writing-plans

name	writing-plans
description	Use when you have a spec or requirements for a multi-step task, before touching code — creates comprehensive implementation plans with bite-sized tasks, exact file paths, and complete code in every step.
metadata	{"version":"2.0.0","author":"erebus","tags":["software-development","planning","documentation"]}

Writing Implementation Plans

Write comprehensive plans assuming the engineer has zero context and questionable taste. Document everything they need: which files to touch, exact code, how to test it. Every task is bite-sized (2-5 minutes). DRY. YAGNI. TDD. Frequent commits.

When to Use

• Before starting a multi-file implementation
• After brainstorming has produced an approved design spec
• When the user wants a detailed roadmap before execution
• For architecture documentation

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]

---

File Structure Section

Before defining tasks, map out which files will be created or modified:

## Files

**Created:**
- `src/path/new_file.py` — [one-sentence responsibility]

**Modified:**
- `src/path/existing.py` — [what changes]
- `tests/path/test_existing.py` — [what tests added]

Design units with clear boundaries. Each file should have one responsibility. Files that change together should live together.

Task Structure

Each task must follow this exact format:

### Task N: [Component Name]

**Files:**
- Create: `exact/path/to/file.py`
- Modify: `exact/path/to/existing.py`
- Test: `tests/exact/path/to/test_file.py`

- [ ] **Step 1: Write the failing test**

```python
def test_specific_behavior():
    result = function_under_test(input_value)
    assert result == expected_output
```

- [ ] **Step 2: Run test to verify it fails**

```bash
pytest tests/path/test_file.py::test_specific_behavior -v
```

Expected: FAIL with "function_under_test not defined" or similar

- [ ] **Step 3: Write minimal implementation**

```python
def function_under_test(input_value):
    return expected_output
```

- [ ] **Step 4: Run test to verify it passes**

```bash
pytest tests/path/test_file.py::test_specific_behavior -v
```

Expected: PASS

- [ ] **Step 5: Commit**

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

Bite-Sized Task Granularity

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

• "Write the failing test" — step
• "Run it to see it fail" — step
• "Write minimal code to pass" — step
• "Run tests to confirm pass" — step
• "Commit" — step

No Placeholders

These are plan failures — never write them:

• "TBD", "TODO", "implement later", "fill in details"
• "Add appropriate error handling" (without showing the code)
• "Write tests for the above" (without actual test code)
• "Similar to Task N" (repeat the code — tasks may be read out of order)
• Steps that describe what to do without showing how

Every step must contain the actual content an engineer needs.

Self-Review

After writing the complete plan, review it:

1. Spec coverage — can you point to a task for every requirement?
2. Placeholder scan — any of the patterns above? Fix them.
3. Type consistency — do all types match across tasks?
4. Command accuracy — are file paths exact? Test commands correct?

Fix issues inline. Present the reviewed plan to the user.

Rules

• Exact file paths always (never path/to/file)
• Complete code in every step — if a step changes code, show the code
• Exact commands with expected output
• Order tasks by dependency — no forward references
• DRY, YAGNI, TDD, frequent commits