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/components/views/PlanView.tsx

@@ -239,7 +239,7 @@ export const PlanView: React.FC = () => {
     setLineSelection(null);
 
     toast.success('Comment saved');
-  }, [lineSelection, commentText, content, displayPath, resolvedPath, addDraft, getSessionKey]);
+  }, [lineSelection, commentText, content, displayPath, resolvedPath, addDraft, getSessionKey, extractSelectedCode]);
 
   const editorExtensions = React.useMemo(() => {
     const extensions = [createFlexokiCodeMirrorTheme(currentTheme)];

packages/ui/src/components/views/SettingsView.tsx

@@ -104,10 +104,10 @@ export const SettingsView: React.FC<SettingsViewProps> = ({ onClose, forceMobile
   const startXRef = React.useRef(0);
   const startWidthRef = React.useRef(sidebarWidth);
 
-  const [isDesktopApp, setIsDesktopApp] = React.useState<boolean>(() => {
+  const isTauri = React.useMemo(() => {
     if (typeof window === 'undefined') return false;
-    return typeof (window as typeof window & { opencodeDesktop?: unknown }).opencodeDesktop !== 'undefined';
-  });
+    return Boolean((window as unknown as { __TAURI__?: unknown }).__TAURI__);
+  }, []);
 
   const isMacPlatform = React.useMemo(() => {
     if (typeof navigator === 'undefined') return false;
@@ -118,10 +118,7 @@ export const SettingsView: React.FC<SettingsViewProps> = ({ onClose, forceMobile
 
   const settingsSections = React.useMemo(() => getSettingsSections(isVSCode), [isVSCode]);
 
-  React.useEffect(() => {
-    if (typeof window === 'undefined') return;
-    setIsDesktopApp(typeof (window as typeof window & { opencodeDesktop?: unknown }).opencodeDesktop !== 'undefined');
-  }, []);
+  const isDesktopApp = isTauri;
 
   // Track container width for responsive tab labels
   React.useEffect(() => {

packages/ui/src/components/views/TerminalView.tsx

@@ -17,7 +17,6 @@ import { useUIStore } from '@/stores/useUIStore';
 import { Button } from '@/components/ui/button';
 import { useDeviceInfo } from '@/lib/device';
 import { useRuntimeAPIs } from '@/hooks/useRuntimeAPIs';
-import { isDesktopRuntime, isWebRuntime } from '@/lib/desktop';
 
 type Modifier = 'ctrl' | 'cmd';
 type MobileKey =
@@ -74,12 +73,13 @@ const getSequenceForKey = (key: MobileKey, modifier: Modifier | null): string |
 };
 
 export const TerminalView: React.FC = () => {
-    const { terminal } = useRuntimeAPIs();
+    const { terminal, runtime } = useRuntimeAPIs();
     const { currentTheme } = useThemeSystem();
     const { monoFont } = useFontPreferences();
     const terminalFontSize = useUIStore(state => state.terminalFontSize);
     const { isMobile, hasTouchInput } = useDeviceInfo();
-    const enableTabs = !isMobile && (isWebRuntime() || isDesktopRuntime());
+    // Tabs are supported for web + desktop runtimes (not VSCode).
+    const enableTabs = !isMobile && runtime.platform !== 'vscode';
     const showTerminalQuickKeysOnDesktop = useUIStore((state) => state.showTerminalQuickKeysOnDesktop);
     const showQuickKeys = isMobile || showTerminalQuickKeysOnDesktop;
 

packages/ui/src/components/views/git/PullRequestSection.tsx

@@ -73,19 +73,25 @@ type PullRequestDraftSnapshot = {
 
 const pullRequestDraftSnapshots = new Map<string, PullRequestDraftSnapshot>();
 
+type TauriShell = {
+  shell?: {
+    open?: (url: string) => Promise<unknown>;
+  };
+};
+
 const openExternal = async (url: string) => {
   if (typeof window === 'undefined') return;
-  const desktop = (window as typeof window & { opencodeDesktop?: { openExternal?: (url: string) => Promise<unknown> } }).opencodeDesktop;
-  if (desktop?.openExternal) {
+
+  const tauri = (window as unknown as { __TAURI__?: TauriShell }).__TAURI__;
+  if (tauri?.shell?.open) {
     try {
-      const result = await desktop.openExternal(url);
-      if (result && typeof result === 'object' && 'success' in result && (result as { success?: boolean }).success === true) {
-        return;
-      }
+      await tauri.shell.open(url);
+      return;
     } catch {
       // fall through
     }
   }
+
   try {
     window.open(url, '_blank', 'noopener,noreferrer');
   } catch {