spec-to-planlisted

# Turn a PRD into an Implementation Plan This skill translates **what** needs to be built (the PRD) into **how** it will be built (a phased implementation plan). It breaks the PRD into tracer-bullet vertical slices, orders them into phases, and writes the result as a Markdown plan file in `./plans/`. ## When to Use Use this skill when: - You already have a PRD or equivalent spec and now need a concrete implementation plan. - You want to think in **phases**, not just issues: what gets built first, what can be deferred, and how slices build on each other. - You intend to drive downstream work (e.g. `/slice-the-spec`, `/incremental-tdd`) from a single, durable planning document. If the requirements are still fuzzy, use `/grill-me` and `/spec-writer` first. ## Workflow You can compress steps if the context is already clear, but keep the core structure: PRD → slices → phases → plan file. 1. **Confirm the PRD is in context** - Ensure the PRD is available in the conversation or repo. - If not, ask the user to paste it or point you to the file path or issue. - Skim for: goals, user stories, functional requirements, non-goals, and constraints. 2. **Explore the codebase (light)** - If you have not already explored the codebase for this feature, do a quick pass to understand major modules, integration layers, and architectural patterns. - Note any constraints that will affect slicing (e.g. existing routing, data models, auth, third-party boundaries). 3. **Iden