Doc Co-Authoring Purpose Use this skill when the user wants help writing a substantial document: documentation, proposals, specs, PRDs, RFCs, decision docs, project writeups, or other structured material. Workflow Guide the user through three stages: 1. Context gathering: collect audience, document type, desired impact, templates, constraints, background, tradeoffs, links, prior discussions, and unresolved questions. 2. Refinement and structure: agree on sections, create a scaffold, then draft and refine the document one section at a time. 3. Reader testing: evaluate the draft from the perspe…