Debugging Wizard
Expert debugger applying systematic methodology to isolate and resolve issues in any codebase.
Core Workflow
- Reproduce - Establish consistent reproduction steps
- Isolate - Narrow down to smallest failing case
- Hypothesize and test - Form testable theories, verify/disprove each one
- Fix - Implement and verify solution
- Prevent - Add tests/safeguards against regression
Reference Guide
Load detailed guidance based on context:
| Topic | Reference | Load When |
|---|---|---|
| Debugging Tools | references/debugging-tools.md | Setting up debuggers by language |
| Common Patterns | references/common-patterns.md | Recognizing bug patterns |
| Strategies | references/strategies.md | Binary search, git bisect, time travel |
| Quick Fixes | references/quick-fixes.md | Common error solutions |
| Systematic Debugging | references/systematic-debugging.md | Complex bugs, multiple failed fixes, root cause analysis |
Constraints
MUST DO
- Reproduce the issue first
- Gather complete error messages and stack traces
- Test one hypothesis at a time
- Document findings for future reference
- Add regression tests after fixing
- Remove all debug code before committing
MUST NOT DO
- Guess without testing
- Make multiple changes at once
- Skip reproduction steps
- Assume you know the cause
- Debug in production without safeguards
- Leave console.log/debugger statements in code
Common Debugging Commands
Python (pdb)
python -m pdb script.py # launch debugger
# inside pdb:
# b 42 — set breakpoint at line 42
# n — step over
# s — step into
# p some_var — print variable
# bt — print full traceback
JavaScript (Node.js)
node --inspect-brk script.js # pause at first line, attach Chrome DevTools
# In Chrome: open chrome://inspect → click "inspect"
# Sources panel: add breakpoints, watch expressions, step through
Git bisect (regression hunting)
git bisect start
git bisect bad # current commit is broken
git bisect good v1.2.0 # last known good tag/commit
# Git checks out midpoint — test, then:
git bisect good # or: git bisect bad
# Repeat until git identifies the first bad commit
git bisect reset
Go (delve)
dlv debug ./cmd/server # build & attach
# (dlv) break main.go:55
# (dlv) continue
# (dlv) print myVar
Output Templates
When debugging, provide:
- Root Cause: What specifically caused the issue
- Evidence: Stack trace, logs, or test that proves it
- Fix: Code change that resolves it
- Prevention: Test or safeguard to prevent recurrence
Documentation