Bug Review

Review: $0

Mode: $1 (default: diagnose)

Diagnose Mode

1. Reproduce the conditions — Understand what triggers the bug:

   • What input or sequence of actions causes it?
   • Is it environment-specific (OS, browser, Node version)?
   • Is it timing-dependent (race condition, async ordering)?

2. Trace the execution path — Read the code flow from entry point to failure:

   • Follow the data through each function call
   • Identify where the actual behavior diverges from expected
   • Check recent changes that touched this code path (git log -p)

3. Identify root cause — Distinguish symptom from cause:

   • Is the bug in this code, or in a dependency it trusts?
   • Is it a logic error, a state management issue, or a data integrity problem?
   • Could this same root cause manifest elsewhere?

4. Propose fix — Suggest a minimal fix that:

   • Addresses the root cause, not just the symptom
   • Doesn't introduce new edge cases
   • Includes a test that would have caught this

Verify-Fix Mode

1. Read the fix — Understand what changed and why.

2. Check completeness:

   • Does it fix the root cause or just the symptom?
   • Does it handle all the edge cases discovered during diagnosis?
   • Are there other call sites that have the same bug?

3. Check for regressions:

   • Does the fix change behavior for any existing valid inputs?
   • Does it break any existing tests?
   • Does it change the API contract?

4. Check test coverage:

   • Is there a test that reproduces the original bug?
   • Does the test fail without the fix and pass with it?
   • Are edge cases from the bug also tested?

Output Format

## Bug Review: <target>

### Root Cause
<1-3 sentences explaining the fundamental issue>

### Impact
- **Severity**: critical | high | medium | low
- **Blast radius**: <what's affected>
- **Frequency**: <how often this triggers>

### Fix
<Code diff or description of the fix>

### Regression Risk
- <potential regression 1>
- <potential regression 2>

### Test Case
```typescript
it("reproduces the bug scenario", () => {
  // Setup that triggers the bug
  // Assert correct behavior
});

Related Code

• <other locations with the same pattern>

## Constraints

- Always identify root cause before suggesting fixes
- The fix should be minimal — don't refactor surrounding code
- Check if the same pattern exists elsewhere in the codebase
- A fix without a regression test is incomplete