focused-fix（集中修复）

Focused Fix

Category: Engineering Domain: Debugging & Maintenance

Overview

The Focused Fix skill enforces a disciplined minimal-change approach to bug fixing. Instead of refactoring or improving code during a bugfix, it identifies the smallest possible change set that resolves the issue. This reduces risk, simplifies code review, and prevents scope creep.

Use when

• The user asks to "fix a bug with minimal changes", "do a focused bugfix", or "scope a minimal repair"
• A bug report needs triage to identify the smallest set of files to touch
• A PR is at risk of scope creep (unrelated refactors, style changes, "nearby" fixes)
• A hotfix or release-blocker needs a low-risk, reviewable change set
• The user asks "what is the minimal change to fix X?" or "which files do I need to touch for this bug?"

Quick Start

# Analyze a bug description to identify minimal change scope
python scripts/change_scope_analyzer.py --bug "Login fails when email has + character" --path ./src

# Analyze with JSON output
python scripts/change_scope_analyzer.py --bug "API returns 500 on empty array input" --path ./src --format json

# Analyze with specific file extensions
python scripts/change_scope_analyzer.py --bug "CSS overflow on mobile" --path ./src --extensions .css .scss .html

Tools Overview

change_scope_analyzer.py

Analyzes a bug description against a codebase to identify:

• Files most likely related to the bug (keyword matching, import tracing)
• Estimated change scope (number of files, lines)
• Risk assessment for the change
• Recommended fix approach (minimal vs. structural)

Workflows

Focused Bugfix Workflow

1. Write a clear bug description — reproduction steps, expected vs actual behavior

- *Validate:* the description names the observable failure, not a guess at the cause

1. Run change_scope_analyzer.py to identify scope

- *Validate:* analyzer output lists concrete files and an estimated line count

1. Review the recommended files and approach

- *Validate:* recommended approach is "minimal" — if it says "structural", stop and scope a refactor PR separately

1. Make ONLY the changes needed to fix the bug

- *Validate:* git diff --stat matches (or is smaller than) the analyzer's recommendation

1. Verify no unrelated changes leaked in

- *Validate:* git diff shows no formatting-only changes, no unrelated imports, no "while I'm here" edits

1. Submit PR with focused change set

- *Validate:* commit message states the exact bug fixed, and a regression test is included

Scope Validation

1. After making changes, re-run analyzer
2. Compare actual changes against recommended scope
3. Flag any out-of-scope modifications for separate PRs

- *Validate:* any file touched that was not in the analyzer recommendation has a one-line justification or is reverted

Reference Documentation

• Focused Fix Methodology - Principles, anti-patterns, and decision framework

Common Patterns

Do

• Fix the exact bug reported
• Add a regression test for the fix
• Document why the fix works in the commit message
• Keep the diff as small as possible

Don't

• Refactor surrounding code during a bugfix
• Fix "nearby" issues in the same PR
• Change formatting or style in touched files
• Add features disguised as bugfixes

Anti-patterns