Advanced debugging specialist for diagnosing and resolving code issues. Use when user encounters bugs, errors, unexpected behavior, or mentions debugging.

Debugger An advanced debugging specialist that helps diagnose and resolve code issues systematically. When This Skill Activates Activates when you: Report an error or bug Mention "debug this" or "help debug" Describe unexpected behavior Ask why something isn't working Debugging Process Phase 1: Understand the Problem 1. Reproduce the issue What are the exact steps to reproduce? What is the expected behavior? What is the actual behavior? What error messages appear? 2. Gather context Phase 2: Isolate the Issue 1. Locate the error source Stack trace analysis Error code lookup Log correlation 2. Narrow down scope Binary search (comment out half) Minimize reproduction case Identify affected components Phase 3: Analyze the Root Cause Common Error Categories Category Symptoms Investigation Steps Null/Undefined "Cannot read X of undefined" Trace the variable origin Type Errors "X is not a function" Check actual vs expected type Async Issues Race conditions, timing Check promise handling, async/await State Issues Stale data, wrong state Trace state mutations Network Timeouts, connection refused Check endpoints, CORS, auth Environment Works locally, not in prod Compare env vars, versions Memory Leaks, OOM Profile memory usage Concurrency Deadlocks, race conditions Check locks, shared state Phase 4: Form Hypotheses For each potential cause: 1. Form a hypothesis 2. Create a test to validate 3. Run the test 4. Confirm or reject Phase 5: Fix and Verify 1. Implement the fix 2. Add logging if needed 3. Test the fix 4. Add regression test Debugging Commands General Debugging Language Specific JavaScript/TypeScript: Python: Go: Common Debugging Patterns Pattern 1: Divide and Conquer Pattern 2: Add Logging Pattern 3: Minimal Reproduction Error Message Analysis Common Error Messages Error Likely Cause Solution Cannot read property 'X' of undefined Accessing property on null/undefined Add null check, use optional chaining X is not a function Wrong type, shadowing Check typeof, verify import Unexpected token Syntax error Check line before error, validate syntax Module not found Import path wrong Check relative path, verify file exists EADDRINUSE Port already in use Kill existing process, use different port Connection refused Service not running Start service, check port Timeout Request too slow Increase timeout, check network Debugging Checklist [ ] I can reproduce the issue consistently [ ] I have identified the exact error location [ ] I understand the root cause [ ] I have a proposed fix [ ] The fix doesn't break existing functionality [ ] I've added a test to prevent regression Scripts Generate a debug report: References references/checklist.md Debugging checklist references/patterns.md Common debugging patterns references/errors.md Error message reference

debugger