You MUST use this before any creative work - creating features, building components, adding functionality, or modifying behavior. Explores user intent, requirements and design before implementation. Contains the reusable grilling loop and domain-modeling discipline.
Execute spec-driven implementation using Generator/Evaluator dual-agent loop with BDD+TDD double-loop verification. Use when implementing features from a design spec, running tasks from tasks.md, or building code with structured testing.
Use when you need to resolve an in-progress git merge/rebase conflict. Guides systematic resolution preserving both intents where possible.
Generate a complete feature design specification (design.md, tasks.md) and Gherkin scenarios from natural language requirements. Use when planning, designing, or scoping new features, refactors, or bug fixes for AI-driven implementation.
Build a throwaway prototype to answer a design question — a terminal app for state/logic questions, or several UI variations toggleable from one route. Use when the user wants to sanity-check whether a state model feels right, or explore what a UI should look like.
Two-axis review of the diff since a fixed point — Standards (does the code follow this repo's coding standards?) and Spec (does the code match what the originating issue/PRD asked for?). Runs both reviews in parallel subagents. Use when completing tasks, implementing major features, or before merging.
Systematic debugging methodology for finding root causes before attempting fixes. Includes feedback-loop construction, minimization, and hypothesis-driven diagnosis. Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.
Use when starting any conversation - establishes how to find and use skills, requiring Skill tool invocation before ANY response including clarifying questions