fix

/fix - Bug Fix Workflow

Purpose

Smart debugging and bug fixing workflow that analyzes errors, identifies root causes, implements fixes, and adds regression tests.

Usage

/fix [error message, bug description, or issue reference]

Arguments

• $ARGUMENTS: Error message, stack trace, bug description, or issue number

---

Analyze and fix the following issue: $ARGUMENTS

Workflow

Phase 1: Error Analysis

1. Parse Error Information

   • Extract error type and message
   • Parse stack trace if available
   • Identify the failing location

2. Gather Context

   • When does this error occur?
   • What triggers it?
   • Is it reproducible?
   • When did it start happening?

3. Check for Known Patterns

   • Common error patterns
   • Similar issues in codebase
   • Recent changes that might have caused it

Phase 2: Root Cause Investigation

1. Trace Execution

   • Follow the code path to the error
   • Identify state at each step
   • Find where expectations diverge

2. Form Hypotheses

   • List possible causes ranked by likelihood
   • Identify minimal tests to validate each

3. Validate Hypothesis

   • Test the most likely cause first
   • Confirm root cause before fixing
   • Don’t fix symptoms only

Phase 3: Search Related Code

1. Find Similar Code

   • Search for similar patterns
   • Check if same bug exists elsewhere
   • Identify shared code that might be affected

2. Review Recent Changes

   git log --oneline -20
   git blame [file]

Phase 4: Implement Fix

1. Develop Minimal Fix

   • Fix the root cause, not symptoms
   • Keep changes minimal and focused
   • Consider edge cases

2. Add Defensive Code (if appropriate)

   • Input validation
   • Null checks
   • Error handling

3. Update Related Code (if needed)

   • Fix same issue in similar code
   • Update shared utilities

Phase 5: Verification

1. Test the Fix

   • Verify original error is resolved
   • Check related functionality
   • Run existing test suite

2. Add Regression Test

   • Write test that would have caught this bug
   • Include edge cases discovered
   • Ensure test fails without fix

3. Run Full Test Suite

   # Python
   pytest -v
   
   # TypeScript
   pnpm test

Phase 6: Documentation

1. Document the Fix

   • What was the issue
   • What caused it
   • How it was fixed

2. Update Comments (if needed)

   • Add clarifying comments
   • Document non-obvious behavior

Output

Bug Fix Summary

## Bug Fix Complete

### Issue
[Original error/bug description]

### Root Cause
[Explanation of what caused the bug]

### Location
`path/to/file.ts:42` - [function/method name]

### Fix Applied

**Before:**
```typescript
// Problematic code

After:

// Fixed code

Explanation

[Why this fix resolves the issue]

Regression Test Added

path/to/test.ts - test_[scenario]

Verification

• Original error no longer occurs
• Existing tests pass
• New regression test passes
• No new issues introduced

Related Areas Checked

• path/to/similar.ts - No similar issue

Commands to Verify

pytest tests/test_file.py -v
# or
pnpm test path/to/file.test.ts

## Common Fix Patterns

### Null/Undefined Access

```typescript
// Before
const name = user.profile.name;

// After
const name = user?.profile?.name ?? 'Unknown';

Missing Error Handling

# Before
data = json.loads(response.text)

# After
try:
    data = json.loads(response.text)
except json.JSONDecodeError as e:
    logger.error(f"Invalid JSON response: {e}")
    raise InvalidResponseError("Failed to parse response")

Race Condition

// Before
const data = await fetchData();
setState(data); // May be unmounted

// After
useEffect(() => {
  let cancelled = false;
  fetchData().then(data => {
    if (!cancelled) setState(data);
  });
  return () => { cancelled = true; };
}, []);

Off-by-One Error

# Before
for i in range(len(items) + 1):  # IndexError
    process(items[i])

# After
for i in range(len(items)):
    process(items[i])
# or
for item in items:
    process(item)

Example

Input: /fix TypeError: Cannot read property 'email' of undefined in UserService.ts:45

Output:

1. Analysis: User object is undefined when accessed
2. Root cause: async fetch didn’t await, user not loaded yet
3. Fix: Add null check and proper async handling
4. Regression test: Test for case when user is not loaded

Flags

Flag	Description	Example
--mode=[mode]	Use specific behavioral mode	--mode=deep-research
--persona=[type]	Apply persona expertise	--persona=security
--depth=[1-5]	Investigation thoroughness	--depth=4
--format=[fmt]	Output format (concise/detailed)	--format=concise
--skip-regression	Skip regression test creation	--skip-regression
--checkpoint	Create checkpoint before fixing	--checkpoint

Flag Usage Examples

/fix --mode=deep-research "intermittent timeout error"
/fix --persona=security "SQL injection vulnerability"
/fix --depth=5 "race condition in auth flow"
/fix --format=concise "typo in error message"

Persona Options

Persona	Focus Area
security	Security vulnerabilities, OWASP
performance	Speed, memory, efficiency
reliability	Error handling, edge cases

MCP Integration

This command leverages MCP servers for enhanced debugging:

Reasoning - Root Cause Analysis (Primary)

ALWAYS use Reasoning for debugging:
- Trace execution path step-by-step
- Form and test hypotheses systematically
- Track confidence in each potential cause
- Revise understanding as evidence emerges

Memory - Bug Context

Store and recall debugging context:
- Remember similar bugs from previous sessions
- Recall fix patterns that worked before
- Store root cause analysis for future reference
- Create relations between bugs and affected components

Browser tools - Browser Testing

For UI/frontend bugs:
- Reproduce the bug in browser environment
- Test fix across different browsers
- Verify visual regressions are resolved
- Automate regression test for the fix

Web Search - Library Issues

When debugging library-related issues:
- Fetch current documentation for correct usage
- Check for known issues or breaking changes
- Find correct patterns and examples

Filesystem - Code Search

For tracing bug across codebase:
- Use grep_search to find related code
- Use view_file to examine suspicious areas
- Track changes with file history

Variations

Modify behavior via CLAUDE.md:

• Set required test coverage for fixes
• Define severity levels for bugs
• Configure error reporting format
• Set required review process

Gap Analysis Rule

Always identify gaps and suggest next steps to users. In case there is no gaps anymore, then AI should clearly state that there is no gap left.