plan

Task: $ARGUMENTS Create `docs/work/<YYYY-MM-DD>-<slug>.md` from `.claude/skills/plan/template.md`. One file per task; if one exists for this slug, extend it — never a second file. The file is not published (`internal/docs/guides.go` skips `docs/work/`), and `/ship` deletes it in the shipping commit. Fill it in this order, reading code for every claim: 1. **Goal and the decision it serves.** For a measurement: which layer (activity / output / outcome / impact), what a zero means, what the reader does differently with the figure. 2. **Open questions with a default answer each** — the answer the work proceeds on if nobody objects. A question without a default blocks nothing and helps nobody. 3. **Decisions with the alternative considered.** For L work, 2–3 alternatives with their cost, and the one chosen with the reason. 4. **Blast radius as a checklist**: every surface the change touches (see `.claude/rules/surfaces.md`: changelog, FEATURES row, BACKLOG line, README, site, PRIVACY, reference regeneration, ADR, golden files, corpus proof). Each box is a completion criterion. 5. **Tracks**: files, behaviour change, tests, verification command, executor and tier (`coder`/opus, this session, `text-broker`), dependencies. Tracks that share a file are one track. A track's verification command is something `runner` can execute without judgement. 6. **Handoff**: what is done, what is next, what was decided alone and how to reverse it. Keep it current after ev...