Review Blockers (Pre-Mortem + Self-Review)

One skill, two modes, same checklist categories — because the goal is identical in both cases: surface what a strict senior reviewer would flag as a P1/P2, either before the code exists (so it's built in correctly) or after (so it's caught before a human reviewer catches it).

Mode selection

• PLAN mode: no implementation exists yet for this change. Produce a checklist the implementation must satisfy.
• DIFF mode: implementation already exists (a diff, a just-written file, existing code). Review it against the checklist directly.

If it's ambiguous which mode applies, ask once, or infer from context (e.g. if the user just asked you to write code and now says "double check it," that's DIFF mode).

Checklist categories