What problem does it solve? Specs written after the fact or left with silent gaps let agents ship behavior nobody decided. This Skill writes and grows a living PRODUCT_SPEC.md that states every reachable situation, marks undecided calls as ⟨DECIDE⟩ instead of guessing, and stays structured so a formal review pass can find the holes. ## Core Features & Use Cases - Structured spec authoring: Writes requirements with Context blocks, User Stories, and named-case acceptance criteria, plus a closed-vocabulary glossary and a generated code-to-location table. - Composition sweep: Enumerates every stateful surface across canonical axes (view, mode, tier, viewport, persistence, concurrency, sibling surfaces) so cross-section bugs are specified before code exists. - Completeness and facet passes: Runs checklists covering entities, transitions, invariants, regression fences, and per-feature facets, ending each as a decided or [default]-tagged spec sentence. - Use Case: You say "add a date filter to the report page" and the Skill grows the spec delta — fences for neighboring promises, the new behavior, facet sentences, non-goals, and a success measure — ready for product-prover review before tests or code. ## Quick Start Ask the agent to start a spec for the feature you are about to build, or to add a new feature to the existing PRODUCT_SPEC.md.
