implement

Execute a structured implementation plan. Work through each step with developer oversight.

Phase 1 — Locate the Plan

Find the plan to execute:

• If the developer specifies a file, use it.
• Otherwise, search for recent plan-*.md or implementation plan files in the working directory.
• If multiple candidates exist, ask which one to use.

Read the plan. Summarize: what will change, how many steps, which files are affected. Ask the developer to confirm before touching any files.

Phase 2 — Execute Steps

For each numbered step in the plan:

1. Announce — state which step is being executed and what it involves.
2. Implement — make the change as specified.
3. Verify — if the plan includes verification for this step (test commands, expected behavior), run it. If not, confirm the change looks correct in context.
4. Report — brief result before moving to the next step.

If something unexpected comes up during a step (a file doesn't exist, a function signature changed, a test fails), stop and surface it to the developer. Do not improvise fixes outside the plan scope.

Phase 3 — Verification

After all steps are complete, run any verification commands specified in the plan:

• Automated tests
• Build commands
• Manual verification steps (describe what to check)

Report pass/fail for each.

Phase 4 — Summary

Provide:

• Steps completed
• Files modified
• Tests run and results
• Any deviations from the plan (with reasoning)
• Any new issues discovered (for separate follow-up)

Constraints

• Stay in scope. Implement exactly what the plan specifies. If something adjacent needs fixing, note it — do not fix it.
• Do not commit. The developer decides when to commit.
• Do not deploy. No deploy or push commands.
• Surface surprises. If reality doesn't match the plan, stop and ask rather than guessing.