Mission Run Overview
Mission Run: Implement lane-allocation integrity: fail-closed on destroyed lanes + coord-branch planning-commit hygiene
Stop 'spec-kitty implement' from silently stranding committed work or blocking the second work package on coordination-topology missions.
Two release-blocking reliability defects live in the implement lane-allocation path. When a lane's worktree and branch are both removed while a work package is still in progress, re-running implement silently cuts a new empty lane and reports success, stranding the committed work while status still says in_progress. Separately, on coordination-topology missions the agent claim commit writes the work-package file onto the coordination branch, so the next lane's planning-artifact merge fails with an add/add conflict and the second work package cannot start. This mission makes both paths fail closed / stay correct so the operator is never told the workspace is ready when committed work is unreachable, and every work package on a coord mission can start.