fix: allow process restart after update and detect Homebrew version mismatch

apps/desktop/src-tauri/Cargo.toml

@@ -22,6 +22,7 @@ tauri-plugin-deep-link = "2"
 tauri-plugin-updater = "2"
 tauri-plugin-autostart = "2"
 tauri-plugin-dialog = "2"
+tauri-plugin-process = "2"
 image = { version = "0.25", default-features = false, features = ["png"] }
 serde.workspace = true
 serde_json.workspace = true

apps/desktop/src-tauri/capabilities/default.json

@@ -17,6 +17,7 @@
     "opener:default",
     "deep-link:default",
     "updater:default",
+    "process:allow-restart",
     "dialog:default"
   ]
 }

apps/desktop/src-tauri/src/lib.rs

@@ -122,12 +122,48 @@ fn init_tracing() -> tracing_appender::non_blocking::WorkerGuard {
     guard
 }
 
-/// Get app version
+/// Get app version (compiled into the binary)
 #[tauri::command]
 fn get_version() -> String {
     env!("CARGO_PKG_VERSION").to_string()
 }
 
+/// Get the on-disk bundle version (macOS only).
+///
+/// After a Homebrew Cask upgrade, the `.app` bundle on disk has the new version
+/// but the running process still has the old compiled-in version. Comparing
+/// `get_version()` with `get_bundle_version()` lets the frontend detect this
+/// mismatch and prompt the user to restart.
+#[tauri::command]
+fn get_bundle_version() -> Option<String> {
+    #[cfg(target_os = "macos")]
+    {
+        // Read CFBundleShortVersionString from the running app's Info.plist
+        let exe = std::env::current_exe().ok()?;
+        // exe is typically: Foo.app/Contents/MacOS/Foo
+        let contents_dir = exe.parent()?.parent()?;
+        let plist_path = contents_dir.join("Info.plist");
+        let plist = std::fs::read_to_string(&plist_path).ok()?;
+
+        // Simple extraction — avoids adding a plist parsing dependency.
+        // Looks for <key>CFBundleShortVersionString</key>\n<string>X.Y.Z</string>
+        let key = "CFBundleShortVersionString";
+        let key_pos = plist.find(key)?;
+        let after_key = &plist[key_pos + key.len()..];
+        let string_start = after_key.find("<string>")? + "<string>".len();
+        let string_end = after_key[string_start..].find("</string>")?;
+        Some(
+            after_key[string_start..string_start + string_end]
+                .trim()
+                .to_string(),
+        )
+    }
+    #[cfg(not(target_os = "macos"))]
+    {
+        None
+    }
+}
+
 /// Get the path to the logs directory
 #[tauri::command]
 fn get_logs_path() -> String {
@@ -195,6 +231,7 @@ pub fn run() {
             Some(vec!["--hidden"]), // Start minimized to tray
         ))
         .plugin(tauri_plugin_updater::Builder::new().build())
+        .plugin(tauri_plugin_process::init())
         .plugin(tauri_plugin_single_instance::init(|app, args, cwd| {
             // This callback is called when a second instance is launched
             info!("Second instance detected, focusing existing window");
@@ -691,6 +728,7 @@ pub fn run() {
         })
         .invoke_handler(tauri::generate_handler![
             get_version,
+            get_bundle_version,
             // Space commands
             commands::list_spaces,
             commands::get_space,

apps/desktop/src/features/settings/UpdateChecker.tsx

@@ -1,4 +1,4 @@
-import { useState } from 'react';
+import { useState, useEffect } from 'react';
 import { check, Update } from '@tauri-apps/plugin-updater';
 import { relaunch } from '@tauri-apps/plugin-process';
 import {
@@ -9,7 +9,7 @@ import {
   CardDescription,
   CardContent,
 } from '@mcpmux/ui';
-import { Download, Loader2, CheckCircle, AlertCircle, RefreshCw } from 'lucide-react';
+import { Download, Loader2, CheckCircle, AlertCircle, RefreshCw, RotateCcw } from 'lucide-react';
 import { invoke } from '@tauri-apps/api/core';
 
 interface DownloadEvent {
@@ -27,6 +27,7 @@ export function UpdateChecker() {
   const [downloadProgress, setDownloadProgress] = useState({ downloaded: 0, total: 0 });
   const [message, setMessage] = useState<{ type: 'success' | 'error'; text: string } | null>(null);
   const [currentVersion, setCurrentVersion] = useState<string>('');
+  const [bundleVersionMismatch, setBundleVersionMismatch] = useState<string | null>(null);
 
   // Load current version on mount
   useState(() => {
@@ -35,6 +36,23 @@ export function UpdateChecker() {
       .catch((err) => console.error('Failed to get version:', err));
   });
 
+  // Check if the on-disk bundle version differs from the running version (Homebrew Cask upgrades)
+  useEffect(() => {
+    if (!currentVersion) return;
+    invoke<string | null>('get_bundle_version')
+      .then((bundleVersion) => {
+        if (bundleVersion && bundleVersion !== currentVersion) {
+          console.log(
+            `[Updater] Bundle version mismatch: running=${currentVersion}, on-disk=${bundleVersion}`
+          );
+          setBundleVersionMismatch(bundleVersion);
+        }
+      })
+      .catch(() => {
+        // Expected to return null on non-macOS platforms
+      });
+  }, [currentVersion]);
+
   const checkForUpdates = async () => {
     setChecking(true);
     setMessage(null);
@@ -149,8 +167,32 @@ export function UpdateChecker() {
             </p>
           </div>
 
+          {/* Bundle version mismatch (e.g., after brew upgrade) */}
+          {bundleVersionMismatch && (
+            <div
+              className="border rounded-lg p-4 space-y-3 bg-surface-secondary"
+              data-testid="restart-required"
+            >
+              <div>
+                <p className="font-medium text-lg">Restart Required</p>
+                <p className="text-sm text-[rgb(var(--muted))] mt-1">
+                  Version v{bundleVersionMismatch} has been installed on disk, but you are still
+                  running v{currentVersion}. Restart to apply the update.
+                </p>
+              </div>
+              <Button
+                onClick={() => relaunch()}
+                variant="primary"
+                data-testid="restart-now-btn"
+              >
+                <RotateCcw className="h-4 w-4 mr-2" />
+                Restart Now
+              </Button>
+            </div>
+          )}
+
           {/* Check Button */}
-          {!updateInfo && (
+          {!updateInfo && !bundleVersionMismatch && (
             <Button
               onClick={checkForUpdates}
               disabled={checking || downloading}