implement

name	implement
description	Launcher — pick up a Linear ticket or task description and drive it through the full phased workflow (pickup → understand → plan → implement → quality → verify → ship).
user-invocable	true

Usage

/implement AGE-XX [--profile full|standard|quick]

Or with a plain text description:

/implement "Add a health check endpoint to the API"

Behavior

1. Parse input — extract ticket identifier (AGE-XX pattern) or use as plain text description

2. Determine profile — from --profile flag or default to standard

   • full: pickup → understand → plan (human gate) → implement → quality → verify → ship → review (human gate) → cleanup
   • standard: pickup → understand → plan → implement → quality → verify → ship → review (human gate) → cleanup
   • quick: pickup → implement → quality → verify → ship → review (human gate) → cleanup

3. Create worktree — each agent gets an isolated workspace to avoid overlapping with other agents:

   BRANCH="age-xx-short-description"  # or feat/short-description for plain text
   git worktree add .worktrees/$BRANCH -b $BRANCH
   cd .worktrees/$BRANCH
   pnpm install
   

   • The .worktrees/ directory is gitignored in the repo root
   • Each worktree is named after its branch for easy identification
   • Run pnpm install after creation to set up dependencies

4. Write state file — .harness/state.json (inside the worktree) with lifecycle phases and statuses based on profile

State file format

{
  "task": "AGE-XX",
  "branch": "age-xx-short-description",
  "worktree": ".worktrees/age-xx-short-description",
  "profile": "standard",
  "phases": [
    { "name": "pickup", "status": "pending", "skill": "harness-pickup" },
    { "name": "understand", "status": "pending", "skill": "harness-understand" },
    { "name": "plan", "status": "pending", "skill": "harness-plan" },
    { "name": "implement", "status": "pending", "skill": "harness-implement" },
    { "name": "quality", "status": "pending", "skill": "harness-quality" },
    { "name": "verify", "status": "pending", "skill": "harness-verify" },
    { "name": "ship", "status": "pending", "skill": "harness-ship" },
    { "name": "review", "status": "waiting", "owner": "human", "reason": "PR review on GitHub" },
    { "name": "cleanup", "status": "pending", "skill": "harness-cleanup" }
  ],
  "outputs": {}
}

• The review phase starts as waiting (not pending) — it's a human gate, not agent work. The engine will hit it after ship completes and stop.
• When the human approves and tells the agent to continue (e.g. "approved, go merge it"), session recovery flips review to done and re-invokes the engine, which moves into cleanup.
• cleanup is where the agent runs gh pr merge, the Railway healthcheck, the Linear → "Done" update, and finally removes the worktree.
• Skipped phases (based on profile) get { "status": "skipped", "reason": "profile:quick" }.

5. Change working directory — cd into the worktree before invoking the engine so all phase skills operate in the isolated workspace
6. Invoke /harness-engine with the state file path

Worktree Cleanup

Worktree removal is owned by the harness-cleanup phase, which runs after the human approves the PR and the review phase flips from waiting to done. Cleanup performs the merge, Railway healthcheck, Linear "Done" update, and only then removes the worktree (with a hard safety check that the worktree is clean — never --force).

If the workflow is aborted before cleanup runs, the worktree is left in place — the human can remove it manually with git worktree remove .worktrees/$BRANCH from the repo root.

Session Recovery

If .harness/state.json already exists in the worktree and matches the task:

• cd into the worktree first
• Read it, find the current phase
• If a phase has status: "waiting" (human gate), present context and ask for approval
  • Approved → set to done, invoke engine to continue
  • Rejected → set to blocked with reason, stop
• Otherwise invoke engine to resume from current phase

If the worktree path is recorded in the state file but doesn't exist (e.g., was cleaned up), recreate it:

git worktree add .worktrees/$BRANCH $BRANCH  # reattach existing branch
cd .worktrees/$BRANCH
pnpm install