Verification: P0.3.3 β Writeback Contract Enforcement

Task: P0.3.3
Branch: feature/p0-3-3-writeback-enforcement
Verifier: Claude (T3 Executor)
Date: 2026-04-17
Commit: 262bd809

1. Gate results

Gate	Command	Result
Tests	`npm test`	PASS — 702/702
Lint	`npm run lint`	PASS — 0 errors, 0 warnings
Build	`npm run build`	PASS — 0 TypeScript errors

2. New tests

File: src/__tests__/domains/tasks/writeback.test.ts

Tests added: 23

Describe block	Count
WritebackRequiredError	5
writebackRequired	6
enforceWriteback — direct	6
updateTask → DONE enforcement (integration)	6
Total	23

All 23 new tests pass.

3. Existing test modifications

File: src/__tests__/domains/tasks/repository.test.ts

Changes:

makeTestDb() now applies both 002_tasks.sql AND 003_thought_records.sql (P0.3.3 enforcement requires thought_records table to exist at test time).
Added insertThoughtRecord(db, taskId) helper (raw SQL, isolated from ζ repository).
Updated 'allows arbitrary status transitions (no FSM enforcement)' to call insertThoughtRecord before updateTask(..., { status: 'DONE' }).

These changes preserve the test’s intent (repository allows any status, no FSM policing) while satisfying the new writeback invariant.

4. Coverage

From npm test --coverage output:

src/domains/tasks
  writeback.ts      | 100 | 83.33 | 100 | 100 | 107
  repository.ts     | 100 |   100 | 100 | 100 |
  state-machine.ts  | 100 |   100 | 100 | 100 |

writeback.ts line 107: const cnt = row?.cnt ?? 0 — the ?? 0 branch (row undefined) is not hit because COUNT(*) always returns a non-null row. This is a defensive null guard that cannot be triggered via normal DB operation; the 83.33% branch coverage is the practical maximum for this pattern.

5. Acceptance criteria verification

#	Criterion	Status
AC1	`writebackRequired(db, taskId)` returns `true` for DONE task with 0 thought_records	PASS — test T6
AC2	`enforceWriteback(db, taskId)` throws `WritebackRequiredError` when not satisfied	PASS — tests T10a/T10b
AC3	`enforceWriteback` returns `void` when satisfied	PASS — test T9
AC4	Runtime blocking: task→DONE without thought_record throws `WritebackRequiredError`	PASS — test T1
AC5	Runtime blocking: task→DONE with thought_record succeeds	PASS — test T2
AC6	`WritebackRequiredError` has `taskId: string` and `missing_fields: string[]`	PASS — tests T10b, T12c
AC7	Transition to DONE without thought_record → task status unchanged	PASS — test T1b
AC8	Transition to DONE with thought_record → task status = DONE	PASS — test T2
AC9	`writebackRequired` returns false for non-DONE tasks	PASS — tests T5a/T5b
AC10	Direct `enforceWriteback` void when satisfied	PASS — test T9
AC11	Direct `enforceWriteback` throws when not satisfied	PASS — test T10a
AC12	Idempotency: two `enforceWriteback` calls on satisfied task = void both times	PASS — test T11

All 12 acceptance criteria pass.

6. Integration proof

The hook in src/domains/tasks/repository.ts:updateTask:

// P0.3.3: block status→DONE without a ζ thought_record (writeback enforcement).
if ((patch as Record<string, unknown>)['status'] === 'DONE') {
  enforceWriteback(db, id);
}

Placement: after bindings are built, before getUpdateStatement / stmt.run. This ensures the SQL UPDATE is never executed when writeback is absent.

The integration test 'throws WritebackRequiredError when no thought_record and patch.status = DONE' proves this end-to-end via updateTask (not just direct enforceWriteback call).

7. File summary

Created:

src/domains/tasks/writeback.ts — 3 exports: WritebackRequiredError, enforceWriteback, writebackRequired
src/__tests__/domains/tasks/writeback.test.ts — 23 tests
docs/audits/p0-3-3-writeback-enforcement-audit.md
docs/contracts/p0-3-3-writeback-enforcement-contract.md
docs/packets/p0-3-3-writeback-enforcement-packet.md
docs/verification/p0-3-3-writeback-enforcement-verification.md (this file)

Modified:

src/domains/tasks/repository.ts — 1 new import + 4-line enforcement block in updateTask
src/__tests__/domains/tasks/repository.test.ts — dual-migration setup + helper + 1 test updated

8. Residual risks

WritebackRequiredError fires before TaskNotFoundError for unknown IDs with status: DONE patches. Contract §8 documents this. P0.3.4 MCP tools must validate task existence before calling updateTask with DONE — or handle both error types. Low risk: P0.3.4 is the next step.
enforceWriteback + stmt.run are not in the same transaction. A concurrent out-of-process writer could delete the thought_record between the check and the SQL write. Phase 0 is single-process. Noted for P1 if concurrent writers are introduced.
createTask with status: 'DONE' bypasses enforcement. createTask is not modified. Direct DONE inserts at creation time are not blocked. In practice the FSM starts at INIT; P0.3.4 tools will enforce this. Low risk.
Test thought_record helper uses random string as hash (not a real SHA-256 over canonical JSON). These rows satisfy the count check but would fail P0.7.3 chain verification. Test isolation is intentional; P0.7.3 will run against real createThoughtRecord data.