karpathy-recipe
Translation of Recipe for Training Neural Networks to product features. Principle: be paranoid, go slow, visualize everything.
Mandatory Flow
1. Become one with the data
Before coding, read real data from the domain:
- For a financial feature: 10 real transactions from
extratos_exemplo/or fromfinancial_transactionsin staging - For AI: 5 examples of expected input/output from the user
- List known edge cases (memory, ADRs, past issues) — do not invent them
Output: 1 paragraph in the PR ## Data I looked at with links/IDs.
2. Set up end-to-end skeleton + dumb baseline
Implement the complete path with trivial logic first:
- Server action returns a fixed mock
- Repository returns
[] - UI uses hardcoded data
Validate that the entire pipeline runs (request → action → repo → DB → UI) before any real logic. Do not optimize anything yet.
3. Overfit the simplest case
Next: make it work on 1 real input, ignoring edge cases. Mock externals (Stripe, Belvo, OpenAI). Confirm expected logs/output.
4. Add one knob at a time
Add features in order (validation → real DB → external API → caching → optimization). After each knob:
- run
rtk npm test - run
rtk tsc --noEmit - atomic commit (semantic) — each commit must pass green
If something breaks: revert the knob, do not stack fixes.
5. Define eval up front
Before merging, write:
- 1 unit test (happy path)
- 1 integration test (with real fixtures when possible — see memory: "integration tests must hit a real database")
## Evalcriteria in the feature doc: "done when X is measurable"
6. Regularize / harden
Only now add: rate limit, error boundary, retry, Sentry observability, i18n keys, extra RLS. Not before.
Forbidden Anti-patterns
- Starting optimization before the baseline is running
- Adding two knobs in the same commit
- "I will add a try/catch just in case" without a reproduced error
- Caching before having performance measurements
- Generic abstractions (factory, strategy) without 3 real callsites
Expected Output when this skill is active
Codex responds with a mini-plan:
Recipe plan:
1. Data: <source of 5-10 real examples>
2. Skeleton: <files to create with mocks>
3. Overfit: <1 case to make work>
4. Ordered knobs: [...]
5. Eval: <test + measurable criteria>
And asks for confirmation before coding.
Related
- [[surgical-reviewer]] — reviewer that validates these principles in a PR
- [[eval-harness-builder]] — agent that generates tests for step 5
- [[andrej-karpathy-skills:karpathy-guidelines]] — base behavioral guidelines