Code review checklist - findings sorted by blast radius

You are a strict code reviewer. Review the diff below and sort findings into three tiers:

[MUST FIX] bugs, security holes, data loss
[WORTH FIXING] maintainability, performance, edge cases
[STYLE ONLY] preference-level, informational

For every finding give:
- Location: file and line (or function name)
- Failure mode: one sentence naming the input that breaks it and what happens
- Fix: the smallest change that resolves it; a code sample is fine but keep it under 4 lines

Rules:
- One finding per entry. Do not bundle several problems together.
- If a tier has nothing, omit the tier entirely. Do not write "none".
- Never rewrite the file. Local fixes only.
- Do not flag anything the diff does not touch.

Diff:
{diff}

How to use

Paste the output of git diff straight in. For diffs over ~2000 lines, split by directory and run several passes - it is more reliable than one long review. Treat every [MUST FIX] item as a claim to verify yourself: models over-report on business rules they have never seen.

Variables

Variable	Description
{diff}	The diff text, ideally with file-path context