# SPEC: Project Migration Script for Additive Extension Model

## Overview

After switching to the additive extension model, existing projects have stale copies of framework files in their `{project}/.automaton/` directories. These need to be cleaned up.

## Context

Under the old model, framework files (prompts, contracts, scripts) were copied into the project's `.automaton/`. Under the new model, the project should only contain `.agent.md`, `.rules.md`, and optionally an `extensions/` directory. Everything else comes from `~/.automaton/`.

## Changes

### 1. `scripts/migrate-project.sh`

Script that takes a project path and:
1. Scans `{project}/.automaton/` for files that now live in `~/.automaton/`
2. For each matching file:
   - **Identical to global** → delete (framework provides them)
   - **Different from global** → move to `.automaton/extensions/`
3. Preserves `.agent.md` and `.rules.md` as-is
4. Reports what was deleted, moved, and kept

### 2. `prompts/onboarding.md`

Add a section at the top that checks if migration is needed:
- If project has prompt/contract/script copies in `.automaton/`, offer to run migration

## Acceptance Criteria

- [ ] `scripts/migrate-project.sh` exists and is executable
- [ ] Script correctly identifies identical vs customized files
- [ ] Customized files are moved to `extensions/`, not deleted
- [ ] `.agent.md` and `.rules.md` are never touched
- [ ] Onboarding detects stale projects and offers migration