/ship-check

Run a fast pre-ship review of the change I'm about to push. Check, in order:

1. Does it do the one thing it's supposed to — and nothing extra?
2. What's the smallest test that proves it works?
3. What breaks if this is wrong? (blast radius)
4. Is there a rollback?

Reply with PASS or a numbered list of what to fix first. Be terse.