Writing Plans
Overview
Create implementation plans for an engineer with zero codebase context.
Each plan includes:
- Exact file paths for every operation
- Complete code (not "add validation here")
- Test-first approach with verification commands
- Bite-sized steps (2-5 min each)
Principles: DRY, YAGNI, TDD, frequent commits.
Announce at start: "I'm using the writing-plans skill to create the implementation plan."
Context: Run in dedicated worktree. If none exists, use using-git-worktrees skill first.
Save plans to: docs/plans/YYYY-MM-DD-<feature-name>.md
Before Writing
- Read spec/requirements completely
- Explore project structure (
view.) - Identify tech stack (package.json, pyproject.toml, etc.)
- Note existing patterns in similar files
- Check docs/ for existing conventions
Bite-Sized Task Granularity
Each step is one action (2-5 minutes), independently verifiable:
- "Write the failing test" — step
- "Run it to confirm failure" — step
- "Implement minimal code to pass" — step
- "Run tests to confirm pass" — step
- "Commit" — step
Plan Document Header
Every plan MUST start with this header:
# [Feature Name] Implementation Plan
**Goal:** [One sentence describing what this builds]
**Architecture:** [2-3 sentences about approach]
**Tech Stack:** [Key technologies/libraries]
---Task Structure
### Task N: [Component Name]
**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"
Before Handoff
Verify plan completeness:
- Every file path exists or will be created
- Every command can be run exactly as written
- No TODO/placeholder text remains
- Tests cover all acceptance criteria from spec
- Include exact test code, not descriptions
Execution Handoff
After saving plan, present:
"Plan saved to docs/plans/<filename>.md. Choose execution mode:
- Subagent-Driven — same session, fresh subagent per task, fast iteration
- Parallel Session — new session, batched execution with checkpoints
Which approach?"
If Subagent-Driven chosen
- Stay in this session
- REQUIRED SUB-SKILL:
subagent-driven-development - Fresh subagent per task + two-stage review
If Parallel Session chosen
- Guide user to open new session in worktree
- REQUIRED SUB-SKILL: New session uses
executing-plans