refactor(desktop): make Tauri thin shell running web sidecar (#273)

## What / Why
This PR finishes the desktop refactor: the Tauri app is now a thin shell that launches the web server as a sidecar and loads the UI from `http://127.0.0.1:<port>`. All real backend logic lives in `packages/web/server/index.js`; desktop Rust keeps only native integrations (menu/dialog/notifications/updater/deep-link + window chrome).
This unblocks:
- consistent behavior across web/desktop/vscode (single backend)
- simpler desktop maintenance (no duplicated Rust backend)
- host switching between Local + remote instances in desktop
- reliable cold-start behavior on slow machines (VSCode + desktop)
## Key changes
- Desktop sidecar runtime
  - build pipeline to bundle web dist + `openchamber-server` sidecar (`packages/desktop/scripts/build-sidecar.mjs`)
  - robust local port selection (prefer saved/default, fallback to random; persisted in `~/.config/openchamber/settings.json`)
  - improved PATH handling so the sidecar can locate `opencode` CLI (incl `~/.opencode/bin`, overrides, common bins)
  - disable native right-click context menu in production builds (dev keeps it)
- Desktop instance switcher (Tauri-only)
  - header button + modal to add/edit/delete remote hosts, set default, probe status/ping, switch back to Local escape hatch
  - auth gate includes host switcher so you can recover when a remote host is broken/auth-required
  - host list stored desktop-locally (not tied to the currently selected remote server)
- Notifications
  - decision logic moved server-side; desktop notifications emitted via sidecar stdout and shown natively by Tauri
  - prevent double-notifications on desktop Local origin (UI ignores SSE notification when native path is active)
  - restore macOS notification sound
- Updates
  - Tauri updater used only when viewing Local instance in desktop shell (avoid “remote web update” triggering desktop restart)
- Settings persistence & UX polish
  - persist model favorites/recents via `/api/config/settings` (works for web + desktop; not origin-dependent)
  - persist per-project sidebar collapse state in `projects[].sidebarCollapsed` via `/api/config/settings` (with debounce on toggles)
  - macOS header sizing/traffic-lights offsets fixed (marketing macOS major injected from desktop; MultiRun header aligned)
  - VSCode cold-start: keep retrying provider/agent loads after connection to avoid empty UI on slow machines
  - misc lint/type fixes + bun.lock sync
- Desktop bootstrap / resiliency
  - show onboarding screen when OpenCode CLI is missing (desktop Local origin), with retry hook to restart OpenCode after install
## Testing notes
- Desktop (macOS): switch Local <-> remote, set default host, verify auth gate recovery, native notifications (with sound), updater gated to Local
- Web: favorites/recents + per-project collapsed state persist across reload/restart
- VSCode: slow startup no longer results in missing providers/agents/models

packages/ui/src/App.tsx

@@ -16,6 +16,8 @@ import { usePushVisibilityBeacon } from '@/hooks/usePushVisibilityBeacon';
 import { GitPollingProvider } from '@/hooks/useGitPolling';
 import { useConfigStore } from '@/stores/useConfigStore';
 import { hasModifier } from '@/lib/utils';
+import { isDesktopLocalOriginActive, isDesktopShell, isTauriShell } from '@/lib/desktop';
+import { OnboardingScreen } from '@/components/onboarding/OnboardingScreen';
 import { useSessionStore } from '@/stores/useSessionStore';
 import { useDirectoryStore } from '@/stores/useDirectoryStore';
 import { opencodeClient } from '@/lib/opencode/client';
@@ -25,8 +27,6 @@ import { ConfigUpdateOverlay } from '@/components/ui/ConfigUpdateOverlay';
 import { AboutDialog } from '@/components/ui/AboutDialog';
 import { RuntimeAPIProvider } from '@/contexts/RuntimeAPIProvider';
 import { registerRuntimeAPIs } from '@/contexts/runtimeAPIRegistry';
-import { OnboardingScreen } from '@/components/onboarding/OnboardingScreen';
-import { isCliAvailable } from '@/lib/desktop';
 import { useUIStore } from '@/stores/useUIStore';
 import { useGitHubAuthStore } from '@/stores/useGitHubAuthStore';
 import type { RuntimeAPIs } from '@/lib/api/types';
@@ -53,17 +53,12 @@ function App({ apis }: AppProps) {
   const [showMemoryDebug, setShowMemoryDebug] = React.useState(false);
   const { uiFont, monoFont } = useFontPreferences();
   const refreshGitHubAuthStatus = useGitHubAuthStore((state) => state.refreshStatus);
-  const [isDesktopRuntime, setIsDesktopRuntime] = React.useState<boolean>(() => apis.runtime.isDesktop);
   const [isVSCodeRuntime, setIsVSCodeRuntime] = React.useState<boolean>(() => apis.runtime.isVSCode);
-  const [cliAvailable, setCliAvailable] = React.useState<boolean>(() => {
-    if (!apis.runtime.isDesktop) return true;
-    return isCliAvailable();
-  });
+  const [showCliOnboarding, setShowCliOnboarding] = React.useState(false);
 
   React.useEffect(() => {
-    setIsDesktopRuntime(apis.runtime.isDesktop);
     setIsVSCodeRuntime(apis.runtime.isVSCode);
-  }, [apis.runtime.isDesktop, apis.runtime.isVSCode]);
+  }, [apis.runtime.isVSCode]);
 
   React.useEffect(() => {
     registerRuntimeAPIs(apis);
@@ -175,6 +170,19 @@ function App({ apis }: AppProps) {
 
   useMenuActions(handleToggleMemoryDebug);
 
+  const settingsAutoCreateWorktree = useConfigStore((state) => state.settingsAutoCreateWorktree);
+  React.useEffect(() => {
+    if (!isTauriShell()) {
+      return;
+    }
+    const tauri = (window as unknown as { __TAURI__?: { core?: { invoke?: (cmd: string, args?: Record<string, unknown>) => Promise<unknown> } } }).__TAURI__;
+    if (typeof tauri?.core?.invoke !== 'function') {
+      return;
+    }
+
+    void tauri.core.invoke('desktop_set_auto_worktree_menu', { enabled: settingsAutoCreateWorktree });
+  }, [settingsAutoCreateWorktree]);
+
 
 
   useSessionStatusBootstrap();
@@ -199,15 +207,42 @@ function App({ apis }: AppProps) {
     }
   }, [error, clearError]);
 
+  React.useEffect(() => {
+    if (!isDesktopShell() || !isDesktopLocalOriginActive()) {
+      return;
+    }
+
+    let cancelled = false;
+    const run = async () => {
+      try {
+        const res = await fetch('/health', { method: 'GET' });
+        if (!res.ok) return;
+        const data = (await res.json().catch(() => null)) as null | { openCodeRunning?: unknown; lastOpenCodeError?: unknown };
+        if (!data || cancelled) return;
+        const openCodeRunning = data.openCodeRunning === true;
+        const err = typeof data.lastOpenCodeError === 'string' ? data.lastOpenCodeError : '';
+        const cliMissing = !openCodeRunning && /ENOENT|spawn\s+opencode|opencode(\.exe)?\s+not\s+found|not\s+found/i.test(err);
+        setShowCliOnboarding(cliMissing);
+      } catch {
+        // ignore
+      }
+    };
+
+    void run();
+    return () => {
+      cancelled = true;
+    };
+  }, []);
+
   const handleCliAvailable = React.useCallback(() => {
-    setCliAvailable(true);
+    setShowCliOnboarding(false);
     window.location.reload();
   }, []);
 
-  if (isDesktopRuntime && !cliAvailable) {
+  if (showCliOnboarding) {
     return (
       <ErrorBoundary>
-        <div className={`h-full text-foreground bg-transparent`}>
+        <div className="h-full text-foreground bg-transparent">
           <OnboardingScreen onCliAvailable={handleCliAvailable} />
         </div>
       </ErrorBoundary>