Summary

The feature-dev:code-reviewer and pr-review-toolkit:silent-failure-hunter agents currently miss a class of bugs where methods return a failure status but leave the object in a stale/invalid state.

Example Bug Missed

In a recent PR review, both agents missed this issue (caught by Codex):

spawn(excludePositions, currentTick) {
    // Try random positions...
    // Fallback to exhaustive search...
    
    if (validCells.length > 0) {
        this.position = validCells[randomIndex];
        this.spawnTick = currentTick;
        return true;
    }

    // Bug: returns false but doesn't clear existing state
    return false;  // ← position and spawnTick still have old values!
}

Impact: When spawn() fails (grid full), the old position/spawnTick persist, causing stale data to be rendered and collected.

Fix was:

// No valid position available (grid is full)
// Clear food state to prevent stale data
this.position = null;
this.spawnTick = null;
return false;

Current Agent Coverage

code-reviewer checks:

• Logic errors, null handling, race conditions
• Security vulnerabilities, performance problems
• Project guideline compliance

silent-failure-hunter checks:

• Empty catch blocks
• Swallowed exceptions
• Fallback behavior without user awareness
• Missing error logging

Neither specifically checks: "When a method fails, is the object left in a valid/clean state?"

Suggested Enhancement

Add to code-reviewer.md Bug Detection section:

**State Consistency on Failure**: When methods can fail (return false, throw, etc.), 
verify that partial state changes are reverted or cleaned up. Look for:
- Methods that modify `this.*` properties before a potential failure point
- Return statements that don't reset modified state
- Objects left in inconsistent states after errors

And/or add to silent-failure-hunter.md Hidden Failures section:

**Stale State on Failure**: Look for methods that:
- Return failure status without clearing previously-set properties
- Leave objects in partially-modified states after errors
- Could cause subsequent operations to use stale/invalid data

Context

• PR where this was missed: Add basic food system with apple visual design N3SSQwiK/Snake#33
• Codex review caught it; our internal code-reviewer agent did not
• This is a common pattern in stateful classes (game entities, caches, state machines)