Reduz consumo de tokens e créditos no Cursor com leitura mínima de contexto. Use quando o usuário pedir para "ler só o necessário", diminuir custo, definir .cursorignore/.gitignore, limitar escopo, ou trabalhar com contexto grande.
Turn a PRD into a multi-phase implementation plan using tracer-bullet vertical slices, saved under ./prd/PRD-NNN-feature-slug/plan.md (see prd/INDEX.md). Use when user wants to break down a PRD, create an implementation plan, plan phases from a PRD, or mentions "tracer bullets".
Deep vs shallow modules (Ousterhout). Use when designing APIs, reviewing module boundaries, or when the user wants smaller interfaces with richer implementations.
Interview the user relentlessly about a plan or design until reaching shared understanding, resolving each branch of the decision tree. Use when user wants to stress-test a plan, get grilled on their design, or mentions "grill me".
Interface design for testability (dependency injection, pure results, small surface). Use when designing APIs, reviewing testability, or refactoring for tests.
When and how to mock (system boundaries only, DI, SDK-style APIs). Use when writing tests, reviewing mocks, or the user asks what to mock.
Refactor candidates after TDD (duplication, long methods, shallow modules, etc.). Use during refactor phase of red-green-refactor or when reviewing code quality.
Test-driven development with red-green-refactor loop. Use when user wants to build features or fix bugs using TDD, mentions "red-green-refactor", wants integration tests, or asks for test-first development.