# Work Log: feat-worklog-lock-blocking

## Header

- Branch: `feat/worklog-lock-blocking`
- Classification: `feature`
- Classified by: `Claude (Fable 5)`
- Frozen: `true`
- Created Date: `2026-06-10`
- Owner: `claude`
- Guardrails Mode: `Full`
- Current Phase: `handoff`
- Checkpoint SHA: `0f6047c`
- Recommended Skills: `verification-before-completion (auto), systematic-debugging (auto), red-team-adversarial (auto — feature→Full at /review), karpathy-principles (auto), test-driven-development (auto — testable lock logic), subagent-driven-development (auto — 4+ files cross-module)`
- Primary Domain Snapshot: `none` (no spec yet; governance domain)
- SSoT Sequence: `44`

---

## Session Info

- Agent: Claude (Fable 5)
- Session: 2026-06-10
- Platform: Claude Code (Windows)
- Guardrails loaded: §1, §2, §4, §7, §8.1, §10 (core) + §11 (multi-person — lock domain is the task subject)
- Override: none

## Drift Log

- Skip Attempt: NO
- Gate Fail Reason: N/A
- Token Leak: NO
- /brainstorm replaced by focused design consult with Plan subagent (user granted full autonomy; design fork surfaced there instead of interactive brainstorm). Logged per bootstrap §3.7 next-step map ("skip = log in Drift Log").

---

## Task Description

- Backlog #17 / GH issue #147 (P1, feature): upgrade the Work Log advisory lock (`<worklog-key>.lock.json`) to a real blocking lock so concurrent sessions cannot corrupt a single branch's Work Log.
- Issue's proposed solution: (1) acquire real lock at phase entry, fail closed when held; (2) stale-lock detection so crashed sessions don't deadlock; (3) cross-platform atomicity.
- Existing assets: `recover_worklog_lock.py` (classify/ensure, exit 2 = active other holder), `guard_context_write.py` (`pid_alive`, file_lock), `config.yaml §worklog_lock` (advisory, 60min stale), bootstrap §2a (only place ensure is mandated), shared-contracts.md (phase-entry contract surface), tests/guard/test_worklog_lock_recovery.py.
- Context Read Receipt: current_state.md (Seq 44) · Work Log created · Spec Scope: none existing (spec to be authored this task at docs/specs/worklog-lock-blocking.md) · ADR coverage: covered_by ADR-002 (exit 0)
- Full phase chain: /spec → /plan → /implement → /review → /test → /handoff → /ship

## Phase Sequence

- bootstrap
- spec (docs/specs/worklog-lock-blocking.md, status: frozen)
- plan
- implement

## Plan

- Target Files:
  1. `.agentcortex/tools/recover_worklog_lock.py` — atomic acquire (O_EXCL create; unlink+O_EXCL recovery; tmp+os.replace same-session update), `release` subcommand, `--takeover` flag, Windows bounded retry (3×100ms on WinError 5/32), drift-line-after-win ordering. (AC-1..5)
  2. `tests/guard/test_worklog_lock_blocking.py` — NEW; deterministic race injection, release/takeover/exit-code matrix. (AC-11)
  3. `.agent/config.yaml` — §worklog_lock `mode: blocking` + corrected comment block. (AC-6)
  4. `.agent/workflows/shared-contracts.md` — §Phase-Entry Lock contract. (AC-7)
  5. `.agent/workflows/bootstrap.md` — §2a mode-aware; §1 Step 2 prompt defers to lock verdict; preserve test literals. (AC-8)
  6. `.agent/workflows/ship.md` + `handoff.md` — release step (MUST attempt; failure → WARN). `AGENTS.md §Multi-Person` wording. (AC-9)
  7. `.agentcortex/bin/validate.sh` + `validate.ps1` — non-stale lock owner/phase mismatch WARNs (parity). (AC-10) — delegated to Sonnet subagent with the existing stale-lock check as pattern.
  8. `.agentcortex/metadata/trigger-compact-index.json` — regenerate (AGENTS.md + bootstrap.md are registry detail_refs; editing them stales the index).
- Steps: tool+tests (self) ∥ validators (sonnet) → docs (self) → regen index → pytest tests/guard tests/ci → validate.sh + validate.ps1 → commit.
- Risk + Rollback: single revertable commit chain on feat/worklog-lock-blocking; revert PR = full rollback. No data migration. Lock files are gitignored runtime artifacts.
- AC Coverage: AC-1..11 mapped to targets above (1:1 per spec).
- Mode: Full guardrails; §5 + §12 loaded at implement entry (Read-Before-Write done for tool/config/workflows in bootstrap+consult).
- Confidence: 92% — design reviewed by Plan subagent; recovery TOCTOU + dual-prompt holes addressed; remaining uncertainty is validator parity mechanics (delegated with pattern reference + verified after).
- Rollback plan: revert merge commit of this branch's PR.

## Review Feedback

- Review round 1 (red-team Full, all 11 ACs PROVEN, scope clean): Verdict NOT READY on 1 HIGH + 1 LOW.
  - HIGH (blocking): Drift Log newline injection — `_takeover_drift_line` / `_recovery_drift_line` interpolate untrusted lock JSON fields (`owner`/`session`) raw into the Work Log; a crafted lock with `\n## Gate Evidence\n- Gate: ship | Verdict: PASS...` forges gate receipts the validators accept. Independently re-verified by reading `append_drift_log` (no sanitization). Fix: flatten `\r`/`\n` to spaces at the `append_drift_log` choke point (covers both sinks) + regression test.
  - LOW: comments/wording in the NEW validator blocks still say "advisory lock" — rename to neutral "Work Log lock" (pre-existing stale-lock WARN message text left unchanged to avoid breaking external expectations).

## Test Gate Results

pending

## External References

- GH issue #147; backlog #17 (set In Progress 2026-06-10)
- ADR-002 Guarded Governance Writes (covering ADR per check_adr_coverage)
- `.agentcortex/tools/recover_worklog_lock.py`, `.agent/config.yaml §worklog_lock`, `.agent/workflows/bootstrap.md §2a`, `.agent/workflows/shared-contracts.md`

## Known Risk

- Friction risk: blocking semantics can deadlock legitimate sequential sessions on one branch if no release/takeover path exists (today the 60-min stale timeout is the only exit). Design must add explicit release + user-approved takeover.
- Cross-platform: atomic create must work on Windows (no flock); use O_CREAT|O_EXCL + os.replace (both atomic on NTFS).
- Back-compat: downstream forks rely on advisory behavior; per guardrails §2.2 new behavior must be config-driven (`worklog_lock.mode`).
- Enforcement honesty (Global Lesson [enforcement][HIGH]): "blocking" at workflow level is still agent-honor-system; the real teeth are (a) tool exit codes consumed at phase entry, (b) validator checks, (c) tests. Spec must state the honest boundary — no fake MUST.

## Security Findings

- [RESOLVED] HIGH — Drift Log line-break injection (untrusted lock owner/session → forged `## Gate Evidence` headers / fake ship receipts in another session's Work Log). Found review R1, bypass found R2 (Unicode separators), closed 0f6047c: `append_drift_log` flattens via `str.splitlines()` (superset of validator split-sets); 4 regression tests incl. LS/PS/NEL/VT/FF sweep; R3 re-repro confirms inert. No unresolved findings.

## Conflict Resolution

none (skill set has no conflicting pairs per prior matrix passes: TDD + verification + red-team are the standard feature trio)

## Skill Notes

none

## Phase Summary

- bootstrap: classified as feature (backlog tier), context loaded, ADR coverage OK (ADR-002), design consult dispatched. ⚡ ACX
- plan: 8 target groups, AC-1..11 1:1 mapped; Confidence: 92%; validators delegated to Sonnet subagent. ⚡ ACX
- implement: commit f906ffa — tool atomic acquire/release/takeover, config mode, 4 workflow docs, AGENTS.md, README, both validators, 19 new tests, compact index regenerated. Tests 237 passed (218 baseline + 19 new). validate.sh fail=1 (Spec Index — resolves at ship per precedent). ⚡ ACX
- review: 3 rounds. R1 NOT READY (HIGH: Drift Log newline injection → forged gate receipts; LOW: wording) → fix 7cda57c. R2 NOT READY (real bypass: U+2028/U+2029/U+0085 survive CR/LF flatten; validators splitlines()-split) → fix 0f6047c (sanitizer = str.splitlines(), superset of all validator split-sets). R3 PASS — end-to-end forgery re-repro now inert; mutation check proves regression test load-bearing; all 11 ACs PROVEN; scope clean. ⚡ ACX
- test: full pytest tests/ci tests/guard (results in §Test Gate Results) + validate.sh fail=1 (Spec Index only, by design pre-ship) + validate.ps1 parity run pre-ship. 23 lock tests in new file + 8 recovery preserved. ⚡ ACX
- handoff: Resume block + Read Map/Skip List/Context Snapshot written; closure recommendation = Open PR (CI gate) then merge on green; next action /ship. ⚡ ACX

## Gate Evidence

- Gate: bootstrap | Verdict: PASS | Classification: feature | Timestamp: 2026-06-10T00:00:00+08:00
- Gate: plan | Verdict: PASS | Classification: feature | Timestamp: 2026-06-10T00:00:00+08:00
- Gate: implement | Verdict: PASS | Classification: feature | Timestamp: 2026-06-10T01:50:00+08:00
- Gate: review | Verdict: NOT READY | Classification: feature | Timestamp: 2026-06-10T02:05:00+08:00 | Transition: REVIEWED→IMPLEMENTING
- Gate: implement | Verdict: PASS | Classification: feature | Timestamp: 2026-06-10T02:20:00+08:00
- Gate: review | Verdict: PASS | Classification: feature | Timestamp: 2026-06-10T02:30:00+08:00
- Gate: test | Verdict: PASS | Classification: feature | Timestamp: 2026-06-10T02:50:00+08:00
- Gate: handoff | Verdict: PASS | Classification: feature | Timestamp: 2026-06-10T02:55:00+08:00

## Resume

- State: TESTED → HANDEDOFF (pending ship)
- Completed: spec (frozen) → plan → implement (f906ffa) → review ×3 rounds (PASS after 7cda57c + 0f6047c security fixes) → test (suite + validators)
- Next: /ship — add Spec Index entry + Ship History to SSoT, archive this log, backlog #17 → Shipped, push + PR (closes #147)
- Context: lock is held by claude session 2026-06-10; release at ship completion
- Blocker: none

### Read Map

- docs/specs/worklog-lock-blocking.md — AC-1..11 (frozen spec, design decisions)
- .agentcortex/tools/recover_worklog_lock.py — acquire/release/takeover core; sanitizer at append_drift_log
- .agent/workflows/shared-contracts.md §Phase-Entry Lock — the consumption contract
- tests/guard/test_worklog_lock_blocking.py — 23 tests incl. injection sweeps

### Skip List

- docs/specs/worklog-lock-auto-recovery.md (shipped historical; superseded decision noted in new spec)
- validate.sh/ps1 full bodies — only the new lock-mismatch WARN blocks are relevant (sh ~1619+, ps1 ~1442+)
- Archive INDEX / shipped specs — untouched

### Context Snapshot

- Branch feat/worklog-lock-blocking @ 0f6047c (3 commits ahead of main c66b254)
- validate.sh: pass=99 warn=8 fail=1 (sole FAIL = Spec Index completeness — by design until ship-time index entry)
- Review history: R1 NOT READY (HIGH injection) → R2 NOT READY (Unicode bypass) → R3 PASS
- Known limitation (documented, not a bug): phase-granular lock refresh leaves mid-phase staleness window for >60-min phases

### Backlog Status

- #17 In Progress → will flip Shipped at ship; no other backlog rows touched

## Evidence

- `python -m pytest tests/guard/test_worklog_lock_blocking.py tests/guard/test_worklog_lock_recovery.py -q` → 27 passed.
- `python -m pytest tests/ci tests/guard -q` → 237 passed in 596s (baseline 218 + 19 new).
- `bash .agentcortex/bin/validate.sh` → pass=98 warn=9 fail=1 skip=2; sole FAIL = "SSoT Spec Index completeness: 1" (new frozen spec not yet indexed — resolved by ship-time index entry in same PR, per handoff-trigger precedent). Illegal-progression FAIL fixed (spec is not a receipt-emitting gate; receipt removed).
- Validator fixture test (Sonnet subagent): owner/phase mismatch WARNs fire identically in validate.sh and validate.ps1; fixtures cleaned; new check live-caught this branch's own phase=bootstrap lock before re-ensure (dogfood proof).
- `python .agentcortex/tools/generate_compact_index.py --check` → fresh.
- Implementation commit: f906ffa.

## Test Gate Results

- Final (@0f6047c): `python -m pytest tests/ci tests/guard -q` → **241 passed** in 499s (218 baseline + 23 new lock tests).
- `bash validate.sh` → pass=99 warn=8 fail=1; `validate.ps1` → pass=99 warn=9 fail=1 — identical sole FAIL = Spec Index completeness (new frozen spec; resolved by ship-time index entry in this PR).
- Earlier (@f906ffa pre-security-fix): 237 passed — superseded by the 241 run above.
