SMP: Minecraft-style join window with live status; allow beta tunnel origin for dev HMR

opencode.md

@@ -83,7 +83,7 @@ src/app/
     MobileHome.tsx      → "skeuo" theme, phone: app grid + dock
     WinWindow.tsx       → a single draggable/resizable window
     apps.tsx            → APPS registry + the content of each app + in-app terminal
-                          + embedded-site windows
+                          + embedded-site windows + the Minecraft-style SMP menu
     useDesktopIcons.ts  → desktop icon grid + drag/drop  (THE KEY FILE, see below)
     useDragOrder.ts     → simple list reordering (mobile home screen only)
     useTheme.ts         → theme state via useSyncExternalStore
@@ -211,6 +211,15 @@ list reordering, not free placement. Don't confuse the two.
   `eslint-disable-next-line` with a comment. Don't add more without a reason.
 - Watch for `pointercancel`: any custom pointer gesture over an `<img>`, link,
   or text selection needs `draggable=false` / `user-select: none`.
+- Exposing the **dev** server over a tunnel needs the tunnel host in
+  `allowedDevOrigins` (`next.config.ts`). Without it Next dev rejects the
+  cross-origin HMR WebSocket, so the client never hydrates — the page is SSR
+  only: icons all stacked at `(0,0)`, buttons dead. Changing `next.config.ts`
+  needs a dev-server restart. For a public URL prefer a production build
+  (`npm run build && npm run start`): no HMR socket, so nothing to reject.
+- The SMP service shortcut opens `SMP_APP` (in `apps.tsx`, registered in
+  `APP_BY_ID` only, like `ALACRITTY_APP`) — a Minecraft-style join menu that
+  reads live data from `/api/ping?url=minecraft://…`.
 - Service shortcuts show the real site in an iframe via
   `createWebsiteApp({ embed: true })` (the shortcut's `embed` flag). It only
   works for sites that don't send `X-Frame-Options` / a `frame-ancestors` CSP.