feature: Add browser compatibility detection for Web Bluetooth

Detects if the browser supports Web Bluetooth API and displays an
informative warning when unsupported. Provides users with clear
options: use a compatible browser or download the desktop app.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/App.tsx

@@ -12,6 +12,7 @@ import { BluetoothDevicePicker } from './components/BluetoothDevicePicker';
 import { getErrorDetails } from './utils/errorCodeHelpers';
 import { getStateVisualInfo } from './utils/machineStateHelpers';
 import { CheckCircleIcon, BoltIcon, PauseCircleIcon, ExclamationTriangleIcon, ArrowPathIcon, XMarkIcon, InformationCircleIcon } from '@heroicons/react/24/solid';
+import { isBluetoothSupported } from './utils/bluetoothSupport';
 import './App.css';
 
 function App() {
@@ -333,27 +334,60 @@ function App() {
         <div className="flex-1 grid grid-cols-1 lg:grid-cols-[480px_1fr] gap-4 md:gap-5 lg:gap-6 lg:overflow-hidden">
           {/* Left Column - Controls */}
           <div className="flex flex-col gap-4 md:gap-5 lg:gap-6 lg:overflow-hidden">
-            {/* Connect Button - Show when disconnected */}
+            {/* Connect Button or Browser Hint - Show when disconnected */}
             {!isConnected && (
-              <div className="bg-white dark:bg-gray-800 p-4 rounded-lg shadow-md border-l-4 border-gray-400 dark:border-gray-600">
+              <>
-                <div className="flex items-start gap-3 mb-3">
+                {isBluetoothSupported() ? (
-                  <div className="w-6 h-6 text-gray-600 dark:text-gray-400 flex-shrink-0 mt-0.5">
+                  <div className="bg-white dark:bg-gray-800 p-4 rounded-lg shadow-md border-l-4 border-gray-400 dark:border-gray-600">
-                    <svg className="w-6 h-6" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                    <div className="flex items-start gap-3 mb-3">
-                      <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M8.111 16.404a5.5 5.5 0 017.778 0M12 20h.01m-7.08-7.071c3.904-3.905 10.236-3.905 14.141 0M1.394 9.393c5.857-5.857 15.355-5.857 21.213 0" />
+                      <div className="w-6 h-6 text-gray-600 dark:text-gray-400 flex-shrink-0 mt-0.5">
-                    </svg>
+                        <svg className="w-6 h-6" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                          <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M8.111 16.404a5.5 5.5 0 017.778 0M12 20h.01m-7.08-7.071c3.904-3.905 10.236-3.905 14.141 0M1.394 9.393c5.857-5.857 15.355-5.857 21.213 0" />
+                        </svg>
+                      </div>
+                      <div className="flex-1 min-w-0">
+                        <h3 className="text-sm font-semibold text-gray-900 dark:text-white mb-1">Get Started</h3>
+                        <p className="text-xs text-gray-600 dark:text-gray-400">Connect to your embroidery machine</p>
+                      </div>
+                    </div>
+                    <button
+                      onClick={connect}
+                      className="w-full flex items-center justify-center gap-2 px-3 py-2.5 sm:py-2 bg-blue-600 dark:bg-blue-700 text-white rounded font-semibold text-sm hover:bg-blue-700 dark:hover:bg-blue-600 active:bg-blue-800 dark:active:bg-blue-500 transition-colors cursor-pointer"
+                    >
+                      Connect to Machine
+                    </button>
                   </div>
-                  <div className="flex-1 min-w-0">
+                ) : (
-                    <h3 className="text-sm font-semibold text-gray-900 dark:text-white mb-1">Get Started</h3>
+                  <div className="bg-amber-50 dark:bg-amber-900/20 p-4 rounded-lg shadow-md border-l-4 border-amber-500 dark:border-amber-600">
-                    <p className="text-xs text-gray-600 dark:text-gray-400">Connect to your embroidery machine</p>
+                    <div className="flex items-start gap-3">
+                      <ExclamationTriangleIcon className="w-6 h-6 text-amber-600 dark:text-amber-400 flex-shrink-0 mt-0.5" />
+                      <div className="flex-1 min-w-0">
+                        <h3 className="text-base font-semibold text-amber-900 dark:text-amber-100 mb-2">Browser Not Supported</h3>
+                        <p className="text-sm text-amber-800 dark:text-amber-200 mb-3">
+                          Your browser doesn't support Web Bluetooth, which is required to connect to your embroidery machine.
+                        </p>
+                        <div className="space-y-2">
+                          <p className="text-sm font-semibold text-amber-900 dark:text-amber-100">Please try one of these options:</p>
+                          <ul className="text-sm text-amber-800 dark:text-amber-200 space-y-1.5 ml-4 list-disc">
+                            <li>Use a supported browser (Chrome, Edge, or Opera)</li>
+                            <li>
+                              Download the Desktop app from{' '}
+                              <a
+                                href="https://github.com/jhbruhn/respira/releases/latest"
+                                target="_blank"
+                                rel="noopener noreferrer"
+                                className="font-semibold underline hover:text-amber-900 dark:hover:text-amber-50 transition-colors"
+                              >
+                                GitHub Releases
+                              </a>
+                            </li>
+                          </ul>
+                        </div>
+                      </div>
+                    </div>
                   </div>
-                </div>
+                )}
-                <button
+              </>
-                  onClick={connect}
-                  className="w-full flex items-center justify-center gap-2 px-3 py-2.5 sm:py-2 bg-blue-600 dark:bg-blue-700 text-white rounded font-semibold text-sm hover:bg-blue-700 dark:hover:bg-blue-600 active:bg-blue-800 dark:active:bg-blue-500 transition-colors cursor-pointer"
-                >
-                  Connect to Machine
-                </button>
-              </div>
             )}
 
             {/* Pattern File - Show during upload stage (before pattern is uploaded) */}

src/utils/bluetoothSupport.ts

@@ -0,0 +1,17 @@
+/**
+ * Check if the current browser/environment supports Web Bluetooth API
+ * @returns true if Web Bluetooth is supported (or running in Electron), false otherwise
+ */
+export function isBluetoothSupported(): boolean {
+  // Always supported in Electron app
+  if (typeof window !== 'undefined' && (window as any).electronAPI) {
+    return true;
+  }
+
+  // Check for Web Bluetooth API support in browser
+  if (typeof navigator !== 'undefined' && 'bluetooth' in navigator) {
+    return true;
+  }
+
+  return false;
+}