Verify Changes — Prove Code Works

"Code that exists" ≠ "Code that works." This skill ensures changes are verified through execution.

Core Principle

❌ Verification by inspection:  "I can see the function exists, it should work"
❌ Verification by assumption:  "The types check out, so it's correct"
✅ Verification by execution:   "I ran it, here's the output, it works because [evidence]"

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Verification Protocol

Step 1: Identify What Changed

- Which files were modified?
- What behavior should be different now?
- What was the original bug/requirement?

Step 2: Determine Verification Method

Change Type	Verification Method
Bug fix	Reproduce the original bug scenario → confirm it no longer occurs
New feature	Run the feature → confirm expected output
Refactor	Run existing tests → confirm nothing broke
API change	Call the endpoint → confirm response shape
UI change	Render the component → confirm visual output
Config change	Load the config → confirm values applied
Build/infra	Run build command → confirm success

Step 3: Execute Verification

# For Node.js projects
npm run build          # Does it compile?
npm run test           # Do tests pass?
npm run dev            # Does it start?

# For specific files
node -e "require('./path/to/module'); console.log('✅ Loads correctly')"

# For API endpoints
curl http://localhost:3000/api/endpoint

# For scripts
python script.py --test

Step 4: Report Evidence

## Verification Report

### What was changed
- [File list and summary]

### How it was verified
- [Exact commands run]

### Evidence
- Build: ✅ Compiled without errors
- Tests: ✅ 42/42 passing
- Runtime: ✅ Server starts, endpoint returns expected JSON
- Edge case: ✅ Empty input handled correctly

### Not yet verified
- [Anything that couldn't be tested automatically]

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Verification Checklist by Project Type

Web Application

• npm run build — compiles without errors
• npm run lint — no linting errors
• npm run test — all tests pass
• Dev server starts successfully
• Changed pages render correctly
• No console errors in browser

API / Backend

• Server starts without errors
• Changed endpoints respond correctly
• Error cases return appropriate status codes
• Database queries execute successfully

CLI / Script

• Script runs without errors
• Expected output matches actual output
• Error handling works (bad input test)
• Help/usage text is correct

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Anti-Patterns

Anti-Pattern	Why It's Bad	Fix
"It should work"	No evidence	Run it and show output
Only checking happy path	Bugs hide in edge cases	Test error paths too
Verifying only compilation	Compiles ≠ correct	Test runtime behavior
Skipping verification for "trivial" changes	Trivial changes cause real bugs	Verify everything

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Integration with Other Skills

After Using	Verify With
frontend-design → UI changes	Render in browser, check console
backend-specialist → API changes	curl endpoints, check responses
database-design → Schema changes	Run migrations, query data
testing-patterns → New tests	Run test suite, check coverage