In reuse-task-worktree mode the merger detaches HEAD in the task worktree so
the squash commit lands on detached HEAD; nothing previously advanced the
project root's local integration branch, so changes never appeared on main.
Step 5c now applies the squash to projectRootDir via git merge --ff-only,
falling back to a regular merge with AI conflict resolution if main has
diverged. pushAfterMerge (when enabled) now runs from projectRootDir where
the branch was just advanced, so parsePushRemoteTarget can resolve a branch
instead of failing on the worktree's detached HEAD.
Also tightens acquireReuseHandoff: the executor-lease check above the
queue-lease acquisition was non-atomic, letting a local executor grab the
task between checks. Re-check after acquisition and release the queue
lease with a precise diagnostic instead of proceeding into a generic
failure later.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>