# Implementer — F-005 Identity: register, login, sessions

done -> work/artifacts/F-005/implementer.md

## Delivered
- Migration `migrations/002_identity.js`: `identity_users` + `identity_sessions`
  (token_hash UNIQUE, FK ON DELETE CASCADE, user_id index). Reversible.
- Hexagonal module `src/modules/identity`:
  - domain: user.ts, session.ts (7-day TTL), errors.ts, ports.ts
  - application: register-user.ts, login.ts, logout.ts, login-rate-limiter.ts
  - infrastructure: argon2-password-hasher.ts (argon2id m=19456 t=2 p=1),
    pg-user-repository.ts, pg-session-repository.ts, session-token.ts
  - api: identity.routes.ts (zod via parseJson, envelope v2 mapping)
- Foundation wiring: `createPool(connectionString)`, `COOKIE_SECURE` in config
  (default true), `buildApp({ pool, cookieSecure })`, server creates pool from config.

## Deps added (justified in spec/tech.md)
- argon2, @fastify/cookie

## Evidence
- `npm run lint` ✅ (prettier clean after format pass)
- `npm run lint:boundaries` ✅ (39 files, R1/R2 OK — module tests stay in-subtree,
  DB integration tests live in src/app/tests)
- `npm run typecheck` / `npm run build` ✅
- `npm test`: 46 passed, 14 skipped (integration) ✅
- `npm run test:integration`: 14/14 ✅ (register argon2-only storage, dup 409,
  invalid 400, cookie flags, identical 401 bodies, revocation + idempotent logout,
  10 failures → 429 + Retry-After, foundation-only app keeps /auth 404)
- Live smoke (curl): 201 register / 200 login + `mdv_session …; HttpOnly; Secure;
  SameSite=Lax; Max-Age=604800` / 401 identical for wrong-password vs unknown-email /
  204 logout clears cookie / 10×401 → 429 + `retry-after: 900`
- `./scripts/verify.sh` ✅

## Notes / deviations
- F-002 migrations.itest baseline rollback test updated: `down` now uses `count: 0`
  (full revert) since the suite has two migrations; test asserts identity tables AND
  app_meta are gone. Helper `runMigrations` gained an optional count param.
- Rate limiter is in-memory per instance (documented in DESIGN risks; interface ready
  for Redis swap).
- `project/.env` (gitignored) supplies TEST_DATABASE_URL to the `test:integration`
  script via `node --env-file-if-exists=.env`.