What problem does it solve? Engineers often write technical design documents that are vague, untraceable to requirements, or duplicate API specs and schemas, forcing implementers to re-derive the design. This Skill provides a design-research method and an 11-point implementability bar so a TDD for one feature can be built from directly. ## Core Features & Use Cases - Bidirectional requirement tracing: Every design decision traces to a PRD or feature-spec requirement, and every requirement gets a design, eliminating coverage gaps and scope creep. - Reference-not-duplicate discipline: Interfaces and schemas owned by an API spec or data model are referenced with only the delta stated, preventing documentation drift. - Amend-as-delta workflow: Approved TDDs are changed as scoped, versioned, ripple-analyzed deltas with changelogs rather than rewritten. - Use Case: Given an approved PRD and feature-spec for a CSV export feature, produce a TDD with component decomposition, a synced Mermaid sequence diagram plus narration, failure modes with handling, observability signals, a real alternative with a decision criterion, and a rollback plan with measurable triggers. ## Quick Start Use authoring-technical-design to write a technical design document for the export feature based on the approved PRD and feature-spec.
