# Look Before Edit

> Forces investigation of file dependencies before editing code to prevent cascade failures.

- Skill: `theheavenlyd3mon/look-before-edit` (Agent Skill)
- Install (CLI): `npx skillmds add theheavenlyd3mon/look-before-edit`
- Raw SKILL.md: https://api.skillmd.com/api/skills/theheavenlyd3mon/look-before-edit/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools, Code Review, Debugging
- Tags: Blast Radius, Code Review, Dependency Analysis, File Imports, Grep, Safe Refactoring
- Author: theheavenlyd3mon (https://skillmd.com/u/theheavenlyd3mon)
- Updated: 2026-08-22
- Page: https://skillmd.com/skills/theheavenlyd3mon/look-before-edit

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# Look Before Edit

Before changing a file, check what connects to it. Prevents cascade failures.

## When To Use
Before making any code change that isn't a brand-new file. Especially for:
- Modifying API routes or handlers
- Changing shared utilities or helpers
- Updating type definitions or interfaces
- Modifying config files
- Touching database schemas

## Steps

### 1. Find Who Imports This File
```bash
# For JS/TS files
grep -rn "from.*['\"].*FILENAME\|require.*FILENAME\|import.*FILENAME" --include='*.{js,ts,jsx,tsx}' . | grep -v node_modules

# For Python files
grep -rn "import.*FILENAME\|from.*FILENAME" --include='*.py' . | grep -v __pycache__
```

### 2. Check What This File Exports
- Read the file's exports/functions/types
- Understand what other code depends on

### 3. Check Data Flow
- What arguments does this function take?
- What does it return?
- What side effects does it have (DB writes, API calls, file I/O)?

### 4. Read The User's Actual Request
- What specifically did they ask for?
- What's the MINIMUM change needed?
- Am I about to change more than asked?

### 5. Make The Change
- Only after completing steps 1-4
- Change the minimum necessary
- Preserve existing behavior for anything not explicitly asked about

## Red Flags (Stop and Ask)
- The file is imported by 10+ other files → high blast radius
- Changing a function signature → will break callers
- Modifying a config that other services read
- Database schema change → needs migration plan
- Deleting exports that other files use

## What NOT To Do
- Don't refactor while fixing a bug (separate PR)
- Don't "improve" code that wasn't asked about
- Don't change variable names for style (breaks git blame)
- Don't add features the user didn't request