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fix: serialize worktree lifecycle operations with a flock on .cwm/lock - #17
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create_worktree, remove_worktree, prune_stale and register_agent_symlink mutated .git/worktrees and the per-branch metadata under .cwm/worktrees/ without any locking. Concurrent agents driving 'git worktree add'/'prune' through the PR #15 git-hook could corrupt both. Add cwm_lock(cwm_dir), a blocking fcntl.flock(LOCK_EX) context manager on .cwm/lock, and wrap the critical region of each lifecycle method. Both the CLI commands and the agent git-hook converge on the same WSM methods, so locking at the method boundary serializes every entry path. Build and test operations are intentionally left lockless so parallel builds across worktrees stay concurrent.
HansRobo
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release:patch
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Summary
Worktree lifecycle operations were unsynchronized:
create_worktree,remove_worktree,prune_staleandregister_agent_symlinkmutated.git/worktreesand the per-branch metadata under.cwm/worktrees/with no locking. Concurrent agents drivinggit worktree add/prunethrough the PR #15 git-hook could corrupt both.This adds
cwm_lock(cwm_dir)— a blocking POSIXfcntl.flock(LOCK_EX)context manager on.cwm/lock— and wraps the critical region of each lifecycle method. The CLI commands and the agent git-hook both converge on the same WSM methods, so locking at the method boundary serializes every entry path. Build and test operations stay lockless by design, so parallel builds across worktrees remain concurrent.Changes
src/cwm/util/lock.py:cwm_lockcontext manager (blockingLOCK_EX,EINTRretry, lock file never deleted, body exceptions propagate unchanged).src/cwm/core/wsm.py: wrap the critical region ofcreate_worktree(incl. the existence/collision check, closing a TOCTOU window),remove_worktree,prune_stale, andregister_agent_symlink.tests/unit/test_lock.py: 5 unit tests (real fcntl; a second open file description proves mutual exclusion deterministically).tests/unit/test_wsm.py:TestLifecycleLocking— 4 tests asserting the lock is held across each lifecycle method's git operation.README.md: "Concurrency / locking" section.Testing
uv run python -m pytest tests/→ 179 passed (full suite, same environment as CI). The 9 new tests (test_lock.py×5,TestLifecycleLocking×4) all pass; no regressions.Release: patch → v6.1.2