Write Plan: Spec Into Implementation Plan

Turn a brainstorm-beagle spec into a comprehensive implementation plan that an engineer (or a downstream agent) can execute task-by-task without re-deriving intent.

The output is a single markdown plan document at .beagle/concepts/<slug>/plan.md, sitting beside the spec in the same concept folder. The plan captures HOW — file structure, task decomposition, exact code, exact commands — while the spec already owns WHAT and WHY.

<hard_gate> Do NOT start writing the plan until a brainstorm-beagle spec exists at .beagle/concepts/<slug>/spec.md. If one is missing, stop and route the user to brainstorm-beagle first. Skipping the spec produces plans that bake in unexamined assumptions — the spec is the contract this skill plans against. </hard_gate>

Workflow

Complete these steps in order: