cairn

Implement one named Project issue with red-green TDD and return a structured task outcome.

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.

Use when designing, writing, reviewing, or refactoring React components and features. Covers component boundaries, state ownership, composition, prop design, custom hooks, useEffect avoidance, memoization, Zustand, TanStack Query, loading/error/empty states, async event handling, TypeScript state modeling, and file organization. Trigger for React component design questions, component-tree restructuring, state management choices, data fetching, effect cleanup, reusable UI composition, prop drilling, render performance, error boundaries, optimistic updates, double-submit prevention, race conditions, or organizing a React codebase.

Generate Brief artifact content and persist it through the Brief and Project context tools.

Use only after a fresh slice PRD exists under the Project's .cairn/prds/ folder and the user-approved slice needs to be broken into local implementation issue files.

Use only after the project brief is concrete, the Cairn has proposed a smallest meaningful first slice, and the user has agreed to that slice; silently draft the slice PRD.

Generate Tasks tab content from issue paths and persist it through the Tasks artifact tool.

Review one implemented Project issue for correctness, regressions, missing tests, and quality risks. Return a structured verify result.

Generate Plan artifact content for the agreed first slice and persist it through Plan tools.

Run the active Project's build and typecheck heuristic and return a structured verification result.