SDD-Skill

Verify an implementation conforms to its contract — the feature's PRD.md (preferred; its Gherkin acceptance-criteria scenarios) or BRIEF.md — using the Acceptance Criteria as the oracle. For each clause, first derive the expected outcome from the spec alone, then judge independently whether the test asserts that outcome and whether the production code produces it. Emits a Traceability Matrix with a per-clause conformance verdict; flags gaps, mis-asserted/shallow tests, behavior violations, and orphans. Never edits source code. Triggered by: "contract", "trace contract", "verify contract", "/contract".

Two modes: (1) FEATURE — conduct a requirements interview and generate a business-language PRD under .sdd/, turning the brief's requirement examples into Gherkin acceptance criteria; (2) PROJECT — analyze UL-MAP.md and project architecture to produce or update .sdd/PROJECT.md (vision, tech stack, conventions). Triggered by: "prd", "write a PRD", "feature spec", "product requirement", "/prd", "/prd project", "project overview", "project map".

Turn a feature's BRIEF.md and/or PRD.md into a single self-contained HTML page that visualizes the plan — goal, scope, personas, user stories, business flow, acceptance criteria (as Gherkin scenarios), and risks — using diagrams and charts so developers can see what is being built at a glance. Never edits source code. Triggered by: "visionize", "visualize the plan", "/visionize".

Drive implementation via TDD against a feature's PRD.md (acceptance criteria) and ARCH.md (the technical design). Extracts test cases from the PRD scenarios, runs red-green-refactor per case, and commits every cycle. Tests verify behavior only. Triggered by: "tdd", "implement with tdd", "/tdd".

Phase between PRD and TDD. Reads a feature's PRD.md and designs the technical approach — the change scope and the new classes/modules with their responsibilities — from the perspective of the next engineer who has to extend it, so future requirements land with minimal load. Outputs ARCH.md. Never edits source code. Triggered by: "architecture", "arch", "design architecture", "/architecture", "/arch".

Reach 100% intent consensus with the user, pin the intent down with concrete examples that cover boundaries and exceptions, then compile a requirements brief written purely in business language for handoff to PRD. Never edits source code. Triggered by: "clarify", "/clarify".

Improve the design quality of an existing codebase by identifying fragmented logic and consolidating it into deep modules — simple interfaces hiding complex internals. Triggered by: "improve codebase", "deep module", "/improve-codebase".

Manage a Ubiquitous Language Map — bridges business terms, code names, and UI labels within a Bounded Context. Use when: initializing a new UL map, or updating/reconciling an existing one. Triggered by: "ubiquitous language", "UL map", "domain glossary", "/ul-init", "/ul-update".