Ralph
Ralph is an autonomous AI agent loop that runs AI coding tools (Amp or Claude Code) repeatedly until all PRD items are complete. Each iteration is a fresh instance with clean context. Memory persists via git history, progress.txt, and prd.json.
Based on Geoffrey Huntley's Ralph pattern.
Read my in-depth article on how I use Ralph
Prerequisites
- One of the following AI coding tools installed and authenticated:
jq installed (brew install jq on macOS)- A git repository for your project
Setup
Option 1: Copy to your project
Copy the ralph files into your project:
# From your project root
mkdir -p scripts/ralph
cp /path/to/ralph/ralph.sh scripts/ralph/
# Copy the prompt template for your AI tool of choice:
cp /path/to/ralph/prompt.md scripts/ralph/prompt.md # For Amp
# OR
cp /path/to/ralph/CLAUDE.md scripts/ralph/CLAUDE.md # For Claude Code
chmod +x scripts/ralph/ralph.sh
Option 2: Install skills globally (Amp)
Copy the skills to your Amp or Claude config for use across all projects:
For AMP
cp -r skills/prd ~/.config/amp/skills/
cp -r skills/ralph ~/.config/amp/skills/
For Claude Code (manual)
cp -r skills/prd ~/.claude/skills/
cp -r skills/ralph ~/.claude/skills/
Option 3: Use as Claude Code Marketplace
Add the Ralph marketplace to Claude Code:
/plugin marketplace add snarktank/ralph
Then install the skills:
/plugin install ralph-skills@ralph-marketplace
Available skills after installation:
/prd - Generate Product Requirements Documents/ralph - Convert PRDs to prd.json format
Skills are automatically invoked when you ask Claude to:
- "create a prd", "write prd for", "plan this feature"
- "convert this prd", "turn into ralph format", "create prd.json"
Add to ~/.config/amp/settings.json:
{
"amp.experimental.autoHandoff": { "context": 90 }
}
This enables automatic handoff when context fills up, allowing Ralph to handle large stories that exceed a single context window.
Workflow
1. Create a PRD
Use the PRD skill to generate a detailed requirements document:
Load the prd skill and create a PRD for [your feature description]
Answer the clarifying questions. The skill saves output to tasks/prd-[feature-name].md.
Use the Ralph skill to convert the markdown PRD to JSON:
Load the ralph skill and convert tasks/prd-[feature-name].md to prd.json
This creates prd.json with user stories structured for autonomous execution.
3. Run Ralph
# Using Amp (default)
./scripts/ralph/ralph.sh [max_iterations]
# Using Claude Code
./scripts/ralph/ralph.sh --tool claude [max_iterations]
Default is 10 iterations. Use --tool amp or --tool claude to select your AI coding tool.
Ralph will:
- Create a feature branch (from PRD
branchName)
- Pick the highest priority story where
passes: false
- Implement that single story
- Run quality checks (typecheck, tests)
- Commit if checks pass
- Update
prd.json to mark story as passes: true
- Append learnings to
progress.txt
- Repeat until all stories pass or max iterations reached
Key Files
| File |
Purpose |
ralph.sh |
The bash loop that spawns fresh AI instances (supports --tool amp or --tool claude) |
prompt.md |
Prompt template for Amp |
CLAUDE.md |
Prompt template for Claude Code |
prd.json |
User stories with passes status (the task list) |
prd.json.example |
Example PRD format for reference |
progress.txt |
Append-only learnings for future iterations |
skills/prd/ |
Skill for generating PRDs (works with Amp and Claude Code) |
skills/ralph/ |
Skill for converting PRDs to JSON (works with Amp and Claude Code) |
.claude-plugin/ |
Plugin manifest for Claude Code marketplace discovery |
flowchart/ |
Interactive visualization of how Ralph works |
Flowchart
View Interactive Flowchart - Click through to see each step with animations.
The flowchart/ directory contains the source code. To run locally:
cd flowchart
npm install
npm run dev
Critical Concepts
Each Iteration = Fresh Context
Each iteration spawns a new AI instance (Amp or Claude Code) with clean context. The only memory between iterations is:
- Git history (commits from previous iterations)
progress.txt (learnings and context)prd.json (which stories are done)
Small Tasks
Each PRD item should be small enough to complete in one context window. If a task is too big, the LLM runs out of context before finishing and produces poor 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"
- "Add authentication"
- "Refactor the API"
AGENTS.md Updates Are Critical
After each iteration, Ralph updates the relevant AGENTS.md files with learnings. This is key because AI coding tools automatically read these files, so future iterations (and future human developers) benefit from discovered patterns, gotchas, and conventions.
Examples of what to add to AGENTS.md:
- Patterns discovered ("this codebase uses X for Y")
- Gotchas ("do not forget to update Z when changing W")
- Useful context ("the settings panel is in component X")
Feedback Loops
Ralph only works if there are feedback loops:
- Typecheck catches type errors
- Tests verify behavior
- CI must stay green (broken code compounds across iterations)
Browser Verification for UI Stories
Frontend stories must include "Verify in browser using dev-browser skill" in acceptance criteria. Ralph will use the dev-browser skill to navigate to the page, interact with the UI, and confirm changes work.
Stop Condition
When all stories have passes: true, Ralph outputs <promise>COMPLETE</promise> and the loop exits.
Debugging
Check current state:
# See which stories are done
cat prd.json | jq '.userStories[] | {id, title, passes}'
# See learnings from previous iterations
cat progress.txt
# Check git history
git log --oneline -10
Customizing the Prompt
After copying prompt.md (for Amp) or CLAUDE.md (for Claude Code) to your project, customize it for your project:
- Add project-specific quality check commands
- Include codebase conventions
- Add common gotchas for your stack
Archiving
Ralph automatically archives previous runs when you start a new feature (different branchName). Archives are saved to archive/YYYY-MM-DD-feature-name/.
References
Ralph 是一个自主运行的 AI 代理循环,会一遍又一遍地运行 AI 编程工具(Amp 或 Claude Code),直到 PRD 里的每一项都完成为止。每次迭代都会以干净的上下文启动一个全新的实例。