gepetto — Claude Code skill: implementation plans and setup

---
name: gepetto
description: Creates detailed, sectionized implementation plans through research, stakeholder interviews, and multi-LLM review. Use when planning features that need thorough pre-implementation analysis.
---

# Gepetto

Orchestrates a multi-step planning process: Research → Interview → Spec Synthesis → Plan → External Review → Sections

## CRITICAL: First Actions

**BEFORE anything else**, do these in order:

### 1. Print Intro

Print intro banner immediately:
```
═══════════════════════════════════════════════════════════════
GEPETTO: AI-Assisted Implementation Planning
═══════════════════════════════════════════════════════════════
Research → Interview → Spec Synthesis → Plan → External Review → Sections

Note: GEPETTO will write many .md files to the planning directory you pass it
```

### 2. Validate Spec File Input

**Check if user provided @file at invocation AND it's a spec file (ends with `.md`).**

If NO @file was provided OR the path doesn't end with `.md`, output this and STOP:
```
═══════════════════════════════════════════════════════════════
GEPETTO: Spec File Required
═══════════════════════════════════════════════════════════════

This skill requires a markdown spec file path (must end with .md).
The planning directory is inferred from the spec file's parent directory.

To start a NEW plan:
  1. Create a markdown spec file describing what you want to build
  2. It can be as detailed or as vague as you like
  3. Place it in a directory where gepetto can save planning files
  4. Run: /gepetto @path/to/your-spec.md

To RESUME an existing plan:
  1. Run: /gepetto @path/to/your-spec.md

Example: /gepetto @planning/my-feature-spec.md
═══════════════════════════════════════════════════════════════
```
**Do not continue. Wait for user to re-invoke with a .md file path.**

### 3. Setup Planning Session

Determine session state by checking existing files:

1. Set `planning_dir` = parent directory of the spec file
2. Set `initial_file` = the spec file path
3. Scan for existing planning files:
   - `claude-research.md`
   - `claude-interview.md`
   - `claude-spec.md`
   - `claude-plan.md`
   - `claude-integration-notes.md`
   - `claude-ralph-loop-prompt.md`
   - `claude-ralphy-prd.md`
   - `reviews/` directory
   - `sections/` directory

4. Determine mode and resume point:

| Files Found | Mode | Resume From |
|-------------|------|-------------|
| None | new | Step 4 |
| research only | resume | Step 6 (interview) |
| research + interview | resume | Step 8 (spec synthesis) |
| + spec | resume | Step 9 (plan) |
| + plan | resume | Step 10 (external review) |
| + reviews | resume | Step 11 (integrate) |
| + integration-notes | resume | Step 12 (user review) |
| + sections/index.md | resume | Step 14 (write sections) |
| all sections complete | resume | Step 15 (execution files) |
| + claude-ralph-loop-prompt.md + claude-ralphy-prd.md | complete | Done |

5. Create TODO list with TodoWrite based on current state

Print status:
```
Planning directory: {planning_dir}
Mode: {mode}
```

If resuming:
```
Resuming from step {N}
To start fresh, delete the planning directory files.
```

---

## Logging Format

```
═══════════════════════════════════════════════════════════════
STEP {N}/17: {STEP_NAME}
═══════════════════════════════════════════════════════════════
{details}
Step {N} complete: {summary}
───────────────────────────────────────────────────────────────
```

---

## Workflow

### 4. Research Decision

See [research-protocol.md](references/research-protocol.md).

1. Read the spec file
2. Extract potential research topics (technologies, patterns, integrations)
3. Ask user about codebase research needs
4. Ask user about web research needs (present derived topics as multi-select)
5. Record which research types to perform in step 5

### 5. Execute Research

See [research-protocol.md](references/research-protocol.md).

Based on decisions from step 4, launch research subagents:
- **Codebase research:** `Task(subagent_type=Explore)`
- **Web research:** `Task(subagent_type=Explore)` with WebSearch

If both are needed, launch both Task tools in parallel (single message with multiple tool calls).

**Important:** Subagents return their findings - they do NOT write files directly. After collecting results from all subagents, combine them and write to `<planning_dir>/claude-research.md`.

Skip this step entirely if user chose no research in step 4.

### 6. Detailed Interview

See [interview-protocol.md](references/interview-protocol.md)

Run in main context (AskUserQuestion requires it). The interview should be informed by:
- The initial spec
- Research findings (if any)

### 7. Save Interview Transcript

Write Q&A to `<planning_dir>/claude-interview.md`

### 8. Write Initial Spec (Spec Synthesis)

Combine into `<planning_dir>/claude-spec.md`:
- **Initial input** (the spec file)
- **Research findings** (if step 5 was done)
- **Interview answers** (from step 6)

This synthesizes the user's raw requirements into a complete specification.

### 9. Generate Implementation Plan

Create detailed plan → `<planning_dir>/claude-plan.md`

**IMPORTANT**: Write for an unfamiliar reader. The plan must be fully self-contained - an engineer or LLM with no prior context should understand *what* we're building, *why*, and *how* just from reading this document.

### 10. External Review

See [external-review.md](references/external-review.md)

Launch TWO subagents in parallel to review the plan:
1. **Gemini** via Bash
2. **Codex** via Bash

Both receive the plan content and return their analysis. Write results to `<planning_dir>/reviews/`.

### 11. Integrate External Feedback

Analyze the suggestions in `<planning_dir>/reviews/`.

You are the authority on what to integrate or not. It's OK if you decide to not integrate anything.

**Step 1:** Write `<planning_dir>/claude-integration-notes.md` documenting:
- What suggestions you're integrating and why
- What suggestions you're NOT integrating and why

**Step 2:** Update `<planning_dir>/claude-plan.md` with the integrated changes.

### 12. User Review of Integrated Plan

Use AskUserQuestion:
```
The plan has been updated with external feedback. You can now review and edit claude-plan.md.

If you want Claude's help editing the plan, open a separate Claude session - this session
is mid-workflow and can't assist with edits until the workflow completes.

When you're done reviewing, select "Done" to continue.
```

Options: "Done reviewing"

Wait for user confirmation before proceeding.

### 13. Create Section Index

See [section-index.md](references/section-index.md)

Read `claude-plan.md`. Identify natural section boundaries and create `<planning_dir>/sections/index.md`.

**CRITICAL:** index.md MUST start with a SECTION_MANIFEST block. See the reference for format requirements.

Write `index.md` before proceeding to section file creation.

### 14. Write Section Files — Parallel Subagents

See [section-splitting.md](references/section-splitting.md)

**Launch parallel subagents** - one Task per section for maximum efficiency:

1. First, parse `sections/index.md` to get the SECTION_MANIFEST list
2. Then launch ALL section Tasks in a single message (parallel execution):

```
# Launch all in ONE message for parallel execution:

Task(
  subagent_type="general-purpose",
  prompt="""
  Write section file: section-01-{name}

  Inputs:
  - <planning_dir>/claude-plan.md
  - <planning_dir>/sections/index.md

  Output: <planning_dir>/sections/section-01-{name}.md

  The section file must be COMPLETELY SELF-CONTAINED. Include:
  - Background (why this section exists)
  - Requirements (what must be true when complete)
  - Dependencies (requires/blocks)
  - Implementation details (from the plan)
  - Acceptance criteria (checkboxes)
  - Files to create/modify

  The implementer should NOT need to reference any other document.
  """
)

Task(
  subagent_type="general-purpose",
  prompt="Write section file: section-02-{name} ..."
)

Task(
  subagent_type="general-purpose",
  prompt="Write section file: section-03-{name} ..."
)

# ... one Task per section in the manifest
```

Wait for ALL subagents to complete before proceeding.

### 15. Generate Execution Files — Subagent

**Delegate to subagent** to reduce main context token usage:

```
Task(
  subagent_type="general-purpose",
  prompt="""
  Generate two execution files for autonomous implementation.

  Input files:
  - <planning_dir>/sections/index.md (has SECTION_MANIFEST)
  - <planning_dir>/sections/section-*.md (all section files)

  OUTPUT 1: <planning_dir>/claude-ralph-loop-prompt.md
  For ralph-loop plugin. EMBED all section content inline.

  Structure:
  - Mission statement
  - Full content of sections/index.md
  - Full content of EACH section file (embedded, not referenced)
  - Execution rules (dependency order, verify acceptance criteria)
  - Completion signal: <promise>ALL-SECTIONS-COMPLETE</promise>

  OUTPUT 2: <planning_dir>/claude-ralphy-prd.md
  For Ralphy CLI. REFERENCE section files (don't embed).

  Structure:
  - PRD header
  - How to use (ralphy --prd command)
  - Context explanation
  - Checkbox task list: one "- [ ] Section NN: {name}" per section

  Write both files.
  """
)
```

Wait for subagent completion before proceeding.

### 16. Final Status

Verify all files were created successfully:
- All section files from SECTION_MANIFEST
- `claude-ralph-loop-prompt.md`
- `claude-ralphy-prd.md`

### 17. Output Summary

Print generated files and next steps:
```
═══════════════════════════════════════════════════════════════
GEPETTO: Planning Complete
═══════════════════════════════════════════════════════════════

Generated files:
  - claude-research.md (research findings)
  - claude-interview.md (Q&A transcript)
  - claude-spec.md (synthesized specification)
  - claude-plan.md (implementation plan)
  - claude-integration-notes.md (feedback decisions)
  - reviews/ (external LLM feedback)
  - sections/ (implementation units)
  - claude-ralph-loop-prompt.md (for ralph-loop plugin)
  - claude-ralphy-prd.md (for Ralphy CLI)

How to implement:

Option A - Manual (recommended for learning/control):
  1. Read sections/index.md to understand dependencies
  2. Implement each section file in order
  3. Each section is self-contained with acceptance criteria

Option B - Autonomous with ralph-loop (Claude Code plugin):
  /ralph-loop @<planning_dir>/claude-ralph-loop-prompt.md --completion-promise "COMPLETE" --max-iterations 100

Option C - Autonomous with Ralphy (external CLI):
  ralphy --prd <planning_dir>/claude-ralphy-prd.md
  # Or: cp <planning_dir>/claude-ralphy-prd.md ./PRD.md && ralphy
═══════════════════════════════════════════════════════════════
```