Pre-computed context

Current branch: !git branch --show-current 2>/dev/null || echo "unknown" Working tree status: !git status --porcelain 2>/dev/null | head -20 || echo "clean" Recent commits: !git log --oneline -5 2>/dev/null || echo "no commits" Uncommitted changes: !git diff --stat HEAD 2>/dev/null | tail -1 || echo "none"

Purpose

Implementation is where plans become code. This skill structures the execution phase so changes are made incrementally, validated continuously, and abandoned early when the approach isn't working — rather than pushing through a broken implementation and discovering problems at PR time.

It sits between planning and verification: exploration and external research provide understanding, a planning pass produces an approved plan, this skill executes it with discipline, and the companion skills in the separate testing and verification plugins (/testing:plan, /testing:write, /testing:diagnose, /verification:confirm) — no longer siblings of this skill after the plugin split — validate the result when those plugins are installed.

Philosophy: cost of a mid-implementation replan is minutes; cost of discovering a flawed approach at PR review is hours. Validate incrementally, commit at checkpoints, and route back to planning the moment something feels wrong.

Progress tracking

Track skill Steps 0–5 in-session via the task list. Durable progress lives in the plan artifact itself (phase tags, - [ ] step boxes) plus the handoff notes written at phase boundaries (Step 4) — do not mirror progress into a second checklist file. Placement resolves per the topic-docs binding (${CLAUDE_PLUGIN_ROOT}/reference/topic-docs.md): the plan artifact is contract-tier — <contract_dir>/<slug>/PLAN.md (default docs/topics/), committed on the task branch (or the memory tier under contract_tier: local) — and handoff notes are memory-tier under <memory_dir>/handoffs/ (default .work/handoffs/).