ai-regression-testing

# AI Regression Testing Testing patterns specifically designed for AI-assisted development, where the same model writes code and reviews it — creating systematic blind spots that only automated tests can catch. ## When to Activate - AI agent (Claude Code, Cursor, Codex) has modified API routes or backend logic - A bug was found and fixed — need to prevent re-introduction - Project has a sandbox/mock mode that can be leveraged for DB-free testing - Running `/bug-check` or similar review commands after code changes - Multiple code paths exist (sandbox vs production, feature flags, etc.) ## The Core Problem When an AI writes code and then reviews its own work, it carries the same assumptions into both steps. This creates a predictable failure pattern: ``` AI writes fix → AI reviews fix → AI says "looks correct" → Bug still exists ``` **Real-world example** (observed in production): ``` Fix 1: Added notification_settings to API response → Forgot to add it to the SELECT query → AI reviewed and missed it (same blind spot) Fix 2: Added it to SELECT query → TypeScript build error (column not in generated types) → AI reviewed Fix 1 but didn't catch the SELECT issue Fix 3: Changed to SELECT * → Fixed production path, forgot sandbox path → AI reviewed and missed it AGAIN (4th occurrence) Fix 4: Test caught it instantly on first run PASS: ``` The pattern: **sandbox/production path inconsistency** is the #1 AI-introduced regression. ## Sandbox-Mode API Testing Mo...