- /eval on one's own PR may omit sha=: the guard auto-pins the
dispatch-time head (commenter == PR author leaves no third-party
swap window); dispatching another author's PR still requires the
explicit reviewed SHA (keeps the P1-2 TOCTOU remedy where the
threat lives)
- cases= is now validated structurally per git check-ref-format
semantics (leading/trailing//double slashes, '..', dot-leading
components, .lock suffixes) and rejects '-'-leading values to
prevent git fetch option injection (review P2)