apps/gateway/src/coord/coord.module.ts

@@ -1,10 +1,30 @@
 import { Module } from '@nestjs/common';
+import { InMemoryMosCoordinationPort } from '@mosaicstack/coord';
 import { CoordService } from './coord.service.js';
 import { CoordController } from './coord.controller.js';
+import {
+  MOS_COORDINATION_CONFIG,
+  MOS_COORDINATION_PORT,
+  MosCoordinationService,
+} from './mos-coordination.service.js';
 
 @Module({
-  providers: [CoordService],
+  providers: [
+    CoordService,
+    {
+      provide: MOS_COORDINATION_PORT,
+      useFactory: (): InMemoryMosCoordinationPort => new InMemoryMosCoordinationPort(),
+    },
+    {
+      provide: MOS_COORDINATION_CONFIG,
+      useFactory: () => ({
+        interactionAgentId: process.env['MOSAIC_AGENT_NAME'],
+        orchestrationAgentId: process.env['MOSAIC_ORCHESTRATOR_AGENT_NAME'],
+      }),
+    },
+    MosCoordinationService,
+  ],
   controllers: [CoordController],
-  exports: [CoordService],
+  exports: [CoordService, MosCoordinationService],
 })
 export class CoordModule {}

apps/gateway/src/coord/mos-coordination.dto.ts

@@ -0,0 +1,25 @@
+import type {
+  CoordinationObservation,
+  CoordinationResult,
+  MosHandoffReceipt,
+} from '@mosaicstack/coord';
+
+/** Input accepted at the gateway coordination boundary. Agent identity is not caller-controlled. */
+export interface CreateMosHandoffDto {
+  idempotencyKey: string;
+  summary: string;
+  context?: string;
+  missionId?: string;
+}
+
+export interface MosCoordinationResponseDto {
+  receipt: MosHandoffReceipt;
+}
+
+export interface MosCoordinationObservationDto {
+  observation: CoordinationObservation;
+}
+
+export interface MosCoordinationResultDto {
+  result: CoordinationResult;
+}

apps/gateway/src/coord/mos-coordination.service.test.ts

@@ -0,0 +1,217 @@
+import { describe, expect, it, vi } from 'vitest';
+import {
+  InMemoryMosCoordinationPort,
+  type MosCoordinationPort,
+  type MosHandoff,
+} from '@mosaicstack/coord';
+import type { RuntimeProviderRequestContext } from '../agent/runtime-provider-registry.service.js';
+import {
+  MosCoordinationService,
+  type MosCoordinationConfig,
+  type MosCoordinationGatewayError,
+} from './mos-coordination.service.js';
+
+const context: RuntimeProviderRequestContext = {
+  actorScope: { userId: 'operator-1', tenantId: 'tenant-a' },
+  channelId: 'cli',
+  correlationId: 'corr-1',
+};
+
+const config: MosCoordinationConfig = {
+  interactionAgentId: 'Nova',
+  orchestrationAgentId: 'Conductor',
+};
+
+function service(
+  port: MosCoordinationPort = new InMemoryMosCoordinationPort(),
+  options: {
+    config?: MosCoordinationConfig;
+    handoffIdFactory?: () => string;
+  } = {},
+): MosCoordinationService {
+  return new MosCoordinationService(
+    port,
+    options.config ?? config,
+    options.handoffIdFactory ?? (() => 'handoff-1'),
+  );
+}
+
+describe('MosCoordinationService authority boundary', (): void => {
+  it('derives identity and actor/tenant scope server-side, then round-trips the native adapter', async (): Promise<void> => {
+    const adapter = new InMemoryMosCoordinationPort();
+    const coordination = service(adapter);
+
+    await expect(
+      coordination.handoff(
+        { idempotencyKey: 'request-1', summary: 'Implement the requested feature' },
+        context,
+      ),
+    ).resolves.toEqual({
+      handoffId: 'handoff-1',
+      targetAgentId: 'Conductor',
+      status: 'queued',
+      correlationId: 'corr-1',
+    });
+
+    adapter.recordActivity('handoff-1', 'running', 'Mos accepted the request');
+    adapter.recordResult('handoff-1', 'completed', 'Merged by Mos');
+
+    const followUpContext = { ...context, correlationId: 'corr-2' };
+    await expect(coordination.observe('handoff-1', followUpContext)).resolves.toMatchObject({
+      targetAgentId: 'Conductor',
+      status: 'completed',
+    });
+    await expect(coordination.result('handoff-1', followUpContext)).resolves.toMatchObject({
+      targetAgentId: 'Conductor',
+      status: 'completed',
+      summary: 'Merged by Mos',
+    });
+  });
+
+  it('fails closed without calling a port when the interaction requester is unconfigured', async (): Promise<void> => {
+    const adapter = new InMemoryMosCoordinationPort();
+    const handoff = vi.spyOn(adapter, 'handoff');
+    const coordination = service(adapter, {
+      config: { interactionAgentId: '', orchestrationAgentId: 'Conductor' },
+    });
+
+    await expect(
+      coordination.handoff(
+        { idempotencyKey: 'request-1', summary: 'Implement the requested feature' },
+        context,
+      ),
+    ).rejects.toMatchObject({
+      code: 'unconfigured_requester',
+    } satisfies Partial<MosCoordinationGatewayError>);
+    expect(handoff).not.toHaveBeenCalled();
+  });
+
+  it('rejects self-delegation configuration before delivering work', async (): Promise<void> => {
+    const adapter = new InMemoryMosCoordinationPort();
+    const handoff = vi.spyOn(adapter, 'handoff');
+    const coordination = service(adapter, {
+      config: { interactionAgentId: 'Nova', orchestrationAgentId: 'Nova' },
+    });
+
+    await expect(
+      coordination.handoff(
+        { idempotencyKey: 'request-1', summary: 'Implement the requested feature' },
+        context,
+      ),
+    ).rejects.toThrow('Interaction and orchestration identities must differ');
+    expect(handoff).not.toHaveBeenCalled();
+  });
+
+  it('denies cross-tenant observe and result before calling the adapter', async (): Promise<void> => {
+    const adapter = new InMemoryMosCoordinationPort();
+    const observe = vi.spyOn(adapter, 'observe');
+    const result = vi.spyOn(adapter, 'result');
+    const coordination = service(adapter);
+    await coordination.handoff(
+      { idempotencyKey: 'request-1', summary: 'Implement the requested feature' },
+      context,
+    );
+
+    const otherTenant = {
+      ...context,
+      actorScope: { ...context.actorScope, tenantId: 'tenant-b' },
+    };
+    await expect(coordination.observe('handoff-1', otherTenant)).rejects.toMatchObject({
+      code: 'cross_tenant_forbidden',
+    } satisfies Partial<MosCoordinationGatewayError>);
+    await expect(coordination.result('handoff-1', otherTenant)).rejects.toMatchObject({
+      code: 'cross_tenant_forbidden',
+    } satisfies Partial<MosCoordinationGatewayError>);
+    expect(observe).not.toHaveBeenCalled();
+    expect(result).not.toHaveBeenCalled();
+  });
+
+  it('scopes idempotency by actor and joins concurrent retries without duplicate delivery', async (): Promise<void> => {
+    let handoffSequence = 0;
+    let release: (() => void) | undefined;
+    const delivered = new Promise<void>((resolve: () => void): void => {
+      release = resolve;
+    });
+    const adapter: MosCoordinationPort = {
+      handoff: vi.fn(async (handoff: MosHandoff) => {
+        await delivered;
+        return {
+          handoffId: handoff.handoffId,
+          targetAgentId: handoff.targetAgentId,
+          status: 'queued' as const,
+          correlationId: handoff.scope.correlationId,
+        };
+      }),
+      observe: vi.fn(),
+      result: vi.fn(),
+    };
+    const coordination = service(adapter, {
+      handoffIdFactory: (): string => `handoff-${++handoffSequence}`,
+    });
+    const request = { idempotencyKey: 'request-1', summary: 'Implement the requested feature' };
+
+    const first = coordination.handoff(request, context);
+    const retry = coordination.handoff(request, context);
+    expect(adapter.handoff).toHaveBeenCalledTimes(1);
+    release?.();
+    await expect(Promise.all([first, retry])).resolves.toEqual([
+      expect.objectContaining({ handoffId: 'handoff-1' }),
+      expect.objectContaining({ handoffId: 'handoff-1' }),
+    ]);
+
+    await expect(
+      coordination.handoff(request, {
+        ...context,
+        actorScope: { ...context.actorScope, userId: 'operator-2' },
+      }),
+    ).resolves.toMatchObject({ handoffId: 'handoff-2' });
+    expect(adapter.handoff).toHaveBeenCalledTimes(2);
+  });
+
+  it('rejects idempotency-key payload drift and malformed handoff input before delivery', async (): Promise<void> => {
+    const adapter = new InMemoryMosCoordinationPort();
+    const handoff = vi.spyOn(adapter, 'handoff');
+    const coordination = service(adapter);
+    await coordination.handoff(
+      { idempotencyKey: 'request-1', summary: 'Implement the requested feature' },
+      context,
+    );
+
+    await expect(
+      coordination.handoff({ idempotencyKey: 'request-1', summary: 'Different work' }, context),
+    ).rejects.toMatchObject({
+      code: 'handoff_conflict',
+    } satisfies Partial<MosCoordinationGatewayError>);
+    await expect(
+      coordination.handoff({ idempotencyKey: 'request-2', summary: '' }, context),
+    ).rejects.toMatchObject({
+      code: 'invalid_request',
+    } satisfies Partial<MosCoordinationGatewayError>);
+    await expect(
+      coordination.handoff({ idempotencyKey: 'request-3', summary: 'x'.repeat(2_049) }, context),
+    ).rejects.toMatchObject({
+      code: 'invalid_request',
+    } satisfies Partial<MosCoordinationGatewayError>);
+    expect(handoff).toHaveBeenCalledTimes(1);
+  });
+
+  it('fails closed when the port reports a target that drifts from configuration', async (): Promise<void> => {
+    const adapter: MosCoordinationPort = {
+      handoff: vi.fn(async (handoff: MosHandoff) => ({
+        handoffId: handoff.handoffId,
+        targetAgentId: 'Unexpected',
+        status: 'accepted' as const,
+        correlationId: handoff.scope.correlationId,
+      })),
+      observe: vi.fn(),
+      result: vi.fn(),
+    };
+
+    await expect(
+      service(adapter).handoff(
+        { idempotencyKey: 'request-1', summary: 'Implement the requested feature' },
+        context,
+      ),
+    ).rejects.toMatchObject({ code: 'target_drift' });
+  });
+});

apps/gateway/src/coord/mos-coordination.service.ts

@@ -0,0 +1,300 @@
+import { Inject, Injectable } from '@nestjs/common';
+import {
+  MosCoordinationClient,
+  type CoordinationObservation,
+  type CoordinationResult,
+  type CoordinationScope,
+  type MosCoordinationIdentity,
+  type MosCoordinationPort,
+  type MosHandoffReceipt,
+} from '@mosaicstack/coord';
+import type { RuntimeProviderRequestContext } from '../agent/runtime-provider-registry.service.js';
+import type { CreateMosHandoffDto } from './mos-coordination.dto.js';
+
+export const MOS_COORDINATION_PORT = Symbol('MOS_COORDINATION_PORT');
+export const MOS_COORDINATION_CONFIG = Symbol('MOS_COORDINATION_CONFIG');
+
+const HANDOFF_TRACKING_TTL_MS = 60 * 60 * 1_000;
+const MAX_TRACKED_HANDOFFS = 1_000;
+const MAX_IDEMPOTENCY_KEY_LENGTH = 128;
+const MAX_SUMMARY_LENGTH = 2_048;
+const MAX_CONTEXT_LENGTH = 8_192;
+const MAX_MISSION_ID_LENGTH = 128;
+
+export interface MosCoordinationConfig {
+  interactionAgentId?: string;
+  orchestrationAgentId?: string;
+}
+
+interface HandoffOwner {
+  actorId: string;
+  tenantId: string;
+  requesterAgentId: string;
+  correlationId: string;
+  expiresAt: number;
+}
+
+interface NormalizedMosHandoffRequest {
+  idempotencyKey: string;
+  summary: string;
+  context?: string;
+  missionId?: string;
+}
+
+interface TrackedHandoff {
+  request: NormalizedMosHandoffRequest;
+  receipt: Promise<MosHandoffReceipt>;
+  expiresAt: number;
+}
+
+/**
+ * Gateway authority boundary for the interaction agent. It derives requester,
+ * actor, and tenant from trusted server configuration and authentication; no
+ * channel request can name a target or gain Mos-owned orchestration verbs.
+ */
+@Injectable()
+export class MosCoordinationService {
+  private readonly owners = new Map<string, HandoffOwner>();
+  private readonly handoffsByIdempotencyKey = new Map<string, TrackedHandoff>();
+
+  constructor(
+    @Inject(MOS_COORDINATION_PORT) private readonly port: MosCoordinationPort,
+    @Inject(MOS_COORDINATION_CONFIG) private readonly config: MosCoordinationConfig,
+    private readonly handoffIdFactory: () => string = (): string => crypto.randomUUID(),
+  ) {}
+
+  async handoff(
+    request: CreateMosHandoffDto,
+    context: RuntimeProviderRequestContext,
+  ): Promise<MosHandoffReceipt> {
+    this.pruneExpiredTracking();
+    const normalized = this.normalizeRequest(request);
+    const scope = this.scope(context);
+    const idempotencyKey = this.idempotencyKey(normalized.idempotencyKey, scope);
+    const existing = this.handoffsByIdempotencyKey.get(idempotencyKey);
+    if (existing !== undefined) {
+      if (!sameRequest(existing.request, normalized)) {
+        throw new MosCoordinationGatewayError(
+          'handoff_conflict',
+          'Mos handoff idempotency key is already bound to different immutable input',
+        );
+      }
+      return existing.receipt;
+    }
+
+    const pending = this.deliverHandoff(this.handoffIdFactory(), normalized, scope);
+    const tracked: TrackedHandoff = {
+      request: normalized,
+      receipt: pending,
+      expiresAt: this.expiresAt(),
+    };
+    this.handoffsByIdempotencyKey.set(idempotencyKey, tracked);
+    this.enforceTrackingLimit(this.handoffsByIdempotencyKey);
+    try {
+      return await pending;
+    } catch (error: unknown) {
+      if (this.handoffsByIdempotencyKey.get(idempotencyKey) === tracked) {
+        this.handoffsByIdempotencyKey.delete(idempotencyKey);
+      }
+      throw error;
+    }
+  }
+
+  async observe(
+    handoffId: string,
+    context: RuntimeProviderRequestContext,
+  ): Promise<CoordinationObservation> {
+    this.pruneExpiredTracking();
+    const scope = this.scope(context);
+    const owner = this.ownerFor(handoffId, scope);
+    return this.client().observe(handoffId, { ...scope, correlationId: owner.correlationId });
+  }
+
+  async result(
+    handoffId: string,
+    context: RuntimeProviderRequestContext,
+  ): Promise<CoordinationResult> {
+    this.pruneExpiredTracking();
+    const scope = this.scope(context);
+    const owner = this.ownerFor(handoffId, scope);
+    return this.client().result(handoffId, { ...scope, correlationId: owner.correlationId });
+  }
+
+  private async deliverHandoff(
+    handoffId: string,
+    request: NormalizedMosHandoffRequest,
+    scope: CoordinationScope,
+  ): Promise<MosHandoffReceipt> {
+    const receipt = await this.client((): string => handoffId).handoff(request, scope);
+    const owner: HandoffOwner = {
+      actorId: scope.actorId,
+      tenantId: scope.tenantId,
+      requesterAgentId: scope.requesterAgentId,
+      correlationId: scope.correlationId,
+      expiresAt: this.expiresAt(),
+    };
+    const existing = this.owners.get(receipt.handoffId);
+    if (existing !== undefined && !sameOwner(existing, owner)) {
+      throw new MosCoordinationGatewayError(
+        'handoff_conflict',
+        'Mos handoff ID is already bound to a different authenticated scope',
+      );
+    }
+    this.owners.set(receipt.handoffId, owner);
+    this.enforceTrackingLimit(this.owners);
+    return receipt;
+  }
+
+  private client(handoffIdFactory?: () => string): MosCoordinationClient {
+    return new MosCoordinationClient(this.identity(), this.port, handoffIdFactory);
+  }
+
+  private identity(): MosCoordinationIdentity {
+    const interactionAgentId = this.config.interactionAgentId?.trim();
+    const orchestrationAgentId = this.config.orchestrationAgentId?.trim();
+    if (!interactionAgentId) {
+      throw new MosCoordinationGatewayError(
+        'unconfigured_requester',
+        'Interaction agent identity is not configured',
+      );
+    }
+    if (!orchestrationAgentId) {
+      throw new MosCoordinationGatewayError(
+        'unconfigured_target',
+        'Orchestration agent identity is not configured',
+      );
+    }
+    return { interactionAgentId, orchestrationAgentId };
+  }
+
+  private scope(context: RuntimeProviderRequestContext): CoordinationScope {
+    const identity = this.identity();
+    return Object.freeze({
+      actorId: context.actorScope.userId,
+      tenantId: context.actorScope.tenantId,
+      correlationId: context.correlationId,
+      requesterAgentId: identity.interactionAgentId,
+    });
+  }
+
+  private normalizeRequest(request: CreateMosHandoffDto): NormalizedMosHandoffRequest {
+    if (typeof request !== 'object' || request === null) {
+      throw new MosCoordinationGatewayError('invalid_request', 'Mos handoff request is invalid');
+    }
+    const idempotencyKey = this.requiredString(
+      request.idempotencyKey,
+      'idempotency key',
+      MAX_IDEMPOTENCY_KEY_LENGTH,
+    );
+    const summary = this.requiredString(request.summary, 'summary', MAX_SUMMARY_LENGTH);
+    const context = this.optionalString(request.context, 'context', MAX_CONTEXT_LENGTH);
+    const missionId = this.optionalString(request.missionId, 'mission ID', MAX_MISSION_ID_LENGTH);
+    return Object.freeze({
+      idempotencyKey,
+      summary,
+      ...(context === undefined ? {} : { context }),
+      ...(missionId === undefined ? {} : { missionId }),
+    });
+  }
+
+  private idempotencyKey(requestKey: string, scope: CoordinationScope): string {
+    return `${scope.tenantId}\u0000${scope.actorId}\u0000${scope.requesterAgentId}\u0000${requestKey}`;
+  }
+
+  private requiredString(value: unknown, field: string, maximumLength: number): string {
+    if (typeof value !== 'string') {
+      throw new MosCoordinationGatewayError(
+        'invalid_request',
+        `Mos handoff ${field} must be a string`,
+      );
+    }
+    const normalized = value.trim();
+    if (normalized.length === 0 || normalized.length > maximumLength) {
+      throw new MosCoordinationGatewayError('invalid_request', `Mos handoff ${field} is invalid`);
+    }
+    return normalized;
+  }
+
+  private optionalString(value: unknown, field: string, maximumLength: number): string | undefined {
+    if (value === undefined) return undefined;
+    return this.requiredString(value, field, maximumLength);
+  }
+
+  private expiresAt(): number {
+    return Date.now() + HANDOFF_TRACKING_TTL_MS;
+  }
+
+  private pruneExpiredTracking(): void {
+    const now = Date.now();
+    for (const [key, tracked] of this.handoffsByIdempotencyKey) {
+      if (tracked.expiresAt <= now) this.handoffsByIdempotencyKey.delete(key);
+    }
+    for (const [key, owner] of this.owners) {
+      if (owner.expiresAt <= now) this.owners.delete(key);
+    }
+  }
+
+  private enforceTrackingLimit<T>(entries: Map<string, T>): void {
+    while (entries.size > MAX_TRACKED_HANDOFFS) {
+      const oldest = entries.keys().next().value;
+      if (typeof oldest !== 'string') return;
+      entries.delete(oldest);
+    }
+  }
+
+  private ownerFor(handoffId: string, scope: CoordinationScope): HandoffOwner {
+    const owner = this.owners.get(handoffId);
+    if (owner === undefined) {
+      throw new MosCoordinationGatewayError('not_found', 'Mos handoff was not found');
+    }
+    if (
+      owner.tenantId !== scope.tenantId ||
+      owner.actorId !== scope.actorId ||
+      owner.requesterAgentId !== scope.requesterAgentId
+    ) {
+      throw new MosCoordinationGatewayError(
+        'cross_tenant_forbidden',
+        'Mos handoff is outside the authenticated scope',
+      );
+    }
+    return owner;
+  }
+}
+
+export type MosCoordinationGatewayErrorCode =
+  | 'cross_tenant_forbidden'
+  | 'handoff_conflict'
+  | 'invalid_request'
+  | 'not_found'
+  | 'unconfigured_requester'
+  | 'unconfigured_target';
+
+function sameOwner(left: HandoffOwner, right: HandoffOwner): boolean {
+  return (
+    left.actorId === right.actorId &&
+    left.tenantId === right.tenantId &&
+    left.requesterAgentId === right.requesterAgentId
+  );
+}
+
+function sameRequest(
+  left: NormalizedMosHandoffRequest,
+  right: NormalizedMosHandoffRequest,
+): boolean {
+  return (
+    left.idempotencyKey === right.idempotencyKey &&
+    left.summary === right.summary &&
+    left.context === right.context &&
+    left.missionId === right.missionId
+  );
+}
+
+export class MosCoordinationGatewayError extends Error {
+  constructor(
+    readonly code: MosCoordinationGatewayErrorCode,
+    message: string,
+  ) {
+    super(message);
+    this.name = MosCoordinationGatewayError.name;
+  }
+}

docs/scratchpads/tess-m4-001-mos-coordination.md

@@ -0,0 +1,46 @@
+# TESS-M4-001 — Mos Coordination
+
+- **Issue/task:** #710 / TESS-M4-001
+- **Branch/base:** `feat/tess-mos-coordination` rebased onto `origin/main` `f1c6b37b`
+- **Budget assumption:** task estimate 25K; design-first and TDD, with package contract plus gateway boundary only.
+
+## Objective
+
+Implement a transport-neutral coordination contract allowing a configured interaction agent to hand off Mos-owned work, observe activity, and receive results while preventing it from gaining coding/general orchestration authority.
+
+## Plan
+
+1. Document the contract and enforcement-point sketch; request Mos's decision on the initial concrete transport.
+2. Add `@mosaicstack/coord` typed handoff/observe/result contracts and denial errors.
+3. Add a gateway service which derives actor/tenant/requester identity from trusted context/configuration and validates authority.
+4. Add contract and gateway boundary tests for configurable identities, self-delegation, target drift, and cross-tenant read denial.
+5. Run focused, cold-cache, baseline tests; independent review; PR lifecycle.
+
+## Design checkpoint — 2026-07-12
+
+Created `docs/tess/MOS-COORDINATION.md`. Mos approved the design and selected the native in-process `InMemoryMosCoordinationPort` for M4. Fleet/tmux remains a documented M5 adapter seam; no Mos-side consumer is built in this task.
+
+## Progress checkpoint — 2026-07-13
+
+- Implemented `MosCoordinationPort` with handoff/observe/result only, an authority-checking client, and deterministic native adapter in `@mosaicstack/coord`.
+- Implemented the gateway `MosCoordinationService`, deriving requester identity from trusted configuration and actor/tenant/correlation from authenticated context.
+- Added contract and gateway boundary tests for configurable identities, native round-trip, unconfigured requester, self-delegation, target drift, and cross-tenant observe/result denial before adapter invocation.
+- Did not modify `apps/gateway/src/commands/command-authorization.service.ts`.
+
+## Verification
+
+- `pnpm --filter @mosaicstack/coord test` — PASS (16 tests after authority/idempotency remediation).
+- `pnpm --filter @mosaicstack/coord build` — PASS.
+- `pnpm --filter @mosaicstack/gateway test -- mos-coordination.service.test.ts` — PASS (7 tests after authority/idempotency remediation).
+- Standalone gateway typecheck initially reported missing built workspace packages after fresh worktree setup; root validation builds the workspace graph and passed.
+- `TURBO_FORCE=true pnpm typecheck` — PASS (42 tasks, 0 cached).
+- `TURBO_FORCE=true pnpm lint` — PASS (23 tasks, 0 cached after one import-type remediation).
+- `TURBO_FORCE=true pnpm format:check` — PASS.
+- `TURBO_FORCE=true pnpm test` — PASS (42 tasks, 0 cached; expected existing integration skips only).
+
+## Review checkpoint
+
+- Codex code review found idempotency keys needed actor scope and concurrent retries needed an in-flight reservation; both were remediated with regression coverage.
+- Codex security review found whitespace-equivalent self-delegation was accepted by the exported client; identities are now normalized before invariant checks, with regression coverage.
+- Re-review added immutable payload comparison for idempotency reuse, runtime string/size validation, bounded TTL/capacity tracking for gateway and native adapter state, and fresh-correlation follow-up reads; targeted tests pass (16 coord / 7 gateway).
+- Final Codex security review found no issues. PR #735 was opened from commit `7936e15d`; Woodpecker pipeline #1752 is green.

docs/tess/ARCHITECTURE.md

@@ -52,6 +52,21 @@ Termination is fail-closed: a runtime approval verifier consumes a one-time, exa
 | Destructive, privileged, external/customer-visible action                   | Human approval + policy | Propose, wait for durable one-time approval, then execute idempotently |
 | Provider-specific unsupported action                                        | None                    | Fail closed; never emulate silently                                    |
 
+### Mos Coordination Boundary
+
+`@mosaicstack/coord` exposes only the transport-neutral `MosCoordinationPort`
+verbs `handoff`, `observe`, and `result`. Gateway derives the actor, tenant,
+correlation, and interaction-agent identity from authenticated context plus
+trusted configuration; callers never provide an orchestration target. It
+rejects unconfigured identities, self-delegation, target/correlation drift, and
+cross-tenant handoff reads before an adapter call. No dispatch, assignment,
+review, merge, or cancellation API exists at this boundary.
+
+M4 uses a deterministic native in-process queue adapter to prove the handoff →
+observe → result flow without coupling the contract to tmux. A fleet/tmux
+adapter is deferred to the M5 live-deployment seam and must implement the same
+port.
+
 ## Session and State Model
 
 A Tess session has stable `sessionId`, `tenantId`, `ownerId`, provider/runtime identity, ingress bindings, cursor, checkpoint, inbox/outbox, and idempotency records. Discord and CLI bind to the same authorized session. Ownership is verified server-side on every list/read/attach/send/terminate operation.

docs/tess/MOS-COORDINATION.md

@@ -0,0 +1,83 @@
+# Tess–Mos Coordination Contract Sketch
+
+**Task:** TESS-M4-001 · **PRD:** TESS-MOS-001 / AC-TESS-04
+
+## Boundary
+
+Agent identities are deployment data. A configured interaction agent may request
+Mos-owned work; the configured orchestration agent owns decomposition, worker
+assignment, reviews, and merge decisions. The interaction agent receives a
+correlated receipt, read-only activity projection, and terminal result. It has
+no dispatch, assignment, review, merge, or cancellation operation.
+
+## `@mosaicstack/coord` interface
+
+```ts
+interface CoordinationScope {
+  readonly actorId: string;
+  readonly tenantId: string;
+  readonly correlationId: string;
+  readonly requesterAgentId: string; // trusted gateway/configuration data
+}
+
+interface MosHandoffRequest {
+  readonly idempotencyKey: string;
+  readonly summary: string;
+  readonly context?: string;
+  readonly missionId?: string;
+}
+
+interface MosHandoffReceipt {
+  readonly handoffId: string;
+  readonly targetAgentId: string;
+  readonly status: 'accepted' | 'queued';
+  readonly correlationId: string;
+}
+
+interface MosHandoff {
+  readonly handoffId: string;
+  readonly targetAgentId: string;
+  readonly request: MosHandoffRequest;
+  readonly scope: CoordinationScope;
+}
+
+interface MosCoordinationPort {
+  handoff(handoff: MosHandoff): Promise<MosHandoffReceipt>;
+  observe(handoffId: string, scope: CoordinationScope): Promise<CoordinationObservation>;
+  result(handoffId: string, scope: CoordinationScope): Promise<CoordinationResult>;
+}
+```
+
+The port deliberately omits generic orchestrator verbs. It is tenant- and
+correlation-scoped; its gateway implementation obtains `actorId`, `tenantId`,
+and the requester agent from trusted authentication/configuration only.
+
+## Enforcement point
+
+`apps/gateway` owns a `MosCoordinationService` boundary that compares the
+trusted configured requester/target identities and rejects all of the following
+before calling a transport: unconfigured requester, self-delegation, target
+identity drift, cross-tenant observe/result lookup, and attempts to observe or
+receive a result for a handoff outside the originating tenant. The service exposes handoff, observe,
+and result only, and delegates delivery to an injected adapter.
+
+M4 ships a native in-process `InMemoryMosCoordinationPort` as the concrete,
+deterministic adapter. It preserves the immutable handoff ID, tenant, requester
+identity, and correlation ID while demonstrating the handoff → observe → result
+round trip. It is a queue/port adapter, not a Mos-side consumer.
+
+A future fleet/tmux adapter is a documented M5 deployment seam and must
+implement the same `MosCoordinationPort`; no channel client or interaction
+runtime calls a transport directly.
+
+## Required tests
+
+1. A configured non-default interaction identity can hand off work to a
+   configured non-default orchestration identity and receive its result.
+2. The gateway passes only server-derived scope/identity to the adapter.
+3. Self-targeting, target drift, and cross-tenant observe/result all fail closed
+   without invoking the adapter.
+4. The exported public contract has no worker-dispatch, assignment, review,
+   merge, or cancellation capability.
+5. The native adapter round-trips queued work, activity, and a host-recorded
+   terminal result without a live fleet dependency.

docs/tess/VERIFICATION-MATRIX.md

@@ -1,11 +1,11 @@
 # Tess Verification Matrix
 
 | Acceptance criterion | Requirements                             | Planned evidence                                                                                                                                                       | Gate             |
-| -------------------- | ---------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------- | ---------------- |
+| -------------------- | ---------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------- |
 | AC-TESS-01           | TESS-PI-001, TESS-DSC-001, TESS-CLI-001  | Discord/CLI same-session integration and streaming E2E                                                                                                                 | M3-V             |
 | AC-TESS-02           | TESS-ARP-001, TESS-CLI-001, TESS-FLT-001 | CLI contract tests for status/sessions/tree/attach/send/stop, typed denial/error snapshots                                                                             | M3-V             |
 | AC-TESS-03           | TESS-PI-001, TESS-OBS-001                | Clean service launch; status asserts GPT-5.6 Sol, high reasoning and effective tool policy with secret canaries absent                                                 | M2-V, M3-V       |
-| AC-TESS-04           | TESS-MOS-001, TESS-FLT-001               | Authority E2E: coding request creates Mos handoff; safe status runs in Tess; no competing worker claim                          | M4-V             |
+| AC-TESS-04           | TESS-MOS-001, TESS-FLT-001               | M4 contract/gateway native-port handoff → observe → result round trip; configurable identity, target-drift and tenant-denial tests; M4-V fleet authority qualification | M4-001, M4-V     |
 | AC-TESS-05           | TESS-HRM-001                             | Hermes capability contract suite: sessions/stream/send/tree plus Kanban/skills/memory/tools/cron supported-or-denied matrix                                            | M4-V             |
 | AC-TESS-06           | TESS-STA-001, TESS-SEC-008               | Kill/restart/compaction fault injection across inbox/outbox/checkpoint transitions; duplicate side-effect detector                                                     | M2-V, M5-V       |
 | AC-TESS-07           | TESS-SEC-001..009                        | Threat-model abuse suite: authz, tenant isolation, forged identity/approval, injection, redaction, transport identity, GC scope                                        | M1-V, M3-V, M5-V |

packages/coord/src/__tests__/mos-coordination.test.ts

@@ -0,0 +1,154 @@
+import { describe, expect, it, vi } from 'vitest';
+import {
+  InMemoryMosCoordinationPort,
+  MosCoordinationClient,
+  type CoordinationScope,
+  type MosCoordinationAuthorityError,
+  type MosCoordinationPort,
+} from '../index.js';
+
+const scope: CoordinationScope = {
+  actorId: 'operator-1',
+  tenantId: 'tenant-a',
+  correlationId: 'corr-1',
+  requesterAgentId: 'Nova',
+};
+
+function client(
+  port: MosCoordinationPort,
+  handoffIdFactory: () => string = (): string => 'handoff-1',
+): MosCoordinationClient {
+  return new MosCoordinationClient(
+    { interactionAgentId: 'Nova', orchestrationAgentId: 'Conductor' },
+    port,
+    handoffIdFactory,
+  );
+}
+
+describe('MosCoordinationClient', (): void => {
+  it('round-trips handoff, observation, and result through the native port with identities as data', async (): Promise<void> => {
+    const adapter = new InMemoryMosCoordinationPort();
+    const coordination = client(adapter);
+
+    await expect(
+      coordination.handoff(
+        { idempotencyKey: 'handoff-request-1', summary: 'Implement the requested feature' },
+        scope,
+      ),
+    ).resolves.toEqual({
+      handoffId: 'handoff-1',
+      targetAgentId: 'Conductor',
+      status: 'queued',
+      correlationId: 'corr-1',
+    });
+
+    adapter.recordActivity('handoff-1', 'running', 'Mos accepted the request');
+    adapter.recordResult('handoff-1', 'completed', 'Merged by Mos');
+
+    await expect(coordination.observe('handoff-1', scope)).resolves.toMatchObject({
+      status: 'completed',
+      targetAgentId: 'Conductor',
+      activity: expect.arrayContaining([
+        expect.objectContaining({ status: 'queued' }),
+        expect.objectContaining({ status: 'running' }),
+        expect.objectContaining({ status: 'completed' }),
+      ]),
+    });
+    await expect(coordination.result('handoff-1', scope)).resolves.toEqual({
+      handoffId: 'handoff-1',
+      targetAgentId: 'Conductor',
+      status: 'completed',
+      correlationId: 'corr-1',
+      summary: 'Merged by Mos',
+    });
+
+    expect(coordination).not.toHaveProperty('dispatch');
+    expect(coordination).not.toHaveProperty('assign');
+    expect(coordination).not.toHaveProperty('review');
+    expect(coordination).not.toHaveProperty('merge');
+    expect(coordination).not.toHaveProperty('cancel');
+  });
+
+  it('fails closed before delivery when an unconfigured agent requests Mos work', async (): Promise<void> => {
+    const adapter = new InMemoryMosCoordinationPort();
+
+    await expect(
+      client(adapter).handoff(
+        { idempotencyKey: 'handoff-request-1', summary: 'Implement the requested feature' },
+        { ...scope, requesterAgentId: 'Untrusted' },
+      ),
+    ).rejects.toMatchObject({
+      code: 'requester_forbidden',
+    } satisfies Partial<MosCoordinationAuthorityError>);
+  });
+
+  it('rejects self-delegation configuration before constructing a client', (): void => {
+    expect(
+      (): MosCoordinationClient =>
+        new MosCoordinationClient(
+          { interactionAgentId: 'Nova', orchestrationAgentId: 'Nova' },
+          new InMemoryMosCoordinationPort(),
+        ),
+    ).toThrow('Interaction and orchestration identities must differ');
+  });
+
+  it('rejects whitespace-equivalent self-delegation identities', (): void => {
+    expect(
+      (): MosCoordinationClient =>
+        new MosCoordinationClient(
+          { interactionAgentId: 'Nova ', orchestrationAgentId: 'Nova' },
+          new InMemoryMosCoordinationPort(),
+        ),
+    ).toThrow('Interaction and orchestration identities must differ');
+  });
+
+  it('does not expose another tenant handoff to observe or result', async (): Promise<void> => {
+    const adapter = new InMemoryMosCoordinationPort();
+    const coordination = client(adapter);
+    await coordination.handoff(
+      { idempotencyKey: 'handoff-request-1', summary: 'Implement the requested feature' },
+      scope,
+    );
+
+    const otherTenantScope = { ...scope, tenantId: 'tenant-b' };
+    await expect(coordination.observe('handoff-1', otherTenantScope)).rejects.toMatchObject({
+      code: 'forbidden',
+    });
+    await expect(coordination.result('handoff-1', otherTenantScope)).rejects.toMatchObject({
+      code: 'forbidden',
+    });
+  });
+
+  it('bounds native handoff retention by evicting the oldest handoff', async (): Promise<void> => {
+    const adapter = new InMemoryMosCoordinationPort({ maxHandoffs: 1 });
+    const first = client(adapter, (): string => 'handoff-1');
+    const second = client(adapter, (): string => 'handoff-2');
+    await first.handoff({ idempotencyKey: 'handoff-request-1', summary: 'First request' }, scope);
+    await second.handoff({ idempotencyKey: 'handoff-request-2', summary: 'Second request' }, scope);
+
+    await expect(first.observe('handoff-1', scope)).rejects.toMatchObject({ code: 'not_found' });
+    await expect(second.observe('handoff-2', scope)).resolves.toMatchObject({ status: 'queued' });
+  });
+
+  it('fails closed when a transport reports target drift', async (): Promise<void> => {
+    const adapter: MosCoordinationPort = {
+      handoff: vi.fn(async () => ({
+        handoffId: 'handoff-1',
+        targetAgentId: 'Unexpected',
+        status: 'accepted' as const,
+        correlationId: 'corr-1',
+      })),
+      observe: vi.fn(),
+      result: vi.fn(),
+    };
+
+    await expect(
+      client(adapter).handoff(
+        { idempotencyKey: 'handoff-request-1', summary: 'Implement the requested feature' },
+        scope,
+      ),
+    ).rejects.toMatchObject({
+      code: 'target_drift',
+    } satisfies Partial<MosCoordinationAuthorityError>);
+  });
+});

packages/coord/src/in-memory-mos-coordination-port.ts

@@ -0,0 +1,208 @@
+import {
+  type CoordinationObservation,
+  type CoordinationResult,
+  type CoordinationScope,
+  type MosCoordinationActivity,
+  type MosCoordinationPort,
+  type MosHandoff,
+  type MosHandoffReceipt,
+  type MosHandoffStatus,
+} from './mos-coordination.js';
+
+const DEFAULT_HANDOFF_TTL_MS = 60 * 60 * 1_000;
+const DEFAULT_MAX_HANDOFFS = 1_000;
+
+interface StoredHandoff {
+  readonly handoff: MosHandoff;
+  status: MosHandoffStatus;
+  readonly activity: MosCoordinationActivity[];
+  readonly expiresAt: number;
+  result?: CoordinationResult;
+}
+
+export interface InMemoryMosCoordinationPortOptions {
+  now?: () => Date;
+  handoffTtlMs?: number;
+  maxHandoffs?: number;
+}
+
+/**
+ * Native deterministic queue/port adapter for the coordination boundary.
+ * It intentionally has no fleet/tmux dependency. A future deployment adapter
+ * implements MosCoordinationPort without changing interaction-plane callers.
+ */
+export class InMemoryMosCoordinationPort implements MosCoordinationPort {
+  private readonly handoffs = new Map<string, StoredHandoff>();
+  private readonly now: () => Date;
+  private readonly handoffTtlMs: number;
+  private readonly maxHandoffs: number;
+
+  constructor(options: InMemoryMosCoordinationPortOptions = {}) {
+    this.now = options.now ?? (() => new Date());
+    this.handoffTtlMs = options.handoffTtlMs ?? DEFAULT_HANDOFF_TTL_MS;
+    this.maxHandoffs = options.maxHandoffs ?? DEFAULT_MAX_HANDOFFS;
+  }
+
+  async handoff(handoff: MosHandoff): Promise<MosHandoffReceipt> {
+    this.pruneExpiredHandoffs();
+    const existing = this.handoffs.get(handoff.handoffId);
+    if (existing !== undefined) {
+      this.assertSameHandoff(existing.handoff, handoff);
+      return this.receipt(existing.handoff, existing.status);
+    }
+
+    const stored: StoredHandoff = {
+      handoff: snapshotHandoff(handoff),
+      status: 'queued',
+      activity: [activity('queued', 'Handoff accepted by the native coordination queue', this.now)],
+      expiresAt: this.now().getTime() + this.handoffTtlMs,
+    };
+    this.handoffs.set(handoff.handoffId, stored);
+    this.enforceHandoffLimit();
+    return this.receipt(stored.handoff, stored.status);
+  }
+
+  async observe(handoffId: string, scope: CoordinationScope): Promise<CoordinationObservation> {
+    this.pruneExpiredHandoffs();
+    const stored = this.requireScopedHandoff(handoffId, scope);
+    return {
+      handoffId: stored.handoff.handoffId,
+      targetAgentId: stored.handoff.targetAgentId,
+      status: stored.status,
+      correlationId: stored.handoff.scope.correlationId,
+      activity: stored.activity.map(copyActivity),
+    };
+  }
+
+  async result(handoffId: string, scope: CoordinationScope): Promise<CoordinationResult> {
+    this.pruneExpiredHandoffs();
+    const stored = this.requireScopedHandoff(handoffId, scope);
+    return (
+      stored.result ?? {
+        handoffId: stored.handoff.handoffId,
+        targetAgentId: stored.handoff.targetAgentId,
+        status: 'pending',
+        correlationId: stored.handoff.scope.correlationId,
+      }
+    );
+  }
+
+  /** Host-side progression seam; interaction clients never receive this capability. */
+  recordActivity(handoffId: string, status: MosHandoffStatus, summary: string): void {
+    this.pruneExpiredHandoffs();
+    const stored = this.requireHandoff(handoffId);
+    stored.status = status;
+    stored.activity.push(activity(status, summary, this.now));
+  }
+
+  /** Host-side result seam for deterministic qualification; not a Mos consumer. */
+  recordResult(handoffId: string, status: 'completed' | 'failed', summary: string): void {
+    this.pruneExpiredHandoffs();
+    const stored = this.requireHandoff(handoffId);
+    stored.status = status;
+    stored.activity.push(activity(status, summary, this.now));
+    stored.result = {
+      handoffId: stored.handoff.handoffId,
+      targetAgentId: stored.handoff.targetAgentId,
+      status,
+      correlationId: stored.handoff.scope.correlationId,
+      summary,
+    };
+  }
+
+  private receipt(handoff: MosHandoff, status: MosHandoffStatus): MosHandoffReceipt {
+    return {
+      handoffId: handoff.handoffId,
+      targetAgentId: handoff.targetAgentId,
+      status: status === 'accepted' ? 'accepted' : 'queued',
+      correlationId: handoff.scope.correlationId,
+    };
+  }
+
+  private pruneExpiredHandoffs(): void {
+    const nowMs = this.now().getTime();
+    for (const [handoffId, handoff] of this.handoffs) {
+      if (handoff.expiresAt <= nowMs) this.handoffs.delete(handoffId);
+    }
+  }
+
+  private enforceHandoffLimit(): void {
+    while (this.handoffs.size > this.maxHandoffs) {
+      const oldest = this.handoffs.keys().next().value;
+      if (typeof oldest !== 'string') return;
+      this.handoffs.delete(oldest);
+    }
+  }
+
+  private requireScopedHandoff(handoffId: string, scope: CoordinationScope): StoredHandoff {
+    const stored = this.requireHandoff(handoffId);
+    if (
+      stored.handoff.scope.tenantId !== scope.tenantId ||
+      stored.handoff.scope.actorId !== scope.actorId ||
+      stored.handoff.scope.requesterAgentId !== scope.requesterAgentId
+    ) {
+      throw new InMemoryMosCoordinationError('forbidden', 'Handoff scope does not match');
+    }
+    return stored;
+  }
+
+  private requireHandoff(handoffId: string): StoredHandoff {
+    const stored = this.handoffs.get(handoffId);
+    if (stored === undefined) {
+      throw new InMemoryMosCoordinationError('not_found', 'Handoff was not found');
+    }
+    return stored;
+  }
+
+  private assertSameHandoff(existing: MosHandoff, incoming: MosHandoff): void {
+    if (
+      existing.targetAgentId !== incoming.targetAgentId ||
+      existing.request.idempotencyKey !== incoming.request.idempotencyKey ||
+      existing.request.summary !== incoming.request.summary ||
+      existing.request.context !== incoming.request.context ||
+      existing.request.missionId !== incoming.request.missionId ||
+      existing.scope.actorId !== incoming.scope.actorId ||
+      existing.scope.tenantId !== incoming.scope.tenantId ||
+      existing.scope.correlationId !== incoming.scope.correlationId ||
+      existing.scope.requesterAgentId !== incoming.scope.requesterAgentId
+    ) {
+      throw new InMemoryMosCoordinationError(
+        'conflict',
+        'Handoff ID is already bound to different immutable input',
+      );
+    }
+  }
+}
+
+export type InMemoryMosCoordinationErrorCode = 'conflict' | 'forbidden' | 'not_found';
+
+export class InMemoryMosCoordinationError extends Error {
+  constructor(
+    readonly code: InMemoryMosCoordinationErrorCode,
+    message: string,
+  ) {
+    super(message);
+    this.name = InMemoryMosCoordinationError.name;
+  }
+}
+
+function activity(
+  status: MosHandoffStatus,
+  summary: string,
+  now: () => Date,
+): MosCoordinationActivity {
+  return { occurredAt: now().toISOString(), status, summary };
+}
+
+function copyActivity(entry: MosCoordinationActivity): MosCoordinationActivity {
+  return { ...entry };
+}
+
+function snapshotHandoff(handoff: MosHandoff): MosHandoff {
+  return Object.freeze({
+    handoffId: handoff.handoffId,
+    targetAgentId: handoff.targetAgentId,
+    request: Object.freeze({ ...handoff.request }),
+    scope: Object.freeze({ ...handoff.scope }),
+  });
+}

packages/coord/src/index.ts

@@ -2,6 +2,23 @@ export { createMission, loadMission, missionFilePath, saveMission } from './miss
 export { parseTasksFile, updateTaskStatus, writeTasksFile } from './tasks-file.js';
 export { runTask, resumeTask } from './runner.js';
 export { getMissionStatus, getTaskStatus } from './status.js';
+export {
+  InMemoryMosCoordinationError,
+  InMemoryMosCoordinationPort,
+} from './in-memory-mos-coordination-port.js';
+export { MosCoordinationAuthorityError, MosCoordinationClient } from './mos-coordination.js';
+export type {
+  CoordinationObservation,
+  CoordinationResult,
+  CoordinationScope,
+  MosCoordinationActivity,
+  MosCoordinationIdentity,
+  MosCoordinationPort,
+  MosHandoff,
+  MosHandoffReceipt,
+  MosHandoffRequest,
+  MosHandoffStatus,
+} from './mos-coordination.js';
 export type {
   CreateMissionOptions,
   Mission,

packages/coord/src/mos-coordination.ts

@@ -0,0 +1,207 @@
+export type MosHandoffStatus = 'queued' | 'accepted' | 'running' | 'completed' | 'failed';
+
+export interface CoordinationScope {
+  readonly actorId: string;
+  readonly tenantId: string;
+  readonly correlationId: string;
+  /** Trusted gateway/configuration identity; never supplied by a channel client. */
+  readonly requesterAgentId: string;
+}
+
+export interface MosCoordinationIdentity {
+  readonly interactionAgentId: string;
+  readonly orchestrationAgentId: string;
+}
+
+export interface MosHandoffRequest {
+  readonly idempotencyKey: string;
+  readonly summary: string;
+  readonly context?: string;
+  readonly missionId?: string;
+}
+
+export interface MosHandoff {
+  readonly handoffId: string;
+  readonly targetAgentId: string;
+  readonly request: MosHandoffRequest;
+  readonly scope: CoordinationScope;
+}
+
+export interface MosHandoffReceipt {
+  readonly handoffId: string;
+  readonly targetAgentId: string;
+  readonly status: 'queued' | 'accepted';
+  readonly correlationId: string;
+}
+
+export interface MosCoordinationActivity {
+  readonly occurredAt: string;
+  readonly status: MosHandoffStatus;
+  readonly summary: string;
+}
+
+export interface CoordinationObservation {
+  readonly handoffId: string;
+  readonly targetAgentId: string;
+  readonly status: MosHandoffStatus;
+  readonly correlationId: string;
+  readonly activity: readonly MosCoordinationActivity[];
+}
+
+export interface CoordinationResult {
+  readonly handoffId: string;
+  readonly targetAgentId: string;
+  readonly status: 'completed' | 'failed' | 'pending';
+  readonly correlationId: string;
+  readonly summary?: string;
+}
+
+/**
+ * Transport-neutral boundary. The interaction plane can request work and read
+ * its progress/result, but it cannot issue worker, review, merge, or other
+ * general orchestration commands.
+ */
+export interface MosCoordinationPort {
+  handoff(handoff: MosHandoff): Promise<MosHandoffReceipt>;
+  observe(handoffId: string, scope: CoordinationScope): Promise<CoordinationObservation>;
+  result(handoffId: string, scope: CoordinationScope): Promise<CoordinationResult>;
+}
+
+export type MosCoordinationAuthorityErrorCode =
+  | 'invalid_identity'
+  | 'requester_forbidden'
+  | 'target_drift'
+  | 'correlation_drift';
+
+export class MosCoordinationAuthorityError extends Error {
+  constructor(
+    readonly code: MosCoordinationAuthorityErrorCode,
+    message: string,
+  ) {
+    super(message);
+    this.name = MosCoordinationAuthorityError.name;
+  }
+}
+
+/**
+ * Enforces the interaction-to-orchestration authority boundary before a
+ * transport is reached. Identity names remain configuration data.
+ */
+export class MosCoordinationClient {
+  private readonly identity: MosCoordinationIdentity;
+
+  constructor(
+    identity: MosCoordinationIdentity,
+    private readonly port: MosCoordinationPort,
+    private readonly handoffIdFactory: () => string = (): string => crypto.randomUUID(),
+  ) {
+    this.identity = normalizeIdentity(identity);
+  }
+
+  async handoff(request: MosHandoffRequest, scope: CoordinationScope): Promise<MosHandoffReceipt> {
+    this.assertRequester(scope);
+    const handoff: MosHandoff = {
+      handoffId: this.handoffIdFactory(),
+      targetAgentId: this.identity.orchestrationAgentId,
+      request: snapshotRequest(request),
+      scope: snapshotScope(scope),
+    };
+    const receipt = await this.port.handoff(handoff);
+    if (
+      receipt.handoffId !== handoff.handoffId ||
+      receipt.targetAgentId !== handoff.targetAgentId
+    ) {
+      throw new MosCoordinationAuthorityError(
+        'target_drift',
+        'Mos coordination transport returned a mismatched handoff target',
+      );
+    }
+    if (receipt.correlationId !== handoff.scope.correlationId) {
+      throw new MosCoordinationAuthorityError(
+        'correlation_drift',
+        'Mos coordination transport returned a mismatched correlation ID',
+      );
+    }
+    return receipt;
+  }
+
+  async observe(handoffId: string, scope: CoordinationScope): Promise<CoordinationObservation> {
+    this.assertRequester(scope);
+    return this.assertObservation(await this.port.observe(handoffId, snapshotScope(scope)), scope);
+  }
+
+  async result(handoffId: string, scope: CoordinationScope): Promise<CoordinationResult> {
+    this.assertRequester(scope);
+    return this.assertResult(await this.port.result(handoffId, snapshotScope(scope)), scope);
+  }
+
+  private assertRequester(scope: CoordinationScope): void {
+    if (scope.requesterAgentId !== this.identity.interactionAgentId) {
+      throw new MosCoordinationAuthorityError(
+        'requester_forbidden',
+        'Requester is not the configured interaction agent',
+      );
+    }
+  }
+
+  private assertObservation(
+    observation: CoordinationObservation,
+    scope: CoordinationScope,
+  ): CoordinationObservation {
+    if (observation.targetAgentId !== this.identity.orchestrationAgentId) {
+      throw new MosCoordinationAuthorityError(
+        'target_drift',
+        'Mos coordination transport returned an unexpected observation target',
+      );
+    }
+    if (observation.correlationId !== scope.correlationId) {
+      throw new MosCoordinationAuthorityError(
+        'correlation_drift',
+        'Mos coordination transport returned a mismatched observation correlation ID',
+      );
+    }
+    return observation;
+  }
+
+  private assertResult(result: CoordinationResult, scope: CoordinationScope): CoordinationResult {
+    if (result.targetAgentId !== this.identity.orchestrationAgentId) {
+      throw new MosCoordinationAuthorityError(
+        'target_drift',
+        'Mos coordination transport returned an unexpected result target',
+      );
+    }
+    if (result.correlationId !== scope.correlationId) {
+      throw new MosCoordinationAuthorityError(
+        'correlation_drift',
+        'Mos coordination transport returned a mismatched result correlation ID',
+      );
+    }
+    return result;
+  }
+}
+
+function normalizeIdentity(identity: MosCoordinationIdentity): MosCoordinationIdentity {
+  const interactionAgentId = identity.interactionAgentId.trim();
+  const orchestrationAgentId = identity.orchestrationAgentId.trim();
+  if (interactionAgentId.length === 0 || orchestrationAgentId.length === 0) {
+    throw new MosCoordinationAuthorityError(
+      'invalid_identity',
+      'Interaction and orchestration identities are required',
+    );
+  }
+  if (interactionAgentId === orchestrationAgentId) {
+    throw new MosCoordinationAuthorityError(
+      'invalid_identity',
+      'Interaction and orchestration identities must differ',
+    );
+  }
+  return Object.freeze({ interactionAgentId, orchestrationAgentId });
+}
+
+function snapshotRequest(request: MosHandoffRequest): MosHandoffRequest {
+  return Object.freeze({ ...request });
+}
+
+function snapshotScope(scope: CoordinationScope): CoordinationScope {
+  return Object.freeze({ ...scope });
+}