feat(gateway,cli): agent enrollment command family (M4-4b)

Implements the command module for the M4-4-0 design
(docs/plans/2026-08-29-agent-enrollment-command-design.md) over the
M4-4a schema (migration 0021):

- EnrollmentModule: agent.enroll (POST /api/enrollment/agents) and
  agent.enrollment.get (GET /api/enrollment/agents/:id), closed error
  enum, correlation envelope on every result and refusal.
- EnrollmentRepository as the family's sole writer: fence-check ->
  mutate -> audit + outbox in one transaction; actor-bound idempotency
  replay with fresh authorization; intake credentials sealed
  (AES-256-GCM) into provider_credentials, never echoed anywhere;
  reference mode resolves the actor's stored credential; harness
  validated against the live registry (fail-closed in prod until
  adapters register).
- CLI parity (contract 5 s4.5): mosaic agent enroll / enrollment
  subcommands; intake API key read from stdin, never argv.
- 19 integration witnesses covering design s5 items 1-9 and 11
  (never-echo, sealed single-copy, reference resolution, harness
  refusal codes, the s4.3 idempotency set incl. concurrent same-key,
  five-point fault-injection atomicity, zero-mutation, is_system
  closure, correlation + no-existence-oracle, fail-closed) plus an
  8-test CLI parity spec (item 10).

apps/gateway/src/app.module.ts

@@ -25,6 +25,7 @@ import { HarnessModule } from './harness/harness.module.js';
 import { ReloadModule } from './reload/reload.module.js';
 import { WorkspaceModule } from './workspace/workspace.module.js';
 import { HierarchyModule } from './hierarchy/hierarchy.module.js';
+import { EnrollmentModule } from './enrollment/enrollment.module.js';
 import { QueueModule } from './queue/queue.module.js';
 import { FederationModule } from './federation/federation.module.js';
 import { ThrottlerGuard, ThrottlerModule } from '@nestjs/throttler';
@@ -67,6 +68,7 @@ const federationEnabled = loadConfig(resolveGatewayConfigPath()).tier === 'feder
     ReloadModule,
     WorkspaceModule,
     HierarchyModule,
+    EnrollmentModule,
     ...(federationEnabled ? [FederationModule] : []),
   ],
   controllers: [HealthController],

apps/gateway/src/enrollment/enrollment-commands.integration.test.ts

@@ -0,0 +1,508 @@
+import { mkdtemp, rm } from 'node:fs/promises';
+import { randomUUID } from 'node:crypto';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { afterAll, beforeAll, describe, expect, it, vi } from 'vitest';
+import { Test, type TestingModule } from '@nestjs/testing';
+import { Logger, ValidationPipe, type ExecutionContext } from '@nestjs/common';
+import { FastifyAdapter, type NestFastifyApplication } from '@nestjs/platform-fastify';
+import supertest from 'supertest';
+import { unseal } from '@mosaicstack/auth';
+import {
+  agentAuditEvents,
+  agentIdempotencyFence,
+  agentOutbox,
+  agents,
+  and,
+  createPgliteDb,
+  eq,
+  providerCredentials,
+  runPgliteMigrations,
+  sql,
+  users,
+  type DbHandle,
+} from '@mosaicstack/db';
+import { DB } from '../database/database.module.js';
+import { AuthGuard } from '../auth/auth.guard.js';
+import { HarnessRegistry } from '../harness/harness.registry.js';
+import { HARNESS_REGISTRY } from '../harness/harness.tokens.js';
+import { FakeHarnessAdapter } from '../harness/testing/fake-harness.adapter.js';
+import { EnrollmentController } from './enrollment.controller.js';
+import {
+  EnrollmentRepository,
+  type EnrollAgentInput,
+  type EnrollmentResult,
+  type EnrolledAgentView,
+} from './enrollment.repository.js';
+import { EnrollmentService } from './enrollment.service.js';
+
+/**
+ * Command-level witnesses for the agent enrollment family (M4-4b) — design
+ * docs/plans/2026-08-29-agent-enrollment-command-design.md §5 items 1–9 and
+ * 11 (item 10, CLI parity, lives in packages/mosaic). Schema-level
+ * constraints are witnessed in packages/db/src/agent-enrollment.witness.test.ts.
+ *
+ * The suite runs the REAL repository/service/controller graph over PGlite,
+ * with only AuthGuard overridden (a session store is out of scope; the
+ * override binds request.user exactly as the real guard does). The §6.3
+ * static companions — no `any`-typed boundary pass-through, a single audit
+ * emitter (EnrollmentRepository.appendEvent) — are code-surface properties
+ * reviewed on the PR, not runtime probes.
+ */
+describe('enrollment commands integration', (): void => {
+  let dataDir: string;
+  let handle: DbHandle;
+  let moduleRef: TestingModule;
+  let app: NestFastifyApplication;
+  let http: ReturnType<typeof supertest>;
+  let repo: EnrollmentRepository;
+  let previousAuthSecret: string | undefined;
+
+  const OWNER = 'enr-owner';
+  const ADMIN = 'enr-admin';
+  const STRANGER = 'enr-stranger';
+  const HARNESS = 'fake-harness';
+  /** Never-echo probe value (§5.1). Unique enough that any leak is unambiguous. */
+  const SECRET = `enr-secret-value-${randomUUID()}`;
+
+  /** The HTTP-leg acting user; the overridden guard binds it per request. */
+  let currentUserId = OWNER;
+
+  const enrollInput = (overrides: Partial<EnrollAgentInput> = {}): EnrollAgentInput => ({
+    actorId: OWNER,
+    harness: HARNESS,
+    name: `Agent ${randomUUID().slice(0, 8)}`,
+    persona: null,
+    model: 'anthropic/claude-test',
+    provider: `prov-${randomUUID().slice(0, 8)}`,
+    credential: { mode: 'intake', type: 'api_key', value: SECRET },
+    idempotencyKey: randomUUID(),
+    ...overrides,
+  });
+
+  function expectOk<T>(result: EnrollmentResult<T>): { ok: true; correlationId: string } & T {
+    if (!result.ok) throw new Error(`expected ok, got ${JSON.stringify(result)}`);
+    return result;
+  }
+
+  function expectFail<T>(
+    result: EnrollmentResult<T>,
+    error: string,
+  ): { ok: false; error: string; message: string; correlationId: string } {
+    if (result.ok) throw new Error(`expected ${error}, got ok`);
+    expect(result.error).toBe(error);
+    return result;
+  }
+
+  const fenceForKey = (key: string) =>
+    handle.db
+      .select()
+      .from(agentIdempotencyFence)
+      .where(eq(agentIdempotencyFence.idempotencyKey, key));
+
+  const eventsForAgent = (agentId: string) =>
+    handle.db.select().from(agentAuditEvents).where(eq(agentAuditEvents.agentId, agentId));
+
+  const agentsNamed = (name: string) =>
+    handle.db.select().from(agents).where(eq(agents.name, name));
+
+  const credentialsFor = (userId: string, provider: string) =>
+    handle.db
+      .select()
+      .from(providerCredentials)
+      .where(
+        and(eq(providerCredentials.userId, userId), eq(providerCredentials.provider, provider)),
+      );
+
+  const allOutbox = () => handle.db.select().from(agentOutbox);
+
+  beforeAll(async (): Promise<void> => {
+    previousAuthSecret = process.env['BETTER_AUTH_SECRET'];
+    process.env['BETTER_AUTH_SECRET'] = 'enrollment-witness-sealing-key';
+
+    dataDir = await mkdtemp(join(tmpdir(), 'mosaic-gateway-enrollment-commands-'));
+    handle = createPgliteDb(dataDir);
+    await runPgliteMigrations(handle);
+
+    const registry = new HarnessRegistry();
+    registry.register(new FakeHarnessAdapter({ id: HARNESS }));
+
+    moduleRef = await Test.createTestingModule({
+      controllers: [EnrollmentController],
+      providers: [
+        EnrollmentRepository,
+        EnrollmentService,
+        { provide: DB, useValue: handle.db },
+        { provide: HARNESS_REGISTRY, useValue: registry },
+      ],
+    })
+      .overrideGuard(AuthGuard)
+      .useValue({
+        canActivate: (ctx: ExecutionContext): boolean => {
+          const request = ctx.switchToHttp().getRequest<{ user?: unknown }>();
+          request.user = { id: currentUserId };
+          return true;
+        },
+      })
+      .compile();
+
+    app = moduleRef.createNestApplication<NestFastifyApplication>(new FastifyAdapter());
+    // Mirror main.ts exactly — the closure witnesses depend on these options.
+    app.useGlobalPipes(
+      new ValidationPipe({ whitelist: true, forbidNonWhitelisted: true, transform: true }),
+    );
+    await app.init();
+    await app.getHttpAdapter().getInstance().ready();
+    http = supertest(app.getHttpServer());
+    repo = moduleRef.get(EnrollmentRepository);
+
+    await handle.db.insert(users).values([
+      { id: OWNER, name: 'Owner', email: `${OWNER}@example.com` },
+      { id: ADMIN, name: 'Admin', email: `${ADMIN}@example.com`, role: 'admin' },
+      { id: STRANGER, name: 'Stranger', email: `${STRANGER}@example.com` },
+    ]);
+  });
+
+  afterAll(async (): Promise<void> => {
+    await app?.close();
+    await handle.close();
+    await rm(dataDir, { recursive: true, force: true });
+    if (previousAuthSecret === undefined) delete process.env['BETTER_AUTH_SECRET'];
+    else process.env['BETTER_AUTH_SECRET'] = previousAuthSecret;
+  });
+
+  // ── §5.7 wizard-facing zero-mutation (runs FIRST: no call → zero rows) ────
+
+  it('zero-mutation: with no enrollment invocation the family tables hold zero rows', async () => {
+    expect(await handle.db.select().from(agents)).toHaveLength(0);
+    expect(await handle.db.select().from(agentAuditEvents)).toHaveLength(0);
+    expect(await handle.db.select().from(agentOutbox)).toHaveLength(0);
+    expect(await handle.db.select().from(agentIdempotencyFence)).toHaveLength(0);
+  });
+
+  // ── §5.1 never-echo + §5.2 sealed single-copy ─────────────────────────────
+
+  it('never echoes the intake credential value: HTTP result, audit, outbox, fence, and logs are clean', async () => {
+    const logSink: string[] = [];
+    const logSpies = (['log', 'error', 'warn', 'debug', 'verbose'] as const).map((method) =>
+      vi.spyOn(Logger.prototype, method).mockImplementation((...args: unknown[]) => {
+        logSink.push(args.map(String).join(' '));
+      }),
+    );
+    try {
+      currentUserId = OWNER;
+      const provider = `prov-echo-${randomUUID().slice(0, 8)}`;
+      const res = await http.post('/api/enrollment/agents').send({
+        harness: HARNESS,
+        name: 'Echo Probe',
+        persona: 'a persona',
+        model: 'anthropic/claude-test',
+        provider,
+        credential: { mode: 'intake', type: 'api_key', value: SECRET },
+        idempotencyKey: randomUUID(),
+      });
+      expect(res.status).toBe(201);
+      expect(res.text).not.toContain(SECRET);
+      const agentId = (res.body as { agent: EnrolledAgentView }).agent.id;
+
+      const events = await eventsForAgent(agentId);
+      expect(events).toHaveLength(1);
+      expect(JSON.stringify(events)).not.toContain(SECRET);
+      expect(JSON.stringify(await allOutbox())).not.toContain(SECRET);
+      const fences = await handle.db
+        .select()
+        .from(agentIdempotencyFence)
+        .where(eq(agentIdempotencyFence.outcomeAgentId, agentId));
+      expect(fences).toHaveLength(1);
+      expect(JSON.stringify(fences)).not.toContain(SECRET);
+      expect(logSink.join('\n')).not.toContain(SECRET);
+
+      // §5.2 sealed single-copy: exactly one provider_credentials row, sealed
+      // at rest, and it round-trips through unseal — no plaintext column.
+      const creds = await credentialsFor(OWNER, provider);
+      expect(creds).toHaveLength(1);
+      expect(creds[0]?.encryptedValue).not.toBe(SECRET);
+      expect(creds[0]?.encryptedValue).not.toContain(SECRET);
+      expect(unseal(creds[0]?.encryptedValue as string)).toBe(SECRET);
+    } finally {
+      logSpies.forEach((spy) => spy.mockRestore());
+    }
+  });
+
+  it('the agents table itself has no credential-bearing column (§5.2)', async () => {
+    const result = (await handle.db.execute(
+      sql`select column_name from information_schema.columns where table_name = 'agents'`,
+    )) as unknown as { rows?: Array<{ column_name: string }> } & Array<{ column_name: string }>;
+    const names = (result.rows ?? result).map((row) => row.column_name);
+    expect(names.length).toBeGreaterThan(0);
+    for (const name of names) {
+      expect(name).not.toMatch(/credential|secret|token|api_key/i);
+    }
+  });
+
+  // ── §5.3 reference resolution ─────────────────────────────────────────────
+
+  it('refuses an unresolvable credential reference with precondition_failed and creates nothing', async () => {
+    const input = enrollInput({ credential: { mode: 'reference' } });
+    const result = await repo.enroll(input);
+    expectFail(result, 'precondition_failed');
+    expect(await agentsNamed(input.name)).toHaveLength(0);
+    expect(await fenceForKey(input.idempotencyKey)).toHaveLength(0);
+  });
+
+  it('resolves a reference credential stored earlier for (actor, provider)', async () => {
+    const provider = `prov-ref-${randomUUID().slice(0, 8)}`;
+    const seeded = expectOk(await repo.enroll(enrollInput({ provider })));
+    const result = expectOk(
+      await repo.enroll(enrollInput({ provider, credential: { mode: 'reference' } })),
+    );
+    expect(result.agent.id).not.toBe(seeded.agent.id);
+    expect(await credentialsFor(OWNER, provider)).toHaveLength(1);
+  });
+
+  // ── §5.4 harness refusals, both codes ────────────────────────────────────
+
+  it('refuses a syntactically invalid harness as validation_failed and a registry miss as precondition_failed', async () => {
+    const blank = await repo.enroll(enrollInput({ harness: '   ' }));
+    expectFail(blank, 'validation_failed');
+    const miss = await repo.enroll(enrollInput({ harness: 'well-formed-but-unregistered' }));
+    expectFail(miss, 'precondition_failed');
+
+    currentUserId = OWNER;
+    const httpBlank = await http.post('/api/enrollment/agents').send({
+      harness: '',
+      name: 'H',
+      model: 'm',
+      provider: 'p',
+      credential: { mode: 'reference' },
+      idempotencyKey: randomUUID(),
+    });
+    expect(httpBlank.status).toBe(400);
+  });
+
+  // ── §5.5 idempotency set (contract 3 §4.3) ───────────────────────────────
+
+  it('actor-bound replay returns the recorded outcome and executes nothing new', async () => {
+    const input = enrollInput();
+    const first = expectOk(await repo.enroll(input));
+    const replay = expectOk(await repo.enroll({ ...input, correlationId: randomUUID() }));
+    expect(replay.agent.id).toBe(first.agent.id);
+
+    expect(await agentsNamed(input.name)).toHaveLength(1);
+    expect(await fenceForKey(input.idempotencyKey)).toHaveLength(1);
+    const events = await eventsForAgent(first.agent.id);
+    expect(events.filter((e) => e.eventType === 'agent.enrolled')).toHaveLength(1);
+    // A passing replay appends exactly the non-mutation access event.
+    const replayed = events.filter((e) => e.eventType === 'agent.enrollment.replayed');
+    expect(replayed).toHaveLength(1);
+    expect((replayed[0]?.payload as { fenceId?: string }).fenceId).toBeDefined();
+  });
+
+  it('payload-digest mismatch on a recorded key refuses with the single bounded conflict shape', async () => {
+    const input = enrollInput();
+    expectOk(await repo.enroll(input));
+    const mismatch = await repo.enroll({ ...input, name: `${input.name} CHANGED` });
+    const failure = expectFail(mismatch, 'conflict');
+    expect(failure.message).toBe('idempotency conflict');
+  });
+
+  it('replay-mode and scope mismatches on the recorded fence each refuse as the same constant conflict', async () => {
+    const modeInput = enrollInput();
+    expectOk(await repo.enroll(modeInput));
+    await handle.db
+      .update(agentIdempotencyFence)
+      .set({ replayMode: 'shared' })
+      .where(eq(agentIdempotencyFence.idempotencyKey, modeInput.idempotencyKey));
+    const modeFailure = expectFail(await repo.enroll(modeInput), 'conflict');
+
+    const scopeInput = enrollInput();
+    expectOk(await repo.enroll(scopeInput));
+    await handle.db
+      .update(agentIdempotencyFence)
+      .set({ authorizationScope: 'some-other-scope' })
+      .where(eq(agentIdempotencyFence.idempotencyKey, scopeInput.idempotencyKey));
+    const scopeFailure = expectFail(await repo.enroll(scopeInput), 'conflict');
+
+    expect(modeFailure.message).toBe(scopeFailure.message);
+  });
+
+  it('a different actor replaying an actor-bound key is refused conflict, learning nothing', async () => {
+    const input = enrollInput();
+    expectOk(await repo.enroll(input));
+    const failure = expectFail(await repo.enroll({ ...input, actorId: STRANGER }), 'conflict');
+    expect(failure.message).toBe('idempotency conflict');
+  });
+
+  it('a replay is re-authorized fresh: revoked target authority refuses instead of replaying', async () => {
+    const input = enrollInput();
+    const first = expectOk(await repo.enroll(input));
+    // Simulate the legacy CRUD DELETE path removing the outcome agent: the
+    // submitter no longer holds read authority on the referenced row.
+    await handle.db.delete(agents).where(eq(agents.id, first.agent.id));
+    expectFail(await repo.enroll(input), 'conflict');
+  });
+
+  it('a shared replay-mode declaration is refused validation_failed with nothing executed and no fence row', async () => {
+    const input = enrollInput({ replayMode: 'shared' });
+    expectFail(await repo.enroll(input), 'validation_failed');
+    expect(await agentsNamed(input.name)).toHaveLength(0);
+    expect(await fenceForKey(input.idempotencyKey)).toHaveLength(0);
+
+    currentUserId = OWNER;
+    const key = randomUUID();
+    const res = await http.post('/api/enrollment/agents').send({
+      harness: HARNESS,
+      name: 'Shared Probe',
+      model: 'm',
+      provider: 'p',
+      credential: { mode: 'reference' },
+      idempotencyKey: key,
+      replayMode: 'shared',
+    });
+    expect(res.status).toBe(400);
+    expect(await fenceForKey(key)).toHaveLength(0);
+  });
+
+  it('two concurrent same-key submissions produce exactly one mutation, the loser resolving as a replay', async () => {
+    const input = enrollInput();
+    const [a, b] = await Promise.all([
+      repo.enroll(input),
+      repo.enroll({ ...input, correlationId: randomUUID() }),
+    ]);
+    const okA = expectOk(a);
+    const okB = expectOk(b);
+    expect(okA.agent.id).toBe(okB.agent.id);
+    expect(await agentsNamed(input.name)).toHaveLength(1);
+    expect(await fenceForKey(input.idempotencyKey)).toHaveLength(1);
+    const events = await eventsForAgent(okA.agent.id);
+    expect(events.filter((e) => e.eventType === 'agent.enrolled')).toHaveLength(1);
+    expect(events.filter((e) => e.eventType === 'agent.enrollment.replayed')).toHaveLength(1);
+  });
+
+  // ── §5.6 same-tx atomicity fault injection ───────────────────────────────
+
+  it('rolls everything back on failure at each write point — no orphan credential survives', async () => {
+    const injectionPoints = [
+      'writeSealedCredential',
+      'insertAgentRow',
+      'insertFenceRow',
+      'appendEvent',
+      'insertOutboxRow',
+    ] as const;
+
+    for (const point of injectionPoints) {
+      const input = enrollInput();
+      const spy = vi.spyOn(repo, point).mockImplementationOnce(() => {
+        throw new Error(`injected ${point} fault`);
+      });
+      try {
+        const result = await repo.enroll(input);
+        expectFail(result, 'internal_fault');
+        expect(await agentsNamed(input.name)).toHaveLength(0);
+        expect(await fenceForKey(input.idempotencyKey)).toHaveLength(0);
+        // Injection at fence/audit/outbox fires AFTER the sealed credential
+        // write's statement ran — the rollback must leave no orphan row.
+        expect(await credentialsFor(OWNER, input.provider)).toHaveLength(0);
+      } finally {
+        spy.mockRestore();
+      }
+    }
+  });
+
+  // ── §5.8 is_system closure ───────────────────────────────────────────────
+
+  it('rejects an is_system injection attempt at the DTO boundary', async () => {
+    currentUserId = OWNER;
+    const key = randomUUID();
+    const res = await http.post('/api/enrollment/agents').send({
+      harness: HARNESS,
+      name: 'System Probe',
+      model: 'm',
+      provider: 'p',
+      credential: { mode: 'reference' },
+      idempotencyKey: key,
+      isSystem: true,
+    });
+    expect(res.status).toBe(400);
+    expect(await fenceForKey(key)).toHaveLength(0);
+  });
+
+  // ── §5.9 correlation + no-existence-oracle ───────────────────────────────
+
+  it('carries a submitted correlation id into the result, the audit event, and the outbox record', async () => {
+    const correlationId = randomUUID();
+    const input = enrollInput({ correlationId });
+    const result = expectOk(await repo.enroll(input));
+    expect(result.correlationId).toBe(correlationId);
+    const events = await eventsForAgent(result.agent.id);
+    expect(events).toHaveLength(1);
+    expect(events[0]?.correlationId).toBe(correlationId);
+    const outboxRows = await handle.db
+      .select()
+      .from(agentOutbox)
+      .where(eq(agentOutbox.eventId, events[0]?.id as string));
+    expect(outboxRows).toHaveLength(1);
+    expect(outboxRows[0]?.correlationId).toBe(correlationId);
+
+    // Refusals carry the correlation envelope too (contract 5 §4.3).
+    const refusal = expectFail(
+      await repo.enroll({ ...input, name: 'changed name', correlationId }),
+      'conflict',
+    );
+    expect(refusal.correlationId).toBe(correlationId);
+  });
+
+  it('agent.enrollment.get returns owner and admin reads with the correlation envelope, no idempotency key', async () => {
+    const enrolled = expectOk(await repo.enroll(enrollInput()));
+    const correlationId = randomUUID();
+    const asOwner = expectOk(await repo.getEnrollment(OWNER, enrolled.agent.id, correlationId));
+    expect(asOwner.correlationId).toBe(correlationId);
+    expect(asOwner.agent.id).toBe(enrolled.agent.id);
+    const asAdmin = expectOk(await repo.getEnrollment(ADMIN, enrolled.agent.id));
+    expect(asAdmin.correlationId).toMatch(/^[0-9a-f-]{36}$/);
+
+    currentUserId = OWNER;
+    const wire = randomUUID();
+    const res = await http.get(`/api/enrollment/agents/${enrolled.agent.id}?correlationId=${wire}`);
+    expect(res.status).toBe(200);
+    expect((res.body as { correlationId: string }).correlationId).toBe(wire);
+  });
+
+  it('no existence oracle: unauthorized get of a real agent and get of a missing id are indistinguishable', async () => {
+    const enrolled = expectOk(await repo.enroll(enrollInput()));
+
+    currentUserId = STRANGER;
+    const unauthorized = await http.get(`/api/enrollment/agents/${enrolled.agent.id}`);
+    const missing = await http.get(`/api/enrollment/agents/${randomUUID()}`);
+    expect(unauthorized.status).toBe(404);
+    expect(missing.status).toBe(404);
+    const strip = (body: Record<string, unknown>): Record<string, unknown> =>
+      Object.fromEntries(Object.entries(body).filter(([key]) => key !== 'correlationId'));
+    expect(strip(unauthorized.body as Record<string, unknown>)).toEqual(
+      strip(missing.body as Record<string, unknown>),
+    );
+  });
+
+  // ── §5.11 fail-closed ────────────────────────────────────────────────────
+
+  it('fails closed as internal_fault when the store is unreachable, with no fallback write', async () => {
+    const before = (await handle.db.select().from(agents)).length;
+    const txSpy = vi.spyOn(handle.db, 'transaction').mockImplementationOnce(() => {
+      throw new Error('injected store outage');
+    });
+    try {
+      expectFail(await repo.enroll(enrollInput()), 'internal_fault');
+    } finally {
+      txSpy.mockRestore();
+    }
+    const selectSpy = vi.spyOn(handle.db, 'select').mockImplementationOnce(() => {
+      throw new Error('injected store outage');
+    });
+    try {
+      expectFail(await repo.getEnrollment(OWNER, randomUUID()), 'internal_fault');
+    } finally {
+      selectSpy.mockRestore();
+    }
+    expect((await handle.db.select().from(agents)).length).toBe(before);
+  });
+});

apps/gateway/src/enrollment/enrollment.controller.ts

@@ -0,0 +1,61 @@
+import {
+  Body,
+  Controller,
+  Get,
+  Param,
+  ParseUUIDPipe,
+  Post,
+  Query,
+  UseGuards,
+} from '@nestjs/common';
+import { AuthGuard } from '../auth/auth.guard.js';
+import { CurrentUser } from '../auth/current-user.decorator.js';
+import { EnrollAgentDto, GetEnrollmentQueryDto } from './enrollment.dto.js';
+import { EnrollmentRepository } from './enrollment.repository.js';
+import { EnrollmentService } from './enrollment.service.js';
+
+/**
+ * The agent enrollment command family's closed HTTP surface (design
+ * docs/plans/2026-08-29-agent-enrollment-command-design.md §3): one command,
+ * one query. Authentication failures are the guard's (401); everything else
+ * is the repository's closed enum mapped by EnrollmentService.
+ */
+@Controller('api/enrollment')
+@UseGuards(AuthGuard)
+export class EnrollmentController {
+  constructor(
+    private readonly repository: EnrollmentRepository,
+    private readonly service: EnrollmentService,
+  ) {}
+
+  /** agent.enroll (§3.1). */
+  @Post('agents')
+  async enroll(@CurrentUser() user: { id: string }, @Body() dto: EnrollAgentDto) {
+    return this.service.unwrap(
+      await this.repository.enroll({
+        actorId: user.id,
+        harness: dto.harness,
+        name: dto.name,
+        persona: dto.persona ?? null,
+        model: dto.model,
+        provider: dto.provider,
+        credential: dto.credential,
+        idempotencyKey: dto.idempotencyKey,
+        correlationId: dto.correlationId,
+        replayMode: dto.replayMode,
+      }),
+    );
+  }
+
+  /** agent.enrollment.get (§3.2): owner-or-admin; unauthorized and missing fold to one not_found. */
+  @Get('agents/:id')
+  async getEnrollment(
+    @CurrentUser() user: { id: string },
+    @Param('id', ParseUUIDPipe) id: string,
+    @Query() query: GetEnrollmentQueryDto,
+  ) {
+    return this.service.unwrap(
+      await this.repository.getEnrollment(user.id, id, query.correlationId),
+    );
+  }
+}

apps/gateway/src/enrollment/enrollment.dto.ts

@@ -0,0 +1,107 @@
+import { Type } from 'class-transformer';
+import {
+  IsIn,
+  IsOptional,
+  IsString,
+  IsUUID,
+  MaxLength,
+  MinLength,
+  ValidateIf,
+  ValidateNested,
+} from 'class-validator';
+
+/**
+ * Agent enrollment command DTOs (design
+ * docs/plans/2026-08-29-agent-enrollment-command-design.md §3.1/§3.2,
+ * contract 5 §4.1 typed boundary).
+ *
+ * The global ValidationPipe runs with whitelist + forbidNonWhitelisted, so
+ * closure is contract surface here exactly as in the hierarchy DTOs:
+ *  - EnrollAgentDto declares NO isSystem field — `is_system` is never
+ *    settable through this command (design §3.1 rule 4); the pipe refuses it.
+ *  - replayMode admits ONLY 'actor-bound': `shared` is seed-only (contract 3
+ *    §4.3), so a shared declaration is refused `validation_failed` at the
+ *    boundary, executes nothing, and records no fence row (design §3.1).
+ * Every class here must be registered in PIPE_GUARDED_DTOS so the boot-time
+ * assertion proves the pipe sees the decorators.
+ */
+
+/**
+ * Credential input, discriminated on `mode` (design §3.1):
+ *  - `{ mode: 'reference' }` — a stored credential for (actor, provider)
+ *    must already exist; `type`/`value` must be ABSENT (the repository
+ *    refuses a reference that smuggles a value).
+ *  - `{ mode: 'intake', type: 'api_key', value }` — the value is sealed
+ *    into the credential store inside the enrollment transaction and is
+ *    never echoed anywhere (§3.1 rule 1).
+ */
+export class EnrollCredentialDto {
+  @IsIn(['reference', 'intake'])
+  mode!: 'reference' | 'intake';
+
+  @ValidateIf((o: EnrollCredentialDto) => o.mode === 'intake')
+  @IsIn(['api_key'])
+  type?: 'api_key';
+
+  @ValidateIf((o: EnrollCredentialDto) => o.mode === 'intake')
+  @IsString()
+  @MinLength(1)
+  @MaxLength(4096)
+  value?: string;
+}
+
+export class EnrollAgentDto {
+  /** Registered harness name; a well-formed name missing from the registry is `precondition_failed`. */
+  @IsString()
+  @MinLength(1)
+  @MaxLength(200)
+  harness!: string;
+
+  @IsString()
+  @MinLength(1)
+  @MaxLength(200)
+  name!: string;
+
+  /** Stored as the agent's system prompt; null/absent leaves it unset. */
+  @IsOptional()
+  @IsString()
+  @MaxLength(20000)
+  persona?: string | null;
+
+  /** Provider-qualified model id. */
+  @IsString()
+  @MinLength(1)
+  @MaxLength(200)
+  model!: string;
+
+  /** Names the credential's provider. */
+  @IsString()
+  @MinLength(1)
+  @MaxLength(200)
+  provider!: string;
+
+  @ValidateNested()
+  @Type(() => EnrollCredentialDto)
+  credential!: EnrollCredentialDto;
+
+  /** REQUIRED — contract 3 §4.3, ratified into contract 5 §4 via §7 item 4. */
+  @IsUUID()
+  idempotencyKey!: string;
+
+  /** Optional; generated when absent (contract 5 §4.3). */
+  @IsOptional()
+  @IsUUID()
+  correlationId?: string;
+
+  /** Only 'actor-bound' is admissible on this family — see module doc. */
+  @IsOptional()
+  @IsIn(['actor-bound'])
+  replayMode?: 'actor-bound';
+}
+
+/** Query envelope for agent.enrollment.get (design §3.2): correlation only, no idempotency key. */
+export class GetEnrollmentQueryDto {
+  @IsOptional()
+  @IsUUID()
+  correlationId?: string;
+}

apps/gateway/src/enrollment/enrollment.module.ts

@@ -0,0 +1,22 @@
+import { Module } from '@nestjs/common';
+import { HarnessModule } from '../harness/harness.module.js';
+import { EnrollmentController } from './enrollment.controller.js';
+import { EnrollmentRepository } from './enrollment.repository.js';
+import { EnrollmentService } from './enrollment.service.js';
+
+/**
+ * Agent enrollment command family (M4-4b; design
+ * docs/plans/2026-08-29-agent-enrollment-command-design.md). Imports
+ * HarnessModule for the live harness registry — the validation source for
+ * the `harness` field (a well-formed name the registry does not know is a
+ * precondition failure). EnrollmentRepository is the family's sole writer;
+ * every mutation runs fence-check → mutate → audit + outbox in one
+ * transaction.
+ */
+@Module({
+  imports: [HarnessModule],
+  controllers: [EnrollmentController],
+  providers: [EnrollmentRepository, EnrollmentService],
+  exports: [EnrollmentRepository],
+})
+export class EnrollmentModule {}

apps/gateway/src/enrollment/enrollment.repository.ts

@@ -0,0 +1,538 @@
+import { createHash, randomUUID } from 'node:crypto';
+import { Inject, Injectable, Logger } from '@nestjs/common';
+import { seal } from '@mosaicstack/auth';
+import {
+  agentAuditEvents,
+  agentIdempotencyFence,
+  agentOutbox,
+  agents,
+  and,
+  eq,
+  providerCredentials,
+  users,
+  type Db,
+} from '@mosaicstack/db';
+import { DB } from '../database/database.module.js';
+import type { HarnessRegistry } from '../harness/harness.registry.js';
+import { HARNESS_REGISTRY } from '../harness/harness.tokens.js';
+
+/**
+ * Agent enrollment command repository (design
+ * docs/plans/2026-08-29-agent-enrollment-command-design.md §3; contract 5 §4
+ * envelope; contract 3 §4.3 idempotency fence, ratified via §7 item 4).
+ *
+ * The ONLY writer of the enrollment family's tables (`agent_audit_events`,
+ * `agent_outbox`, `agent_idempotency_fence`) and the only path that sets
+ * `agents.harness`/`agents.enrolled_at`. Every enroll runs one transaction:
+ * fence check → (replay | credential handling → agent insert → fence insert →
+ * audit event + outbox), so state, fence, event, and outbox commit or roll
+ * back together (§3.1 rule 6).
+ *
+ * Authorization (v1, §3.1 rule 4) is the AuthGuard-authenticated actor — no
+ * hierarchy grant is consulted because v1 enrollment binds no hierarchy node.
+ * The recorded fence authorization scope is therefore the constant
+ * platform-user identity domain (§3.1 rule 5).
+ *
+ * Never-echo (§3.1 rule 1): the credential value reaches exactly one sink —
+ * the sealed store write — and appears in no result, audit payload, outbox
+ * row, or log line. Log lines here carry correlation ids and error names
+ * only, never request fields.
+ *
+ * The single-write helper methods (writeSealedCredential, insertAgentRow,
+ * insertFenceRow, appendEvent, insertOutboxRow) are ordinary decomposition;
+ * the atomicity witnesses (§5.6) spy on them to inject faults at each write
+ * point without any test-only production switch.
+ */
+
+export const ENROLLMENT_OPERATION = 'agent.enroll';
+/** §3.1 rule 5: v1 authorization is grant-free, so the scope is the authenticated-user identity domain. */
+const AUTHORIZATION_SCOPE = 'platform-user';
+/** The single bounded collision shape (§3.1 rule 5): constant, identifying no record. */
+const CONFLICT_MESSAGE = 'idempotency conflict';
+/** One fixed message for every not_found cause — missing and unauthorized are indistinguishable (§3.2). */
+const NOT_FOUND_MESSAGE = 'agent not found';
+
+/** Closed per-family error enum (§3.3). 401 is produced by AuthGuard; 403 folds to not_found (§3.2). */
+export type EnrollmentErrorCode =
+  | 'validation_failed'
+  | 'authentication_failed'
+  | 'authorization_refused'
+  | 'not_found'
+  | 'conflict'
+  | 'precondition_failed'
+  | 'internal_fault';
+
+export interface EnrollmentFailure {
+  readonly ok: false;
+  readonly error: EnrollmentErrorCode;
+  readonly message: string;
+  /** Refusals carry the correlation id too (contract 5 §4.3 end-to-end traceability). */
+  readonly correlationId: string;
+}
+
+export type EnrollmentResult<T> =
+  | ({ readonly ok: true; readonly correlationId: string } & T)
+  | EnrollmentFailure;
+
+/** The persisted agent row; the table stores no credential material (§3.1 rule 1). */
+export interface EnrolledAgentView {
+  readonly id: string;
+  readonly name: string;
+  readonly provider: string;
+  readonly model: string;
+  readonly status: string;
+  readonly harness: string | null;
+  readonly persona: string | null;
+  readonly ownerId: string | null;
+  readonly enrolledAt: string | null;
+  readonly createdAt: string;
+}
+
+export interface EnrollCredentialInput {
+  readonly mode: 'reference' | 'intake';
+  readonly type?: 'api_key';
+  readonly value?: string;
+}
+
+export interface EnrollAgentInput {
+  readonly actorId: string;
+  readonly harness: string;
+  readonly name: string;
+  readonly persona?: string | null;
+  readonly model: string;
+  readonly provider: string;
+  readonly credential: EnrollCredentialInput;
+  readonly idempotencyKey: string;
+  readonly correlationId?: string;
+  /** Defense in depth below the DTO: anything but 'actor-bound' is refused (seed-only rule). */
+  readonly replayMode?: string;
+}
+
+type Tx = Pick<Db, 'insert' | 'select' | 'update' | 'delete'>;
+type AgentRow = typeof agents.$inferSelect;
+type FenceRow = typeof agentIdempotencyFence.$inferSelect;
+
+/** Raised inside the transaction when the fence insert lost a same-key race (§3.1 rule 5 concurrency). */
+class ConcurrentEnrollmentError extends Error {
+  constructor() {
+    super('concurrent enrollment lost the fence race');
+    this.name = 'ConcurrentEnrollmentError';
+  }
+}
+
+function agentView(row: AgentRow): EnrolledAgentView {
+  return {
+    id: row.id,
+    name: row.name,
+    provider: row.provider,
+    model: row.model,
+    status: row.status,
+    harness: row.harness,
+    persona: row.systemPrompt,
+    ownerId: row.ownerId,
+    enrolledAt: row.enrolledAt?.toISOString() ?? null,
+    createdAt: row.createdAt.toISOString(),
+  };
+}
+
+/** Key-order-independent serialization (jsonb precedent in hierarchy-audit). */
+function canonicalJson(value: unknown): string {
+  if (Array.isArray(value)) return `[${value.map(canonicalJson).join(',')}]`;
+  if (value !== null && typeof value === 'object') {
+    const record = value as Record<string, unknown>;
+    const body = Object.keys(record)
+      .sort()
+      .map((key) => `${JSON.stringify(key)}:${canonicalJson(record[key])}`)
+      .join(',');
+    return `{${body}}`;
+  }
+  return JSON.stringify(value);
+}
+
+interface NormalizedEnrollment {
+  readonly actorId: string;
+  readonly harness: string;
+  readonly name: string;
+  readonly persona: string | null;
+  readonly model: string;
+  readonly provider: string;
+  readonly credential: EnrollCredentialInput;
+  readonly idempotencyKey: string;
+  readonly correlationId: string;
+  readonly digest: string;
+}
+
+/**
+ * Canonicalized-payload digest (§3.1 rule 5). The input EXCLUDES the
+ * credential value by construction: it covers mode and declared type only —
+ * plaintext never reaches the hash.
+ */
+function digestOf(
+  input: Omit<NormalizedEnrollment, 'actorId' | 'idempotencyKey' | 'correlationId' | 'digest'>,
+): string {
+  const canonical = canonicalJson({
+    harness: input.harness,
+    name: input.name,
+    persona: input.persona,
+    model: input.model,
+    provider: input.provider,
+    credential: { mode: input.credential.mode, type: input.credential.type ?? null },
+  });
+  return createHash('sha256').update(canonical).digest('hex');
+}
+
+@Injectable()
+export class EnrollmentRepository {
+  private readonly logger = new Logger(EnrollmentRepository.name);
+
+  constructor(
+    @Inject(DB) private readonly db: Db,
+    @Inject(HARNESS_REGISTRY) private readonly registry: HarnessRegistry,
+  ) {}
+
+  async enroll(input: EnrollAgentInput): Promise<EnrollmentResult<{ agent: EnrolledAgentView }>> {
+    const correlationId = input.correlationId ?? randomUUID();
+    const fail = (error: EnrollmentErrorCode, message: string): EnrollmentFailure => ({
+      ok: false,
+      error,
+      message,
+      correlationId,
+    });
+
+    const harness = input.harness.trim();
+    const name = input.name.trim();
+    if (harness.length === 0) return fail('validation_failed', 'harness must be non-empty');
+    if (name.length === 0 || name.length > 200) {
+      return fail('validation_failed', 'name must be non-empty and at most 200 characters');
+    }
+    if (input.replayMode !== undefined && input.replayMode !== 'actor-bound') {
+      // Seed-only rule (contract 3 §4.3): refused with nothing executed and no fence row.
+      return fail('validation_failed', 'replayMode must be actor-bound');
+    }
+    if (input.credential.mode === 'reference') {
+      if (input.credential.type !== undefined || input.credential.value !== undefined) {
+        return fail('validation_failed', 'a reference credential carries no type or value');
+      }
+    } else if (
+      input.credential.type !== 'api_key' ||
+      typeof input.credential.value !== 'string' ||
+      input.credential.value.length === 0
+    ) {
+      return fail('validation_failed', 'an intake credential requires type api_key and a value');
+    }
+    // Syntactic validity ends above; a well-formed name the live registry
+    // does not know is a precondition failure (§3.1 table).
+    if (!this.registry.has(harness)) {
+      return fail('precondition_failed', 'harness is not registered');
+    }
+
+    const normalized: NormalizedEnrollment = {
+      actorId: input.actorId,
+      harness,
+      name,
+      persona: input.persona ?? null,
+      model: input.model,
+      provider: input.provider,
+      credential: input.credential,
+      idempotencyKey: input.idempotencyKey,
+      correlationId,
+      digest: digestOf({
+        harness,
+        name,
+        persona: input.persona ?? null,
+        model: input.model,
+        provider: input.provider,
+        credential: input.credential,
+      }),
+    };
+
+    // Two attempts: a fence-race loser's transaction rolls back and the retry
+    // resolves through the replay path against the winner's committed row —
+    // or executes afresh if the winner aborted (§3.1 rule 5 concurrency). A
+    // unique-violation race never surfaces as an unhandled internal fault.
+    for (let attempt = 0; attempt < 2; attempt += 1) {
+      try {
+        return await this.db.transaction(async (tx) => this.enrollTx(tx, normalized));
+      } catch (error) {
+        if (error instanceof ConcurrentEnrollmentError && attempt === 0) continue;
+        if (error instanceof ConcurrentEnrollmentError) {
+          return fail('conflict', CONFLICT_MESSAGE);
+        }
+        // §4.4 fail-closed: whatever broke, the transaction rolled back and
+        // the refusal is the internal-fault class — no fallback write or read.
+        this.logger.error(
+          `agent.enroll failed closed (correlation=${correlationId}): ${
+            error instanceof Error ? error.name : 'unknown error'
+          }`,
+        );
+        return fail('internal_fault', 'internal fault');
+      }
+    }
+    return fail('internal_fault', 'internal fault');
+  }
+
+  private async enrollTx(
+    tx: Tx,
+    input: NormalizedEnrollment,
+  ): Promise<EnrollmentResult<{ agent: EnrolledAgentView }>> {
+    const fence = await this.fenceFor(tx, input.idempotencyKey);
+    if (fence) return this.replay(tx, fence, input);
+
+    if (input.credential.mode === 'reference') {
+      // §3.1 rule 3: the reference must resolve for (actor, provider).
+      const existing = await tx
+        .select({ id: providerCredentials.id })
+        .from(providerCredentials)
+        .where(
+          and(
+            eq(providerCredentials.userId, input.actorId),
+            eq(providerCredentials.provider, input.provider),
+          ),
+        )
+        .limit(1);
+      if (existing.length === 0) {
+        return {
+          ok: false,
+          error: 'precondition_failed',
+          message: 'credential reference does not resolve',
+          correlationId: input.correlationId,
+        };
+      }
+    } else {
+      // §3.1 rule 2: sealed-store write inside THIS transaction — a later
+      // failure rolls it back, leaving no orphan credential.
+      await this.writeSealedCredential(
+        tx,
+        input.actorId,
+        input.provider,
+        input.credential.value as string,
+      );
+    }
+
+    const agentRow = await this.insertAgentRow(tx, input);
+    const fenceRow = await this.insertFenceRow(tx, input, agentRow.id);
+    if (!fenceRow) {
+      // A same-(operation, key) winner committed first; abandon our writes.
+      throw new ConcurrentEnrollmentError();
+    }
+    await this.appendEvent(tx, {
+      eventType: 'agent.enrolled',
+      actorId: input.actorId,
+      agentId: agentRow.id,
+      correlationId: input.correlationId,
+      // §3.1 rule 6 payload: harness, provider, name, credentialMode — no credential material.
+      payload: {
+        harness: input.harness,
+        provider: input.provider,
+        name: input.name,
+        credentialMode: input.credential.mode,
+      },
+    });
+    return { ok: true, correlationId: input.correlationId, agent: agentView(agentRow) };
+  }
+
+  /**
+   * Replay path (§3.1 rule 5): a fresh submission of a recorded
+   * (operation, key). The actor is re-authorized exactly as a fresh
+   * submission (v1: authenticated actor — the guard already ran); then mode,
+   * scope, digest, and recorded-actor equality; then target-result read
+   * authority (owner or admin) on the referenced agent. ANY failure refuses
+   * with the single bounded conflict shape — constant, identifying no record.
+   * A passing replay executes nothing and appends only the non-mutation
+   * access event (with its outbox record — one outbox row per event).
+   */
+  private async replay(
+    tx: Tx,
+    fence: FenceRow,
+    input: NormalizedEnrollment,
+  ): Promise<EnrollmentResult<{ agent: EnrolledAgentView }>> {
+    const collision: EnrollmentFailure = {
+      ok: false,
+      error: 'conflict',
+      message: CONFLICT_MESSAGE,
+      correlationId: input.correlationId,
+    };
+    if (fence.replayMode !== 'actor-bound') return collision;
+    if (fence.authorizationScope !== AUTHORIZATION_SCOPE) return collision;
+    if (fence.payloadDigest !== input.digest) return collision;
+    if (fence.actorId !== input.actorId) return collision;
+
+    const rows = await tx.select().from(agents).where(eq(agents.id, fence.outcomeAgentId)).limit(1);
+    const agentRow = rows[0];
+    if (!agentRow) return collision;
+    const authorized =
+      agentRow.ownerId === input.actorId || (await this.isPlatformAdmin(tx, input.actorId));
+    if (!authorized) return collision;
+
+    await this.appendEvent(tx, {
+      eventType: 'agent.enrollment.replayed',
+      actorId: input.actorId,
+      agentId: agentRow.id,
+      correlationId: input.correlationId,
+      payload: { fenceId: fence.id },
+    });
+    return { ok: true, correlationId: input.correlationId, agent: agentView(agentRow) };
+  }
+
+  /**
+   * agent.enrollment.get (§3.2): owner-or-admin read. Unauthorized and
+   * missing fold to the same not_found wire shape (no existence oracle).
+   */
+  async getEnrollment(
+    actorId: string,
+    agentId: string,
+    correlationId?: string,
+  ): Promise<EnrollmentResult<{ agent: EnrolledAgentView }>> {
+    const resolvedCorrelation = correlationId ?? randomUUID();
+    try {
+      const rows = await this.db.select().from(agents).where(eq(agents.id, agentId)).limit(1);
+      const row = rows[0];
+      if (row) {
+        const authorized =
+          row.ownerId === actorId || (await this.isPlatformAdmin(this.db, actorId));
+        if (authorized) {
+          return { ok: true, correlationId: resolvedCorrelation, agent: agentView(row) };
+        }
+      }
+      return {
+        ok: false,
+        error: 'not_found',
+        message: NOT_FOUND_MESSAGE,
+        correlationId: resolvedCorrelation,
+      };
+    } catch (error) {
+      this.logger.error(
+        `agent.enrollment.get failed closed (correlation=${resolvedCorrelation}): ${
+          error instanceof Error ? error.name : 'unknown error'
+        }`,
+      );
+      return {
+        ok: false,
+        error: 'internal_fault',
+        message: 'internal fault',
+        correlationId: resolvedCorrelation,
+      };
+    }
+  }
+
+  private async fenceFor(tx: Tx, idempotencyKey: string): Promise<FenceRow | null> {
+    const rows = await tx
+      .select()
+      .from(agentIdempotencyFence)
+      .where(
+        and(
+          eq(agentIdempotencyFence.operation, ENROLLMENT_OPERATION),
+          eq(agentIdempotencyFence.idempotencyKey, idempotencyKey),
+        ),
+      )
+      .limit(1);
+    return rows[0] ?? null;
+  }
+
+  private async isPlatformAdmin(tx: Tx, actorId: string): Promise<boolean> {
+    const rows = await tx
+      .select({ role: users.role })
+      .from(users)
+      .where(eq(users.id, actorId))
+      .limit(1);
+    return rows[0]?.role === 'admin';
+  }
+
+  /**
+   * Sealed intake write, mirroring ProviderCredentialsService.store semantics
+   * (seal-at-rest, one row per (userId, provider)) but on the enrollment
+   * transaction (§3.1 rule 2). The plaintext exists only in this frame.
+   */
+  async writeSealedCredential(
+    tx: Tx,
+    userId: string,
+    provider: string,
+    value: string,
+  ): Promise<void> {
+    const encryptedValue = seal(value);
+    await tx
+      .insert(providerCredentials)
+      .values({ userId, provider, credentialType: 'api_key', encryptedValue, metadata: null })
+      .onConflictDoUpdate({
+        target: [providerCredentials.userId, providerCredentials.provider],
+        set: {
+          credentialType: 'api_key',
+          encryptedValue,
+          metadata: null,
+          updatedAt: new Date(),
+        },
+      });
+  }
+
+  async insertAgentRow(tx: Tx, input: NormalizedEnrollment): Promise<AgentRow> {
+    const rows = await tx
+      .insert(agents)
+      .values({
+        name: input.name,
+        provider: input.provider,
+        model: input.model,
+        harness: input.harness,
+        systemPrompt: input.persona,
+        // §3.1 rule 4: owner is the authenticated actor; is_system stays default false.
+        ownerId: input.actorId,
+        enrolledAt: new Date(),
+      })
+      .returning();
+    const row = rows[0];
+    if (!row) throw new Error('agent insert returned no row');
+    return row;
+  }
+
+  async insertFenceRow(
+    tx: Tx,
+    input: NormalizedEnrollment,
+    outcomeAgentId: string,
+  ): Promise<FenceRow | null> {
+    const rows = await tx
+      .insert(agentIdempotencyFence)
+      .values({
+        operation: ENROLLMENT_OPERATION,
+        idempotencyKey: input.idempotencyKey,
+        actorId: input.actorId,
+        authorizationScope: AUTHORIZATION_SCOPE,
+        payloadDigest: input.digest,
+        replayMode: 'actor-bound',
+        outcomeAgentId,
+      })
+      .onConflictDoNothing()
+      .returning();
+    return rows[0] ?? null;
+  }
+
+  /** Append one audit event and its outbox record on the caller's transaction (one outbox row per event). */
+  async appendEvent(
+    tx: Tx,
+    input: {
+      eventType: 'agent.enrolled' | 'agent.enrollment.replayed';
+      actorId: string;
+      agentId: string;
+      correlationId: string;
+      payload: Record<string, unknown>;
+      causationId?: string;
+    },
+  ): Promise<void> {
+    const inserted = await tx
+      .insert(agentAuditEvents)
+      .values({
+        eventType: input.eventType,
+        actorId: input.actorId,
+        agentId: input.agentId,
+        correlationId: input.correlationId,
+        causationId: input.causationId ?? null,
+        payload: input.payload,
+      })
+      .returning();
+    const event = inserted[0];
+    if (!event) throw new Error('agent audit event insert returned no row');
+    await this.insertOutboxRow(tx, event.id, input.correlationId);
+  }
+
+  async insertOutboxRow(tx: Tx, eventId: string, correlationId: string): Promise<void> {
+    await tx.insert(agentOutbox).values({ eventId, correlationId });
+  }
+}

apps/gateway/src/enrollment/enrollment.service.ts

@@ -0,0 +1,45 @@
+import { HttpException, HttpStatus, Injectable } from '@nestjs/common';
+import type {
+  EnrollmentErrorCode,
+  EnrollmentFailure,
+  EnrollmentResult,
+} from './enrollment.repository.js';
+
+/**
+ * Maps enrollment result unions onto the closed HTTP status set (design
+ * docs/plans/2026-08-29-agent-enrollment-command-design.md §3.3, contract 5
+ * §4.2). Every refusal body carries the correlation id (contract 5 §4.3
+ * end-to-end traceability) alongside the enum code. `not_found` carries one
+ * fixed message for every cause — missing agent and unauthorized caller are
+ * indistinguishable on the wire (§3.2).
+ */
+const HTTP_STATUS: Record<EnrollmentErrorCode, HttpStatus> = {
+  validation_failed: HttpStatus.BAD_REQUEST,
+  authentication_failed: HttpStatus.UNAUTHORIZED,
+  authorization_refused: HttpStatus.FORBIDDEN,
+  not_found: HttpStatus.NOT_FOUND,
+  conflict: HttpStatus.CONFLICT,
+  precondition_failed: HttpStatus.UNPROCESSABLE_ENTITY,
+  internal_fault: HttpStatus.INTERNAL_SERVER_ERROR,
+};
+
+@Injectable()
+export class EnrollmentService {
+  unwrap<T>(result: EnrollmentResult<T>): { ok: true; correlationId: string } & T {
+    if (result.ok) return result;
+    throw this.toException(result);
+  }
+
+  private toException(failure: EnrollmentFailure): HttpException {
+    const status = HTTP_STATUS[failure.error];
+    return new HttpException(
+      {
+        statusCode: status,
+        error: failure.error,
+        message: failure.message,
+        correlationId: failure.correlationId,
+      },
+      status,
+    );
+  }
+}

apps/gateway/src/validation-pipe-check.ts

@@ -13,6 +13,11 @@ import {
   TransferEstateDto,
   TransferPlatformProjectDto,
 } from './hierarchy/hierarchy.dto.js';
+import {
+  EnrollAgentDto,
+  EnrollCredentialDto,
+  GetEnrollmentQueryDto,
+} from './enrollment/enrollment.dto.js';
 
 /**
  * Boot-time self-check: the global ValidationPipe must be able to SEE the
@@ -105,6 +110,31 @@ export const PIPE_GUARDED_DTOS: Array<{
     target: ChangeGrantDto,
     properties: ['role', 'idempotencyKey'],
   },
+  {
+    name: 'EnrollAgentDto',
+    target: EnrollAgentDto,
+    properties: [
+      'harness',
+      'name',
+      'persona',
+      'model',
+      'provider',
+      'credential',
+      'idempotencyKey',
+      'correlationId',
+      'replayMode',
+    ],
+  },
+  {
+    name: 'EnrollCredentialDto',
+    target: EnrollCredentialDto,
+    properties: ['mode', 'type', 'value'],
+  },
+  {
+    name: 'GetEnrollmentQueryDto',
+    target: GetEnrollmentQueryDto,
+    properties: ['correlationId'],
+  },
 ];
 
 export class PipeMetatypeCheckError extends Error {

packages/db/drizzle/0021_agent_enrollment.sql

@@ -0,0 +1,47 @@
+CREATE TYPE "public"."agent_outbox_status" AS ENUM('pending', 'processing', 'delivered');--> statement-breakpoint
+CREATE TABLE "agent_audit_events" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"seq" bigint GENERATED ALWAYS AS IDENTITY (sequence name "agent_audit_events_seq_seq" INCREMENT BY 1 MINVALUE 1 MAXVALUE 9223372036854775807 START WITH 1 CACHE 1),
+	"event_type" text NOT NULL,
+	"actor_id" text NOT NULL,
+	"agent_id" uuid NOT NULL,
+	"correlation_id" text NOT NULL,
+	"causation_id" uuid,
+	"payload" jsonb NOT NULL,
+	"created_at" timestamp with time zone DEFAULT now() NOT NULL,
+	CONSTRAINT "agent_audit_events_type_check" CHECK (event_type IN ('agent.enrolled', 'agent.enrollment.replayed'))
+);
+--> statement-breakpoint
+CREATE TABLE "agent_idempotency_fence" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"operation" text NOT NULL,
+	"idempotency_key" text NOT NULL,
+	"actor_id" text NOT NULL,
+	"authorization_scope" text NOT NULL,
+	"payload_digest" text NOT NULL,
+	"replay_mode" text DEFAULT 'actor-bound' NOT NULL,
+	"outcome_agent_id" uuid NOT NULL,
+	"created_at" timestamp with time zone DEFAULT now() NOT NULL,
+	CONSTRAINT "agent_idempotency_fence_replay_mode_check" CHECK (replay_mode IN ('actor-bound', 'shared'))
+);
+--> statement-breakpoint
+CREATE TABLE "agent_outbox" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"event_id" uuid NOT NULL,
+	"correlation_id" text NOT NULL,
+	"status" "agent_outbox_status" DEFAULT 'pending' NOT NULL,
+	"created_at" timestamp with time zone DEFAULT now() NOT NULL,
+	"updated_at" timestamp with time zone DEFAULT now() NOT NULL,
+	"delivered_at" timestamp with time zone
+);
+--> statement-breakpoint
+ALTER TABLE "agents" ADD COLUMN "harness" text;--> statement-breakpoint
+ALTER TABLE "agents" ADD COLUMN "enrolled_at" timestamp with time zone;--> statement-breakpoint
+ALTER TABLE "agent_audit_events" ADD CONSTRAINT "agent_audit_events_causation_id_agent_audit_events_id_fk" FOREIGN KEY ("causation_id") REFERENCES "public"."agent_audit_events"("id") ON DELETE restrict ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "agent_outbox" ADD CONSTRAINT "agent_outbox_event_id_agent_audit_events_id_fk" FOREIGN KEY ("event_id") REFERENCES "public"."agent_audit_events"("id") ON DELETE restrict ON UPDATE no action;--> statement-breakpoint
+CREATE UNIQUE INDEX "agent_audit_events_seq_idx" ON "agent_audit_events" USING btree ("seq");--> statement-breakpoint
+CREATE INDEX "agent_audit_events_agent_seq_idx" ON "agent_audit_events" USING btree ("agent_id","seq");--> statement-breakpoint
+CREATE INDEX "agent_audit_events_correlation_idx" ON "agent_audit_events" USING btree ("correlation_id");--> statement-breakpoint
+CREATE UNIQUE INDEX "agent_idempotency_fence_operation_key_idx" ON "agent_idempotency_fence" USING btree ("operation","idempotency_key");--> statement-breakpoint
+CREATE UNIQUE INDEX "agent_outbox_event_idx" ON "agent_outbox" USING btree ("event_id");--> statement-breakpoint
+CREATE INDEX "agent_outbox_status_created_idx" ON "agent_outbox" USING btree ("status","created_at");

packages/db/drizzle/meta/_journal.json

@@ -148,6 +148,13 @@
       "when": 1787963521142,
       "tag": "0020_special_betty_brant",
       "breakpoints": true
+    },
+    {
+      "idx": 21,
+      "version": "7",
+      "when": 1788053011351,
+      "tag": "0021_agent_enrollment",
+      "breakpoints": true
     }
   ]
 }

packages/db/src/agent-enrollment.witness.test.ts

@@ -0,0 +1,412 @@
+/**
+ * Agent enrollment schema witnesses — M4-4a, the schema-level half of the
+ * witness list in docs/plans/2026-08-29-agent-enrollment-command-design.md §5.
+ *
+ * Witnesses the guarantees migration 0021's tables themselves carry: the
+ * event-type CHECK, monotonic per-agent append order (`seq`), deletion-safe
+ * linkage (no foreign key from the events or fence tables into `agents` —
+ * rows survive a legacy CRUD DELETE of the agent), the causation self-FK,
+ * the outbox's FK/uniqueness/status shape, the fence's UNIQUE
+ * (operation, key) and replay-mode CHECK, and the nullable enrollment
+ * columns on `agents` (legacy rows insert without them). The command-level
+ * witnesses (never-echo, same-tx atomicity, replay semantics, correlation,
+ * CLI parity, fail-closed) belong to the M4-4b implementation slice.
+ *
+ * Two legs run the same witness body:
+ *  - PGlite (WASM Postgres): always runs.
+ *  - Real PostgreSQL: runs when DATABASE_URL is set — the binding witness;
+ *    CI migrates ci-postgres before `pnpm test`.
+ */
+import { randomUUID } from 'node:crypto';
+import { mkdtempSync, rmSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { sql } from 'drizzle-orm';
+import { afterAll, beforeAll, describe, expect, it } from 'vitest';
+import { createDb } from './client.js';
+import { createPgliteDb } from './client-pglite.js';
+import { runPgliteMigrations } from './migrate.js';
+import { agentAuditEvents, agentIdempotencyFence, agentOutbox, agents } from './schema.js';
+
+type AnyDb = {
+  db: {
+    insert: (t: unknown) => { values: (v: unknown) => Promise<unknown> };
+    execute: (q: unknown) => Promise<{ rows?: unknown[] } | unknown[]>;
+  };
+  close: () => Promise<void>;
+};
+
+/** Match a constraint failure anywhere along drizzle's cause chain. */
+async function expectViolation(p: Promise<unknown>, re: RegExp, label = ''): Promise<void> {
+  let err: unknown;
+  try {
+    await p;
+  } catch (e) {
+    err = e;
+  }
+  expect(err, label || 'expected the statement to be refused').toBeDefined();
+  const messages: string[] = [];
+  let cur: unknown = err;
+  while (cur instanceof Error) {
+    messages.push(cur.message);
+    cur = (cur as { cause?: unknown }).cause;
+  }
+  expect(messages.join(' | '), label).toMatch(re);
+}
+
+function rows(res: { rows?: unknown[] } | unknown[]): Record<string, unknown>[] {
+  return (Array.isArray(res) ? res : (res.rows ?? [])) as Record<string, unknown>[];
+}
+
+/** Unique per-run prefix so real-PG runs never collide and clean up safely. */
+const T = `agent-e-${randomUUID().slice(0, 8)}`;
+
+type EventInsert = typeof agentAuditEvents.$inferInsert;
+
+function eventRow(overrides: Partial<EventInsert> = {}): EventInsert {
+  return {
+    eventType: 'agent.enrolled',
+    actorId: `${T}-actor`,
+    agentId: randomUUID(),
+    correlationId: `${T}-corr-${randomUUID()}`,
+    payload: {
+      harness: 'claude-code',
+      provider: 'anthropic',
+      name: 'x',
+      credentialMode: 'reference',
+    },
+    ...overrides,
+  };
+}
+
+type FenceInsert = typeof agentIdempotencyFence.$inferInsert;
+
+function fenceRow(overrides: Partial<FenceInsert> = {}): FenceInsert {
+  return {
+    operation: 'agent.enroll',
+    idempotencyKey: `${T}-${randomUUID()}`,
+    actorId: `${T}-actor`,
+    authorizationScope: 'platform-user',
+    payloadDigest: `${T}-digest`,
+    outcomeAgentId: randomUUID(),
+    ...overrides,
+  };
+}
+
+function witnessSuite(getHandle: () => AnyDb): void {
+  const db = () => getHandle().db as unknown as ReturnType<typeof createDb>['db'];
+
+  afterAll(async () => {
+    const d = db();
+    await d.execute(sql`DELETE FROM agent_outbox WHERE correlation_id LIKE ${T + '%'}`);
+    // Caused events first: the causation self-FK is RESTRICT.
+    await d.execute(
+      sql`DELETE FROM agent_audit_events WHERE correlation_id LIKE ${T + '%'} AND causation_id IS NOT NULL`,
+    );
+    await d.execute(sql`DELETE FROM agent_audit_events WHERE correlation_id LIKE ${T + '%'}`);
+    await d.execute(sql`DELETE FROM agent_idempotency_fence WHERE actor_id LIKE ${T + '%'}`);
+    await d.execute(sql`DELETE FROM agents WHERE name LIKE ${T + '%'}`);
+  });
+
+  // ── agents: nullable enrollment columns (no backfill semantics) ────────────
+
+  it('legacy agent rows insert without enrollment columns; enrolled rows carry both', async () => {
+    const legacyId = randomUUID();
+    await db()
+      .insert(agents)
+      .values({
+        id: legacyId,
+        name: `${T}-legacy`,
+        provider: 'anthropic',
+        model: 'claude-fable-5',
+      });
+    const legacy = rows(
+      await db().execute(sql`SELECT harness, enrolled_at FROM agents WHERE id = ${legacyId}`),
+    )[0]!;
+    expect(legacy['harness']).toBeNull();
+    expect(legacy['enrolled_at']).toBeNull();
+
+    const enrolledId = randomUUID();
+    await db()
+      .insert(agents)
+      .values({
+        id: enrolledId,
+        name: `${T}-enrolled`,
+        provider: 'anthropic',
+        model: 'claude-fable-5',
+        harness: 'claude-code',
+        enrolledAt: new Date(),
+      });
+    const enrolled = rows(
+      await db().execute(sql`SELECT harness, enrolled_at FROM agents WHERE id = ${enrolledId}`),
+    )[0]!;
+    expect(enrolled['harness']).toBe('claude-code');
+    expect(enrolled['enrolled_at']).not.toBeNull();
+  });
+
+  // ── agent_audit_events: CHECK, ordering, deletion-safe linkage ─────────────
+
+  it('accepts both declared event types and refuses an undeclared one', async () => {
+    await db()
+      .insert(agentAuditEvents)
+      .values(eventRow({ eventType: 'agent.enrolled' }));
+    await db()
+      .insert(agentAuditEvents)
+      .values(eventRow({ eventType: 'agent.enrollment.replayed' }));
+    await expectViolation(
+      db()
+        .insert(agentAuditEvents)
+        .values(eventRow({ eventType: 'agent.deleted' })),
+      /type_check|violates check/i,
+      'undeclared event type must be refused',
+    );
+  });
+
+  it('assigns strictly increasing seq in insert order for one agent', async () => {
+    const agentId = randomUUID();
+    const c1 = `${T}-seq-1-${randomUUID()}`;
+    const c2 = `${T}-seq-2-${randomUUID()}`;
+    await db()
+      .insert(agentAuditEvents)
+      .values(eventRow({ agentId, correlationId: c1 }));
+    await db()
+      .insert(agentAuditEvents)
+      .values(eventRow({ agentId, eventType: 'agent.enrollment.replayed', correlationId: c2 }));
+    const res = rows(
+      await db().execute(
+        sql`SELECT correlation_id, seq FROM agent_audit_events WHERE agent_id = ${agentId} ORDER BY seq ASC`,
+      ),
+    );
+    expect(res.map((r) => r['correlation_id'])).toEqual([c1, c2]);
+    expect(Number(res[1]!['seq'])).toBeGreaterThan(Number(res[0]!['seq']));
+  });
+
+  it('has no foreign key into agents, and events survive agent deletion', async () => {
+    const fks = rows(
+      await db().execute(sql`
+        SELECT ccu.table_name AS referenced_table
+        FROM information_schema.table_constraints tc
+        JOIN information_schema.constraint_column_usage ccu
+          ON ccu.constraint_name = tc.constraint_name AND ccu.constraint_schema = tc.constraint_schema
+        WHERE tc.constraint_type = 'FOREIGN KEY' AND tc.table_name = 'agent_audit_events'
+      `),
+    );
+    // The causation self-FK is the ONLY foreign key on the events table.
+    expect([...new Set(fks.map((r) => r['referenced_table']))]).toEqual(['agent_audit_events']);
+
+    const agentId = randomUUID();
+    await db()
+      .insert(agents)
+      .values({ id: agentId, name: `${T}-doomed`, provider: 'anthropic', model: 'claude-fable-5' });
+    const corr = `${T}-survive-${randomUUID()}`;
+    await db()
+      .insert(agentAuditEvents)
+      .values(eventRow({ agentId, correlationId: corr }));
+    await db().execute(sql`DELETE FROM agents WHERE id = ${agentId}`);
+    const after = rows(
+      await db().execute(
+        sql`SELECT agent_id FROM agent_audit_events WHERE correlation_id = ${corr}`,
+      ),
+    );
+    expect(after).toHaveLength(1);
+    expect(after[0]!['agent_id']).toBe(agentId);
+  });
+
+  it('enforces the causation self-FK and RESTRICTs deleting a cause', async () => {
+    await expectViolation(
+      db()
+        .insert(agentAuditEvents)
+        .values(eventRow({ causationId: randomUUID() })),
+      /foreign key/i,
+      'causation must reference an existing event',
+    );
+    const causeCorr = `${T}-cause-${randomUUID()}`;
+    await db()
+      .insert(agentAuditEvents)
+      .values(eventRow({ correlationId: causeCorr }));
+    const cause = rows(
+      await db().execute(
+        sql`SELECT id FROM agent_audit_events WHERE correlation_id = ${causeCorr}`,
+      ),
+    )[0]!;
+    await db()
+      .insert(agentAuditEvents)
+      .values(
+        eventRow({
+          eventType: 'agent.enrollment.replayed',
+          causationId: cause['id'] as string,
+        }),
+      );
+    await expectViolation(
+      db().execute(sql`DELETE FROM agent_audit_events WHERE id = ${cause['id'] as string}`),
+      /foreign key/i,
+      'a cause with dependent events must not be deletable',
+    );
+  });
+
+  // ── agent_outbox shape ─────────────────────────────────────────────────────
+
+  it('outbox rows require an existing event, one outbox row per event, closed status enum', async () => {
+    await expectViolation(
+      db()
+        .insert(agentOutbox)
+        .values({ eventId: randomUUID(), correlationId: `${T}-corr` }),
+      /foreign key/i,
+      'outbox must reference an existing event',
+    );
+    const corr = `${T}-ob-${randomUUID()}`;
+    await db()
+      .insert(agentAuditEvents)
+      .values(eventRow({ correlationId: corr }));
+    const event = rows(
+      await db().execute(sql`SELECT id FROM agent_audit_events WHERE correlation_id = ${corr}`),
+    )[0]!;
+    const eventId = event['id'] as string;
+    await db().insert(agentOutbox).values({ eventId, correlationId: corr });
+    await expectViolation(
+      db()
+        .insert(agentOutbox)
+        .values({ eventId, correlationId: `${T}-ob2` }),
+      /duplicate key|unique/i,
+      'one outbox record per event',
+    );
+    await expectViolation(
+      db().execute(
+        sql`INSERT INTO agent_outbox (event_id, correlation_id, status)
+            VALUES (${eventId}, ${`${T}-ob3`}, 'failed')`,
+      ),
+      /invalid input value for enum|22P02/i,
+      'status outside pending/processing/delivered must be refused',
+    );
+  });
+
+  it('outbox FK RESTRICTs event deletion while the outbox row exists', async () => {
+    const corr = `${T}-obr-${randomUUID()}`;
+    await db()
+      .insert(agentAuditEvents)
+      .values(eventRow({ correlationId: corr }));
+    const event = rows(
+      await db().execute(sql`SELECT id FROM agent_audit_events WHERE correlation_id = ${corr}`),
+    )[0]!;
+    await db()
+      .insert(agentOutbox)
+      .values({ eventId: event['id'] as string, correlationId: corr });
+    await expectViolation(
+      db().execute(sql`DELETE FROM agent_audit_events WHERE id = ${event['id'] as string}`),
+      /foreign key/i,
+    );
+  });
+
+  // ── agent_idempotency_fence: (operation, key) uniqueness, mode CHECK ───────
+
+  it('refuses a duplicate (operation, key) pair but allows the same key under another operation', async () => {
+    const key = `${T}-fence-${randomUUID()}`;
+    await db()
+      .insert(agentIdempotencyFence)
+      .values(fenceRow({ idempotencyKey: key }));
+    await expectViolation(
+      db()
+        .insert(agentIdempotencyFence)
+        .values(fenceRow({ idempotencyKey: key })),
+      /duplicate key|unique/i,
+      'fence uniqueness is (operation, key)',
+    );
+    // Same key, different operation identifier: a distinct fence.
+    await db()
+      .insert(agentIdempotencyFence)
+      .values(fenceRow({ idempotencyKey: key, operation: 'agent.other' }));
+  });
+
+  it('defaults replay mode to actor-bound and refuses an undeclared mode', async () => {
+    const key = `${T}-mode-${randomUUID()}`;
+    await db()
+      .insert(agentIdempotencyFence)
+      .values(fenceRow({ idempotencyKey: key }));
+    const row = rows(
+      await db().execute(
+        sql`SELECT replay_mode FROM agent_idempotency_fence WHERE idempotency_key = ${key}`,
+      ),
+    )[0]!;
+    expect(row['replay_mode']).toBe('actor-bound');
+    await expectViolation(
+      db()
+        .insert(agentIdempotencyFence)
+        .values(fenceRow({ replayMode: 'unbound' as 'actor-bound' })),
+      /replay_mode_check|violates check/i,
+      'a mode outside actor-bound/shared must be refused',
+    );
+  });
+
+  it('fence has no foreign key at all, and rows survive agent deletion', async () => {
+    const fks = rows(
+      await db().execute(sql`
+        SELECT ccu.table_name AS referenced_table
+        FROM information_schema.table_constraints tc
+        JOIN information_schema.constraint_column_usage ccu
+          ON ccu.constraint_name = tc.constraint_name AND ccu.constraint_schema = tc.constraint_schema
+        WHERE tc.constraint_type = 'FOREIGN KEY' AND tc.table_name = 'agent_idempotency_fence'
+      `),
+    );
+    expect(fks).toHaveLength(0);
+
+    const agentId = randomUUID();
+    await db()
+      .insert(agents)
+      .values({
+        id: agentId,
+        name: `${T}-fdoomed`,
+        provider: 'anthropic',
+        model: 'claude-fable-5',
+      });
+    const key = `${T}-fsurvive-${randomUUID()}`;
+    await db()
+      .insert(agentIdempotencyFence)
+      .values(fenceRow({ idempotencyKey: key, outcomeAgentId: agentId }));
+    await db().execute(sql`DELETE FROM agents WHERE id = ${agentId}`);
+    const after = rows(
+      await db().execute(
+        sql`SELECT outcome_agent_id FROM agent_idempotency_fence WHERE idempotency_key = ${key}`,
+      ),
+    );
+    expect(after).toHaveLength(1);
+    expect(after[0]!['outcome_agent_id']).toBe(agentId);
+  });
+}
+
+// ── Leg 1: PGlite (always runs — local witness signal) ───────────────────────
+
+describe('agent enrollment schema witnesses — PGlite', () => {
+  let dir: string;
+  let handle: ReturnType<typeof createPgliteDb>;
+
+  beforeAll(async () => {
+    dir = mkdtempSync(join(tmpdir(), 'agent-enroll-witness-'));
+    handle = createPgliteDb(dir);
+    await runPgliteMigrations(handle);
+  });
+
+  afterAll(async () => {
+    await handle.close();
+    rmSync(dir, { recursive: true, force: true });
+  });
+
+  witnessSuite(() => handle as unknown as AnyDb);
+});
+
+// ── Leg 2: real PostgreSQL (binding witness, ci-postgres in CI) ──────────────
+
+const hasPostgres = Boolean(process.env['DATABASE_URL']);
+
+describe.skipIf(!hasPostgres)('agent enrollment schema witnesses — real PostgreSQL', () => {
+  let handle: ReturnType<typeof createDb>;
+
+  beforeAll(() => {
+    handle = createDb(process.env['DATABASE_URL']!);
+  });
+
+  afterAll(async () => {
+    await handle.close();
+  });
+
+  witnessSuite(() => handle as unknown as AnyDb);
+});

packages/db/src/schema.ts

@@ -302,6 +302,11 @@ export const agents = pgTable(
     skills: jsonb('skills').$type<string[]>(),
     isSystem: boolean('is_system').notNull().default(false),
     config: jsonb('config'),
+    // Enrollment (M4-4, docs/plans/2026-08-29-agent-enrollment-command-design.md §4).
+    // NULL on both marks a legacy (non-enrolled) row; no backfill — enrollment
+    // is a fact the rank-4 command creates, not one to invent for existing rows.
+    harness: text('harness'),
+    enrolledAt: timestamp('enrolled_at', { withTimezone: true }),
     createdAt: timestamp('created_at', { withTimezone: true }).notNull().defaultNow(),
     updatedAt: timestamp('updated_at', { withTimezone: true }).notNull().defaultNow(),
   },
@@ -1279,3 +1284,109 @@ export const hierarchyOutbox = pgTable(
     index('hierarchy_outbox_status_created_idx').on(t.status, t.createdAt),
   ],
 );
+
+// ---------------------------------------------------------------------------
+// Agent enrollment (M4-4) — rank-4 command family audit/outbox/fence stores.
+// Design: docs/plans/2026-08-29-agent-enrollment-command-design.md §4.
+// Pattern reuse from the hierarchy audit/outbox pair, separate store. Audit
+// rows reference the agent by snapshot id, deliberately with NO FK, so audit
+// history survives agent deletion through the legacy CRUD DELETE path.
+// Idempotency for this family lives in agent_idempotency_fence (contract 3
+// §4.3 envelope, ratified into contract 5 §4 via contract 3 §7 item 4) — the
+// audit and outbox tables carry no idempotency key of their own.
+
+export const AGENT_AUDIT_EVENT_TYPES = [
+  // Semantic mutation event of agent.enroll.
+  'agent.enrolled',
+  // Non-mutation access class: a passing idempotent replay appends this and
+  // nothing else (accessing principal, current correlation id, fence-row
+  // reference in the payload).
+  'agent.enrollment.replayed',
+] as const;
+
+export const agentAuditEvents = pgTable(
+  'agent_audit_events',
+  {
+    id: uuid('id').primaryKey().defaultRandom(),
+    // Global append order; per-agent ordering is a filter on agent_id ordered
+    // by seq.
+    seq: bigint('seq', { mode: 'number' }).notNull().generatedAlwaysAsIdentity(),
+    eventType: text('event_type').notNull(),
+    // No FK: audit events outlive every principal and every target.
+    actorId: text('actor_id').notNull(),
+    agentId: uuid('agent_id').notNull(),
+    correlationId: text('correlation_id').notNull(),
+    causationId: uuid('causation_id').references((): AnyPgColumn => agentAuditEvents.id, {
+      onDelete: 'restrict',
+    }),
+    // Immutable snapshot at event time; never carries credential material
+    // (§3.1 rule 1: actor, agent id, harness, provider, name, credentialMode).
+    payload: jsonb('payload').notNull(),
+    createdAt: timestamp('created_at', { withTimezone: true }).notNull().defaultNow(),
+  },
+  (t) => [
+    uniqueIndex('agent_audit_events_seq_idx').on(t.seq),
+    index('agent_audit_events_agent_seq_idx').on(t.agentId, t.seq),
+    index('agent_audit_events_correlation_idx').on(t.correlationId),
+    check(
+      'agent_audit_events_type_check',
+      sql`event_type IN ('agent.enrolled', 'agent.enrollment.replayed')`,
+    ),
+  ],
+);
+
+export const agentOutboxStatusEnum = pgEnum('agent_outbox_status', [
+  'pending',
+  'processing',
+  'delivered',
+]);
+
+export const agentOutbox = pgTable(
+  'agent_outbox',
+  {
+    id: uuid('id').primaryKey().defaultRandom(),
+    // FK into the append-only events table: never dangles, RESTRICT is safe.
+    eventId: uuid('event_id')
+      .notNull()
+      .references(() => agentAuditEvents.id, { onDelete: 'restrict' }),
+    correlationId: text('correlation_id').notNull(),
+    status: agentOutboxStatusEnum('status').notNull().default('pending'),
+    createdAt: timestamp('created_at', { withTimezone: true }).notNull().defaultNow(),
+    updatedAt: timestamp('updated_at', { withTimezone: true }).notNull().defaultNow(),
+    deliveredAt: timestamp('delivered_at', { withTimezone: true }),
+  },
+  (t) => [
+    uniqueIndex('agent_outbox_event_idx').on(t.eventId),
+    index('agent_outbox_status_created_idx').on(t.status, t.createdAt),
+  ],
+);
+
+// Contract 3 §4.3 fence shape. Uniqueness is (operation, key); the recorded
+// replay mode is always 'actor-bound' for this family (`shared` is seed-only
+// and refused at validation — design §3.1), but the column keeps the ratified
+// envelope shape and serves the mode-mismatch collision check. The payload
+// digest input EXCLUDES the credential value (design §3.1 rule 5).
+export const agentIdempotencyFence = pgTable(
+  'agent_idempotency_fence',
+  {
+    id: uuid('id').primaryKey().defaultRandom(),
+    operation: text('operation').notNull(),
+    idempotencyKey: text('idempotency_key').notNull(),
+    // No FK: fence rows outlive principals, mirroring the audit tables.
+    actorId: text('actor_id').notNull(),
+    authorizationScope: text('authorization_scope').notNull(),
+    payloadDigest: text('payload_digest').notNull(),
+    replayMode: text('replay_mode').notNull().default('actor-bound'),
+    // Committed-outcome reference (the enrolled agent's id). Snapshot value,
+    // no FK: the fence must keep answering replays after a legacy DELETE.
+    outcomeAgentId: uuid('outcome_agent_id').notNull(),
+    createdAt: timestamp('created_at', { withTimezone: true }).notNull().defaultNow(),
+  },
+  (t) => [
+    uniqueIndex('agent_idempotency_fence_operation_key_idx').on(t.operation, t.idempotencyKey),
+    check(
+      'agent_idempotency_fence_replay_mode_check',
+      sql`replay_mode IN ('actor-bound', 'shared')`,
+    ),
+  ],
+);

packages/mosaic/src/commands/agent-enrollment-command.spec.ts

@@ -0,0 +1,218 @@
+import { Command } from 'commander';
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { registerAgentCommand, runEnroll, runGetEnrollment } from './agent.js';
+import { enrollAgent, fetchEnrollment } from '../tui/gateway-api.js';
+
+/**
+ * CLI-parity witness for the agent enrollment family (design
+ * docs/plans/2026-08-29-agent-enrollment-command-design.md §5 item 10;
+ * contract 5 §4.5): `mosaic agent enroll` / `mosaic agent enrollment <id>`
+ * invoke the same gateway commands with the same request/result/error
+ * contracts the web client uses. The gateway side of the same routes is
+ * witnessed in apps/gateway/src/enrollment/enrollment-commands.integration.test.ts.
+ */
+
+const gateway = 'https://gateway.example.test';
+const auth = { gateway, cookie: 'session=test' };
+
+const agentBody = {
+  id: '3fca4f6a-1111-4222-8333-444455556666',
+  name: 'Nova',
+  provider: 'anthropic',
+  model: 'claude-test',
+  status: 'idle',
+  harness: 'fake-harness',
+  persona: null,
+  ownerId: 'user-1',
+  enrolledAt: '2026-08-29T00:00:00.000Z',
+  createdAt: '2026-08-29T00:00:00.000Z',
+};
+
+const okResponse = (correlationId: string) =>
+  new Response(JSON.stringify({ ok: true, correlationId, agent: agentBody }), {
+    status: 201,
+    headers: { 'Content-Type': 'application/json' },
+  });
+
+afterEach(() => {
+  vi.unstubAllGlobals();
+  vi.restoreAllMocks();
+  process.exitCode = undefined;
+});
+
+describe('agent enrollment CLI registration', (): void => {
+  it('registers enroll and enrollment subcommands under `mosaic agent`', () => {
+    const program = new Command();
+    const cmd = registerAgentCommand(program);
+    const names = cmd.commands.map((c) => c.name());
+    expect(names).toContain('enroll');
+    expect(names).toContain('enrollment');
+  });
+
+  it('the enroll subcommand exposes no argv flag that carries a credential value', () => {
+    const program = new Command();
+    const cmd = registerAgentCommand(program);
+    const enroll = cmd.commands.find((c) => c.name() === 'enroll');
+    expect(enroll).toBeDefined();
+    const flags = (enroll as Command).options.map((o) => o.flags);
+    // --credential selects the MODE only; the intake value arrives via stdin.
+    expect(flags).toContain('--credential <mode>');
+    for (const flag of flags) {
+      expect(flag).not.toMatch(/value|key <secret>|api-key/i);
+    }
+  });
+});
+
+describe('agent.enroll CLI parity', (): void => {
+  it('posts the §3.1 request shape for reference mode and surfaces the typed result', async () => {
+    const fetchMock = vi.fn(async () => okResponse('corr-ref'));
+    vi.stubGlobal('fetch', fetchMock);
+    const log = vi.spyOn(console, 'log').mockImplementation(() => {});
+
+    await runEnroll(auth, {
+      gateway,
+      harness: 'fake-harness',
+      name: 'Nova',
+      model: 'claude-test',
+      provider: 'anthropic',
+      credential: 'reference',
+      idempotencyKey: '9c1a26be-0000-4000-8000-000000000001',
+      correlationId: 'corr-ref',
+    });
+
+    expect(fetchMock).toHaveBeenCalledTimes(1);
+    const [url, init] = fetchMock.mock.calls[0] as unknown as [string, RequestInit];
+    expect(url).toBe(`${gateway}/api/enrollment/agents`);
+    expect(init.method).toBe('POST');
+    expect(JSON.parse(init.body as string)).toEqual({
+      harness: 'fake-harness',
+      name: 'Nova',
+      model: 'claude-test',
+      provider: 'anthropic',
+      credential: { mode: 'reference' },
+      idempotencyKey: '9c1a26be-0000-4000-8000-000000000001',
+      correlationId: 'corr-ref',
+    });
+    expect(log.mock.calls.flat().join('\n')).toContain(agentBody.id);
+    expect(process.exitCode).toBeUndefined();
+  });
+
+  it('intake mode reads the credential from the injected stdin reader, never argv', async () => {
+    const fetchMock = vi.fn(async () => okResponse('corr-intake'));
+    vi.stubGlobal('fetch', fetchMock);
+    vi.spyOn(console, 'log').mockImplementation(() => {});
+
+    await runEnroll(
+      auth,
+      {
+        gateway,
+        harness: 'fake-harness',
+        name: 'Nova',
+        model: 'claude-test',
+        provider: 'anthropic',
+        credential: 'intake',
+        idempotencyKey: '9c1a26be-0000-4000-8000-000000000002',
+      },
+      async () => 'stdin-provided-key',
+    );
+
+    const [, init] = fetchMock.mock.calls[0] as unknown as [string, RequestInit];
+    const body = JSON.parse(init.body as string) as { credential: Record<string, string> };
+    expect(body.credential).toEqual({
+      mode: 'intake',
+      type: 'api_key',
+      value: 'stdin-provided-key',
+    });
+  });
+
+  it('an empty intake credential refuses locally with no gateway call', async () => {
+    const fetchMock = vi.fn();
+    vi.stubGlobal('fetch', fetchMock);
+    vi.spyOn(console, 'error').mockImplementation(() => {});
+
+    await runEnroll(
+      auth,
+      {
+        gateway,
+        harness: 'fake-harness',
+        name: 'Nova',
+        model: 'claude-test',
+        provider: 'anthropic',
+        credential: 'intake',
+      },
+      async () => '',
+    );
+
+    expect(fetchMock).not.toHaveBeenCalled();
+    expect(process.exitCode).toBe(1);
+  });
+
+  it('preserves the gateway refusal contract (closed error enum + correlation) in the CLI error', async () => {
+    vi.stubGlobal(
+      'fetch',
+      vi.fn(
+        async () =>
+          new Response(
+            JSON.stringify({
+              statusCode: 409,
+              error: 'conflict',
+              message: 'idempotency conflict',
+              correlationId: 'corr-409',
+            }),
+            { status: 409, headers: { 'Content-Type': 'application/json' } },
+          ),
+      ),
+    );
+
+    await expect(
+      enrollAgent(gateway, auth.cookie, {
+        harness: 'fake-harness',
+        name: 'Nova',
+        model: 'claude-test',
+        provider: 'anthropic',
+        credential: { mode: 'reference' },
+        idempotencyKey: '9c1a26be-0000-4000-8000-000000000003',
+      }),
+    ).rejects.toThrow(
+      'Failed to enroll agent (409): {"statusCode":409,"error":"conflict",' +
+        '"message":"idempotency conflict","correlationId":"corr-409"}',
+    );
+  });
+});
+
+describe('agent.enrollment.get CLI parity', (): void => {
+  it('reads one enrollment with the correlation envelope on the query string', async () => {
+    const fetchMock = vi.fn(async () => okResponse('corr-get'));
+    vi.stubGlobal('fetch', fetchMock);
+    const log = vi.spyOn(console, 'log').mockImplementation(() => {});
+
+    await runGetEnrollment(auth, agentBody.id, 'corr-get');
+
+    const [url] = fetchMock.mock.calls[0] as unknown as [string];
+    expect(url).toBe(`${gateway}/api/enrollment/agents/${agentBody.id}?correlationId=corr-get`);
+    expect(log.mock.calls.flat().join('\n')).toContain('corr-get');
+  });
+
+  it('preserves the folded not_found contract in the CLI error', async () => {
+    vi.stubGlobal(
+      'fetch',
+      vi.fn(
+        async () =>
+          new Response(
+            JSON.stringify({
+              statusCode: 404,
+              error: 'not_found',
+              message: 'agent not found',
+              correlationId: 'corr-404',
+            }),
+            { status: 404, headers: { 'Content-Type': 'application/json' } },
+          ),
+      ),
+    );
+
+    await expect(fetchEnrollment(gateway, auth.cookie, agentBody.id)).rejects.toThrow(
+      'Failed to get enrollment (404): {"statusCode":404,"error":"not_found",' +
+        '"message":"agent not found","correlationId":"corr-404"}',
+    );
+  });
+});

packages/mosaic/src/commands/agent.ts

@@ -1,3 +1,4 @@
+import { randomUUID } from 'node:crypto';
 import type { Command } from 'commander';
 import { registerFleetAgentCommands, type FleetCommandDeps } from './fleet.js';
 import { withAuth } from './with-auth.js';
@@ -9,8 +10,10 @@ import {
   deleteAgentConfig,
   fetchProjects,
   fetchProviders,
+  enrollAgent,
+  fetchEnrollment,
 } from '../tui/gateway-api.js';
-import type { AgentConfigInfo } from '../tui/gateway-api.js';
+import type { AgentConfigInfo, EnrolledAgentInfo } from '../tui/gateway-api.js';
 
 function formatAgent(a: AgentConfigInfo): string {
   const sys = a.isSystem ? ' [system]' : '';
@@ -75,11 +78,140 @@ export function registerAgentCommand(program: Command, fleetDeps: FleetCommandDe
       },
     );
 
+  registerEnrollmentCommands(cmd);
   registerFleetAgentCommands(cmd, fleetDeps);
 
   return cmd;
 }
 
+// ── Agent enrollment (design docs/plans/2026-08-29-agent-enrollment-command-design.md §3;
+//    CLI parity bound by contract 5 §4.5) ──
+
+export interface EnrollCommandOptions {
+  gateway: string;
+  harness: string;
+  name: string;
+  model: string;
+  provider: string;
+  persona?: string;
+  credential: string;
+  idempotencyKey?: string;
+  correlationId?: string;
+  replayMode?: string;
+}
+
+/**
+ * Read an intake credential value from stdin. Never accepted via argv — a
+ * process argument is world-readable in `ps` for the process lifetime.
+ */
+export async function readCredentialFromStdin(): Promise<string> {
+  if (process.stdin.isTTY) {
+    console.error('Enter API key, then press Enter and Ctrl-D:');
+  }
+  const chunks: Buffer[] = [];
+  for await (const chunk of process.stdin) {
+    chunks.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk));
+  }
+  return Buffer.concat(chunks)
+    .toString('utf8')
+    .replace(/\r?\n$/, '');
+}
+
+function showEnrollment(correlationId: string, agent: EnrolledAgentInfo): void {
+  console.log(`  ID:           ${agent.id}`);
+  console.log(`  Name:         ${agent.name}`);
+  console.log(`  Harness:      ${agent.harness ?? '—'}`);
+  console.log(`  Provider:     ${agent.provider}`);
+  console.log(`  Model:        ${agent.model}`);
+  console.log(`  Status:       ${agent.status}`);
+  console.log(`  Owner:        ${agent.ownerId ?? '—'}`);
+  console.log(`  Enrolled:     ${agent.enrolledAt ?? '—'}`);
+  console.log(`  Correlation:  ${correlationId}`);
+}
+
+export async function runEnroll(
+  auth: { gateway: string; cookie: string },
+  opts: EnrollCommandOptions,
+  readSecret: () => Promise<string> = readCredentialFromStdin,
+): Promise<void> {
+  if (opts.credential !== 'reference' && opts.credential !== 'intake') {
+    console.error(`Unknown credential mode "${opts.credential}" (use reference or intake).`);
+    process.exitCode = 1;
+    return;
+  }
+
+  let credential: { mode: 'reference' } | { mode: 'intake'; type: 'api_key'; value: string };
+  if (opts.credential === 'intake') {
+    const value = await readSecret();
+    if (!value) {
+      console.error('Intake credential requires a non-empty API key on stdin.');
+      process.exitCode = 1;
+      return;
+    }
+    credential = { mode: 'intake', type: 'api_key', value };
+  } else {
+    credential = { mode: 'reference' };
+  }
+
+  const result = await enrollAgent(auth.gateway, auth.cookie, {
+    harness: opts.harness,
+    name: opts.name,
+    model: opts.model,
+    provider: opts.provider,
+    ...(opts.persona !== undefined ? { persona: opts.persona } : {}),
+    credential,
+    idempotencyKey: opts.idempotencyKey ?? randomUUID(),
+    ...(opts.correlationId !== undefined ? { correlationId: opts.correlationId } : {}),
+    ...(opts.replayMode !== undefined ? { replayMode: opts.replayMode } : {}),
+  });
+
+  console.log(`Agent "${result.agent.name}" enrolled.\n`);
+  showEnrollment(result.correlationId, result.agent);
+}
+
+export async function runGetEnrollment(
+  auth: { gateway: string; cookie: string },
+  agentId: string,
+  correlationId?: string,
+): Promise<void> {
+  const result = await fetchEnrollment(auth.gateway, auth.cookie, agentId, correlationId);
+  showEnrollment(result.correlationId, result.agent);
+}
+
+export function registerEnrollmentCommands(cmd: Command): void {
+  cmd
+    .command('enroll')
+    .description('Enroll an agent through the gateway enrollment command (agent.enroll)')
+    .requiredOption('--harness <id>', 'Harness the agent runs on (must be registered)')
+    .requiredOption('--name <name>', 'Agent display name')
+    .requiredOption('--model <model>', 'Model identifier')
+    .requiredOption('--provider <provider>', 'Provider the credential belongs to')
+    .option('--persona <text>', 'Agent persona / system prompt')
+    .option(
+      '--credential <mode>',
+      'Credential mode: "reference" (already stored) or "intake" (API key read from stdin, never argv)',
+      'reference',
+    )
+    .option('--idempotency-key <uuid>', 'Idempotency key (generated when omitted)')
+    .option('--correlation-id <uuid>', 'Correlation id to carry through the audit trail')
+    .option('--replay-mode <mode>', 'Idempotency replay mode (actor-bound)')
+    .action(async (opts: Omit<EnrollCommandOptions, 'gateway'>) => {
+      const parent = cmd.opts<{ gateway: string }>();
+      const auth = await withAuth(parent.gateway);
+      await runEnroll(auth, { ...opts, gateway: parent.gateway });
+    });
+
+  cmd
+    .command('enrollment <agentId>')
+    .description('Read one enrolled agent (agent.enrollment.get; owner or admin)')
+    .option('--correlation-id <uuid>', 'Correlation id to carry through the read')
+    .action(async (agentId: string, opts: { correlationId?: string }) => {
+      const parent = cmd.opts<{ gateway: string }>();
+      const auth = await withAuth(parent.gateway);
+      await runGetEnrollment(auth, agentId, opts.correlationId);
+    });
+}
+
 async function resolveAgent(
   gateway: string,
   cookie: string,

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

@@ -173,6 +173,8 @@ describe('registerFleetCommand', () => {
     expect(agent!.options.map((option) => option.long)).toContain('--list');
     expect(agent!.commands.map((command) => command.name()).sort()).toEqual([
       'comms-block',
+      'enroll',
+      'enrollment',
       'reset',
       'roster',
       'send',

packages/mosaic/src/tui/gateway-api.ts

@@ -562,6 +562,74 @@ export async function fetchInteractionHealth(gatewayUrl: string): Promise<unknow
   return handleResponse<unknown>(res, 'Failed to get interaction readiness');
 }
 
+// ── Agent Enrollment types (design docs/plans/2026-08-29-agent-enrollment-command-design.md §3) ──
+
+export interface EnrolledAgentInfo {
+  id: string;
+  name: string;
+  provider: string;
+  model: string;
+  status: string;
+  harness: string | null;
+  persona: string | null;
+  ownerId: string | null;
+  enrolledAt: string | null;
+  createdAt: string;
+}
+
+export interface EnrollAgentRequest {
+  harness: string;
+  name: string;
+  persona?: string;
+  model: string;
+  provider: string;
+  credential: { mode: 'reference' } | { mode: 'intake'; type: 'api_key'; value: string };
+  idempotencyKey: string;
+  correlationId?: string;
+  replayMode?: string;
+}
+
+export interface EnrollmentOutcome {
+  ok: true;
+  correlationId: string;
+  agent: EnrolledAgentInfo;
+}
+
+// ── Agent Enrollment endpoints ──
+
+/**
+ * agent.enroll. The gateway's typed refusal body (closed error enum +
+ * correlationId) is preserved verbatim in the thrown error, so the CLI
+ * surfaces the same contract the web client receives.
+ */
+export async function enrollAgent(
+  gatewayUrl: string,
+  sessionCookie: string,
+  data: EnrollAgentRequest,
+): Promise<EnrollmentOutcome> {
+  const res = await fetch(`${gatewayUrl}/api/enrollment/agents`, {
+    method: 'POST',
+    headers: jsonHeaders(sessionCookie, gatewayUrl),
+    body: JSON.stringify(data),
+  });
+  return handleResponse<EnrollmentOutcome>(res, 'Failed to enroll agent');
+}
+
+/** agent.enrollment.get: owner-or-admin read of one enrolled agent. */
+export async function fetchEnrollment(
+  gatewayUrl: string,
+  sessionCookie: string,
+  agentId: string,
+  correlationId?: string,
+): Promise<EnrollmentOutcome> {
+  const params = correlationId ? `?${new URLSearchParams({ correlationId }).toString()}` : '';
+  const res = await fetch(
+    `${gatewayUrl}/api/enrollment/agents/${encodeURIComponent(agentId)}${params}`,
+    { headers: headers(sessionCookie, gatewayUrl) },
+  );
+  return handleResponse<EnrollmentOutcome>(res, 'Failed to get enrollment');
+}
+
 // ── Conversation Message types ──
 
 export interface ConversationMessage {