implement-milestone

name	implement-milestone
description	Implements the milestone plan already established in this conversation, following CLAUDE.md's dev workflow and definition of done. Use right after planning a milestone in this same session.
disable-model-invocation	true
argument-hint	[milestone-number]

0. Confirm $ARGUMENTS matches the milestone number recorded in CLAUDE.md's "## Current focus" section. If it doesn't match, stop and flag the mismatch rather than proceeding. 0b. Confirm you are on the milestone's feature branch (created by /plan-milestone, named m$ARGUMENTS-<slug>), not on master. If you are on master, stop and flag — milestone work must not be committed directly to master.

Implement Milestone $ARGUMENTS

Implement Milestone $ARGUMENTS using the plan already established earlier in this conversation.

If no milestone plan is visible in the current context, stop and ask for it — do not invent or assume one.

CLAUDE.md is the single source of truth for how to work. It is always in context; do not re-derive its guidance here. Follow, in particular:

• "Dev workflow" — the verification cadence (targeted test(filter=) while iterating; prefix full-suite runs with TESTTHAT_CPUS=8; check() subsumes test(), so don't stack test()→check()→coverage(); check(vignettes = FALSE) for mid-work checks; the cached() fit memo and its caveats; no two concurrent package-touching R processes).
• "Definition of done (every change)" — including the one-command gate Rscript tools/dod-gate.R (check 0/0/0 → coverage → style → lint → pkgdown::check_pkgdown()), run once before the PR.
• "Git" and "Ask-first / guardrails" — the branch→PR→squash-merge protocol, the release-milestone CI exception, and when to flag before acting.

What this skill adds on top of that shared guidance:

• Build in small, reviewable increments: one coherent change → relevant test(s) → commit → repeat. Do not produce one large commit at the end.
• After any roxygen change, run devtools::document() and commit the regenerated NAMESPACE/docs in the same increment.
• When you add or remove an exported object (the regenerated NAMESPACE gained/lost an export()/S3method(), or you added a dataset under data/), update _pkgdown.yml's reference: list to cover it in the same commit. This does not break local R CMD check, only the pkgdown GitHub Action — the pkgdown::check_pkgdown() step in the DoD gate is the guard.
• Write or update tests for new behavior; update NEWS.md for user-visible changes.
• If you hit a design ambiguity not covered by DESIGN.md, stop and ask rather than deciding unilaterally.

Milestone documentation (do this before the final commit — it is part of the definition of done). The rule is one detailed home, everything else a pointer — do not duplicate the milestone narrative across files:

• MILESTONES.md (single source of truth): add a detailed M$ARGUMENTS (done) entry in numeric order (immediately after M{$ARGUMENTS − 1}; never append out of order or skip a number), in the style of existing entries — what shipped + durable decisions/amendments + final test count and R CMD check status.
• CLAUDE.md "## Completed milestones": add the matching index entry — a true one-liner (title + a single clause naming the headline artifact; no second sentence — see that section's header). Then set "## Current focus" back to the status slot: In flight: nothing. Last shipped: M$ARGUMENTS ….
• NEWS.md: user-facing notes only.
• DESIGN.md §1–14: record any design-contract change in the relevant numbered section — not as a second copy of the milestone log (§15 is only a pointer to MILESTONES.md).
• ROADMAP.md: if this milestone had a section there, delete it (it's now shipped).

Finishing the milestone. Follow CLAUDE.md's "Git" section: push the feature branch, open a PR into master, and squash-merge immediately once the local DoD is green (gh pr merge <n> --squash --delete-branch) — do not gate on remote CI or use --auto. Then sync local: git switch master && git pull --ff-only. If that fast-forward fails, stop and follow CLAUDE.md's divergence-recovery note (inspect, then merge origin/master in — never force-push or reset --hard). The release-milestone exception (wait for the full green CI matrix) is in CLAUDE.md's Git section — flag it explicitly if this is such a milestone.

Do not run /post-milestone-review yourself at the end — that's a separate, deliberate step you trigger after reviewing the work.