Writes comprehensive, bite-sized implementation plans from specs or requirements. Use when you have a spec or requirements for a multi-step task, before touching code.
Write comprehensive implementation plans assuming the engineer has zero context for the codebase and questionable taste. Document everything they need: which files to touch, complete code, test commands with expected output, docs to reference. Give them the whole plan as bite-sized tasks. DRY. YAGNI. TDD. Frequent commits.
Assume a skilled developer who knows almost nothing about the toolset or problem domain, and doesn'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: docs/plans/YYYY-MM-DD-<feature-name>.md
Each step is one action (2-5 minutes):
Every plan MUST start with:
# [Feature Name] Implementation Plan
> **For Claude:** REQUIRED SUB-SKILL: Use 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 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**
```python
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**
```python
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**
```bash
git add tests/path/test.py src/path/file.py
git commit -m "feat: add specific feature"
```
After saving the plan, offer:
Plan saved to docs/plans/<filename>.md. Two execution options:
1. Subagent-Driven (this session) — fresh subagent per task,
review between tasks, fast iteration
2. Parallel Session (separate) — open new session, batch
execution with checkpoints
Which approach?
If Subagent-Driven chosen: Use subagent-driven-development skill.
If Parallel Session chosen: Guide them to open new session → use
executing-plans skill.