skills

Pattern for wrapping third-party SDK clients (Stripe, Resend, AWS, etc.) with Effect. Use when creating Effect services that wrap external libraries with Promise-based APIs. Provides type-safe error handling, automatic tracing, and clean dependency injection via the "use" pattern.

Use when brainstorming, generating, or evaluating startup ideas, deciding what to build, or reasoning about how a startup creates wealth and grows. Encodes Paul Graham's framework — outcome = growth rate × duration, growth comes from users loving the product enough to tell friends (empathy, not exploitation), and the best ideas come from building cool things with friends rather than searching for "startup ideas."

Use when an SPA or SSR app flashes the wrong UI before client-side data resolves — an app-shell skeleton shown to visitors who get bounced to login, a results skeleton before "no results found", a light-theme flash before dark mode, a generic placeholder that swaps to something jarringly different. Covers resolving state at the edge/server, optimistic hint cookies, redirect-back (returnTo) flows, and how to test the loading window.

Review, critique, rewrite, or design product error messages and error-handling UX. Use when Codex is asked to improve validation errors, server failure messages, empty/failure states, toast/dialog copy, support escalation paths, or error-message inventories so users understand what happened, what was not affected, and what to do next.

Use when writing or reviewing TypeScript/full-stack code. Encodes principles for type safety (branded types, discriminated unions, end-to-end types), real tests over mocks, OpenTelemetry observability, and picking the right abstractions instead of premature ones.