Code review as a senior engineerPrompt

Review this diff as a senior engineer on a {{stack}} codebase:

{{diff}}

Report only things worth changing, grouped as:
- Bugs (wrong behavior, crashes, races, security) — include a failing scenario for each.
- Risky (missing tests, unclear error handling, performance traps).
- Simplifications that remove code.

Skip formatting and naming nitpicks unless they hide a bug. For each item give file:line, the problem in one sentence, and the fix. End with "ship / ship after fixes / don't ship".