Module lock 

File-based lock to prevent concurrent devflow advance invocations for the same phase.

Creates .devflow/lock-{phase:02} with the PID of the lock holder. Uses O_EXCL for atomic acquisition — if the file already exists, the lock is contended.

The lock is scoped per-phase (not per-project): advance() holds it across a gate’s multi-day blocking wait, and every phase run ends at a mandatory Ship gate, so a project-wide lock would starve devflow parallel’s sibling phases with no retry (CR-03, 13-REVIEW.md).

Structs

LockGuard

Guard that releases the lock file on drop.

Enums

LockError

Errors produced by lock operations.

Functions

acquire

Acquire an exclusive lock for the given project root and phase.

acquire_project

Acquire the short-held, project-wide lock that serializes mutations of the primary checkout (version-bump commits/tags, docs commits, branch integration/cleanup) across concurrently finishing phases (13-DEFERRED-CR-03 fix shape #3).

acquire_project_blocking

Blocking variant of acquire_project: waits out a sibling phase’s short critical section, polling with backoff up to timeout. Returns the last Contended error if the sibling still holds the lock at the deadline — after timeout of waiting the holder is more likely wedged than slow, and failing loudly beats mutating the checkout concurrently.

holder

Check whether a lock is currently held for this project/phase, returning the PID of the holder if the file exists.

remove_stale_locks

Remove this project’s per-phase lock files, skipping any whose recorded holder PID is still alive — deleting a live holder’s lock would let a duplicate advance acquire it, after which the original holder’s LockGuard::Drop deletes the NEW holder’s file.