Writing Plans — Write implementation plans: bite-sized tasks, paths, code

Writing Plans

Write implementation plans: bite-sized tasks, paths, code.

Skill metadata

Source	Bundled (installed by default)
Path	skills/software-development/writing-plans
Version	1.1.0
Author	Hermes Agent (adapted from obra/superpowers)
License	MIT
Tags	planning, design, implementation, workflow, documentation
Related skills	subagent-driven-development, test-driven-development, requesting-code-review

Reference: full SKILL.md

The following is the complete skill definition that Hermes loads when this skill is triggered. This is what the agent sees as instructions when the skill is active.

Writing Implementation Plans

Overview

Write comprehensive implementation plans assuming the implementer has zero context for the codebase and questionable taste. Document everything they need: which files to touch, complete code, testing commands, docs to check, how to verify. Give them bite-sized tasks. DRY. YAGNI. TDD. Frequent commits.

Assume the implementer is a skilled developer but knows almost nothing about the toolset or problem domain. Assume they don’t know good test design very well.

Core principle: A good plan makes implementation obvious. If someone has to guess, the plan is incomplete.

When to Use

Always use before:

• Implementing multi-step features
• Breaking down complex requirements
• Delegating to subagents via subagent-driven-development

Don’t skip when:

• Feature seems simple (assumptions cause bugs)
• You plan to implement it yourself (future you needs guidance)
• Working alone (documentation matters)

Bite-Sized Task Granularity

Each task = 2-5 minutes of focused work.

Every step is one action:

• “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

Too big:

### Task 1: Build authentication system
[50 lines of code across 5 files]

Right size:

### Task 1: Create User model with email field
[10 lines, 1 file]

### Task 2: Add password hash field to User
[8 lines, 1 file]

### Task 3: Create password hashing utility
[15 lines, 1 file]

Plan Document Structure

Header (Required)

Every plan MUST start with:

# [Feature Name] Implementation Plan

> **For Hermes:** Use subagent-driven-development skill 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 follows this format:

### Task N: [Descriptive Name]

**Objective:** What this task accomplishes (one sentence)

**Files:**
- Create: `exact/path/to/new_file.py`
- Modify: `exact/path/to/existing.py:45-67` (line numbers if known)
- Test: `tests/path/to/test_file.py`

**Step 1: Write failing test**

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

**Step 2: Run test to verify failure**

Run: `pytest tests/path/test.py::test_specific_behavior -v`
Expected: FAIL — "function not defined"

**Step 3: Write minimal implementation**

```python
def function(input):
    return expected
```

**Step 4: Run test to verify pass**

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

**Step 5: Commit**

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

Writing Process

Step 1: Understand Requirements

Read and understand:

• Feature requirements
• Design documents or user description
• Acceptance criteria
• Constraints

Step 2: Explore the Codebase

Use Hermes tools to understand the project:

# Understand project structure
search_files("*.py", target="files", path="src/")

# Look at similar features
search_files("similar_pattern", path="src/", file_glob="*.py")

# Check existing tests
search_files("*.py", target="files", path="tests/")

# Read key files
read_file("src/app.py")

Step 3: Design Approach

Decide:

• Architecture pattern
• File organization
• Dependencies needed
• Testing strategy

Step 4: Write Tasks

Create tasks in order:

1. Setup/infrastructure
2. Core functionality (TDD for each)
3. Edge cases
4. Integration
5. Cleanup/documentation

Step 5: Add Complete Details

For each task, include:

• Exact file paths (not “the config file” but src/config/settings.py)
• Complete code examples (not “add validation” but the actual code)
• Exact commands with expected output
• Verification steps that prove the task works

Step 6: Review the Plan

Check:

• Tasks are sequential and logical
• Each task is bite-sized (2-5 min)
• File paths are exact
• Code examples are complete (copy-pasteable)
• Commands are exact with expected output
• No missing context
• DRY, YAGNI, TDD principles applied

Step 7: Save the Plan

mkdir -p docs/plans
# Save plan to docs/plans/YYYY-MM-DD-feature-name.md
git add docs/plans/
git commit -m "docs: add implementation plan for [feature]"

Principles

DRY (Don’t Repeat Yourself)

Bad: Copy-paste validation in 3 places Good: Extract validation function, use everywhere

YAGNI (You Aren’t Gonna Need It)

Bad: Add “flexibility” for future requirements Good: Implement only what’s needed now

# Bad — YAGNI violation
class User:
    def __init__(self, name, email):
        self.name = name
        self.email = email
        self.preferences = {}  # Not needed yet!
        self.metadata = {}     # Not needed yet!

# Good — YAGNI
class User:
    def __init__(self, name, email):
        self.name = name
        self.email = email

TDD (Test-Driven Development)

Every task that produces code should include the full TDD cycle:

1. Write failing test
2. Run to verify failure
3. Write minimal code
4. Run to verify pass

See test-driven-development skill for details.

Frequent Commits

Commit after every task:

git add [files]
git commit -m "type: description"

Common Mistakes

Vague Tasks

Bad: “Add authentication” Good: “Create User model with email and password_hash fields”

Incomplete Code

Bad: “Step 1: Add validation function” Good: “Step 1: Add validation function” followed by the complete function code

Missing Verification

Bad: “Step 3: Test it works” Good: “Step 3: Run pytest tests/test_auth.py -v, expected: 3 passed”

Missing File Paths

Bad: “Create the model file” Good: “Create: src/models/user.py”

Execution Handoff

After saving the plan, offer the execution approach:

“Plan complete and saved. Ready to execute using subagent-driven-development — I’ll dispatch a fresh subagent per task with two-stage review (spec compliance then code quality). Shall I proceed?”

When executing, use the subagent-driven-development skill:

• Fresh delegate_task per task with full context
• Spec compliance review after each task
• Code quality review after spec passes
• Proceed only when both reviews approve

Remember

Bite-sized tasks (2-5 min each)
Exact file paths
Complete code (copy-pasteable)
Exact commands with expected output
Verification steps
DRY, YAGNI, TDD
Frequent commits

A good plan makes implementation obvious.