# Scaffold — copy, don’t edit in place

```bash
# from product/
cp -r scaffold games/horizon-courier
```

PowerShell:

```powershell
Copy-Item -Recurse scaffold games/horizon-courier
```

Then implement **BRIEF.md** into `games/horizon-courier/`.

- **`src/substrate.js`** — leave unchanged  
- Packs — the mount is the URL `/medium/...` whatever your layout, so count the `../` to YOUR
  serve root. From `src/` that is **`../medium/physics/pack.js`** in a `devtune init` project, and
  `../../../medium/physics/pack.js` in the DevTune monorepo. Using the monorepo path in an `init`
  project is a `verify` FATAL — see `ai/PACKS.md`.  
- This scaffold is a **simple** owned example; the AA brief requires the **medium packs** — upgrade motion/solids/camera to packs while keeping contract shape