Concurrent Task Gate

Complete this gate before the Planning Gate.

Invariants

One active task owns one worktree.
Concurrent tasks use different branches and worktrees.
Resume the same task in its existing worktree; start returns a completed task's registry status to planning.
When an isolated start omits --destination, use <primary-repository-parent>/.codex-worktrees/<repository>/<task_id>.
Never stash, reset, move, delete, or adopt unknown work automatically.
Feature tasks write only their own task record and uniquely named supporting records.
Peer document defects reported as PEER_DOC_WARNING require scope assessment, not peer-document repair before starting the current task. Current-task identity and registry ownership faults remain blocking.
Keep the active task record present until ownership is released.
Treat start, touch, complete, release, and retire as serialized registry transactions; lock timeout or malformed registry state blocks the gate.
Feature-task write boundaries in this gate supersede legacy instructions to update shared or canonical project documents.

The worktree belongs to another active task and isolation did not succeed.
An unowned worktree contains staged, unstaged, or untracked changes.
No reliable committed base was selected for a new worktree.
The runtime cannot keep later Git and file operations rooted in the isolated worktree.