Use when you have a spec or requirements for a multi-step task, before touching code
Generates detailed implementation plans for multi-step tasks with bite-sized steps, exact file paths, and test commands.
/plugin marketplace add astrosteveo/marketplace/plugin install harness@astrosteveo-marketplaceThis skill inherits all available tools. When active, it can use any tool Claude has access to.
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."
Context: This should be run in a dedicated worktree (created by brainstorming skill).
Save plans to: .artifacts/plans/YYYY-MM-DD-<feature-name>.md
Each step is one action (2-5 minutes):
Every plan MUST start with this header:
# [Feature Name] Implementation Plan
> **For Claude:** REQUIRED SUB-SKILL: Use harness: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
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"
## 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
## Manual Test Checklist Section
Every plan ends with a Manual Test Checklist. This goes after all tasks, before any closing notes.
**Template:**
```markdown
---
## Manual Test Checklist
> **For Claude:** Present this checklist at appropriate checkpoints.
> - subagent-driven-development: after all tasks, before finishing-a-development-branch
> - executing-plans: relevant items after each batch
### [Component/Area Name]
<!-- Tasks N-M -->
- [ ] [Concrete action] → [Expected result]
Format: - [ ] [Action] → [Expected result]
What to include:
What NOT to include:
Task mapping: Add <!-- Tasks N-M --> comment after each group heading so executing-plans can identify relevant items per batch.
Example:
## Manual Test Checklist
### Authentication
<!-- Tasks 1-3 -->
- [ ] Login with valid credentials → Redirects to /dashboard, shows username
- [ ] Login with wrong password → Shows "Invalid credentials" error
- [ ] Click "Logout" → Returns to /login, clears session
### Dashboard
<!-- Tasks 4-5 -->
- [ ] Load with no data → Shows empty state message
- [ ] Create item → Appears in list without refresh
After saving the plan, offer execution choice:
"Plan complete and saved to .artifacts/plans/<filename>.md. Two execution options:
1. Subagent-Driven (this session) - I dispatch fresh subagent per task, review between tasks, fast iteration
2. Parallel Session (separate) - Open new session with executing-plans, batch execution with checkpoints
Which approach?"
If Subagent-Driven chosen:
If Parallel Session chosen:
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