bug-hunter

Bug Hunter

Systematically hunt down and fix bugs using proven debugging techniques. No guessing—follow the evidence.

When to Use This Skill

• User reports a bug or error
• Something isn't working as expected
• User says "fix the bug" or "debug this"
• Intermittent failures or weird behavior
• Production issues need investigation

The Debugging Process

1. Reproduce the Bug

First, make it happen consistently:

1. Get exact steps to reproduce
2. Try to reproduce locally
3. Note what triggers it
4. Document the error message/behavior
5. Check if it happens every time or randomly

If you can't reproduce it, gather more info:

• What environment? (dev, staging, prod)
• What browser/device?
• What user actions preceded it?
• Any error logs?

2. Gather Evidence

Collect all available information:

Check logs:

# Application logs
tail -f logs/app.log

# System logs
journalctl -u myapp -f

# Browser console
# Open DevTools → Console tab

Check error messages:

• Full stack trace
• Error type and message
• Line numbers
• Timestamp

Check state:

• What data was being processed?
• What was the user trying to do?
• What's in the database?
• What's in local storage/cookies?

3. Form a Hypothesis

Based on evidence, guess what's wrong:

"The login times out because the session cookie 
expires before the auth check completes"

"The form fails because email validation regex 
doesn't handle plus signs"

"The API returns 500 because the database query 
has a syntax error with special characters"

4. Test the Hypothesis

Prove or disprove your guess:

Add logging:

console.log('Before API call:', userData);
const response = await api.login(userData);
console.log('After API call:', response);

Use debugger:

debugger; // Execution pauses here
const result = processData(input);

Isolate the problem:

// Comment out code to narrow down
// const result = complexFunction();
const result = { mock: 'data' }; // Use mock data