Update README with architecture, backend setup, environment variables, and CI docs

README.md

@@ -6,7 +6,7 @@ A custom web frontend for the Emscripten port of [isle-portable](https://github.
 
 ## Requirements
 
-- [Node.js](https://nodejs.org/)
+- [Node.js](https://nodejs.org/) 20 or later
 
 ## Quick Start
 
@@ -45,17 +45,83 @@ A custom web frontend for the Emscripten port of [isle-portable](https://github.
 
 7. Open the URL shown in the terminal (usually `http://localhost:5173`).
 
+## Architecture
+
+The project consists of three components:
+
+| Component | Directory | Required | Description |
+|-----------|-----------|----------|-------------|
+| **Frontend** | Root | Yes | Svelte SPA served from Cloudflare R2 |
+| **API Worker** | `server/` | No | Hono-based Cloudflare Worker handling auth, cloud sync, crash reports, and memories (backed by D1) |
+| **Multiplayer Relay** | External | No | WebSocket relay for peer-to-peer multiplayer ([source](https://github.com/isledecomp/isle-portable/tree/master/extensions/src/multiplayer/server)) |
+| **Share Worker** | `worker/` | No | Cloudflare Worker that injects Open Graph meta tags for `/memory/*` and `/scene/*` share URLs |
+
+The frontend degrades gracefully without the optional components — single-player gameplay, the save editor, and the full UI all work without them.
+
+## Backend Setup (Optional)
+
+### API Worker
+
+Optional. Enables authentication, cloud sync, crash reports, and memory features.
+
+```bash
+docker build -t isle-pizza-api -f server/Dockerfile . && docker run --rm -p 8788:8788 isle-pizza-api
+```
+
+The server starts on port 8788. To enable Discord authentication, create `server/.dev.vars` with:
+
+```
+BETTER_AUTH_SECRET=<random secret>
+DISCORD_CLIENT_ID=<your Discord app client ID>
+DISCORD_CLIENT_SECRET=<your Discord app client secret>
+```
+
+### Multiplayer Relay
+
+Optional. Enables the multiplayer lobby and in-game networking. The relay server lives in the [isle-portable repository](https://github.com/isledecomp/isle-portable/tree/master/extensions/src/multiplayer/server).
+
+From the isle-portable repo:
+```bash
+docker build -t isle-relay -f docker/relay/Dockerfile . && docker run --rm -p 8787:8787 isle-relay
+```
+
+## Environment Variables
+
+### Build-time (frontend)
+
+| Variable | Default | Description |
+|----------|---------|-------------|
+| `RELAY_URL` | `ws://localhost:8787` | Multiplayer relay WebSocket URL |
+| `API_URL` | `http://localhost:8788` | Backend API URL |
+| `BUILD_VERSION` | `null` | Version string injected into the build |
+
+These are configured in `site.config.js` and injected via Vite's `define`.
+
+### Runtime (API worker)
+
+| Variable | Description |
+|----------|-------------|
+| `BETTER_AUTH_SECRET` | Encryption key for auth sessions |
+| `DISCORD_CLIENT_ID` | Discord OAuth2 application ID |
+| `DISCORD_CLIENT_SECRET` | Discord OAuth2 secret |
+
+Set these in `server/.dev.vars` for local development.
+
 ## Scripts
 
 | Command | Description |
 |---------|-------------|
-| `npm run prepare:assets` | Set up LEGO Island game assets via symlinks |
-| `npm run generate:save-editor-assets` | Extract save editor assets (animations, sounds, textures, icons) into `save-editor.bin` |
 | `npm run dev` | Start development server with hot reload |
-| `npm run build` | Build for production (outputs to `dist/`) |
+| `npm run build` | Build for production (copies game files to `dist/`, injects service worker) |
+| `npm run build:ci` | CI build (skips copying game files) |
+| `npm run check` | Run svelte-check with warnings as errors |
 | `npm run preview` | Preview the production build locally |
+| `npm run prepare:assets` | Set up LEGO Island game assets via symlinks |
+| `npm run generate:save-editor-assets` | Extract save editor assets into `save-editor.bin` |
 | `npm run deploy` | Deploy to dev environment (R2) |
-| `npm run deploy -- production` | Deploy to production environment (R2) |
+| `npm run deploy:assets` | Deploy to dev environment including game assets |
+| `npm run deploy:prod` | Deploy to production environment (R2) |
+| `npm run deploy:prod:assets` | Deploy to production including game assets |
 
 ## Project Structure
 
@@ -71,16 +137,24 @@ isle.pizza/
 │   │   ├── savegame/      # Save game constants, actor data, color tables
 │   │   └── ...            # Audio, OPFS, cloud sync, auth, service worker, asset loading
 │   └── lib/               # UI components and pages (save editor, multiplayer, scene player, etc.)
-├── server/                # Cloudflare Workers backend (auth, cloud sync, crash reports, memories)
+├── server/                # API worker (Cloudflare Workers + D1)
+│   ├── src/               # Hono routes: auth, memories, cloud sync, crash reports
+│   ├── migrations/        # D1 database migrations
+│   ├── Dockerfile         # Local development container
+│   └── wrangler.toml      # Cloudflare Workers config
+├── worker/                # Share/OG worker (Cloudflare Workers + R2)
+│   ├── src/               # Open Graph tag injection for share URLs
+│   └── wrangler.toml      # Cloudflare Workers config
+├── scripts/               # Build, asset generation, and deploy scripts
+├── src-sw/                # Service worker source (Workbox-based caching and offline support)
 ├── public/
 │   └── images/            # UI images (menu buttons, tab icons)
-├── scripts/               # Build, asset generation, and deploy scripts
+├── site.config.js         # Build-time environment config (RELAY_URL, API_URL)
-├── src-sw/                # Service worker source
 ├── index.html             # HTML entry point
 ├── isle.js                # Emscripten JS (not in repo, build from isle-portable)
 ├── isle.wasm              # Emscripten WASM (not in repo, build from isle-portable)
-├── save-editor.bin        # Packed save editor assets: animations, sounds, textures, icons (not in repo, generated)
+├── save-editor.bin        # Packed save editor assets (not in repo, generated)
-└── LEGO/                  # Game data directory (not in repo)
+└── LEGO/                  # Game data directory (not in repo, symlinked)
 ```
 
 ## Building the Game Files
@@ -92,6 +166,10 @@ The `isle.js` and `isle.wasm` files are not included in this repository. To obta
 
 Alternatively, a [Docker image that bundles the runtime with this frontend](https://github.com/isledecomp/isle-portable/wiki/Installation#web-port-emscripten) is available.
 
+## CI
+
+The [build workflow](.github/workflows/build.yml) runs on pushes to `master` and on pull requests. It installs dependencies, runs `npm run check` (svelte-check), and builds with `npm run build:ci`. Deployment is done manually via the deploy scripts.
+
 ## Tech Stack
 
 - [Svelte 5](https://svelte.dev/) - UI framework
@@ -100,6 +178,8 @@ Alternatively, a [Docker image that bundles the runtime with this frontend](http
 - [Workbox](https://developer.chrome.com/docs/workbox/) - Service worker and offline support
 - [Hono](https://hono.dev/) - Backend API framework (Cloudflare Workers)
 - [better-auth](https://www.better-auth.com/) - Authentication (Discord)
+- [Cloudflare D1](https://developers.cloudflare.com/d1/) - Database for the API worker
+- [Cloudflare R2](https://developers.cloudflare.com/r2/) - Static asset hosting and share worker storage
 
 ## License