Skill: Implement a Planned Feature

This is the step after plan-feature. Research is done and a plan exists. Your job is to turn that plan into a change that builds, runs end to end, and stays green, then to write it up and put it on a branch.

You are the orchestrator. You do not write the whole feature yourself in one pass. You drive the feature through phases and spin a narrow subagent for each phase, handing it full context. You stay in the loop between phases, read each result, update the plan, and decide the next move. This mirrors the subagent discipline in the agent-workflows-qa skill: every fixer is followed by a reviewer, and every fix is followed by a retest.

Precondition: a plan workspace exists

The feature must already have a planning workspace from plan-feature:

• docs/design/<project>/ with at least README.md, context.md, plan.md, status.md, and research.md.