Spec Kitty

Mission Run: Terminus-Safety Invariant

Completion commands (merge, accept, mission close) must refuse before they mutate, and roll back if a later step fails — never leaving a mission wedged, split-brain, or falsely completed.

Today a merge run under the default warn gate mode, or a mission close on an unmerged mission, proceeds past a precondition it never hard-enforced and then fails or fabricates a completion record with no rollback — wedging in-flight missions and, worse, letting unreviewed code reach the mainline. This mission establishes one terminus-safety invariant across the completion surface so a single mis-timed command can no longer corrupt mission state, protecting the launch walkthrough from unrecoverable dead-ends.