Code-review follow-ups on 24686cade:
- Only `git reset --hard HEAD` / `git clean -fd` after the stash is confirmed (non-empty SHA + store succeeded). Previously an empty `git stash create` result (no throw) would still trigger the reset and wipe the user's dirty edits before the refusal was raised.
- Quote the stash label with a local `quoteAutostashArg` helper to match `merger.ts`'s `quoteArg` pattern. Task IDs are alphanumeric today, but defense-in-depth keeps `git stash store -m` safe against future label content.
- Add `merge:reuse-handoff-autostash` to the typed audit unions in `run-audit.ts` and `emitReuseHandoffAuditEvent`, so subscribers see it as part of the closed set instead of relying on the `as any` escape hatch.
- Best-effort `git reset` (unstage) in the autostash-failure path so the worktree isn't left half-staged when we refuse.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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