stat();
+    if (
+      !metadata.isFile() ||
+      metadata.uid !== (typeof process.getuid === 'function' ? process.getuid() : 0) ||
+      (metadata.mode & 0o077) !== 0
+    ) {
+      return null;
+    }
+    return handle.readFile({ encoding: 'utf8' });
+  } catch {
+    return null;
+  } finally {
+    await handle.close();
+  }
+}
+
+function parseBreadcrumb(value: unknown): PromotionBreadcrumb | null {
+  if (!isRecord(value) || Object.keys(value).length !== 6) return null;
+  const { attempt_id, expires_at_wallclock, reason, session_id, ts, verified } = value;
+  if (
+    typeof attempt_id !== 'string' ||
+    !ATTEMPT_ID_PATTERN.test(attempt_id) ||
+    typeof verified !== 'boolean' ||
+    typeof session_id !== 'string' ||
+    !ATTEMPT_ID_PATTERN.test(session_id) ||
+    typeof ts !== 'number' ||
+    !Number.isFinite(ts) ||
+    (expires_at_wallclock !== null &&
+      (typeof expires_at_wallclock !== 'number' || !Number.isFinite(expires_at_wallclock))) ||
+    (reason !== null && typeof reason !== 'string')
+  ) {
+    return null;
+  }
+  return { attempt_id, expires_at_wallclock, reason, session_id, ts, verified };
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === 'object' && value !== null && !Array.isArray(value);
+}
+
+function normalizeTimeout(value: number | undefined): number {
+  return value !== undefined && Number.isFinite(value) ? Math.max(0, value) : DEFAULT_TIMEOUT_MS;
+}
+
+function normalizePollInterval(value: number | undefined): number {
+  return value !== undefined && Number.isFinite(value)
+    ? Math.max(1, value)
+    : DEFAULT_POLL_INTERVAL_MS;
+}
+
+function parseOptionTimeout(value: string | undefined): number | undefined {
+  if (value === undefined) return undefined;
+  const parsed = Number.parseInt(value, 10);
+  return Number.isFinite(parsed) ? parsed : undefined;
+}
+
+function unverifiedUnresolvedSeat(seat: string, reason: string): PromotionResult {
+  return {
+    bundle: 'unresolved',
+    expiresAtWallclock: null,
+    reason,
+    seat,
+    sessionId: 'unresolved',
+    status: 'UNVERIFIED',
+  };
+}
+
+function unverified(target: PromotionTarget, reason: string): PromotionResult {
+  return {
+    bundle: target.bundle,
+    expiresAtWallclock: null,
+    reason,
+    seat: target.seat,
+    sessionId: target.sessionId,
+    status: 'UNVERIFIED',
+  };
+}
+
+function errorMessage(error: unknown): string {
+  return error instanceof Error ? error.message : String(error);
+}
+
+function wallClockSeconds(): number {
+  return Date.now() / 1_000;
+}
+
+function defaultSleep(milliseconds: number): Promise<void> {
+  return new Promise((resolve) => setTimeout(resolve, milliseconds));
+}
+
+function runCommand(
+  command: string,
+  args: string[],
+): Promise<{
+  exitCode: number;
+  stderr: string;
+  stdout: string;
+}> {
+  return new Promise((resolve) => {
+    const child = spawn(command, args, { stdio: ['ignore', 'pipe', 'pipe'] });
+    let stdout = '';
+    let stderr = '';
+    let settled = false;
+    const finish = (result: { exitCode: number; stderr: string; stdout: string }): void => {
+      if (settled) return;
+      settled = true;
+      clearTimeout(timeout);
+      resolve(result);
+    };
+    const timeout = setTimeout(() => {
+      child.kill('SIGKILL');
+      finish({
+        exitCode: 124,
+        stderr: `Promotion transport subprocess timed out after ${SUBPROCESS_TIMEOUT_MS}ms.`,
+        stdout,
+      });
+    }, SUBPROCESS_TIMEOUT_MS);
+    child.stdout.on('data', (chunk: Buffer) => {
+      stdout += chunk.toString('utf8');
+    });
+    child.stderr.on('data', (chunk: Buffer) => {
+      stderr += chunk.toString('utf8');
+    });
+    child.on('error', (error: Error) => {
+      finish({ exitCode: 127, stderr: error.message, stdout });
+    });
+    child.on('close', (code: number | null) => {
+      finish({ exitCode: code ?? 1, stderr, stdout });
+    });
+  });
+}

packages/mosaic/src/commands/skill.spec.ts

@@ -332,9 +332,11 @@ describe('Claude skill bridge', () => {
       expect(result.status, result.stderr).toBe(0);
       expect(readlinkSync(liveForeignLink)).toBe(liveForeignTarget);
       expect(readlinkSync(danglingForeignLink)).toBe(join(mosaicHome, 'foreign-missing'));
-      expect(readlinkSync(join(paths.claudeSkillsDir, 'missing'))).toBe(
+      // Skills now link into the mosaic-owned harness home, never the base install.
+      expect(readlinkSync(join(mosaicHome, '.claude', 'skills', 'missing'))).toBe(
         join(paths.mosaicSkillsDir, 'missing'),
       );
+      expect(existsSync(join(paths.claudeSkillsDir, 'missing'))).toBe(false);
     });
 
     it('preserves live and dangling foreign Claude symlinks while linking missing skills', () => {
@@ -349,17 +351,20 @@ describe('Claude skill bridge', () => {
       symlinkSync(external, liveLink);
       symlinkSync(join(root, 'external-missing'), danglingLink);
 
+      const mosaicHome = join(root, '.config', 'mosaic');
       const result = spawnSync('bash', [LEGACY_SYNC_SCRIPT, '--link-only'], {
         encoding: 'utf8',
-        env: { ...process.env, HOME: root, MOSAIC_HOME: join(root, '.config', 'mosaic') },
+        env: { ...process.env, HOME: root, MOSAIC_HOME: mosaicHome },
       });
 
       expect(result.status, result.stderr).toBe(0);
       expect(readlinkSync(liveLink)).toBe(external);
       expect(readlinkSync(danglingLink)).toBe(join(root, 'external-missing'));
-      expect(readlinkSync(join(paths.claudeSkillsDir, 'missing'))).toBe(
+      // Skills now link into the mosaic-owned harness home, never the base install.
+      expect(readlinkSync(join(mosaicHome, '.claude', 'skills', 'missing'))).toBe(
         join(paths.mosaicSkillsDir, 'missing'),
       );
+      expect(existsSync(join(paths.claudeSkillsDir, 'missing'))).toBe(false);
     });
   });
 

packages/mosaic/src/fleet/promotion-transport.spec.ts

@@ -0,0 +1,104 @@
+import { describe, expect, it, vi } from 'vitest';
+import type { CommandResult, CommandRunner, FleetRoster } from '../commands/fleet.js';
+import { TmuxPromotionTransport } from './promotion-transport.js';
+
+const sessionId = 'a'.repeat(64);
+const roster: FleetRoster = {
+  agents: [{ className: 'worker', name: 'claude-seat', runtime: 'claude' }],
+  defaults: { workingDirectory: '~/src' },
+  runtimes: {},
+  tmux: { holderSession: '_holder', socketName: 'mosaic-fleet' },
+  transport: 'tmux',
+  version: 1,
+};
+
+function result(stdout = '', exitCode = 0, stderr = ''): CommandResult {
+  return { exitCode, stderr, stdout };
+}
+
+describe('TmuxPromotionTransport', () => {
+  it('resolves the exact roster seat and sends the registered command literally', async () => {
+    const runner = vi
+      .fn<CommandRunner>()
+      .mockResolvedValueOnce(result('1234 claude 0 0 0 0\n'))
+      .mockResolvedValueOnce(result())
+      .mockResolvedValueOnce(result());
+    const environmentReader = vi.fn(async () => `MOSAIC_LEASE_SESSION_ID=${sessionId}\0`);
+    const transport = new TmuxPromotionTransport({
+      environmentReader,
+      mosaicHome: '/mosaic',
+      rosterLoader: async () => roster,
+      runner,
+    });
+
+    const target = await transport.resolve('claude-seat');
+    await transport.sendPromotion(target);
+
+    expect(target).toEqual({
+      bundle: 'mosaic-fleet',
+      seat: 'claude-seat',
+      sessionId,
+    });
+    expect(environmentReader).toHaveBeenCalledWith(1234);
+    expect(runner).toHaveBeenNthCalledWith(2, 'tmux', [
+      '-L',
+      'mosaic-fleet',
+      'send-keys',
+      '-t',
+      '=claude-seat:0.0',
+      '-l',
+      '/mosaic-promote',
+    ]);
+    expect(runner).toHaveBeenNthCalledWith(3, 'tmux', [
+      '-L',
+      'mosaic-fleet',
+      'send-keys',
+      '-t',
+      '=claude-seat:0.0',
+      'Enter',
+    ]);
+  });
+
+  // Regression for #1124: the launcher runs claude as a spawnSync CHILD of
+  // node(mosaic), so the lease env is on the child, not the tmux pane pid. The
+  // transport must WALK the subtree. This test exercises the real walk (no
+  // full mock of the resolution) — the seam the original unit test hid.
+  it('walks the pane subtree to the claude child that carries the lease id', async () => {
+    const runner = vi.fn<CommandRunner>().mockResolvedValueOnce(result('1234 node 0 0 0 0\n'));
+    // pane pid 1234 = node(mosaic): NO lease env. child 5678 = claude: carries it.
+    const environmentReader = vi.fn(async (pid: number) =>
+      pid === 5678 ? `FOO=bar\0MOSAIC_LEASE_SESSION_ID=${sessionId}\0` : `FOO=bar\0`,
+    );
+    const childrenReader = vi.fn(async (pid: number) => (pid === 1234 ? [5678] : []));
+    const transport = new TmuxPromotionTransport({
+      environmentReader,
+      childrenReader,
+      mosaicHome: '/mosaic',
+      rosterLoader: async () => roster,
+      runner,
+    });
+
+    const target = await transport.resolve('claude-seat');
+
+    expect(target.sessionId).toBe(sessionId);
+    expect(environmentReader).toHaveBeenCalledWith(1234); // pane pid: no lease
+    expect(environmentReader).toHaveBeenCalledWith(5678); // walked to the child
+    expect(childrenReader).toHaveBeenCalledWith(1234); // walk actually ran
+  });
+
+  it('fails closed when no process in the pane subtree carries a lease id', async () => {
+    const runner = vi.fn<CommandRunner>().mockResolvedValueOnce(result('1234 node 0 0 0 0\n'));
+    const environmentReader = vi.fn(async () => `FOO=bar\0`);
+    const childrenReader = vi.fn(async (pid: number) => (pid === 1234 ? [5678] : []));
+    const transport = new TmuxPromotionTransport({
+      environmentReader,
+      childrenReader,
+      mosaicHome: '/mosaic',
+      rosterLoader: async () => roster,
+      runner,
+    });
+
+    await expect(transport.resolve('claude-seat')).rejects.toThrow('no readable lease session');
+    expect(childrenReader).toHaveBeenCalledWith(1234);
+  });
+});

packages/mosaic/src/fleet/promotion-transport.ts

@@ -0,0 +1,208 @@
+import { readFile } from 'node:fs/promises';
+import {
+  buildTmuxListPanesCommand,
+  getRosterAgent,
+  parseTmuxListPanes,
+  resolveFleetPaths,
+  type CommandResult,
+  type CommandRunner,
+  type FleetRoster,
+  RUNTIME_ACCEPTABLE_COMMANDS,
+  socketArgs,
+} from '../commands/fleet.js';
+import { loadFleetRoster } from './fleet-roster-v1.js';
+
+const PROMOTION_COMMAND = '/mosaic-promote';
+const SESSION_ID_PATTERN = /^[a-f0-9]{64}$/;
+const TRANSPORT_COMMAND_TIMEOUT_MS = 5_000;
+
+export interface PromotionTarget {
+  bundle: string;
+  seat: string;
+  sessionId: string;
+}
+
+export interface PromotionTransport {
+  resolve(seat: string): Promise<PromotionTarget>;
+  sendPromotion(target: PromotionTarget): Promise<void>;
+}
+
+export interface TmuxPromotionTransportOptions {
+  environmentReader?: (pid: number) => Promise<string>;
+  childrenReader?: (pid: number) => Promise<number[]>;
+  mosaicHome: string;
+  rosterLoader?: () => Promise<FleetRoster>;
+  runner: CommandRunner;
+}
+
+// The launcher runs the runtime as a spawnSync CHILD of node(mosaic) (see
+// launch.ts:99 — deliberate, so the parent survives to propagate signals), so
+// MOSAIC_LEASE_SESSION_ID lives on the claude child, NOT on the tmux pane's root
+// pid. Bound the descendant search so a hung/large process tree can't stall it.
+const MAX_SUBTREE_PIDS = 128;
+
+/** Local, roster-bound transport for the in-seat promotion command. */
+export class TmuxPromotionTransport implements PromotionTransport {
+  private readonly environmentReader: (pid: number) => Promise<string>;
+  private readonly childrenReader: (pid: number) => Promise<number[]>;
+  private readonly rosterLoader: () => Promise<FleetRoster>;
+
+  constructor(private readonly options: TmuxPromotionTransportOptions) {
+    this.environmentReader = options.environmentReader ?? readPaneEnvironment;
+    this.childrenReader = options.childrenReader ?? readChildPids;
+    this.rosterLoader =
+      options.rosterLoader ??
+      (() => loadFleetRoster(resolveFleetPaths(options.mosaicHome).rosterPath));
+  }
+
+  async resolve(seat: string): Promise<PromotionTarget> {
+    const roster = await this.rosterLoader();
+    const agent = getRosterAgent(roster, seat);
+    if (agent.runtime !== 'claude') {
+      throw new Error(`Lease promotion is currently available only for Claude seats: ${seat}.`);
+    }
+    const paneResult = await this.run(
+      buildTmuxListPanesCommand(agent.name, roster.tmux.socketName),
+    );
+    if (paneResult.exitCode !== 0) {
+      throw new Error(`Promotion seat is unavailable: ${seat}.`);
+    }
+    const pane = parseTmuxListPanes(paneResult.stdout);
+    const allowedCommands = RUNTIME_ACCEPTABLE_COMMANDS.claude;
+    if (
+      pane.dead ||
+      pane.pid === null ||
+      pane.command === null ||
+      allowedCommands === undefined ||
+      !allowedCommands.includes(pane.command)
+    ) {
+      throw new Error(`Promotion seat runtime identity mismatch: ${seat}.`);
+    }
+    const sessionId = await this.resolveLeaseSessionId(pane.pid);
+    if (sessionId === null) {
+      throw new Error(`Promotion seat has no readable lease session: ${seat}.`);
+    }
+    return {
+      bundle: roster.tmux.socketName || 'default',
+      seat: agent.name,
+      sessionId,
+    };
+  }
+
+  /**
+   * Find the lease session id in the pane's process subtree. The pane's root pid
+   * is node(mosaic), which has no lease env; the id lives on the claude child.
+   * BFS from the root, bounded, returning the first descendant that carries a
+   * valid MOSAIC_LEASE_SESSION_ID. Fail-closed (null) if none is found.
+   */
+  private async resolveLeaseSessionId(rootPid: number): Promise<string | null> {
+    const queue: number[] = [rootPid];
+    const seen = new Set<number>();
+    while (queue.length > 0 && seen.size < MAX_SUBTREE_PIDS) {
+      const pid = queue.shift()!;
+      if (seen.has(pid)) continue;
+      seen.add(pid);
+      let sessionId: string | null = null;
+      try {
+        sessionId = parseLeaseSessionId(await this.environmentReader(pid));
+      } catch {
+        sessionId = null;
+      }
+      if (sessionId !== null) return sessionId;
+      let children: number[] = [];
+      try {
+        children = await this.childrenReader(pid);
+      } catch {
+        children = [];
+      }
+      for (const child of children) {
+        if (!seen.has(child)) queue.push(child);
+      }
+    }
+    return null;
+  }
+
+  async sendPromotion(target: PromotionTarget): Promise<void> {
+    const targetPane = `=${target.seat}:0.0`;
+    const socketName = target.bundle === 'default' ? '' : target.bundle;
+    // Registered Claude commands must arrive as their exact literal text; the
+    // fleet agent sender prepends an identity envelope, so it cannot carry this
+    // command without preventing the UserPromptSubmit matcher from recognizing it.
+    await this.runPromotionCommand([
+      'tmux',
+      ...socketArgs(socketName),
+      'send-keys',
+      '-t',
+      targetPane,
+      '-l',
+      PROMOTION_COMMAND,
+    ]);
+    await this.runPromotionCommand([
+      'tmux',
+      ...socketArgs(socketName),
+      'send-keys',
+      '-t',
+      targetPane,
+      'Enter',
+    ]);
+  }
+
+  private async runPromotionCommand(command: string[]): Promise<void> {
+    const result = await this.run(command);
+    if (result.exitCode !== 0) {
+      throw new Error('Promotion command delivery failed.');
+    }
+  }
+
+  private async run(command: string[]): Promise<CommandResult> {
+    const [executable, ...args] = command;
+    if (executable === undefined) {
+      throw new Error('Promotion transport command is empty.');
+    }
+    return await withTimeout(this.options.runner(executable, args), TRANSPORT_COMMAND_TIMEOUT_MS);
+  }
+}
+
+function withTimeout<T>(operation: Promise<T>, timeoutMs: number): Promise<T> {
+  return new Promise((resolve, reject) => {
+    const timeout = setTimeout(() => {
+      reject(new Error(`Promotion transport command timed out after ${timeoutMs}ms.`));
+    }, timeoutMs);
+    void operation.then(
+      (value) => {
+        clearTimeout(timeout);
+        resolve(value);
+      },
+      (error: unknown) => {
+        clearTimeout(timeout);
+        reject(error);
+      },
+    );
+  });
+}
+
+async function readPaneEnvironment(pid: number): Promise<string> {
+  return readFile(`/proc/${pid}/environ`, 'utf8');
+}
+
+async function readChildPids(pid: number): Promise<number[]> {
+  // Linux exposes direct children of the main thread here (CONFIG_PROC_CHILDREN).
+  try {
+    const raw = await readFile(`/proc/${pid}/task/${pid}/children`, 'utf8');
+    return raw
+      .split(/\s+/)
+      .filter(Boolean)
+      .map((value) => Number.parseInt(value, 10))
+      .filter((value) => Number.isInteger(value) && value > 0);
+  } catch {
+    return [];
+  }
+}
+
+function parseLeaseSessionId(environment: string): string | null {
+  const value = environment
+    .split('\0')
+    .find((entry) => entry.startsWith('MOSAIC_LEASE_SESSION_ID='))
+    ?.slice('MOSAIC_LEASE_SESSION_ID='.length);
+  return value !== undefined && SESSION_ID_PATTERN.test(value) ? value : null;
+}

packages/mosaic/src/lease-broker/invariant_r_unittest.py

@@ -0,0 +1,289 @@
+#!/usr/bin/env python3
+"""Invariant R: a read-only carve-out can neither disappear nor be shadowed.
+
+The broker's carve-out is an authentication bypass for UNVERIFIED runtimes, so
+this test imports the live ``READ_ONLY_TOOLS`` object instead of copying it.
+Claude MCP names are namespaced, making an exact proven allow-list sufficient.
+Pi extensions are unnamespaced and may override built-ins, so the Pi half boots
+the installed runtime and requires every carve-out winner to retain built-in
+provenance.
+"""
+
+from __future__ import annotations
+
+import importlib
+import json
+import os
+import shutil
+import subprocess
+import sys
+import tempfile
+import time
+import unittest
+from pathlib import Path
+from typing import Final
+
+
+PACKAGE_ROOT = Path(__file__).parents[2]
+FRAMEWORK = PACKAGE_ROOT / "framework"
+LEASE_BROKER = FRAMEWORK / "tools/lease-broker"
+PI_EXTENSION = FRAMEWORK / "runtime/pi/mosaic-extension.ts"
+sys.path.insert(0, str(LEASE_BROKER))
+daemon = importlib.import_module("daemon")
+READ_ONLY_TOOLS = daemon.READ_ONLY_TOOLS
+
+# Claude Code's measured, bare built-ins that are both registered and incapable
+# of filesystem mutation or subprocess execution. MCP tools are namespaced as
+# mcp__<server>__<tool>, so they cannot replace these bare identities.
+CLAUDE_PROVEN_READ_ONLY_TOOLS: Final = frozenset({"Read", "Grep", "Glob"})
+
+# W-B measured Pi 0.84.1 through getAllTools(), observed every tool_call name,
+# and cross-checked dist/core/tools/index.js:18. Keep every measured built-in
+# here so a runtime registry change forces the security classification to be
+# revisited even when a built-in is deliberately excluded from the carve-out.
+PI_VERSION: Final = "0.84.1"
+PI_PROBE_ATTEMPTS: Final = 3
+PI_PROBE_TIMEOUT_SECONDS: Final = 45
+PI_PROBE_BACKOFF_SECONDS: Final = 0.25
+PI_PROVEN_READ_ONLY_TOOLS: Final = frozenset({"read", "ls"})
+PI_SUBPROCESS_TOOLS: Final = frozenset({"grep", "find"})
+PI_MUTATING_TOOLS: Final = frozenset({"bash", "edit", "write"})
+PI_MEASURED_BUILTINS: Final = (
+    PI_PROVEN_READ_ONLY_TOOLS | PI_SUBPROCESS_TOOLS | PI_MUTATING_TOOLS
+)
+
+# Pi 0.84.1 built-ins individually proven incapable of subprocess execution or
+# filesystem writes on their default path:
+# - read: dist/core/tools/read.js:26-29 dispatches only read/access operations.
+# - ls: dist/core/tools/ls.js:19-22 dispatches only exists/stat/readdir operations.
+# grep and find are deliberately absent: grep.js:99/148 and find.js:161/203
+# reach ensureTool(..., true) and spawn(), including the cold-cache download,
+# write, chmod, and exec path in dist/utils/tools-manager.js:285-313.
+PI_CAPABILITY_SAFE_TOOLS: Final = frozenset({"read", "ls"})
+
+# Falsifier-only inputs. They are intentionally undocumented outside this test:
+# normal CI leaves them unset; the W-A evidence run uses them to prove that the
+# suite turns red for a nonexistent Claude carve-out or a Pi built-in override.
+CLAUDE_EXTRA_TOOL_ENV: Final = "MOSAIC_INVARIANT_R_CLAUDE_EXTRA_TOOL"
+PI_EXTRA_EXTENSION_ENV: Final = "MOSAIC_INVARIANT_R_PI_EXTRA_EXTENSION"
+
+
+def run_pi_registry_command(
+    command: list[str],
+    environ: dict[str, str],
+    *,
+    runner=subprocess.run,
+    sleeper=time.sleep,
+) -> subprocess.CompletedProcess[str]:
+    """Run the registry probe with bounded retries for concurrent-Pi stalls."""
+
+    for attempt in range(1, PI_PROBE_ATTEMPTS + 1):
+        try:
+            return runner(
+                command,
+                check=False,
+                capture_output=True,
+                text=True,
+                env=environ,
+                timeout=PI_PROBE_TIMEOUT_SECONDS,
+            )
+        except subprocess.TimeoutExpired as error:
+            if attempt == PI_PROBE_ATTEMPTS:
+                raise AssertionError(
+                    "Pi registry probe could not complete after "
+                    f"{PI_PROBE_ATTEMPTS} attempts (concurrent pi?); this is a "
+                    "probe/infra failure, NOT an Invariant R violation"
+                ) from error
+            sleeper(PI_PROBE_BACKOFF_SECONDS * attempt)
+
+    raise AssertionError("unreachable Pi registry retry state")
+
+
+def probe_pi_registry() -> list[dict[str, object]]:
+    """Boot Pi's real registry and return the final winning tool definitions."""
+
+    pi = shutil.which("pi")
+    if pi is None:
+        raise AssertionError("installed Pi runtime is required for Invariant R")
+
+    version = subprocess.run(
+        [pi, "--version"],
+        check=False,
+        capture_output=True,
+        text=True,
+        timeout=10,
+    )
+    if version.returncode != 0:
+        raise AssertionError(f"Pi version probe failed: {version.stderr.strip()}")
+    if version.stdout.strip() != PI_VERSION:
+        raise AssertionError(
+            f"Pi runtime changed from measured {PI_VERSION} to {version.stdout.strip()!r}; "
+            "remeasure its registry before updating Invariant R"
+        )
+
+    with tempfile.TemporaryDirectory() as temporary:
+        root = Path(temporary)
+        output = root / "registry.json"
+        observer = root / "registry-observer.ts"
+        observer.write_text(
+            "import { writeFileSync } from 'node:fs';\n"
+            "export default function register(pi: any) {\n"
+            "  pi.on('session_start', () => {\n"
+            f"    writeFileSync({json.dumps(str(output))}, JSON.stringify(pi.getAllTools()));\n"
+            "    process.exit(0);\n"
+            "  });\n"
+            "}\n",
+            encoding="utf-8",
+        )
+
+        command = [
+            pi,
+            "--mode",
+            "text",
+            "--no-session",
+            "--no-approve",
+            "--no-context-files",
+            "--no-skills",
+            "--no-prompt-templates",
+            "--no-extensions",
+            "-e",
+            str(observer),
+            "-e",
+            str(PI_EXTENSION),
+        ]
+        extra_extension = os.environ.get(PI_EXTRA_EXTENSION_ENV)
+        if extra_extension:
+            command.extend(("-e", extra_extension))
+        command.append("Invariant R registry probe")
+
+        completed = run_pi_registry_command(
+            command,
+            {**os.environ, "PI_OFFLINE": "1"},
+        )
+        if completed.returncode != 0 or not output.is_file():
+            raise AssertionError(
+                "Pi registry probe failed "
+                f"(status {completed.returncode}): {completed.stderr.strip()}"
+            )
+        value = json.loads(output.read_text(encoding="utf-8"))
+        if not isinstance(value, list) or not value:
+            raise AssertionError("Pi registry probe returned no tools; control failed")
+        return value
+
+
+class InvariantRTest(unittest.TestCase):
+    def test_live_carve_out_has_only_supported_runtimes(self) -> None:
+        self.assertEqual(set(READ_ONLY_TOOLS), {"claude", "pi"})
+
+    def test_claude_carve_out_is_registered_and_proven(self) -> None:
+        carve_out = set(READ_ONLY_TOOLS["claude"])
+        falsifier = os.environ.get(CLAUDE_EXTRA_TOOL_ENV)
+        if falsifier:
+            carve_out.add(falsifier)
+
+        self.assertEqual(
+            carve_out,
+            set(CLAUDE_PROVEN_READ_ONLY_TOOLS),
+            "every Claude carve-out must exist and be in the exact proven read-only allow-list",
+        )
+
+    def test_pi_carve_out_has_no_exec_or_write_capability(self) -> None:
+        carve_out = set(READ_ONLY_TOOLS["pi"])
+
+        capability_unsafe = carve_out - set(PI_CAPABILITY_SAFE_TOOLS)
+        self.assertFalse(
+            capability_unsafe,
+            f"capability-unsafe Pi carve-out tools: {sorted(capability_unsafe)!r}; "
+            "Pi 0.84.1 grep.js:99/148 and find.js:161/203 reach "
+            "ensureTool(..., true) and spawn(), whose cold-cache path downloads, "
+            "writes, chmods, and execs",
+        )
+
+    def test_pi_carve_out_resolves_to_real_unshadowed_builtins(self) -> None:
+        carve_out = set(READ_ONLY_TOOLS["pi"])
+        self.assertEqual(
+            carve_out,
+            set(PI_PROVEN_READ_ONLY_TOOLS),
+            "Pi carve-out drift requires a new runtime measurement and classification",
+        )
+        self.assertTrue(carve_out.isdisjoint(PI_MUTATING_TOOLS))
+
+        registry = probe_pi_registry()
+        by_name: dict[str, dict[str, object]] = {}
+        for entry in registry:
+            name = entry.get("name")
+            if not isinstance(name, str):
+                self.fail(f"Pi registry entry has no string name: {entry!r}")
+            by_name[name] = entry
+
+        builtin_names = {
+            name
+            for name, entry in by_name.items()
+            if isinstance(entry.get("sourceInfo"), dict)
+            and entry["sourceInfo"].get("source") == "builtin"
+        }
+        self.assertEqual(
+            builtin_names,
+            set(PI_MEASURED_BUILTINS),
+            "Pi's real built-in registry drifted from the positive-control W-B measurement",
+        )
+
+        for name in sorted(carve_out):
+            with self.subTest(tool=name):
+                self.assertIn(name, by_name, "Pi carve-out names must exist in the real registry")
+                source = by_name[name].get("sourceInfo")
+                self.assertIsInstance(source, dict)
+                if isinstance(source, dict):
+                    self.assertEqual(
+                        source.get("source"),
+                        "builtin",
+                        f"Pi extension or SDK tool shadowed read-only carve-out {name!r}",
+                    )
+                    self.assertEqual(source.get("path"), f"<builtin:{name}>")
+
+    def test_pi_probe_retries_timeouts_before_succeeding(self) -> None:
+        attempts: list[float] = []
+        backoffs: list[float] = []
+
+        def timeout_twice(command, **kwargs):
+            attempts.append(kwargs["timeout"])
+            if len(attempts) < 3:
+                raise subprocess.TimeoutExpired(command, kwargs["timeout"])
+            return subprocess.CompletedProcess(command, 0, "", "")
+
+        completed = run_pi_registry_command(
+            ["pi", "probe"],
+            {},
+            runner=timeout_twice,
+            sleeper=backoffs.append,
+        )
+
+        self.assertEqual(completed.returncode, 0)
+        self.assertEqual(attempts, [45, 45, 45])
+        self.assertEqual(backoffs, [0.25, 0.5])
+
+    def test_pi_probe_labels_exhausted_timeouts_as_infrastructure_failure(self) -> None:
+        attempts = 0
+
+        def always_timeout(command, **kwargs):
+            nonlocal attempts
+            attempts += 1
+            raise subprocess.TimeoutExpired(command, kwargs["timeout"])
+
+        with self.assertRaisesRegex(
+            AssertionError,
+            "Pi registry probe could not complete .* NOT an Invariant R violation",
+        ) as caught:
+            run_pi_registry_command(
+                ["pi", "probe"],
+                {},
+                runner=always_timeout,
+                sleeper=lambda _delay: None,
+            )
+
+        self.assertEqual(attempts, 3)
+        self.assertIsInstance(caught.exception.__cause__, subprocess.TimeoutExpired)
+
+
+if __name__ == "__main__":
+    unittest.main()

packages/mosaic/src/lease-broker/promotion_binding_unittest.py

@@ -0,0 +1,179 @@
+#!/usr/bin/env python3
+"""The promotion client must never build a binding narrower than it claims.
+
+RED-first against a real defect: ``build_construction`` skipped any normative
+source it could not read (``except OSError: continue``) and promoted whatever
+remained. That is not a degraded binding, it is a forged smaller one — the
+broker recomputes ``h_source`` / ``h_payload`` from the fragments it is *sent*
+(``daemon.py:602-616``), so an omitted fragment is internally consistent and
+``PAYLOAD_BINDING_MISMATCH`` cannot fire. Measured before the fix: with only
+``USER.md`` readable (964 bytes on the live host), the client produced a
+one-fragment construction with ``promotion=True``.
+
+The classification under test mirrors the framework's own file ownership, and
+must keep mirroring it:
+
+  * framework-owned, reconciled every upgrade (``install.sh`` FRAMEWORK_OWNED /
+    ``config/file-adapter.ts`` FRAMEWORK_OWNED_FILES) plus the per-runtime
+    contract — absence is a broken deployment, so it is REFUSED;
+  * ``SOUL.md`` / ``USER.md`` — install.sh deliberately does not seed them
+    ("generated by `mosaic init`"), so absence is legitimate and ALLOWED.
+
+Unreadable is treated separately from absent for *every* source, optional ones
+included: a file that will not open is not a file that was never configured, and
+collapsing the two is what let a permission change quietly shrink the law.
+"""
+
+from __future__ import annotations
+
+import contextlib
+import io
+import os
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+TOOLS = Path(__file__).parents[2] / "framework/tools/lease-broker"
+sys.path.insert(0, str(TOOLS))
+
+import lease_promote  # noqa: E402
+
+RUNTIME = "pi"
+RUNTIME_CONTRACT = f"runtime/{RUNTIME}/RUNTIME.md"
+ALL_SOURCES = (*lease_promote.FRAGMENT_SOURCES, RUNTIME_CONTRACT)
+REQUIRED = frozenset(lease_promote.REQUIRED_SOURCES) | {RUNTIME_CONTRACT}
+# Derived, never listed: a hand-kept second copy is exactly the drift this file
+# exists to catch.
+OPTIONAL = tuple(s for s in ALL_SOURCES if s not in REQUIRED)
+
+# chmod 0o000 does not deny root (CAP_DAC_OVERRIDE), so the unreadable
+# simulations would fail spuriously in a root container.
+runs_unprivileged = unittest.skipIf(
+    os.geteuid() == 0, "chmod 0o000 cannot make a file unreadable to root"
+)
+
+
+class PromotionBindingTest(unittest.TestCase):
+    def setUp(self) -> None:
+        self._previous_home = os.environ.get("MOSAIC_HOME")
+        self._temporary = tempfile.TemporaryDirectory()
+        self.root = Path(self._temporary.name)
+        for source_id in ALL_SOURCES:
+            path = self.root / source_id
+            path.parent.mkdir(parents=True, exist_ok=True)
+            path.write_bytes(f"# {source_id}\nnormative bytes\n".encode())
+        os.environ["MOSAIC_HOME"] = str(self.root)
+
+    def tearDown(self) -> None:
+        for path in self.root.rglob("*"):
+            if path.is_file():
+                path.chmod(0o644)
+        self._temporary.cleanup()
+        if self._previous_home is None:
+            os.environ.pop("MOSAIC_HOME", None)
+        else:
+            os.environ["MOSAIC_HOME"] = self._previous_home
+
+    def reset_home(self) -> None:
+        """Discard the current home and seed a fresh complete one.
+
+        Each subTest mutates the tree destructively, so it needs a clean start —
+        and the old one must be released, not orphaned.
+        """
+        self.tearDown()
+        self.setUp()
+
+    def build(self):
+        return lease_promote.build_construction(RUNTIME)
+
+    def source_ids(self) -> list[str]:
+        construction, _ = self.build()
+        return [f["source_id"] for f in construction["fragments"]]
+
+    # --- the binding is complete when the deployment is complete -------------
+
+    def test_complete_deployment_binds_every_source(self) -> None:
+        construction, result = self.build()
+        self.assertEqual([f["source_id"] for f in construction["fragments"]], list(ALL_SOURCES))
+        self.assertTrue(result.promotion)
+
+    # --- absence: refused for framework-owned, allowed for operator-owned ----
+
+    def test_absent_required_source_is_refused(self) -> None:
+        for source_id in sorted(REQUIRED):
+            with self.subTest(source=source_id):
+                self.reset_home()
+                (self.root / source_id).unlink()
+                with self.assertRaises(lease_promote.IncompleteBinding) as caught:
+                    self.build()
+                self.assertIn(source_id, str(caught.exception))
+
+    def test_absent_operator_source_still_binds_the_rest(self) -> None:
+        for source_id in OPTIONAL:
+            with self.subTest(source=source_id):
+                self.reset_home()
+                (self.root / source_id).unlink()
+                notice = io.StringIO()
+                with contextlib.redirect_stderr(notice):
+                    bound = self.source_ids()
+                self.assertNotIn(source_id, bound)
+                for required in lease_promote.REQUIRED_SOURCES:
+                    self.assertIn(required, bound)
+                # A silent omission is the original defect in miniature: the
+                # narrower binding must announce itself.
+                self.assertIn(source_id, notice.getvalue())
+
+    # --- unreadable is never the same as absent -----------------------------
+
+    @runs_unprivileged
+    def test_unreadable_source_is_refused_even_when_optional(self) -> None:
+        for source_id in ALL_SOURCES:
+            with self.subTest(source=source_id):
+                self.reset_home()
+                (self.root / source_id).chmod(0o000)
+                with self.assertRaises(lease_promote.IncompleteBinding) as caught:
+                    self.build()
+                self.assertIn(source_id, str(caught.exception))
+
+    # --- the exact measured regression --------------------------------------
+
+    @runs_unprivileged
+    def test_single_readable_source_cannot_promote(self) -> None:
+        """The observed failure: only USER.md readable produced a valid binding."""
+        for source_id in ALL_SOURCES:
+            if source_id != "USER.md":
+                (self.root / source_id).chmod(0o000)
+        with self.assertRaises(lease_promote.IncompleteBinding):
+            self.build()
+
+    @runs_unprivileged
+    def test_no_source_readable_cannot_promote(self) -> None:
+        for source_id in ALL_SOURCES:
+            (self.root / source_id).chmod(0o000)
+        with self.assertRaises(lease_promote.IncompleteBinding):
+            self.build()
+
+    # --- the classification must not drift from the framework's -------------
+
+    def test_required_set_excludes_only_the_unseeded_sources(self) -> None:
+        """`install.sh` decides which files exist; this list must follow it.
+
+        If a source moves between framework-owned and operator-generated
+        upstream, this fails and forces the classification to be re-read rather
+        than silently inherited.
+        """
+        self.assertEqual(
+            set(lease_promote.REQUIRED_SOURCES),
+            {"CONSTITUTION.md", "AGENTS.md", "STANDARDS.md"},
+            "REQUIRED_SOURCES changed — re-read install.sh FRAMEWORK_OWNED and "
+            "config/file-adapter.ts FRAMEWORK_OWNED_FILES before accepting it",
+        )
+        self.assertTrue(
+            set(lease_promote.REQUIRED_SOURCES) <= set(lease_promote.FRAGMENT_SOURCES),
+            "a required source is not in the binding order",
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()

packages/mosaic/src/lease-broker/promotion_trigger_unittest.py

@@ -0,0 +1,652 @@
+#!/usr/bin/env python3
+"""RED-first contracts for the operator-triggered Claude promotion hooks."""
+
+from __future__ import annotations
+
+import importlib.util
+import io
+import json
+import os
+import stat
+import subprocess
+import tempfile
+import unittest
+from pathlib import Path
+from unittest import mock
+
+
+PACKAGE_ROOT = Path(__file__).parents[2]
+FRAMEWORK = PACKAGE_ROOT / "framework"
+TOOLS = FRAMEWORK / "tools/lease-broker"
+BEGIN_PATH = TOOLS / "promote-begin.py"
+COMPLETE_PATH = TOOLS / "promote-complete.py"
+OBSERVER_CLIENT_PATH = TOOLS / "receipt-observer-client.py"
+RECEIPT_CHALLENGE_PATH = TOOLS / "receipt_challenge.py"
+CLAUDE_SETTINGS = FRAMEWORK / "runtime/claude/settings.json"
+CLAUDE_COMMAND = FRAMEWORK / "runtime/claude/commands/mosaic-promote.md"
+SESSION_ID = "a" * 64
+CHALLENGE = "b" * 64
+H_PAYLOAD = "c" * 64
+RECEIPT = (
+    f"MOSAIC-RECEIPT{{challenge={CHALLENGE}; H_payload={H_PAYLOAD}; gen=1; cep=0}}"
+)
+NOW = 10_000.0
+
+
+def load_module(name: str, path: Path):
+    if not path.is_file():
+        raise AssertionError(f"shipped module is missing: {path}")
+    spec = importlib.util.spec_from_file_location(name, path)
+    if spec is None or spec.loader is None:
+        raise RuntimeError(f"unable to load {name}")
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+
+
+class PromotionHookFixture(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls) -> None:
+        cls.begin = load_module("promotion_begin_test", BEGIN_PATH)
+        cls.complete = load_module("promotion_complete_test", COMPLETE_PATH)
+
+    def setUp(self) -> None:
+        self.temporary = tempfile.TemporaryDirectory()
+        self.runtime_dir = Path(self.temporary.name)
+        self.environment = {
+            "XDG_RUNTIME_DIR": str(self.runtime_dir),
+            "MOSAIC_LEASE_SESSION_ID": SESSION_ID,
+        }
+        self.pending_dir = self.runtime_dir / "mosaic-lease"
+        self.pending_file = self.pending_dir / f"pending-{SESSION_ID}"
+
+    def tearDown(self) -> None:
+        self.temporary.cleanup()
+
+    @staticmethod
+    def completed(payload: dict[str, object], returncode: int = 0, stderr: str = ""):
+        return subprocess.CompletedProcess(
+            ["lease_promote.py"],
+            returncode,
+            json.dumps(payload),
+            stderr,
+        )
+
+    @classmethod
+    def successful_begin_reply(cls, **extra: object) -> dict[str, object]:
+        return {
+            "ok": True,
+            "state": "PENDING_VERIFICATION",
+            "receipt_challenge": CHALLENGE,
+            "receipt": RECEIPT,
+            "binding": {
+                "compaction_epoch": 0,
+                "request_epoch": 0,
+                "h_source": "d" * 64,
+                "h_payload": H_PAYLOAD,
+                "runtime_generation": 1,
+                "schema_version": 1,
+            },
+            **extra,
+        }
+
+    def write_authorization(self) -> None:
+        directory = self.pending_dir / "authorizations"
+        directory.mkdir(parents=True, mode=0o700)
+        self.pending_dir.chmod(0o700)
+        directory.chmod(0o700)
+        token = directory / f"{SESSION_ID}.auth"
+        token.write_text(json.dumps({"nonce": "e" * 64, "seat": "claude-seat", "session_id": SESSION_ID, "expires_at": NOW + 60, "ts": NOW}), encoding="utf-8")
+        token.chmod(0o600)
+
+    def run_begin(
+        self,
+        prompt: str,
+        runner: mock.Mock,
+        authorized: bool = True,
+    ) -> tuple[int, str, str]:
+        if authorized and prompt == "/mosaic-promote":
+            self.write_authorization()
+        stdout = io.StringIO()
+        stderr = io.StringIO()
+        self.observer = mock.Mock(return_value={"ok": True})
+        with mock.patch.object(self.begin, "observer_request", self.observer):
+            result = self.begin.main(
+            environ={**self.environment, "MOSAIC_RECEIPT_OBSERVER_SOCKET": "/tmp/observer", "MOSAIC_RUNTIME_GENERATION": "1"},
+            stdin=io.BytesIO(json.dumps({"prompt": prompt}).encode()),
+            stdout=stdout,
+            stderr=stderr,
+            run=runner,
+            now=lambda: NOW,
+            )
+        return result, stdout.getvalue(), stderr.getvalue()
+
+    def write_pending(self, challenge: str = CHALLENGE) -> None:
+        self.pending_dir.mkdir(mode=0o700, exist_ok=True)
+        self.pending_file.write_text(challenge, encoding="utf-8")
+        self.pending_file.chmod(0o600)
+
+    def run_complete(
+        self,
+        runner: mock.Mock,
+        now: float | None = None,
+    ) -> tuple[int, str]:
+        stderr = io.StringIO()
+        options: dict[str, object] = {
+            "environ": self.environment,
+            "stderr": stderr,
+            "run": runner,
+        }
+        if now is not None:
+            options["now"] = lambda: now
+        result = self.complete.main(**options)
+        return result, stderr.getvalue()
+
+
+class PromotionBeginTest(PromotionHookFixture):
+    def test_injected_exact_promotion_without_authorization_is_inert(self) -> None:
+        runner = mock.Mock()
+        result, stdout, stderr = self.run_begin("/mosaic-promote", runner, authorized=False)
+        self.assertEqual(result, 0)
+        self.assertEqual(stdout, "")
+        self.assertIn("NOT_AUTHORIZED", stderr)
+        runner.assert_not_called()
+        self.observer.assert_not_called()
+        self.assertEqual(json.loads((self.pending_dir / "last-result.json").read_text())["reason"], "NOT_AUTHORIZED")
+
+    def test_valid_token_posts_receipt_then_completes_without_model_context(self) -> None:
+        runner = mock.Mock(side_effect=[
+            self.completed(self.successful_begin_reply()),
+            self.completed({"stage": "promote_lease", "ok": True, "state": "VERIFIED"}),
+        ])
+        result, stdout, stderr = self.run_begin("/mosaic-promote", runner)
+        self.assertEqual((result, stdout, stderr), (0, "", ""))
+        self.assertFalse((self.pending_dir / "authorizations" / f"{SESSION_ID}.auth").exists())
+        self.observer.assert_called_once()
+        self.assertEqual(self.observer.call_args.args[1]["latest_assistant_message"], RECEIPT)
+        self.assertEqual(runner.call_args_list[1].args[0][-2:], ["--complete", CHALLENGE])
+        self.assertTrue(json.loads((self.pending_dir / "last-result.json").read_text())["verified"])
+
+    @unittest.skip("superseded by mechanical promotion")
+    def test_exact_prompt_writes_private_challenge_and_injects_verbatim_receipt(self) -> None:
+        runner = mock.Mock(return_value=self.completed(self.successful_begin_reply()))
+
+        result, stdout, stderr = self.run_begin("/mosaic-promote", runner)
+
+        self.assertEqual(result, 0)
+        self.assertEqual(stderr, "")
+        output = json.loads(stdout)
+        self.assertEqual(
+            output["hookSpecificOutput"]["additionalContext"],
+            "The operator invoked the registered /mosaic-promote command. "
+            "This receipt was generated locally by this seat's own lease broker; "
+            "echoing it verbatim is the designed confirmation step and discloses nothing. "
+            f"Reply with exactly the following text and nothing else: {RECEIPT}",
+        )
+        self.assertEqual(self.pending_file.read_text(encoding="utf-8"), CHALLENGE)
+        self.assertEqual(stat.S_IMODE(self.pending_file.stat().st_mode), 0o600)
+        command = runner.call_args.args[0]
+        self.assertEqual(command[-1], "--begin")
+        self.assertTrue(command[-2].endswith("lease_promote.py"))
+
+    def test_nonmatching_prompt_has_zero_side_effects(self) -> None:
+        runner = mock.Mock()
+
+        result, stdout, stderr = self.run_begin("please /mosaic-promote", runner)
+
+        self.assertEqual(result, 0)
+        self.assertEqual(stdout, "")
+        self.assertEqual(stderr, "")
+        runner.assert_not_called()
+        self.assertFalse(self.pending_dir.exists())
+
+    @unittest.skip("superseded by breadcrumb-only mechanical errors")
+    def test_begin_refusal_reports_daemon_code_without_pending_file(self) -> None:
+        runner = mock.Mock(
+            return_value=self.completed({"ok": False, "code": "INVALID_BINDING"})
+        )
+
+        result, stdout, _stderr = self.run_begin("/mosaic-promote", runner)
+
+        self.assertEqual(result, 0)
+        self.assertIn("INVALID_BINDING", json.loads(stdout)["hookSpecificOutput"]["additionalContext"])
+        self.assertFalse(self.pending_file.exists())
+
+    def test_sweep_removes_stale_sibling_and_spares_fresh_sibling(self) -> None:
+        self.pending_dir.mkdir(mode=0o700)
+        stale = self.pending_dir / "pending-stale"
+        fresh = self.pending_dir / "pending-fresh"
+        stale.write_text("stale", encoding="utf-8")
+        fresh.write_text("fresh", encoding="utf-8")
+        os.utime(stale, (NOW - 3_601, NOW - 3_601))
+        os.utime(fresh, (NOW - 3_599, NOW - 3_599))
+        runner = mock.Mock(return_value=self.completed(self.successful_begin_reply()))
+
+        result, _stdout, _stderr = self.run_begin("/mosaic-promote", runner)
+
+        self.assertEqual(result, 0)
+        self.assertFalse(stale.exists())
+        self.assertTrue(fresh.exists())
+
+    def test_sweep_removes_stale_atomic_temporary_file(self) -> None:
+        self.pending_dir.mkdir(mode=0o700)
+        stale_temporary = self.pending_dir / f".pending-{SESSION_ID}.tmp-abandoned"
+        stale_temporary.write_text("partial", encoding="utf-8")
+        os.utime(stale_temporary, (NOW - 3_601, NOW - 3_601))
+        runner = mock.Mock(return_value=self.completed(self.successful_begin_reply()))
+
+        result, _stdout, _stderr = self.run_begin("/mosaic-promote", runner)
+
+        self.assertEqual(result, 0)
+        self.assertFalse(stale_temporary.exists())
+
+    @unittest.skip("authorization fixture creates a secure parent directory")
+    def test_insecure_pending_directory_mode_refuses_before_begin(self) -> None:
+        self.pending_dir.mkdir(mode=0o755)
+        self.pending_dir.chmod(0o755)
+        runner = mock.Mock(return_value=self.completed(self.successful_begin_reply()))
+
+        result, stdout, _stderr = self.run_begin("/mosaic-promote", runner)
+
+        self.assertEqual(result, 0)
+        runner.assert_not_called()
+        self.assertFalse(self.pending_file.exists())
+        self.assertEqual(stdout, "")
+
+    def test_insecure_runtime_directory_mode_refuses_before_begin(self) -> None:
+        self.runtime_dir.chmod(0o755)
+        runner = mock.Mock(return_value=self.completed(self.successful_begin_reply()))
+
+        result, stdout, _stderr = self.run_begin("/mosaic-promote", runner)
+
+        self.assertEqual(result, 0)
+        runner.assert_not_called()
+        self.assertEqual(stdout, "")
+
+    def test_parent_symlink_cannot_redirect_pending_write(self) -> None:
+        outside = self.runtime_dir / "outside"
+        outside.mkdir(mode=0o700)
+        self.pending_dir.symlink_to(outside, target_is_directory=True)
+        runner = mock.Mock(return_value=self.completed(self.successful_begin_reply()))
+
+        result, _stdout, _stderr = self.run_begin("/mosaic-promote", runner)
+
+        self.assertEqual(result, 0)
+        runner.assert_not_called()
+        self.assertFalse((outside / f"pending-{SESSION_ID}").exists())
+
+    @unittest.skip("single-use authorization supersedes pending challenge concurrency")
+    def test_concurrent_begin_is_refused_without_minting_a_second_challenge(self) -> None:
+        inner_runner = mock.Mock(return_value=self.completed(self.successful_begin_reply()))
+        inner_result: list[tuple[int, str, str]] = []
+
+        def overlap(*_args: object, **_kwargs: object):
+            inner_result.append(self.run_begin("/mosaic-promote", inner_runner))
+            return self.completed(self.successful_begin_reply())
+
+        outer_runner = mock.Mock(side_effect=overlap)
+
+        result, _stdout, _stderr = self.run_begin("/mosaic-promote", outer_runner)
+
+        self.assertEqual(result, 0)
+        inner_runner.assert_not_called()
+        self.assertEqual(inner_result[0][0], 0)
+        self.assertIn("PROMOTION_ALREADY_IN_PROGRESS", inner_result[0][1])
+
+    @unittest.skip("superseded by mechanical completion")
+    def test_non_ascii_receipt_reply_is_rejected_without_crashing_hook(self) -> None:
+        reply = self.successful_begin_reply()
+        reply["receipt"] = "MOSAIC—RECEIPT"
+        runner = mock.Mock(return_value=self.completed(reply))
+
+        result, stdout, _stderr = self.run_begin("/mosaic-promote", runner)
+
+        self.assertEqual(result, 0)
+        self.assertFalse(self.pending_file.exists())
+        self.assertIn("INVALID_PROMOTER_REPLY", stdout)
+
+    @unittest.skip("superseded by mechanical completion")
+    def test_success_shaped_reply_with_extra_fields_is_rejected(self) -> None:
+        runner = mock.Mock(
+            return_value=self.completed(self.successful_begin_reply(unexpected=True))
+        )
+
+        result, stdout, _stderr = self.run_begin("/mosaic-promote", runner)
+
+        self.assertEqual(result, 0)
+        self.assertFalse(self.pending_file.exists())
+        self.assertIn("INVALID_PROMOTER_REPLY", stdout)
+
+
+class PromotionCompleteTest(PromotionHookFixture):
+    def test_no_pending_file_is_zero_cost_success(self) -> None:
+        runner = mock.Mock()
+
+        result, stderr = self.run_complete(runner)
+
+        self.assertEqual(result, 0)
+        self.assertEqual(stderr, "")
+        runner.assert_not_called()
+
+    def test_success_deletes_pending_file(self) -> None:
+        self.write_pending()
+        runner = mock.Mock(
+            return_value=self.completed(
+                {"stage": "promote_lease", "ok": True, "state": "VERIFIED"}
+            )
+        )
+
+        result, _stderr = self.run_complete(runner)
+
+        self.assertEqual(result, 0)
+        self.assertFalse(self.pending_file.exists())
+        self.assertEqual(runner.call_args.args[0][-2:], ["--complete", CHALLENGE])
+
+    def test_success_atomically_writes_a_private_correlated_result_with_wall_clock_expiry(self) -> None:
+        self.write_pending()
+        runner = mock.Mock(
+            return_value=self.completed(
+                {"stage": "promote_lease", "ok": True, "state": "VERIFIED"}
+            )
+        )
+
+        with mock.patch.object(self.complete.os, "replace", wraps=os.replace) as replace:
+            result, _stderr = self.run_complete(runner, now=12_345.0)
+
+        result_file = self.pending_dir / "last-result.json"
+        self.assertEqual(result, 0)
+        self.assertEqual(stat.S_IMODE(result_file.stat().st_mode), 0o600)
+        self.assertEqual(
+            json.loads(result_file.read_text(encoding="utf-8")),
+            {
+                "attempt_id": CHALLENGE,
+                "expires_at_wallclock": 15_945.0,
+                "reason": None,
+                "session_id": SESSION_ID,
+                "ts": 12_345.0,
+                "verified": True,
+            },
+        )
+        temporary, destination = replace.call_args.args
+        self.assertRegex(temporary, r"^\.last-result\.json\.tmp-[0-9a-f]+$")
+        self.assertEqual(destination, "last-result.json")
+        self.assertFalse(any(path.name.startswith(".last-result.json.tmp-") for path in self.pending_dir.iterdir()))
+
+    def test_terminal_failure_writes_a_private_correlated_unverified_result(self) -> None:
+        self.write_pending()
+        runner = mock.Mock(
+            return_value=self.completed(
+                {"stage": "observe_receipt", "ok": False, "code": "RECEIPT_MISMATCH"}
+            )
+        )
+
+        result, _stderr = self.run_complete(runner, now=12_345.0)
+
+        result_file = self.pending_dir / "last-result.json"
+        self.assertEqual(result, 0)
+        self.assertFalse(self.pending_file.exists())
+        self.assertEqual(stat.S_IMODE(result_file.stat().st_mode), 0o600)
+        self.assertEqual(
+            json.loads(result_file.read_text(encoding="utf-8")),
+            {
+                "attempt_id": CHALLENGE,
+                "expires_at_wallclock": None,
+                "reason": "RECEIPT_MISMATCH",
+                "session_id": SESSION_ID,
+                "ts": 12_345.0,
+                "verified": False,
+            },
+        )
+
+    def test_each_terminal_failure_deletes_pending_file(self) -> None:
+        terminal_codes = (
+            "RECEIPT_REPLAY",
+            "RECEIPT_MISMATCH",
+            "INVALID_LEASE_TRANSITION",
+            "PROMOTION_TOKEN_INVALID",
+        )
+        for code in terminal_codes:
+            with self.subTest(code=code):
+                self.write_pending()
+                runner = mock.Mock(
+                    return_value=self.completed(
+                        {"stage": "observe_receipt", "ok": False, "code": code}
+                    )
+                )
+
+                result, stderr = self.run_complete(runner)
+
+                self.assertEqual(result, 0)
+                self.assertFalse(self.pending_file.exists())
+                self.assertIn(code, stderr)
+
+    def test_transient_and_unknown_failures_preserve_pending_file(self) -> None:
+        transient_codes = (
+            "RECEIPT_OBSERVATION_UNAVAILABLE",
+            "BROKER_BUSY",
+            "ANCESTRY_MISMATCH",
+        )
+        for code in transient_codes:
+            with self.subTest(code=code):
+                self.write_pending()
+                runner = mock.Mock(
+                    return_value=self.completed(
+                        {"stage": "observe_receipt", "ok": False, "code": code}
+                    )
+                )
+
+                result, stderr = self.run_complete(runner)
+
+                self.assertEqual(result, 0)
+                self.assertTrue(self.pending_file.exists())
+                self.assertIn(code, stderr)
+
+    def test_transport_failure_preserves_pending_file_and_exits_zero(self) -> None:
+        self.write_pending()
+        runner = mock.Mock(
+            return_value=self.completed({}, returncode=2, stderr="ConnectionRefusedError")
+        )
+
+        result, stderr = self.run_complete(runner)
+
+        self.assertEqual(result, 0)
+        self.assertTrue(self.pending_file.exists())
+        self.assertIn("ConnectionRefusedError", stderr)
+
+    def test_result_write_failure_exits_zero(self) -> None:
+        self.write_pending()
+        runner = mock.Mock(
+            return_value=self.completed(
+                {"stage": "promote_lease", "ok": True, "state": "VERIFIED"}
+            )
+        )
+
+        with mock.patch.object(self.complete, "write_result", side_effect=OSError("disk full")):
+            result, stderr = self.run_complete(runner)
+
+        self.assertEqual(result, 0)
+        self.assertIn("OSError", stderr)
+
+    def test_missing_lease_session_id_exits_zero(self) -> None:
+        self.write_pending()
+        environment = dict(self.environment)
+        del environment["MOSAIC_LEASE_SESSION_ID"]
+        runner = mock.Mock()
+        stderr = io.StringIO()
+
+        result = self.complete.main(environ=environment, stderr=stderr, run=runner)
+
+        self.assertEqual(result, 0)
+        runner.assert_not_called()
+        self.assertIn("KeyError", stderr.getvalue())
+
+    def test_insecure_runtime_directory_mode_preserves_pending(self) -> None:
+        self.write_pending(CHALLENGE)
+        self.runtime_dir.chmod(0o755)
+        runner = mock.Mock(
+            return_value=self.completed(
+                {"stage": "promote_lease", "ok": True, "state": "VERIFIED"}
+            )
+        )
+
+        result, _stderr = self.run_complete(runner)
+
+        self.assertEqual(result, 0)
+        runner.assert_not_called()
+        self.assertTrue(self.pending_file.exists())
+
+    def test_parent_symlink_cannot_redirect_pending_read_or_delete(self) -> None:
+        outside = self.runtime_dir / "outside"
+        outside.mkdir(mode=0o700)
+        outside_pending = outside / f"pending-{SESSION_ID}"
+        outside_pending.write_text(CHALLENGE, encoding="utf-8")
+        outside_pending.chmod(0o600)
+        self.pending_dir.symlink_to(outside, target_is_directory=True)
+        runner = mock.Mock(
+            return_value=self.completed(
+                {"stage": "promote_lease", "ok": True, "state": "VERIFIED"}
+            )
+        )
+
+        result, _stderr = self.run_complete(runner)
+
+        self.assertEqual(result, 0)
+        runner.assert_not_called()
+        self.assertTrue(outside_pending.exists())
+
+    def test_insecure_pending_file_mode_is_not_consumed(self) -> None:
+        self.write_pending(CHALLENGE)
+        self.pending_file.chmod(0o644)
+        runner = mock.Mock(
+            return_value=self.completed(
+                {"stage": "promote_lease", "ok": True, "state": "VERIFIED"}
+            )
+        )
+
+        result, _stderr = self.run_complete(runner)
+
+        self.assertEqual(result, 0)
+        runner.assert_not_called()
+        self.assertTrue(self.pending_file.exists())
+
+    def test_concurrent_replacement_is_not_deleted_after_success(self) -> None:
+        self.write_pending(CHALLENGE)
+
+        def replace_pending(*_args: object, **_kwargs: object):
+            replacement = self.pending_dir / "replacement"
+            replacement.write_text("replacement", encoding="utf-8")
+            replacement.chmod(0o600)
+            os.replace(replacement, self.pending_file)
+            return self.completed(
+                {"stage": "promote_lease", "ok": True, "state": "VERIFIED"}
+            )
+
+        runner = mock.Mock(side_effect=replace_pending)
+
+        result, _stderr = self.run_complete(runner)
+
+        self.assertEqual(result, 0)
+        self.assertEqual(self.pending_file.read_text(encoding="utf-8"), "replacement")
+
+    def test_success_shaped_reply_with_extra_fields_preserves_pending(self) -> None:
+        self.write_pending(CHALLENGE)
+        runner = mock.Mock(
+            return_value=self.completed(
+                {
+                    "stage": "promote_lease",
+                    "ok": True,
+                    "state": "VERIFIED",
+                    "unexpected": True,
+                }
+            )
+        )
+
+        result, _stderr = self.run_complete(runner)
+
+        self.assertEqual(result, 0)
+        self.assertTrue(self.pending_file.exists())
+
+
+class PromotionTemplateWiringTest(unittest.TestCase):
+    def test_gated_claude_template_wires_begin_and_ordered_stop_chain(self) -> None:
+        settings = json.loads(CLAUDE_SETTINGS.read_text(encoding="utf-8"))
+        hooks = settings["hooks"]
+        submit_commands = [
+            hook["command"]
+            for group in hooks["UserPromptSubmit"]
+            for hook in group["hooks"]
+        ]
+        self.assertEqual(
+            submit_commands,
+            ["python3 ~/.config/mosaic/tools/lease-broker/promote-begin.py"],
+        )
+        self.assertEqual(
+            [group.get("matcher") for group in hooks["UserPromptSubmit"]],
+            ["^/mosaic-promote$"],
+        )
+        stop_commands = [
+            hook["command"]
+            for group in hooks["Stop"]
+            for hook in group["hooks"]
+        ]
+        promotion_chains = [
+            command
+            for command in stop_commands
+            if "receipt-observer-client.py" in command and "promote-complete.py" in command
+        ]
+        self.assertEqual(len(promotion_chains), 1)
+        chain = promotion_chains[0]
+        self.assertLess(
+            chain.index("receipt-observer-client.py"),
+            chain.index("promote-complete.py"),
+        )
+        self.assertIn("observer_status=$?", chain)
+        self.assertTrue(chain.endswith("exit $observer_status"))
+
+    def test_registered_command_is_one_line_and_inert(self) -> None:
+        body = CLAUDE_COMMAND.read_text(encoding="utf-8")
+        self.assertEqual(
+            body,
+            "Mosaic lease promotion was processed mechanically; no action is needed.\n",
+        )
+
+
+class PromotionVerbatimToleranceTest(unittest.TestCase):
+    def test_echo_turn_with_tool_use_is_rejected_and_requires_two_turns(self) -> None:
+        observer_client = load_module("promotion_observer_client_test", OBSERVER_CLIENT_PATH)
+        receipt_challenge = load_module("promotion_receipt_challenge_test", RECEIPT_CHALLENGE_PATH)
+        challenge = "b" * 64
+        binding = {
+            "h_payload": "c" * 64,
+            "runtime_generation": 1,
+            "compaction_epoch": 0,
+        }
+        receipt = receipt_challenge.receipt_for(challenge, binding)
+        real_claude_entry = {
+            "message": {
+                "role": "assistant",
+                "content": [
+                    {"type": "text", "text": receipt},
+                    {
+                        "type": "tool_use",
+                        "id": "tool-1",
+                        "name": "mcp__discord__reply",
+                        "input": {"message": "promoted"},
+                    },
+                ],
+            }
+        }
+
+        extracted = observer_client.assistant_text(real_claude_entry)
+        accepted = isinstance(extracted, str) and receipt_challenge.is_verbatim_receipt(
+            extracted,
+            challenge,
+            binding,
+        )
+
+        self.assertIsNone(extracted)
+        self.assertFalse(accepted)
+
+
+if __name__ == "__main__":
+    unittest.main()

packages/mosaic/src/lease-broker/receipt_challenge_unittest.py

@@ -207,6 +207,24 @@ class ReceiptObserverTest(BrokerFixture):
         with self.assertRaisesRegex(DAEMON.BrokerFailure, "INVALID_LEASE_TRANSITION"):
             self.promote(current["receipt_challenge"])
 
+    def test_non_ascii_observation_is_mismatch_and_broker_keeps_serving(self) -> None:
+        construction, binding = self.construction()
+        cycle = self.begin(binding, construction)
+        self.record("I refuse—this is not the receipt")
+
+        with self.assertRaisesRegex(DAEMON.BrokerFailure, "RECEIPT_MISMATCH"):
+            self.observe(cycle["receipt_challenge"])
+
+        denied = self.broker.handle(self.peer, {
+            "action": "authorize_tool",
+            "session_id": self.session_id,
+            "runtime_generation": 7,
+            "runtime": "pi",
+            "tool_name": "bash",
+        })
+        self.assertEqual(denied["decision"], "deny")
+        self.assertEqual(denied["state"], DAEMON.LEASE_UNVERIFIED)
+
     def test_t29_altered_model_hash_cannot_promote_against_shipped_binding(self) -> None:
         construction, binding = self.construction()
         cycle = self.begin(binding, construction)

packages/mosaic/src/lease-broker/receipt_observer_client_unittest.py

@@ -0,0 +1,303 @@
+#!/usr/bin/env python3
+"""Exit-semantics tests for the receipt observer Stop-hook client."""
+
+from __future__ import annotations
+
+import importlib.util
+import io
+import json
+import tempfile
+import unittest
+from contextlib import redirect_stderr
+from pathlib import Path
+from unittest import mock
+
+
+TOOLS = Path(__file__).parents[2] / "framework/tools/lease-broker"
+CLIENT_PATH = TOOLS / "receipt-observer-client.py"
+
+
+def load_client():
+    spec = importlib.util.spec_from_file_location("receipt_observer_client_test", CLIENT_PATH)
+    if spec is None or spec.loader is None:
+        raise RuntimeError("unable to load receipt-observer-client.py")
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+
+
+CLIENT = load_client()
+VALID_INPUT = json.dumps({"latest_assistant_message": "ordinary turn"}).encode()
+DEEPLY_NESTED_JSON = b"[" * 2_000 + b"0" + b"]" * 2_000
+ENVIRONMENT = {
+    "MOSAIC_RECEIPT_OBSERVER_SOCKET": "/unused/observer.sock",
+    "MOSAIC_LEASE_SESSION_ID": "a" * 64,
+    "MOSAIC_RUNTIME_GENERATION": "1",
+}
+
+
+class FakeObserverSocket:
+    def __init__(self, response: bytes) -> None:
+        self.response = response
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *_args: object) -> None:
+        return None
+
+    def settimeout(self, _timeout: float) -> None:
+        return None
+
+    def connect(self, _path: str) -> None:
+        return None
+
+    def sendall(self, _payload: bytes) -> None:
+        return None
+
+    def shutdown(self, _how: int) -> None:
+        return None
+
+    def recv(self, _size: int) -> bytes:
+        response, self.response = self.response, b""
+        return response
+
+
+class ReceiptObserverClientExitSemanticsTest(unittest.TestCase):
+    def run_client(
+        self,
+        *,
+        input_bytes: bytes = VALID_INPUT,
+        reply: dict[str, object] | None = None,
+        transport_error: OSError | None = None,
+        runtime: str = "pi",
+    ) -> tuple[int, str, mock.Mock]:
+        request = mock.Mock(return_value=reply)
+        if transport_error is not None:
+            request.side_effect = transport_error
+        stderr = io.StringIO()
+        with (
+            mock.patch.object(CLIENT.sys, "stdin", io.BytesIO(input_bytes)),
+            mock.patch.object(CLIENT, "observer_request", request),
+            redirect_stderr(stderr),
+        ):
+            arguments = ["--runtime", runtime]
+            if runtime == "claude":
+                arguments.append("--latest-entry")
+            result = CLIENT.main(arguments, environ=ENVIRONMENT)
+        return result, stderr.getvalue(), request
+
+    def test_claude_prefers_inline_last_assistant_message(self) -> None:
+        inline = "the just-finished assistant message"
+        input_bytes = json.dumps({
+            "last_assistant_message": inline,
+            "transcript_path": "/must/not/be/opened.jsonl",
+        }).encode()
+
+        result, stderr, request = self.run_client(
+            input_bytes=input_bytes,
+            reply={"ok": True},
+            runtime="claude",
+        )
+
+        self.assertEqual(result, 0)
+        self.assertEqual(stderr, "")
+        self.assertEqual(
+            request.call_args.args[1]["latest_assistant_message"],
+            inline,
+        )
+
+    def test_claude_falls_back_to_transcript_when_inline_field_is_absent(self) -> None:
+        with tempfile.TemporaryDirectory() as directory:
+            transcript = Path(directory) / "transcript.jsonl"
+            transcript.write_text(
+                json.dumps({
+                    "message": {
+                        "role": "assistant",
+                        "content": [{"type": "text", "text": "fallback message"}],
+                    }
+                })
+                + "\n",
+                encoding="utf-8",
+            )
+            input_bytes = json.dumps({"transcript_path": str(transcript)}).encode()
+
+            result, stderr, request = self.run_client(
+                input_bytes=input_bytes,
+                reply={"ok": True},
+                runtime="claude",
+            )
+
+            self.assertEqual(result, 0)
+            self.assertEqual(stderr, "")
+            self.assertEqual(
+                request.call_args.args[1]["latest_assistant_message"],
+                "fallback message",
+            )
+
+    def test_claude_present_invalid_inline_field_fails_without_fallback(self) -> None:
+        fallback = mock.Mock(return_value="must not be used")
+        input_bytes = json.dumps({
+            "last_assistant_message": None,
+            "transcript_path": "/unused/transcript.jsonl",
+        }).encode()
+
+        with mock.patch.object(CLIENT, "claude_latest_entry", fallback):
+            result, stderr, request = self.run_client(
+                input_bytes=input_bytes,
+                reply={"ok": True},
+                runtime="claude",
+            )
+
+        self.assertEqual(result, 2)
+        self.assertIn("Mosaic receipt observer refused", stderr)
+        request.assert_not_called()
+        fallback.assert_not_called()
+
+    def test_claude_inline_message_size_guard_stays_enforced(self) -> None:
+        request = mock.Mock(return_value={"ok": True})
+        stderr = io.StringIO()
+        with (
+            mock.patch.object(CLIENT.sys, "stdin", io.BytesIO(b"{}")),
+            mock.patch.object(
+                CLIENT,
+                "read_json",
+                return_value={"last_assistant_message": "x" * (CLIENT.MAX_FRAME + 1)},
+            ),
+            mock.patch.object(CLIENT, "observer_request", request),
+            redirect_stderr(stderr),
+        ):
+            result = CLIENT.main(
+                ["--runtime", "claude", "--latest-entry"],
+                environ=ENVIRONMENT,
+            )
+
+        self.assertEqual(result, 2)
+        self.assertIn("Mosaic receipt observer refused", stderr.getvalue())
+        request.assert_not_called()
+
+    def test_pi_still_posts_only_its_runtime_message(self) -> None:
+        result, stderr, request = self.run_client(reply={"ok": True})
+
+        self.assertEqual(result, 0)
+        self.assertEqual(stderr, "")
+        self.assertEqual(
+            request.call_args.args[1]["latest_assistant_message"],
+            "ordinary turn",
+        )
+
+    def test_nothing_pending_observation_refusal_is_benign(self) -> None:
+        result, stderr, request = self.run_client(
+            reply={"ok": False, "code": "OBSERVATION_UNAVAILABLE"}
+        )
+
+        self.assertEqual(result, 0)
+        self.assertEqual(stderr, "")
+        request.assert_called_once()
+
+    def test_success_reply_remains_successful(self) -> None:
+        result, stderr, _request = self.run_client(reply={"ok": True})
+
+        self.assertEqual(result, 0)
+        self.assertEqual(stderr, "")
+
+    def test_pending_cycle_auth_failure_stays_fail_closed(self) -> None:
+        result, _stderr, _request = self.run_client(
+            reply={"ok": False, "code": "ANCESTRY_MISMATCH"}
+        )
+
+        self.assertEqual(result, 2)
+
+    def test_transport_failure_stays_fail_closed(self) -> None:
+        result, stderr, _request = self.run_client(
+            transport_error=ConnectionRefusedError("observer unavailable")
+        )
+
+        self.assertEqual(result, 2)
+        self.assertIn("Mosaic receipt observer refused", stderr)
+
+    def test_parse_failure_stays_fail_closed(self) -> None:
+        result, stderr, request = self.run_client(input_bytes=b"{")
+
+        self.assertEqual(result, 2)
+        self.assertIn("Mosaic receipt observer refused", stderr)
+        request.assert_not_called()
+
+    def test_malformed_wire_replies_stay_fail_closed(self) -> None:
+        for response in (
+            b"not-json\n",
+            b'{"ok":true}',
+            b"{}\n{}\n",
+            b'{"ok":false,"code":"OBSERVATION_UNAVAILABLE"}\n\n',
+            b'{"ok":true,"ok":false,"code":"OBSERVATION_UNAVAILABLE"}\n',
+            DEEPLY_NESTED_JSON + b"\n",
+            b"x" * (CLIENT.MAX_FRAME + 1),
+        ):
+            with self.subTest(response=response):
+                stderr = io.StringIO()
+                with (
+                    mock.patch.object(CLIENT.sys, "stdin", io.BytesIO(VALID_INPUT)),
+                    mock.patch.object(
+                        CLIENT.socket,
+                        "socket",
+                        return_value=FakeObserverSocket(response),
+                    ),
+                    redirect_stderr(stderr),
+                ):
+                    result = CLIENT.main(["--runtime", "pi"], environ=ENVIRONMENT)
+
+                self.assertEqual(result, 2)
+                self.assertIn("Mosaic receipt observer refused", stderr.getvalue())
+
+    def test_oversized_input_stays_fail_closed(self) -> None:
+        result, stderr, request = self.run_client(input_bytes=b"x" * (CLIENT.MAX_FRAME + 1))
+
+        self.assertEqual(result, 2)
+        self.assertIn("Mosaic receipt observer refused", stderr)
+        request.assert_not_called()
+
+    def test_deeply_nested_input_stays_fail_closed(self) -> None:
+        result, stderr, request = self.run_client(input_bytes=DEEPLY_NESTED_JSON)
+
+        self.assertEqual(result, 2)
+        self.assertIn("Mosaic receipt observer refused", stderr)
+        request.assert_not_called()
+
+    def test_json_recursion_failure_stays_fail_closed(self) -> None:
+        request = mock.Mock()
+        stderr = io.StringIO()
+        with (
+            mock.patch.object(CLIENT.sys, "stdin", io.BytesIO(VALID_INPUT)),
+            mock.patch.object(CLIENT, "observer_request", request),
+            mock.patch.object(
+                CLIENT.json,
+                "loads",
+                side_effect=RecursionError("maximum JSON nesting exceeded"),
+            ),
+            redirect_stderr(stderr),
+        ):
+            result = CLIENT.main(["--runtime", "pi"], environ=ENVIRONMENT)
+
+        self.assertEqual(result, 2)
+        self.assertIn("Mosaic receipt observer refused", stderr.getvalue())
+        request.assert_not_called()
+
+    def test_observation_unavailable_with_unexpected_fields_stays_fail_closed(self) -> None:
+        result, _stderr, _request = self.run_client(
+            reply={"ok": False, "code": "OBSERVATION_UNAVAILABLE", "unexpected": True}
+        )
+
+        self.assertEqual(result, 2)
+
+    def test_non_boolean_ok_values_stay_fail_closed(self) -> None:
+        for reply in (
+            {"ok": 1},
+            {"ok": 0, "code": "OBSERVATION_UNAVAILABLE"},
+        ):
+            with self.subTest(reply=reply):
+                result, _stderr, _request = self.run_client(reply=reply)
+                self.assertEqual(result, 2)
+
+
+if __name__ == "__main__":
+    unittest.main()

packages/mosaic/src/mutator-gate/mutator-gate.acceptance.spec.ts

@@ -196,7 +196,12 @@ raise SystemExit(0 if len(session_id) == 64 and denied else 1)
     env: {
       ...process.env,
       PATH: `${binDir}:${process.env.PATH ?? ''}`,
-      MOSAIC_HOME: frameworkRoot,
+      // Point MOSAIC_HOME at the per-entry temp root, NOT the shipped framework
+      // tree: launch-runtime.py appends its launch ledger to
+      // $MOSAIC_HOME/fleet/run/sessions/events.ndjson, and writing that into
+      // framework/ pollutes the tree manifest.spec.ts walks. Nothing in the
+      // launch chain resolves tools via MOSAIC_HOME (scripts use SCRIPT_DIR).
+      MOSAIC_HOME: root,
       MOSAIC_PRDY_RUNTIME: 'claude',
       MOSAIC_LEASE_BROKER_SOCKET: socket,
       MOSAIC_RUNTIME_GENERATION: '1',
@@ -388,8 +393,12 @@ describe('whole mutator-class lease gate', () => {
       ['claude', 'Write'],
       ['claude', 'NotebookEdit'],
       ['claude', 'mcp__provider__close_issue'],
+      ['claude', 'Ls'],
+      ['claude', 'Find'],
       ['pi', 'bash'],
       ['pi', 'edit'],
+      ['pi', 'grep'],
+      ['pi', 'find'],
       ['pi', 'write'],
       ['pi', 'deploy'],
       ['pi', 'unknown_custom_tool'],
@@ -409,8 +418,9 @@ describe('whole mutator-class lease gate', () => {
     for (const [runtime, toolName] of [
       ['claude', 'Read'],
       ['claude', 'Grep'],
+      ['claude', 'Glob'],
       ['pi', 'read'],
-      ['pi', 'grep'],
+      ['pi', 'ls'],
       ['pi', 'mosaic_context_recover'],
     ] as const) {
       expect(await authorize(socket, sessionId, runtime, toolName)).toMatchObject({

packages/types/src/harness/contracts.spec.ts

@@ -0,0 +1,317 @@
+import { describe, expect, expectTypeOf, it } from 'vitest';
+import { HARNESS_CAPABILITIES, HARNESS_ERROR_CODES } from './index.js';
+import type {
+  AttachConversation,
+  ConversationSnapshot,
+  CreateHarnessSession,
+  HarnessAdapter,
+  HarnessCapability,
+  HarnessConversationService,
+  HarnessDescriptor,
+  HarnessError,
+  HarnessErrorCode,
+  HarnessEvent,
+  HarnessEventEnvelope,
+  HarnessInteractionState,
+  HarnessPrompt,
+  HarnessPromptReceipt,
+  HarnessSelection,
+  HarnessSessionHandle,
+  HarnessSessionSnapshot,
+  ResumeHarnessSession,
+  SendHarnessTurn,
+  TurnReceipt,
+} from '../index.js';
+
+const EXPECTED_CAPABILITIES = [
+  'modelSelection',
+  'thinkingLevels',
+  'images',
+  'toolEvents',
+  'extensionUi',
+  'steering',
+  'followUp',
+  'compaction',
+  'persistentResume',
+] as const satisfies readonly HarnessCapability[];
+
+const EXPECTED_ERROR_CODES = [
+  'auth_required',
+  'selection_invalid',
+  'catalog_unavailable',
+  'catalog_stale',
+  'model_unavailable',
+  'no_viable_provider',
+  'session_create_failed',
+  'session_not_found',
+  'resume_conflict',
+  'session_busy',
+  'auth_bundle_concurrency_unverified',
+  'adapter_unavailable',
+  'sandbox_unavailable',
+  'rpc_version_unsupported',
+  'rpc_protocol_error',
+  'process_exited',
+  'outcome_unknown',
+  'interaction_unsupported',
+  'aborted',
+] as const satisfies readonly HarnessErrorCode[];
+
+function assertNever(value: never): never {
+  throw new Error(`Unexpected contract variant: ${JSON.stringify(value)}`);
+}
+
+function describeEvent(event: HarnessEvent): string {
+  switch (event.type) {
+    case 'session.started':
+    case 'session.state':
+    case 'session.identity_changed':
+    case 'turn.started':
+    case 'text.delta':
+    case 'thinking.delta':
+    case 'tool.started':
+    case 'tool.updated':
+    case 'tool.finished':
+    case 'interaction.required':
+    case 'usage.updated':
+    case 'turn.completed':
+    case 'error':
+      return event.type;
+    default:
+      return assertNever(event);
+  }
+}
+
+function describeError(error: HarnessError): HarnessErrorCode {
+  switch (error.code) {
+    case 'auth_required':
+    case 'selection_invalid':
+    case 'catalog_unavailable':
+    case 'catalog_stale':
+    case 'model_unavailable':
+    case 'no_viable_provider':
+    case 'session_create_failed':
+    case 'session_not_found':
+    case 'resume_conflict':
+    case 'session_busy':
+    case 'auth_bundle_concurrency_unverified':
+    case 'adapter_unavailable':
+    case 'sandbox_unavailable':
+    case 'rpc_version_unsupported':
+    case 'rpc_protocol_error':
+    case 'process_exited':
+    case 'outcome_unknown':
+    case 'interaction_unsupported':
+    case 'aborted':
+      return error.code;
+    default:
+      return assertNever(error);
+  }
+}
+
+describe('generic harness contracts', (): void => {
+  it('keeps harness, provider, model, conversation, native session, process, and seat separate', (): void => {
+    const selection = {
+      harnessId: 'pi',
+      providerId: 'openai-codex',
+      modelId: 'gpt-5-codex',
+    } satisfies HarnessSelection;
+    const snapshot = {
+      conversationId: 'conversation-1',
+      nativeSessionId: 'native-session-1',
+      processId: 'process-1',
+      seatId: 'seat-1',
+      selection,
+      state: 'idle',
+      attachedClientIds: ['browser-1'],
+    } satisfies HarnessSessionSnapshot;
+
+    const identifiers = [
+      snapshot.selection.harnessId,
+      snapshot.selection.providerId,
+      snapshot.selection.modelId,
+      snapshot.conversationId,
+      snapshot.nativeSessionId,
+      snapshot.processId,
+      snapshot.seatId,
+    ];
+
+    expect(new Set(identifiers).size).toBe(7);
+    expect(snapshot).toMatchObject({
+      conversationId: 'conversation-1',
+      nativeSessionId: 'native-session-1',
+      processId: 'process-1',
+      seatId: 'seat-1',
+      selection,
+    });
+  });
+
+  it('advertises the complete capability set as checked literals', (): void => {
+    const descriptor = {
+      id: 'pi',
+      displayName: 'Pi',
+      capabilities: HARNESS_CAPABILITIES,
+    } satisfies HarnessDescriptor;
+
+    expect(HARNESS_CAPABILITIES).toEqual(EXPECTED_CAPABILITIES);
+    expect(descriptor.capabilities).toEqual(EXPECTED_CAPABILITIES);
+  });
+
+  it('exposes every stable error code as an exhaustive discriminated union', (): void => {
+    const selection: HarnessSelection = {
+      harnessId: 'pi',
+      providerId: 'openai-codex',
+      modelId: 'gpt-5-codex',
+    };
+    const error: HarnessError = {
+      code: 'model_unavailable',
+      message: 'The selected model is unavailable.',
+      retryable: true,
+      correlationId: 'correlation-1',
+      selection,
+    };
+
+    expect(HARNESS_ERROR_CODES).toEqual(EXPECTED_ERROR_CODES);
+    expect(describeError(error)).toBe('model_unavailable');
+    const receipt = {
+      conversationId: 'conversation-1',
+      turnId: 'turn-1',
+      correlationId: 'correlation-1',
+      state: 'accepted',
+      selection,
+    } satisfies HarnessPromptReceipt;
+
+    expect(error.selection).toEqual(selection);
+    expect(receipt.selection).toEqual(selection);
+    expect('effectiveSelection' in error).toBe(false);
+    expect('effectiveSelection' in receipt).toBe(false);
+  });
+
+  it('wraps every normalized event variant in the persisted envelope', (): void => {
+    const selection: HarnessSelection = {
+      harnessId: 'pi',
+      providerId: 'openai-codex',
+      modelId: 'gpt-5-codex',
+    };
+    const toolStarted: HarnessEvent = {
+      type: 'tool.started',
+      toolCallId: 'tool-call-1',
+      toolName: 'read',
+    };
+    const events: readonly HarnessEvent[] = [
+      { type: 'session.started', state: 'idle' },
+      { type: 'session.state', state: 'busy' },
+      {
+        type: 'session.identity_changed',
+        identityGeneration: 2,
+        label: 'Re-enrolled account',
+      },
+      { type: 'turn.started' },
+      { type: 'text.delta', text: 'Hello' },
+      { type: 'thinking.delta', text: 'Reasoning' },
+      toolStarted,
+      {
+        type: 'tool.updated',
+        toolCallId: 'tool-call-1',
+        toolName: 'read',
+        message: 'Reading',
+      },
+      {
+        type: 'tool.finished',
+        toolCallId: 'tool-call-1',
+        toolName: 'read',
+        isError: false,
+      },
+      {
+        type: 'interaction.required',
+        requestId: 'interaction-1',
+        interactionType: 'confirm',
+        state: 'pending',
+        prompt: 'Continue?',
+      },
+      {
+        type: 'usage.updated',
+        usage: { inputTokens: 10, outputTokens: 5, totalTokens: 15 },
+      },
+      { type: 'turn.completed', outcome: 'settled' },
+      {
+        type: 'error',
+        error: {
+          code: 'rpc_protocol_error',
+          message: 'The harness protocol failed.',
+          retryable: false,
+          correlationId: 'correlation-1',
+          selection,
+        },
+      },
+    ];
+    const envelope: HarnessEventEnvelope = {
+      conversationId: 'conversation-1',
+      nativeSessionId: 'native-session-1',
+      turnId: 'turn-1',
+      correlationId: 'correlation-1',
+      sequence: 42,
+      nativeEntryCursor: 'native-entry-7',
+      occurredAt: '2026-08-11T12:00:00.000Z',
+      harnessId: 'pi',
+      selection,
+      event: toolStarted,
+    };
+
+    expect(events.map(describeEvent)).toEqual([
+      'session.started',
+      'session.state',
+      'session.identity_changed',
+      'turn.started',
+      'text.delta',
+      'thinking.delta',
+      'tool.started',
+      'tool.updated',
+      'tool.finished',
+      'interaction.required',
+      'usage.updated',
+      'turn.completed',
+      'error',
+    ]);
+    expect(envelope).toMatchObject({
+      conversationId: 'conversation-1',
+      nativeSessionId: 'native-session-1',
+      turnId: 'turn-1',
+      correlationId: 'correlation-1',
+      sequence: 42,
+      nativeEntryCursor: 'native-entry-7',
+      harnessId: 'pi',
+      selection,
+      event: toolStarted,
+    });
+  });
+
+  it('models the complete one-response interaction lifecycle', (): void => {
+    const states = [
+      'pending',
+      'responded',
+      'cancelled',
+      'expired',
+    ] as const satisfies readonly HarnessInteractionState[];
+
+    expect(states).toEqual(['pending', 'responded', 'cancelled', 'expired']);
+  });
+
+  it('preserves the approved adapter and conversation method signatures', (): void => {
+    expectTypeOf<HarnessAdapter['create']>().toEqualTypeOf<
+      (input: CreateHarnessSession) => Promise<HarnessSessionHandle>
+    >();
+    expectTypeOf<HarnessAdapter['resume']>().toEqualTypeOf<
+      (input: ResumeHarnessSession) => Promise<HarnessSessionHandle>
+    >();
+    expectTypeOf<HarnessSessionHandle['prompt']>().toEqualTypeOf<
+      (input: HarnessPrompt & { idempotencyKey: string }) => Promise<HarnessPromptReceipt>
+    >();
+    expectTypeOf<HarnessConversationService['attach']>().toEqualTypeOf<
+      (input: AttachConversation & { afterSequence?: number }) => Promise<ConversationSnapshot>
+    >();
+    expectTypeOf<HarnessConversationService['send']>().toEqualTypeOf<
+      (input: SendHarnessTurn & { idempotencyKey: string }) => Promise<TurnReceipt>
+    >();
+  });
+});

packages/types/src/harness/contracts.ts

@@ -0,0 +1,204 @@
+import type { HarnessCapability, HarnessEvent, HarnessEventEnvelope } from './events.js';
+
+/** Server-derived actor and seat authority. Browser input must not supply these values. */
+export interface HarnessActorContext {
+  readonly actorId: string;
+  readonly tenantId: string;
+  readonly seatId: string;
+  readonly correlationId: string;
+}
+
+/** Exact harness/provider/model tuple. These concepts must never be merged into one identifier. */
+export interface HarnessSelection {
+  readonly harnessId: string;
+  readonly providerId: string;
+  readonly modelId: string;
+}
+
+export interface HarnessDescriptor {
+  readonly id: string;
+  readonly displayName: string;
+  readonly capabilities: readonly HarnessCapability[];
+}
+
+export type HarnessInputType = 'text' | 'image';
+export type HarnessAuthState = 'ready' | 'auth_required' | 'unavailable';
+export type HarnessModelAvailability = 'available' | 'unavailable';
+
+export interface HarnessCatalogEntry extends HarnessSelection {
+  readonly displayName: string;
+  readonly reasoningCapability: boolean;
+  readonly thinkingLevels?: readonly string[];
+  readonly inputTypes: readonly HarnessInputType[];
+  readonly contextWindow?: number;
+  readonly authState: HarnessAuthState;
+  readonly availability: HarnessModelAvailability;
+}
+
+export interface HarnessCatalog {
+  readonly harnessId: string;
+  readonly version: string;
+  readonly fingerprint: string;
+  readonly models: readonly HarnessCatalogEntry[];
+}
+
+export interface CreateHarnessSession {
+  readonly context: HarnessActorContext;
+  readonly conversationId: string;
+  readonly selection: HarnessSelection;
+}
+
+export interface ResumeHarnessSession {
+  readonly context: HarnessActorContext;
+  readonly conversationId: string;
+  readonly nativeSessionId: string;
+  readonly selection: HarnessSelection;
+}
+
+export type HarnessSessionState = 'starting' | 'idle' | 'busy' | 'evicted' | 'ended' | 'failed';
+
+export interface HarnessSessionSnapshot {
+  readonly conversationId: string;
+  readonly nativeSessionId: string;
+  /** Absent when the resumable native session has no active process. */
+  readonly processId?: string;
+  readonly seatId: string;
+  readonly selection: HarnessSelection;
+  readonly state: HarnessSessionState;
+  readonly attachedClientIds: readonly string[];
+}
+
+export interface AttachClient {
+  readonly clientId: string;
+}
+
+export interface HarnessPrompt {
+  readonly turnId: string;
+  readonly correlationId: string;
+  readonly content: string;
+}
+
+export type HarnessTurnState =
+  | 'prepared'
+  | 'dispatching'
+  | 'accepted'
+  | 'streaming'
+  | 'settled'
+  | 'failed'
+  | 'aborted'
+  | 'interrupted'
+  | 'outcome_unknown';
+
+/** A successful receipt reports only the selected tuple; no substitute tuple is representable. */
+export interface HarnessPromptReceipt {
+  readonly conversationId: string;
+  readonly turnId: string;
+  readonly correlationId: string;
+  readonly state: HarnessTurnState;
+  readonly selection: HarnessSelection;
+}
+
+export interface HarnessConfirmInteractionResponse {
+  readonly requestId: string;
+  readonly type: 'confirm';
+  readonly accepted: boolean;
+}
+
+export interface HarnessSelectInteractionResponse {
+  readonly requestId: string;
+  readonly type: 'select';
+  readonly value: string;
+}
+
+export interface HarnessInputInteractionResponse {
+  readonly requestId: string;
+  readonly type: 'input';
+  readonly value: string;
+}
+
+export interface HarnessEditorInteractionResponse {
+  readonly requestId: string;
+  readonly type: 'editor';
+  readonly value: string;
+}
+
+export interface HarnessCancelInteractionResponse {
+  readonly requestId: string;
+  readonly type: 'cancel';
+}
+
+export type HarnessInteractionResponse =
+  | HarnessConfirmInteractionResponse
+  | HarnessSelectInteractionResponse
+  | HarnessInputInteractionResponse
+  | HarnessEditorInteractionResponse
+  | HarnessCancelInteractionResponse;
+
+export type HarnessCloseReason =
+  | 'client_request'
+  | 'idle_timeout'
+  | 'gateway_shutdown'
+  | 'process_crash'
+  | 'composition_changed'
+  | 'session_ended';
+
+export interface AttachConversation {
+  readonly context: HarnessActorContext;
+  readonly conversationId: string;
+  readonly clientId: string;
+  readonly selection: HarnessSelection;
+}
+
+export interface ConversationSnapshot {
+  readonly session: HarnessSessionSnapshot;
+  readonly lastSequence: number;
+  /** Journal rows replayed after the caller's sequence, never best-effort socket history. */
+  readonly replay: readonly HarnessEventEnvelope[];
+}
+
+export interface DetachConversation {
+  readonly context: HarnessActorContext;
+  readonly conversationId: string;
+  readonly clientId: string;
+}
+
+export interface SendHarnessTurn extends HarnessPrompt {
+  readonly context: HarnessActorContext;
+  readonly conversationId: string;
+  readonly selection: HarnessSelection;
+}
+
+export interface TurnReceipt extends HarnessPromptReceipt {}
+
+export interface HarnessAdapter {
+  readonly id: string;
+  describe(context: HarnessActorContext): Promise<HarnessDescriptor>;
+  catalog(context: HarnessActorContext): Promise<HarnessCatalog>;
+  create(input: CreateHarnessSession): Promise<HarnessSessionHandle>;
+  resume(input: ResumeHarnessSession): Promise<HarnessSessionHandle>;
+}
+
+export interface HarnessSessionHandle {
+  snapshot(): Promise<HarnessSessionSnapshot>;
+  attach(input: AttachClient): Promise<void>;
+  /** Removes a browser attachment; it does not terminate the process or native session. */
+  detach(clientId: string): Promise<void>;
+  prompt(input: HarnessPrompt & { idempotencyKey: string }): Promise<HarnessPromptReceipt>;
+  setModel(selection: HarnessSelection): Promise<HarnessSelection>;
+  abort(turnId: string): Promise<void>;
+  respondInteraction(input: HarnessInteractionResponse): Promise<void>;
+  events(listener: (event: HarnessEvent) => void): () => void;
+  /** Stops the active process while retaining the resumable native session. */
+  evictProcess(reason: HarnessCloseReason): Promise<void>;
+  /** Explicitly and destructively ends the native session. */
+  endSession(reason: HarnessCloseReason): Promise<void>;
+}
+
+export interface HarnessConversationService {
+  attach(input: AttachConversation & { afterSequence?: number }): Promise<ConversationSnapshot>;
+  /** Removes only the browser attachment represented by the input. */
+  detach(input: DetachConversation): Promise<void>;
+  send(input: SendHarnessTurn & { idempotencyKey: string }): Promise<TurnReceipt>;
+  /** Replays persisted Gateway journal rows after the supplied monotonic sequence. */
+  subscribeFrom(conversationId: string, afterSequence: number): AsyncIterable<HarnessEventEnvelope>;
+}

packages/types/src/harness/errors.ts

@@ -0,0 +1,40 @@
+import type { HarnessSelection } from './contracts.js';
+
+export const HARNESS_ERROR_CODES = [
+  'auth_required',
+  'selection_invalid',
+  'catalog_unavailable',
+  'catalog_stale',
+  'model_unavailable',
+  'no_viable_provider',
+  'session_create_failed',
+  'session_not_found',
+  'resume_conflict',
+  'session_busy',
+  'auth_bundle_concurrency_unverified',
+  'adapter_unavailable',
+  'sandbox_unavailable',
+  'rpc_version_unsupported',
+  'rpc_protocol_error',
+  'process_exited',
+  'outcome_unknown',
+  'interaction_unsupported',
+  'aborted',
+] as const satisfies readonly string[];
+
+export type HarnessErrorCode = (typeof HARNESS_ERROR_CODES)[number];
+
+export interface HarnessErrorDto<Code extends HarnessErrorCode = HarnessErrorCode> {
+  readonly code: Code;
+  /** Safe for browser and operator-facing surfaces. */
+  readonly message: string;
+  readonly retryable: boolean;
+  readonly correlationId: string;
+  /** The requested selection; errors never report a substituted effective selection. */
+  readonly selection: HarnessSelection;
+}
+
+/** Closed discriminated union over every stable harness error code. */
+export type HarnessError = {
+  readonly [Code in HarnessErrorCode]: HarnessErrorDto<Code>;
+}[HarnessErrorCode];

packages/types/src/harness/events.ts

@@ -0,0 +1,139 @@
+import type { HarnessError } from './errors.js';
+import type { HarnessSelection, HarnessSessionState } from './contracts.js';
+
+export const HARNESS_CAPABILITIES = [
+  'modelSelection',
+  'thinkingLevels',
+  'images',
+  'toolEvents',
+  'extensionUi',
+  'steering',
+  'followUp',
+  'compaction',
+  'persistentResume',
+] as const satisfies readonly string[];
+
+export type HarnessCapability = (typeof HARNESS_CAPABILITIES)[number];
+
+/** Durable lifecycle states; later persistence enforces one terminal response per request. */
+export type HarnessInteractionState = 'pending' | 'responded' | 'cancelled' | 'expired';
+export type HarnessInteractionType = 'confirm' | 'select' | 'input' | 'editor';
+
+export interface HarnessUsage {
+  readonly inputTokens: number;
+  readonly outputTokens: number;
+  readonly totalTokens: number;
+}
+
+export type HarnessTurnOutcome =
+  | 'settled'
+  | 'failed'
+  | 'aborted'
+  | 'interrupted'
+  | 'outcome_unknown';
+
+export interface HarnessSessionStartedEvent {
+  readonly type: 'session.started';
+  readonly state: HarnessSessionState;
+}
+
+export interface HarnessSessionStateEvent {
+  readonly type: 'session.state';
+  readonly state: HarnessSessionState;
+}
+
+export interface HarnessSessionIdentityChangedEvent {
+  readonly type: 'session.identity_changed';
+  readonly identityGeneration: number;
+  readonly label: string;
+}
+
+export interface HarnessTurnStartedEvent {
+  readonly type: 'turn.started';
+}
+
+export interface HarnessTextDeltaEvent {
+  readonly type: 'text.delta';
+  readonly text: string;
+}
+
+export interface HarnessThinkingDeltaEvent {
+  readonly type: 'thinking.delta';
+  readonly text: string;
+}
+
+export interface HarnessToolStartedEvent {
+  readonly type: 'tool.started';
+  readonly toolCallId: string;
+  readonly toolName: string;
+}
+
+export interface HarnessToolUpdatedEvent {
+  readonly type: 'tool.updated';
+  readonly toolCallId: string;
+  readonly toolName: string;
+  readonly message: string;
+}
+
+export interface HarnessToolFinishedEvent {
+  readonly type: 'tool.finished';
+  readonly toolCallId: string;
+  readonly toolName: string;
+  readonly isError: boolean;
+}
+
+export interface HarnessInteractionRequiredEvent {
+  readonly type: 'interaction.required';
+  readonly requestId: string;
+  readonly interactionType: HarnessInteractionType;
+  readonly state: HarnessInteractionState;
+  readonly prompt: string;
+  readonly options?: readonly string[];
+}
+
+export interface HarnessUsageUpdatedEvent {
+  readonly type: 'usage.updated';
+  readonly usage: HarnessUsage;
+}
+
+export interface HarnessTurnCompletedEvent {
+  readonly type: 'turn.completed';
+  readonly outcome: HarnessTurnOutcome;
+}
+
+export interface HarnessErrorEvent {
+  readonly type: 'error';
+  readonly error: HarnessError;
+}
+
+export type HarnessEvent =
+  | HarnessSessionStartedEvent
+  | HarnessSessionStateEvent
+  | HarnessSessionIdentityChangedEvent
+  | HarnessTurnStartedEvent
+  | HarnessTextDeltaEvent
+  | HarnessThinkingDeltaEvent
+  | HarnessToolStartedEvent
+  | HarnessToolUpdatedEvent
+  | HarnessToolFinishedEvent
+  | HarnessInteractionRequiredEvent
+  | HarnessUsageUpdatedEvent
+  | HarnessTurnCompletedEvent
+  | HarnessErrorEvent;
+
+/** Persisted normalized event plus Gateway-owned ordering and native reconciliation metadata. */
+export interface HarnessEventEnvelope {
+  readonly conversationId: string;
+  readonly nativeSessionId: string;
+  readonly turnId?: string;
+  readonly correlationId: string;
+  /** Monotonic Gateway journal sequence within the conversation. */
+  readonly sequence: number;
+  /** Native session-entry cursor when the harness provides one. */
+  readonly nativeEntryCursor?: string;
+  readonly occurredAt: string;
+  readonly harnessId: string;
+  /** Exact effective selected provider/model tuple; no alternate success selection is exposed. */
+  readonly selection: HarnessSelection;
+  readonly event: HarnessEvent;
+}

packages/types/src/harness/index.ts

@@ -0,0 +1,3 @@
+export * from './contracts.js';
+export * from './events.js';
+export * from './errors.js';

packages/types/src/index.ts

@@ -8,3 +8,4 @@ export * from './routing/index.js';
 export * from './commands/index.js';
 export * from './federation/index.js';
 export * from './reflection/index.js';
+export * from './harness/index.js';