ralph · snarktank — Claude Code skill: what it does, how to install
Turns an existing PRD into prd.json for the Ralph autonomous agent system. Use it when requirements need to become small, verifiable stories.
npx skills add snarktank/ralph --skill ralph -a claude-codeWhat ralph does
The skill takes a PRD as a Markdown file or plain text and creates prd.json in the Ralph directory. The file contains the project, branch name, description, and user stories with IDs, priorities, acceptance criteria, pass state, and notes.
Each story is sized for one Ralph iteration. The conversion rules use dependency order, assign sequential IDs, and add Typecheck passes to every story. UI stories also get a browser verification criterion using the dev-browser skill. Large features should be split into focused changes such as schema work, backend logic, and UI pieces.
You need an existing PRD before running the skill. The one-iteration limit matters: a story that is too broad can run out of context before the implementation is complete.
What it helps with
- convert a PRD into
prd.json - split a large feature into one-iteration stories
- order stories by their dependencies
- add verifiable acceptance criteria
- derive a Ralph branch name from a feature
Example prompts for the agent
- Convert this PRD to Ralph format and create `prd.json`.
- Turn `feature.md` into small Ralph stories that fit one iteration.
- Create `prd.json` for this feature, add `Typecheck passes`, and order the stories by dependency.
How to install ralph
1Skills CLI (Vercel)
npx skills add snarktank/ralph --skill ralph -a claude-code2Manually: put the files in place
~/.claude/skills/ralph/SKILL.mdCopy the whole skill folder; for one project use .claude/skills/ralph/
1Skills CLI (Vercel)
npx skills add snarktank/ralph --skill ralph -a codex2Manually: put the files in place
.agents/skills/ralph/SKILL.mdFor all projects use ~/.agents/skills/
1Skills CLI (Vercel)
npx skills add snarktank/ralph --skill ralph -a cursor2Manually: put the files in place
.cursor/skills/ralph/SKILL.mdCursor also reads .agents/skills/ and .claude/skills/
1GitHub CLI
gh skill install snarktank/ralph ralph2Manually: put the files in place
.github/skills/ralph/SKILL.md1Skills CLI (Vercel)
npx skills add snarktank/ralph --skill ralph -a gemini-cli2Platform CLI
gemini skills install https://github.com/snarktank/ralph --path skills/ralphManually: put the files in place
.devin/skills/ralph/SKILL.mdThe legacy .windsurf/skills/ path still works
Skills CLI (Vercel)
npx skills add snarktank/ralph --skill ralph -a opencodeClaude.ai
Zip the folder and upload it in Settings → Capabilities → Skills
From the same set2
The whole set →Other versions of ralph
Similar
Questions about ralph
How do I install `ralph` in Codex?
Run npx skills add snarktank/ralph --skill ralph -a codex, then use .agents/skills/ralph/SKILL.md.
What does the `ralph` skill do?
It converts a Markdown or text PRD into prd.json for Ralph autonomous execution. Requirements become prioritized user stories with acceptance criteria.
How large should a Ralph story be?
A story should fit into one Ralph iteration and one context window. Split broad features into focused changes and order them by dependency.
Source text
SKILL.md · MIT
---
name: ralph
description: "Convert PRDs to prd.json format for the Ralph autonomous agent system. Use when you have an existing PRD and need to convert it to Ralph's JSON format. Triggers on: convert this prd, turn this into ralph format, create prd.json from this, ralph json."
user-invocable: true
---
# Ralph PRD Converter
Converts existing PRDs to the prd.json format that Ralph uses for autonomous execution.
---
## The Job
Take a PRD (markdown file or text) and convert it to `prd.json` in your ralph directory.
---
## Output Format
```json
{
"project": "[Project Name]",
"branchName": "ralph/[feature-name-kebab-case]",
"description": "[Feature description from PRD title/intro]",
"userStories": [
{
"id": "US-001",
"title": "[Story title]",
"description": "As a [user], I want [feature] so that [benefit]",
"acceptanceCriteria": [
"Criterion 1",
"Criterion 2",
"Typecheck passes"
],
"priority": 1,
"passes": false,
"notes": ""
}
]
}
```
---
## Story Size: The Number One Rule
**Each story must be completable in ONE Ralph iteration (one context window).**
Ralph spawns a fresh Amp instance per iteration with no memory of previous work. If a story is too big, the LLM runs out of context before finishing and produces broken code.
### Right-sized stories:
- Add a database column and migration
- Add a UI component to an existing page
- Update a server action with new logic
- Add a filter dropdown to a list
### Too big (split these):
- "Build the entire dashboard" - Split into: schema, queries, UI components, filters
- "Add authentication" - Split into: schema, middleware, login UI, session handling
- "Refactor the API" - Split into one story per endpoint or pattern
**Rule of thumb:** If you cannot describe the change in 2-3 sentences, it is too big.
---
## Story Ordering: Dependencies First
Stories execute in priority order. Earlier stories must not depend on later ones.
**Correct order:**
1. Schema/database changes (migrations)
2. Server actions / backend logic
3. UI components that use the backend
4. Dashboard/summary views that aggregate data
**Wrong order:**
1. UI component (depends on schema that does not exist yet)
2. Schema change
---
## Acceptance Criteria: Must Be Verifiable
Each criterion must be something Ralph can CHECK, not something vague.
### Good criteria (verifiable):
- "Add `status` column to tasks table with default 'pending'"
- "Filter dropdown has options: All, Active, Completed"
- "Clicking delete shows confirmation dialog"
- "Typecheck passes"
- "Tests pass"
### Bad criteria (vague):
- "Works correctly"
- "User can do X easily"
- "Good UX"
- "Handles edge cases"
### Always include as final criterion:
```
"Typecheck passes"
```
For stories with testable logic, also include:
```
"Tests pass"
```
### For stories that change UI, also include:
```
"Verify in browser using dev-browser skill"
```
Frontend stories are NOT complete until visually verified. Ralph will use the dev-browser skill to navigate to the page, interact with the UI, and confirm changes work.
---
## Conversion Rules
1. **Each user story becomes one JSON entry**
2. **IDs**: Sequential (US-001, US-002, etc.)
3. **Priority**: Based on dependency order, then document order
4. **All stories**: `passes: false` and empty `notes`
5. **branchName**: Derive from feature name, kebab-case, prefixed with `ralph/`
6. **Always add**: "Typecheck passes" to every story's acceptance criteria
---
## Splitting Large PRDs
If a PRD has big features, split them:
**Original:**
> "Add user notification system"
**Split into:**
1. US-001: Add notifications table to database
2. US-002: Create notification service for sending notifications
3. US-003: Add notification bell icon to header
4. US-004: Create notification dropdown panel
5. US-005: Add mark-as-read functionality
6. US-006: Add notification preferences page
Each is one focused change that can be completed and verified independently.
---
## Example
**Input PRD:**
```markdown
# Task Status Feature
Add ability to mark tasks with different statuses.
## Requirements
- Toggle between pending/in-progress/done on task list
- Filter list by status
- Show status badge on each task
- Persist status in database
```
**Output prd.json:**
```json
{
"project": "TaskApp",
"branchName": "ralph/task-status",
"description": "Task Status Feature - Track task progress with status indicators",
"userStories": [
{
"id": "US-001",
"title": "Add status field to tasks table",
"description": "As a developer, I need to store task status in the database.",
"acceptanceCriteria": [
"Add status column: 'pending' | 'in_progress' | 'done' (default 'pending')",
"Generate and run migration successfully",
"Typecheck passes"
],
"priority": 1,
"passes": false,
"notes": ""
},
{
"id": "US-002",
"title": "Display status badge on task cards",
"description": "As a user, I want to see task status at a glance.",
"acceptanceCriteria": [
"Each task card shows colored status badge",
"Badge colors: gray=pending, blue=in_progress, green=done",
"Typecheck passes",
"Verify in browser using dev-browser skill"
],
"priority": 2,
"passes": false,
"notes": ""
},
{
"id": "US-003",
"title": "Add status toggle to task list rows",
"description": "As a user, I want to change task status directly from the list.",
"acceptanceCriteria": [
"Each row has status dropdown or toggle",
"Changing status saves immediately",
"UI updates without page refresh",
"Typecheck passes",
"Verify in browser using dev-browser skill"
],
"priority": 3,
"passes": false,
"notes": ""
},
{
"id": "US-004",
"title": "Filter tasks by status",
"description": "As a user, I want to filter the list to see only certain statuses.",
"acceptanceCriteria": [
"Filter dropdown: All | Pending | In Progress | Done",
"Filter persists in URL params",
"Typecheck passes",
"Verify in browser using dev-browser skill"
],
"priority": 4,
"passes": false,
"notes": ""
}
]
}
```
---
## Archiving Previous Runs
**Before writing a new prd.json, check if there is an existing one from a different feature:**
1. Read the current `prd.json` if it exists
2. Check if `branchName` differs from the new feature's branch name
3. If different AND `progress.txt` has content beyond the header:
- Create archive folder: `archive/YYYY-MM-DD-feature-name/`
- Copy current `prd.json` and `progress.txt` to archive
- Reset `progress.txt` with fresh header
**The ralph.sh script handles this automatically** when you run it, but if you are manually updating prd.json between runs, archive first.
---
## Checklist Before Saving
Before writing prd.json, verify:
- [ ] **Previous run archived** (if prd.json exists with different branchName, archive it first)
- [ ] Each story is completable in one iteration (small enough)
- [ ] Stories are ordered by dependency (schema to backend to UI)
- [ ] Every story has "Typecheck passes" as criterion
- [ ] UI stories have "Verify in browser using dev-browser skill" as criterion
- [ ] Acceptance criteria are verifiable (not vague)
- [ ] No story depends on a later story
© snarktank · MIT · snarktank/ralph