writing-plans

Writing Plans

Overview

Write comprehensive implementation plans assuming the engineer has zero context for our codebase and questionable taste. Document everything they need to know: which files to touch for each task, code, testing, docs they might need to check, how to test it. Give them the whole plan as bite-sized tasks. DRY. YAGNI. TDD. Frequent commits.

Assume they are a skilled developer, but know almost nothing about our toolset or problem domain. Assume they don't know good test design very well.

Announce at start: "I'm using the writing-plans skill to create the implementation plan."

Save plans to: .plans/YYYY-MM-DD-<feature-name>-plan.md

Bite-Sized Task Granularity

Each step is one action (2-5 minutes):

• "Write the failing test" - step
• "Run it to make sure it fails" - step
• "Implement the minimal code to make the test pass" - step
• "Run the tests and make sure they pass" - step
• "Commit" - step

Plan Document Header

Every plan MUST start with this header:

For Claude: REQUIRED SUB-SKILL: Use Skill(executing-plans) to implement this plan task-by-task.

Goal: [One sentence describing what this builds]

Architecture: [2-3 sentences about approach]

Tech Stack: [Key technologies/libraries]

Task Structure

Each task must following this structure:

Files:

• Create: exact/path/to/file.py
• Modify: exact/path/to/existing.py:123-145
• Test: tests/exact/path/to/test.py

Step 1: Write the failing test

def test_specific_behavior():
    result = function(input)
    assert result == expected

Step 2: Run test to verify it fails

Run: pytest tests/path/test.py::test_name -v Expected: FAIL with "function not defined"

Step 3: Write minimal implementation

def function(input):
    return expected

Step 4: Run test to verify it passes

Run: pytest tests/path/test.py::test_name -v Expected: PASS

Step 5: Commit

git add tests/path/test.py src/path/file.py
git commit -m "feat: add specific feature"

Documentation Task

Before writing tasks, scan the project's documentation files (README.md, CLAUDE.md, docs/, etc.) and identify which sections would become stale after the planned changes. Then:

• If docs need updating: Add a final task that updates the specific files and sections affected. This task follows the same structure as any other task — list the files, the sections to change, the new content, and a commit. It gets spec-reviewed and code-reviewed like everything else.
• If no docs need updating (e.g., pure internal refactor): Add a comment at the end of the plan: <!-- No documentation updates needed --> so it's a conscious decision, not an oversight.

Remember

• Exact file paths always
• Complete code in plan (not "add validation")
• Exact commands with expected output
• Reference relevant skills with @ syntax
• DRY, YAGNI, TDD, frequent commits

Execution Handoff

After saving the plan:

• Commit the plan document to git

Then ask the user if they want to execute using AskUserQuestion:

AskUserQuestion(
  questions: [{
    question: "Plan is ready. How would you like to proceed?",
    header: "Execute",
    multiSelect: false,
    options: [
      { label: "Execute with subagents (Recommended)", description: "Full isolation - best for complex plans or autonomous work" },
      { label: "Execute quickly", description: "Faster - does implementation and reviews in main context" },
      { label: "Execute in sandbox", description: "Runs autonomously in a sandbox VM - doesn't block the host" },
      { label: "Don't execute", description: "Stop here - execute manually later" }
    ]
  }]
)

Based on selection:

Execute with subagents:

• REQUIRED SUB-SKILL: Use Skill(executing-plans)
• Dispatches subagents for implementation and reviews
• Best for complex plans or autonomous work

Execute quickly:

• REQUIRED SUB-SKILL: Use Skill(executing-plans-quickly)
• Does implementation and reviews inline in main context
• Best for simple plans or interactive sessions

Execute in sandbox:

• REQUIRED SUB-SKILL: Use Skill(executing-plans-in-sandbox)
• Pushes plan to sandbox VM, waits for results, reintegrates
• Best for autonomous work where you don't want to block the host

Don't execute:

• Plan is saved for later execution
• User can invoke execution skills in any session