Impl Tracking

# Implementation Tracking: {Domain or Scope}

## Status: {IN_PROGRESS | COMPLETE | BLOCKED}

**Last Updated:** {Date}
**Current Phase:** {Spec | Plan | Implement | Iterate | Monitor}
**Blocking Issues:** {None | Brief description of blockers}

---

## Task Status

| Task ID | Task | Status | Notes |
|---------|------|--------|-------|
| T-1 | {Task description} | DONE | {Completion notes} |
| T-2 | {Task description} | DONE | {Completion notes} |
| T-3 | {Task description} | IN_PROGRESS | {Current state, what remains} |
| T-4 | {Task description} | BLOCKED | {What is blocking, dependency} |
| T-5 | {Task description} | NOT_STARTED | {Prerequisites} |

### Task Dependencies
- T-4 blockedBy T-3 (needs auth module before API integration)
- T-5 blockedBy T-3, T-4

---

## Files Created

| File | Purpose | Spec Reference |
|------|---------|---------------|
| `src/auth/login.{ext}` | Login handler | spec-auth.md R1 |
| `src/auth/session.{ext}` | Session management | spec-auth.md R2 |
| `tests/auth/login.test.{ext}` | Login unit tests | spec-auth.md R1 AC1-3 |

## Files Modified

| File | Change | Reason |
|------|--------|--------|
| `src/app.{ext}` | Added auth middleware | spec-auth.md R3 |
| `src/config.{ext}` | Added session config | spec-auth.md R2 |

---

## Issues & TODOs

- [ ] **Issue:** Session expiry not tested under concurrent access — need load test
- [ ] **TODO:** Add rate limiting to login endpoint (spec-api.md R7)
- [ ] **TODO:** Implement password reset flow (spec-auth.md R4, NOT_STARTED)
- [x] **Resolved:** TypeScript compilation error in session.ts — fixed incorrect import path

---

## Dead Ends & Failed Approaches

### DE-1: JWT with asymmetric keys for session tokens
**What was attempted:** Implemented RS256 JWT tokens with public/private key pair.
**Root cause of failure:** Key rotation complexity exceeded the session management requirements. Added 200+ lines of key management code for no user-visible benefit. Symmetric HS256 with server-side session store is simpler and meets all spec criteria.
**Verdict:** Do not reattempt. Use symmetric tokens with server-side sessions instead.

### DE-2: Redis for session storage
**What was attempted:** Used Redis as the session store backend.
**Root cause of failure:** Redis dependency adds operational complexity. The application's expected concurrent user count (< 10,000) is well within what a database-backed session store handles. Redis would be premature optimization.
**Verdict:** Do not reattempt unless concurrent user requirements change significantly (> 100,000).

### DE-3: Cookie-based CSRF protection
**What was attempted:** Double-submit cookie pattern for CSRF.
**Root cause of failure:** Incompatible with the API's token-based auth flow. Clients send bearer tokens in headers, not cookies. CSRF protection is inherently handled by the token-based approach.
**Verdict:** Do not reattempt. Token-based auth does not need separate CSRF protection.

---

## Test Health

| Test Suite | Passing | Failing | Skipped | Line Coverage |
|------------|---------|---------|---------|---------------|
| Unit tests | 45 | 2 | 0 | 78% |
| Integration | 12 | 1 | 3 | n/a |
| E2E | 0 | 0 | 0 | n/a |

### Failing Tests
- `tests/auth/session.test.{ext}:34` — Session refresh fails when token is expired more than 24h. Needs spec clarification on refresh window.
- `tests/integration/api-auth.test.{ext}:89` — Timeout on concurrent login test. Likely race condition in session creation.

### Test Notes
- E2E tests not yet created (blocked on T-4: API integration)
- Integration test skip: 3 tests require external OAuth provider mock (TODO)

---

## Session Log

### Session 3 (current)
- Completed T-2 (session management)
- Started T-3 (API integration) — 60% complete
- Discovered DE-3 (CSRF not needed with token auth)
- 2 new failing tests identified

### Session 2
- Completed T-1 (login handler)
- Discovered DE-1 (JWT asymmetric keys too complex)
- Discovered DE-2 (Redis premature for this scale)
- Test health: 38 pass, 0 fail

### Session 1
- Set up auth module structure
- Created initial test scaffolding
- Established file ownership: auth/ owned by auth-agent

### DE-{N}: {Short description of the approach}
**What was attempted:** {Specific description of the approach taken}
**Root cause of failure:** {Why it did not work — a clear technical explanation, not just "it broke"}
**Verdict:** Do not reattempt. {Recommended alternative, or conditions under which the approach might become viable}

┌─────────────────────────────────────┐
│  1. Read impl tracking              │
│  2. Identify highest-priority task  │
│  3. Check dead ends for this area   │
│  4. Implement                       │
│  5. Run validation gates            │
│  6. Update impl tracking            │
│  7. Commit                          │
└─────────────────────────────────────┘
        ↓ (next iteration)
┌─────────────────────────────────────┐
│  1. Read impl tracking (updated)    │
│  2. ...                             │
└─────────────────────────────────────┘