Plan Executor

Execute implementation plans with two-stage review, verification, and batch checkpoints.

When This Skill Applies

This skill automatically applies when:

• You're in a worktree created with --plan flag
• Your goal references a plan file at docs/plans/...
• You're executing a multi-task implementation

Core Principles

1. Evidence before claims - Never claim completion without verification output
2. Two-stage review - Spec compliance first, then code quality
3. Batch execution - Execute 3 tasks, checkpoint, continue
4. Fresh context per task - For parallel execution, use separate subagents

---

Execution Flow

Phase 1: Load and Review Plan

1. Read the plan file completely
2. Extract all tasks with their:
   - Files to create/modify
   - Steps to follow
   - Verification commands
   - Dependencies
3. Create mental model of dependency graph
4. Identify independent vs dependent tasks
5. If concerns about the plan, raise with user BEFORE starting

Phase 2: Execute Tasks

For 1-3 tasks: Execute sequentially yourself For 4+ independent tasks: Consider parallel subagents

Per Task Execution

1. Mark task as in_progress (use TaskUpdate)
2. Follow each step exactly as written
3. Run verification commands, capture output
4. Perform two-stage review (see below)
5. Mark task as completed only with evidence
6. Commit the work

Phase 3: Batch Checkpoints

After every 3 tasks (or all independent tasks):

Report to user:
- Tasks completed with evidence
- Issues encountered
- "Ready for feedback"

Wait for user confirmation before continuing.

Phase 4: Dependent Tasks

After independent tasks complete:

1. Identify newly unblocked tasks
2. Execute next batch
3. Repeat until all tasks done

---

Two-Stage Review

Stage 1: Spec Compliance Review

Question: Does the code match the plan exactly?

Check:
- [ ] All required files created at exact paths
- [ ] All modifications match spec
- [ ] Nothing missing from requirements
- [ ] Nothing extra added (YAGNI)
- [ ] Tests cover specified behaviors

If issues found:

• Fix the gaps
• Re-review
• Don't proceed until spec-compliant

Stage 2: Code Quality Review

Question: Is the implementation well-built?

Check:
- [ ] Code follows project patterns
- [ ] Tests are meaningful (not just coverage)
- [ ] No obvious bugs or edge cases missed
- [ ] Error handling appropriate
- [ ] No code smells

If issues found:

• Fix the issues
• Re-review
• Don't proceed until quality approved

---

Verification Before Completion

The Iron Law

NO COMPLETION CLAIMS WITHOUT FRESH VERIFICATION EVIDENCE

Required Evidence

Bad vs Good

❌ BAD: "The tests should pass now"
❌ BAD: "I believe this is working"
❌ BAD: "Task completed successfully"

✅ GOOD: "Tests pass (output: 12/12 pass, 0 failures)"
✅ GOOD: "Build succeeded (exit code 0, no errors)"
✅ GOOD: "Task complete. Evidence:
         - Tests: 12/12 pass
         - Lint: 0 errors
         - Build: success"

When to Verify

• Before claiming any task is done
• Before moving to next task
• Before reporting to user
• Before committing

---

Parallel Execution with Subagents

When you have 4+ independent tasks, use parallel subagents:

Launching Subagents

// Launch multiple Task tools in a SINGLE message
Task({
  description: 'Implement Task 1',
  prompt: `You are implementing Task 1 from the plan.

Task details:
${task1Content}

Requirements:
1. Follow each step exactly
2. Run all verification commands
3. Report actual output, not assumptions
4. Commit when complete

When done, report:
- Files created/modified
- Verification output (actual)
- Any issues encountered`,
  subagent_type: 'general-purpose',
});

// In the SAME message, launch Task 2, 3, etc.

Collecting Results

After subagents complete:

1. Review each result
2. Verify the evidence provided
3. If subagent claimed success without evidence, re-verify yourself
4. Report consolidated results to user

Don't Trust Blindly

❌ Subagent: "Task completed successfully"
   You: "Great, moving on"

✅ Subagent: "Task completed. Tests: 5/5 pass"
   You: [Verify the claim by running tests yourself if suspicious]
   You: "Confirmed, Task 1 complete with 5/5 tests passing"

---

When to Stop and Ask

STOP immediately when:

• Verification fails repeatedly
• Plan has gaps or unclear instructions
• Dependencies aren't actually met
• You're unsure about an approach

Don't:

• Guess when confused
• Force through blockers
• Skip verification
• Proceed with failing tests

---

Example Execution

Agent: I'm executing the plan at docs/plans/2026-02-01-webhooks.md

[Reads plan, extracts 5 tasks]

Task 1 (independent): WebhookConfig model
Task 2 (independent): WebhookDelivery service
Task 3 (independent): API endpoints
Task 4 (depends on 1,2): Integration
Task 5 (depends on 4): E2E tests

Starting with independent tasks 1-3...

---

Task 1: WebhookConfig model
[Following steps from plan]
1. Writing failing test...
2. Running: pnpm test packages/core --grep WebhookConfig
   Output: FAIL - WebhookConfig is not defined
3. Creating model...
4. Running: pnpm test packages/core --grep WebhookConfig
   Output: PASS - 3/3 tests pass

Spec compliance review:
✅ All files created at specified paths
✅ Model matches spec
✅ Tests cover required behaviors
✅ Nothing extra added

Code quality review:
✅ Follows project patterns
✅ Tests are meaningful
✅ No obvious issues

Task 1 complete.
Evidence: Tests pass (3/3), files created at packages/core/src/models/webhook-config.ts
[Commit: "feat: add WebhookConfig model"]

---

[Similar for Tasks 2, 3]

---

Batch checkpoint: Tasks 1-3 complete

Summary:
- Task 1: WebhookConfig model ✅ (3/3 tests)
- Task 2: WebhookDelivery service ✅ (5/5 tests)
- Task 3: API endpoints ✅ (4/4 tests)

All independent tasks verified and committed.

Ready for feedback. Should I proceed with Task 4 (Integration)?

---

Integration with Workflow

/discover (main branch)
    │
    ├── Creates plan at docs/plans/YYYY-MM-DD-feature.md
    │
    └── Creates worktree with --plan flag
            │
            └── plan-executor (this skill)
                    │
                    ├── Execute tasks with verification
                    ├── Two-stage review
                    ├── Batch checkpoints
                    │
                    └── Complete with evidence

---

Anti-Patterns

Don't:

• Claim completion without running verification
• Trust subagent "success" reports blindly
• Skip spec compliance review
• Move to next task with failing tests
• Guess when plan is unclear
• Add features not in the plan (YAGNI)

Do:

• Run every verification command
• Capture and report actual output
• Stop when blocked
• Ask for clarification when needed
• Follow the plan exactly