source-driven

Source-Driven Development

Never rely on training data for API usage. Read the actual source of truth.

Pre-loaded context

• Dependencies: !cat package.json | grep -E '"dependencies"|"devDependencies"' -A 50 | head -60

Workflow

1. Identify Dependencies

• Read package.json (or equivalent manifest) for exact versions
• Note the exact version of each library involved in the task

2. Fetch Official Docs

For each dependency involved:

1. Find the correct docs URL for that specific version (not "latest")
2. Fetch the relevant API page using WebFetch
3. Extract: function signatures, required params, return types, breaking changes

If docs are unavailable or ambiguous, read the library source in node_modules/.

3. Implement from Docs

• Use only APIs confirmed in fetched docs
• Match function signatures exactly (param order, types, defaults)
• If a doc page confirms the API: proceed
• If you cannot verify an API: mark it // UNVERIFIED: could not confirm in docs for v{version}

4. Cite Sources

Add a brief comment on non-obvious API usage:

// Ref: https://docs.example.com/v3/api#method

Only cite when the usage is surprising or version-specific. Don't over-comment obvious calls.

Anti-Rationalization

Excuse	Rebuttal
"I know this API from training data"	Training data may be outdated or wrong. Check the version.
"The docs are too slow to fetch"	One fetch now prevents hours debugging a hallucinated API later.
"It's a minor utility, no need to check"	Minor utilities have breaking changes between versions too.
"I'll verify later"	Unverified code compounds. Verify now or mark UNVERIFIED.

Rules

• NEVER guess API signatures — fetch or read source
• NEVER assume "latest" docs match the installed version
• Always mark unverified claims with // UNVERIFIED
• Prefer node_modules/ source over training knowledge when docs unavailable
• Don't cite every line — only non-obvious or version-sensitive usage

Error Handling

• Docs URL returns 404 → try GitHub repo README, then node_modules/ source
• Version not found in docs → use closest version docs + mark // UNVERIFIED: docs for v{closest}, installed v{actual}
• WebFetch blocked/unavailable → read node_modules/{pkg}/README.md or type definitions