Plan Directory Skill

When to Use This Skill

• Scaffolding a new project, feature, or migration that benefits from a structured, step-by-step plan.
• Creating a repeatable plan that an LLM or engineer can execute with explicit, verifiable checkboxes.
• Maintaining an existing plan directory: adding tasks, updating progress, or archiving completed plans.
• When the user says "create a plan", "scaffold a plan", "plan this feature", or similar intent implying structured task breakdown.

Do not use this skill for ad-hoc todo lists, single-file notes, or when the user explicitly wants a different format.

LLM Intake (Required Inputs)

Before writing any files, gather these inputs. If any are missing, ask the user for them explicitly.

When updating an existing plan, read the current PLAN.md first to understand context before modifying.

Invariants (Do Not Violate)

1. PLAN.md is the index, not the content. It contains only the purpose, usage instructions, locked decisions, and a task index with checkboxes. Detailed steps live in individual task files.

2. Task files use 3-digit numbering. Format: NNN-<slug>.md where NNN is zero-padded (001, 002, ..., 999) and <slug> is hyphenated lowercase.

3. Every task file has six sections. Goal, Scope, Checklist, Tests, Completion Criteria, and Dependencies. All are required (use "None" for Dependencies if truly independent, "N/A" for Tests only with justification).

4. Checkboxes are the only status markers. Do not add "Status: Done" fields, emoji indicators, or separate progress sections. Check - [x] when complete, leave - [ ] when pending.

5. Mirror completion in PLAN.md. When all checklist items in a task file are checked, check the corresponding task in PLAN.md.

6. Do not renumber existing tasks. Once a task number is assigned and work has started, it is permanent. Append new tasks at the end.

7. Keep task files self-contained. A reader should understand the task from the file alone without reading other task files.

8. Track blockers explicitly. When a task is blocked, add a ## Blockers section describing what's blocking and link to the blocking task or issue.

Workflow

1. Determine Mode: Create or Update

• Create: No plan directory exists. Scaffold everything from scratch.
• Update: PLAN.md already exists. Read it, understand the current state, and make targeted modifications.

2. Validate Inputs

• Confirm all required inputs are present.
• If the user provides a vague task list, ask for clarification before proceeding.
• For updates, verify the plan slug and location match the existing plan.

3. Create or Update the Plan Directory

For new plans:

1. Create the directory at the target location.
2. Write PLAN.md with the master index.
3. Write each task file (001-*.md, 002-*.md, etc.).

For updates:

1. Read the existing PLAN.md and relevant task files.
2. Apply changes: add new tasks, update checklists, check completed items.
3. Ensure PLAN.md index stays in sync with task files.

4. Fill PLAN.md (Master Index)

Keep it minimal. Include only:

• Purpose: 1-3 bullets on why the plan exists.
• How to use: Brief instructions for working the plan.
• Decisions (locked): Key constraints that should not change.
• Task Index: Checkbox list linking to task files.
• Completion: Definition of when the entire plan is done.

5. Fill Task Files

Each task file must include:

• Goal: Single sentence describing the outcome.
• Dependencies: List of task numbers that must complete first, or "None".
• Scope: Bulleted list of what's in scope (and optionally out of scope).
• Checklist: 3-8 concrete, actionable steps with checkboxes.
• Tests: Specific test commands, files, or manual QA steps.
• Completion Criteria: Measurable definitions of done.
• Notes (optional): Constraints, references, warnings.
• Blockers (optional): Added when work is blocked; removed when unblocked.

6. Maintain Progress

As work completes:

1. Check items in the task file's Checklist and Tests sections.
2. When all items are checked, check the Completion Criteria items.
3. Check the corresponding task in PLAN.md's Task Index.

Task Sizing Rules

• Target 3-8 checklist items per task. This keeps tasks focused and completable in a reasonable session.
• Split if exceeding 10 items. If a task grows beyond ~10 checklist items, break it into subtasks.
• Tests must be explicit. Include runnable commands or specific file paths. Avoid vague "test that it works" items.
• Completion criteria must be measurable. Use "X is true" or "Y passes" rather than narrative descriptions.

Update Rules (Existing Plans)

Templates

PLAN.md

# <Plan Title> - Master Plan

## Purpose

- <Why this plan exists>
- <What it delivers when complete>

## How to Use

1. Work tasks in order unless dependencies indicate otherwise.
2. Check items in task files as they are completed.
3. This file is the index only; details live in task files.

## Decisions (Locked)

- <Key constraint or choice that should not change>
- <Another locked decision>

## Task Index

- [ ] 001 - <Task Name> (`001-<slug>.md`)
- [ ] 002 - <Task Name> (`002-<slug>.md`)
- [ ] 003 - <Task Name> (`003-<slug>.md`)

## Completion

- [ ] All tasks in the index are checked.
- [ ] All tests listed in task files pass.
- [ ] <Any additional project-specific completion criteria>

Task File (NNN-<slug>.md)

# NNN - <Task Name>

## Goal

<Single sentence describing the outcome of this task.>

## Dependencies

- Requires: 001, 002 (or "None" if independent)
- Blocks: 004, 005 (tasks waiting on this one)

## Scope

**In scope:**
- <What this task covers>
- <Another in-scope item>

**Out of scope:**
- <What this task explicitly does not cover>

## Checklist

- [ ] <Concrete implementation step with verifiable outcome>
- [ ] <Another concrete step>
- [ ] <Another concrete step>

## Tests

- [ ] Run `<test command>` and verify all pass
- [ ] Manual QA: <specific verification step>

## Completion Criteria

- [ ] <Measurable definition of done>
- [ ] <Another measurable definition>

## Notes

- <Optional: constraints, references, links, or warnings>

Blocked Task (when work cannot proceed)

When a task is blocked, add a ## Blockers section immediately after Dependencies:

## Blockers

- **Blocked by:** External API not yet available (ETA: 2024-02-15)
- **Blocked by:** Waiting on 003 to complete first
- **Action needed:** Contact platform team for API access

Remove the Blockers section when the task is unblocked.

Quality Checklist (LLM Preflight)

Before delivering a plan, verify:

• All required inputs were gathered or reasonable defaults applied.
• PLAN.md is short and contains only the index, not detailed steps.
• Task filenames match the patt