Executing Plans

Overview

Execute implementation plans by dispatching subagents for each phase: implementation, spec review, and code quality review. The main context only orchestrates while subagents do the heavy lifting, preventing context pollution that degrades model quality.

Core principle: Subagent per phase + controller orchestration = preserved model quality throughout long execution runs.

Announce at start: "I'm using the executing-plans skill to implement this plan."

The Process

For each task triplet (Implement → Spec Review → Code Review):
  1. Mark "Implement" in_progress
  2. Dispatch implementer subagent with full task text
  3. Implementer implements, tests, commits, self-reviews
  4. Parse implementer report, capture agent ID and commit SHA
  5. Mark "Implement" complete
  6. Mark "Spec Review" in_progress
  7. Dispatch spec reviewer subagent
  8. If APPROVED → mark "Spec Review" complete
     If ISSUES → resume implementer to fix, re-dispatch spec reviewer
  9. Mark "Code Review" in_progress
  10. Dispatch code quality reviewer subagent
  11. If APPROVED → mark "Code Review" complete
      If ISSUES → resume implementer to fix, re-dispatch code reviewer
  12. Proceed to next triplet (now unblocked)

After all triplets:
  Use completing-work

Step 1: Load Plan and Initialize Tasks

1. Read plan file
2. Review critically - identify any questions or concerns
3. If concerns: Raise them before starting
4. If no concerns: Initialize task tracking

Initialize task tracking:

TaskList

• If tasks exist for this plan: Use AskUserQuestion to ask:

AskUserQuestion(
  questions: [{
    question: "Found existing tasks for this plan. How would you like to proceed?",
    header: "Resume",
    multiSelect: false,
    options: [
      { label: "Continue (Recommended)", description: "Resume from first incomplete task" },
      { label: "Start fresh", description: "Start new session for clean execution" }
    ]
  }]
)

• Continue: Use existing tasks, resume from first non-completed triplet
• Start fresh: Advise user to start a new session for clean execution (tasks are session-scoped and cannot be deleted)
• If no tasks exist: Create all task triplets from the plan (see "Creating Tasks from Plan" below)

Creating Tasks from Plan

Parse the plan document and create a task triplet for each task:

For each Task N in the plan:

1. Create Implementation task:

   TaskCreate:
     subject: "Task N: Implement [Component Name]"
     description: |
       [Copy task content from plan: Files, Steps, Acceptance Criteria]
     activeForm: "Implementing [Component Name]"
   

2. Create Spec Review task:

   TaskCreate:
     subject: "Task N: Spec Review"
     description: |
       Review implementation of Task N for spec compliance.
       Verify all requirements are met, nothing extra added.
       Use spec-reviewer-prompt.md template.
     activeForm: "Reviewing spec compliance for [Component Name]"
   

3. Create Code Review task:

   TaskCreate:
     subject: "Task N: Code Review"
     description: |
       Review implementation of Task N for code quality.
       Check tests, error handling, maintainability.
       Use code-quality-reviewer-prompt.md template.
     activeForm: "Reviewing code quality for [Component Name]"
   

After all tasks created, set blocking relationships:

# Within each triplet:
TaskUpdate:
  taskId: [spec-review-id]
  addBlockedBy: [implement-id]

TaskUpdate:
  taskId: [code-review-id]
  addBlockedBy: [spec-review-id]

# Between triplets (Task N+1 blocked by Task N's code review):
TaskUpdate:
  taskId: [task-N+1-implement-id]
  addBlockedBy: [task-N-code-review-id]

This creates the execution chain:

Implement 1 → Spec Review 1 → Code Review 1 → Implement 2 → Spec Review 2 → ...

Step 2: Execute Each Task Triplet

For each task triplet in order:

2a. Implementation Phase

Mark in progress:

TaskUpdate:
  taskId: [implement-task-id]
  status: in_progress

This triggers the CLI spinner showing the task's activeForm.

Dispatch implementer subagent:

Use prompt template at ./implementer-prompt.md. Fill in:

• Task description (full text from plan)
• Context (where task fits, dependencies, architectural notes)
• Working directory

Task tool (general-purpose):
  description: "Implement Task N: [task name]"
  prompt: [filled template from implementer-prompt.md]

Parse implementer report:

Extract from subagent output:

• implementer_agent_id: The agent ID returned by Task tool (for resumption)
• commit_sha: The commit SHA from the report
• base_sha: Commit before this task (HEAD~1 at dispatch time)

Mark complete:

TaskUpdate:
  taskId: [implement-task-id]
  status: completed

2b. Spec Review Phase

Mark in progress:

TaskUpdate:
  taskId: [spec-review-task-id]
  status: in_progress

Dispatch spec reviewer subagent:

Use prompt template at ./spec-reviewer-prompt.md. Fill in task requirements and implementation summary.

Parse subagent output:

• If output starts with APPROVED: → mark spec review complete
• If output starts with ISSUES: → resume implementer to fix, re-dispatch spec reviewer

Fix/re-review loop:

1. Resume implementer subagent with fix instructions:

   Task tool (general-purpose):
     resume: [implementer_agent_id]
     prompt: |
       The spec reviewer found issues:
       [ISSUES from reviewer output]
   
       Fix these issues, run tests, amend commit, report back.
   

2. Parse response for new commit SHA
3. Re-dispatch spec reviewer
4. Repeat until APPROVED

Mark complete (only after APPROVED):

TaskUpdate:
  taskId: [spec-review-task-id]
  status: completed

2c. Code Quality Review Phase

Mark in progress:

TaskUpdate:
  taskId: [code-review-task-id]
  status: in_progress

Dispatch code quality reviewer subagent:

Use prompt template at ./code-quality-reviewer-prompt.md. The code-reviewer subagent uses the template at ./code-reviewer-template.md.

Fill in:

• WHAT_WAS_IMPLEMENTED: Task summary
• PLAN_OR_REQUIREMENTS: Task text from plan
• BASE_SHA: Commit before this task
• HEAD_SHA: Current commit
• DESCRIPTION: Brief description

Parse subagent output:

• If output starts with APPROVED: → mark code review complete
• If output starts with APPROVED_WITH_MINOR: → mark complete, note minor issues
• If output starts with ISSUES: → resume implementer to fix, re-dispatch code reviewer

Fix/re-review loop (for critical/important issues):

1. Resume implementer subagent with fix instructions:

   Task tool (general-purpose):
     resume: [implementer_agent_id]
     prompt: |
       The code quality reviewer found issues:
       [ISSUES from reviewer output]
   
       Fix these issues, run tests, amend commit, report back.
   

2. Parse response for new commit SHA
3. Re-dispatch code reviewer
4. Repeat until APPROVED or APPROVED_WITH_MINOR

Mark complete:

TaskUpdate:
  taskId: [code-review-task-id]
  status: completed

Proceed to next triplet.

Step 3: Complete Development

After all tasks complete:

1. Run full test suite to verify everything works together
2. REQUIRED SUB-SKILL: Use Skill(completing-work)
3. Follow that skill to verify tests, present options, execute choice

When to Stop and Ask

STOP executing immediately when:

• Hit a blocker (missing dependency, unclear instruction)
• Test fails and fix is not obvious
• Spec reviewer identifies fundamental misunderstanding
• Code reviewer identifies Critical architectural issues

Ask for clarification rather than guessing.

Prompt Templates

• ./implementer-prompt.md - Dispatch implementer subagent (includes fix prompt)
• ./spec-reviewer-prompt.md - Verify implementation matches spec
• ./code-quality-reviewer-prompt.md - Verify implementation is well-built
• ./code-reviewer-template.md - Full template for code-reviewer subagent

Review Order Matters

Implementation → Spec Review → Code Quality Review
                     ↓              ↓
              "Did we build    "Did we build
               the right        it well?"
               thing?"

Never skip spec review. Code quality review on wrong code is wasted effort.

Never skip code quality review. Spec-compliant code can still be buggy or unmaintainable.

Red Flags

Never:

• Skip either review stage
• Proceed to code quality before spec compliance passes
• Ignore Critical or Important issues
• Guess when blocked

Always:

• Follow plan steps exactly
• Use TDD for implementation
• Fix issues before proceeding to next task
• Commit after each task (before review)

Integration

Required skills:

• test-driven-development - Implementation discipline
• completing-work - Complete development after all tasks

Used by:

• writing-plans - Creates plans this skill executes

Native Task Notes

• Tasks are created by this skill at the start of execution, not during planning
• Task triplets: Implement, Spec Review, Code Review for each plan task
• Blocking chain: Implement N → Spec Review N → Code Review N → Implement N+1
• Plan document is the source of truth for what to do
• Native tasks track progress and enforce review gates
• The activeForm field shows in the CLI spinner during in_progress status
• If resuming execution, existing tasks are reused; otherwise created fresh