feat: add YouTube Live chat connection controls with UI

client/app/dashboard/page.tsx

@@ -9,6 +9,7 @@ const POLL_INTERVAL = 2500;
 export default function DashboardPage() {
   const { messages, refresh, error: pollError } = useChatMessages();
   const { selection, status: overlayStatus } = useOverlaySelection();
+  const { connected, liveId, connect, disconnect, connecting } = useConnection();
 
   const handleSelect = useCallback(
     async (message: ChatMessage) => {
@@ -61,6 +62,14 @@ export default function DashboardPage() {
         </div>
       </header>
 
+      <ConnectionControl
+        connected={connected}
+        liveId={liveId}
+        connecting={connecting}
+        onConnect={connect}
+        onDisconnect={disconnect}
+      />
+
       <section className="dashboard__main">
         <div className="chatPanel">
           <div className="chatPanel__header">
@@ -213,3 +222,118 @@ function useOverlaySelection() {
 
   return { selection, status };
 }
+
+function useConnection() {
+  const [connected, setConnected] = useState(false);
+  const [liveId, setLiveId] = useState<string | null>(null);
+  const [connecting, setConnecting] = useState(false);
+
+  const checkStatus = useCallback(async () => {
+    try {
+      const response = await fetch(`${BACKEND_URL}/health`);
+      const data = await response.json();
+      setConnected(data.connected);
+      setLiveId(data.liveId);
+    } catch (error) {
+      console.error('Failed to check connection status', error);
+    }
+  }, []);
+
+  useEffect(() => {
+    checkStatus();
+    const interval = setInterval(checkStatus, 5000);
+    return () => clearInterval(interval);
+  }, [checkStatus]);
+
+  const connect = useCallback(async (liveId: string) => {
+    setConnecting(true);
+    try {
+      const response = await fetch(`${BACKEND_URL}/chat/connect`, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ liveId })
+      });
+      
+      if (!response.ok) {
+        const error = await response.json();
+        throw new Error(error.error || 'Failed to connect');
+      }
+      
+      await checkStatus();
+    } catch (error) {
+      console.error('Failed to connect', error);
+      alert('Failed to connect to YouTube Live chat. Please check the Live ID.');
+    } finally {
+      setConnecting(false);
+    }
+  }, [checkStatus]);
+
+  const disconnect = useCallback(async () => {
+    try {
+      await fetch(`${BACKEND_URL}/chat/disconnect`, { method: 'POST' });
+      await checkStatus();
+    } catch (error) {
+      console.error('Failed to disconnect', error);
+    }
+  }, [checkStatus]);
+
+  return { connected, liveId, connect, disconnect, connecting };
+}
+
+type ConnectionControlProps = {
+  connected: boolean;
+  liveId: string | null;
+  connecting: boolean;
+  onConnect: (liveId: string) => void;
+  onDisconnect: () => void;
+};
+
+function ConnectionControl({ connected, liveId, connecting, onConnect, onDisconnect }: ConnectionControlProps) {
+  const [inputValue, setInputValue] = useState('');
+
+  const handleSubmit = (e: React.FormEvent) => {
+    e.preventDefault();
+    if (inputValue.trim()) {
+      onConnect(inputValue.trim());
+    }
+  };
+
+  return (
+    <div className="connectionControl">
+      <div className="connectionControl__content">
+        {connected ? (
+          <div className="connectionControl__connected">
+            <div className="connectionControl__info">
+              <span className="connectionControl__badge">🟢 Connected</span>
+              <span className="connectionControl__liveId">Live ID: {liveId}</span>
+            </div>
+            <button className="btn-disconnect" onClick={onDisconnect}>
+              Disconnect
+            </button>
+          </div>
+        ) : (
+          <form className="connectionControl__form" onSubmit={handleSubmit}>
+            <div className="connectionControl__input">
+              <label htmlFor="liveId">YouTube Live Stream ID or URL</label>
+              <input
+                id="liveId"
+                type="text"
+                value={inputValue}
+                onChange={(e) => setInputValue(e.target.value)}
+                placeholder="e.g., dQw4w9WgXcQ or https://youtube.com/watch?v=..."
+                disabled={connecting}
+              />
+            </div>
+            <button
+              type="submit"
+              className="btn-connect"
+              disabled={connecting || !inputValue.trim()}
+            >
+              {connecting ? 'Connecting...' : 'Connect to Stream'}
+            </button>
+          </form>
+        )}
+      </div>
+    </div>
+  );
+}

client/app/globals.css

@@ -124,13 +124,147 @@ main {
   display: flex;
   flex-direction: column;
   align-items: center;
-  padding: 2rem clamp(1rem, 5vw, 3rem);
+  padding: 0 clamp(1rem, 5vw, 3rem) 2rem;
   gap: 2rem;
   max-width: 1400px;
   width: 100%;
   margin: 0 auto;
 }
 
+.connectionControl {
+  width: 100%;
+  padding: 1.5rem clamp(1rem, 5vw, 3rem);
+  background: rgba(30, 41, 59, 0.5);
+  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
+}
+
+.connectionControl__content {
+  max-width: 1400px;
+  margin: 0 auto;
+}
+
+.connectionControl__connected {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  gap: 1rem;
+}
+
+.connectionControl__info {
+  display: flex;
+  align-items: center;
+  gap: 1.5rem;
+}
+
+.connectionControl__badge {
+  padding: 0.5rem 1rem;
+  background: rgba(34, 197, 94, 0.2);
+  color: #4ade80;
+  border-radius: 999px;
+  font-weight: 600;
+  font-size: 0.9rem;
+}
+
+.connectionControl__liveId {
+  color: #94a3b8;
+  font-size: 0.9rem;
+  font-family: 'Monaco', 'Courier New', monospace;
+}
+
+.connectionControl__form {
+  display: flex;
+  gap: 1rem;
+  align-items: flex-end;
+}
+
+.connectionControl__input {
+  flex: 1;
+  display: flex;
+  flex-direction: column;
+  gap: 0.5rem;
+}
+
+.connectionControl__input label {
+  color: #94a3b8;
+  font-size: 0.85rem;
+  font-weight: 500;
+}
+
+.connectionControl__input input {
+  padding: 0.75rem 1rem;
+  background: rgba(15, 23, 42, 0.6);
+  border: 1px solid rgba(255, 255, 255, 0.1);
+  border-radius: 8px;
+  color: #e2e8f0;
+  font-size: 0.95rem;
+  font-family: 'Monaco', 'Courier New', monospace;
+  transition: border-color 150ms ease;
+}
+
+.connectionControl__input input:focus {
+  outline: none;
+  border-color: rgba(96, 165, 250, 0.5);
+}
+
+.connectionControl__input input::placeholder {
+  color: #64748b;
+}
+
+.connectionControl__input input:disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+}
+
+.btn-connect,
+.btn-disconnect {
+  padding: 0.75rem 1.5rem;
+  border: none;
+  border-radius: 8px;
+  font-weight: 600;
+  font-size: 0.95rem;
+  cursor: pointer;
+  transition: all 150ms ease;
+  white-space: nowrap;
+}
+
+.btn-connect {
+  background: linear-gradient(135deg, #3b82f6, #8b5cf6);
+  color: #fff;
+}
+
+.btn-connect:hover:not(:disabled) {
+  transform: translateY(-2px);
+  box-shadow: 0 8px 24px rgba(59, 130, 246, 0.3);
+}
+
+.btn-connect:disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+}
+
+.btn-disconnect {
+  background: rgba(239, 68, 68, 0.15);
+  color: #ef4444;
+  border: 1px solid rgba(239, 68, 68, 0.3);
+}
+
+.btn-disconnect:hover {
+  background: rgba(239, 68, 68, 0.25);
+  transform: translateY(-1px);
+}
+
+@media (max-width: 768px) {
+  .connectionControl__form {
+    flex-direction: column;
+    align-items: stretch;
+  }
+  
+  .connectionControl__connected {
+    flex-direction: column;
+    align-items: flex-start;
+  }
+}
+
 .chatPanel {
   width: 100%;
   background: rgba(30, 41, 59, 0.4);
@@ -392,6 +526,28 @@ main {
   background: rgba(0, 0, 0, 0);
 }
 
+@keyframes fadeIn {
+  from {
+    opacity: 0;
+    transform: translateY(20px) scale(0.95);
+  }
+  to {
+    opacity: 1;
+    transform: translateY(0) scale(1);
+  }
+}
+
+@keyframes fadeOut {
+  from {
+    opacity: 1;
+    transform: scale(1);
+  }
+  to {
+    opacity: 0;
+    transform: scale(0.95);
+  }
+}
+
 .overlay__card {
   padding: 2rem 2.5rem;
   border-radius: 24px;
@@ -404,6 +560,11 @@ main {
   display: flex;
   flex-direction: column;
   gap: 1.25rem;
+  animation: fadeIn 0.4s ease-out;
+}
+
+.overlay__card--fadeOut {
+  animation: fadeOut 0.3s ease-in forwards;
 }
 
 .overlay__header {

client/app/overlay/page.tsx

@@ -12,13 +12,30 @@ type SelectionPayload = {
 export default function OverlayPage() {
   const [message, setMessage] = useState<ChatMessage | null>(null);
   const [connected, setConnected] = useState(false);
+  const [fadingOut, setFadingOut] = useState(false);
 
   useEffect(() => {
     const source = new EventSource(`${BACKEND_URL}/overlay/stream`);
+    
     const onSelection = (event: MessageEvent) => {
       try {
         const payload: SelectionPayload = JSON.parse(event.data);
-        setMessage(payload.message);
+        
+        setMessage((prevMessage) => {
+          if (payload.message === null && prevMessage !== null) {
+            // Trigger fade out animation before clearing
+            setFadingOut(true);
+            setTimeout(() => {
+              setMessage(null);
+              setFadingOut(false);
+            }, 300);
+            return prevMessage; // Keep current message during fade
+          } else {
+            setFadingOut(false);
+            return payload.message;
+          }
+        });
+        
         setConnected(true);
       } catch (error) {
         console.error('overlay: failed to parse payload', error);
@@ -33,12 +50,12 @@ export default function OverlayPage() {
       source.removeEventListener('selection', onSelection as EventListener);
       source.close();
     };
-  }, []);
+  }, []); // Empty dependency array - only connect once
 
   return (
     <main className="overlay">
       {message ? (
-        <div className="overlay__card">
+        <div className={`overlay__card ${fadingOut ? 'overlay__card--fadeOut' : ''}`}>
           <div className="overlay__header">
             {message.authorPhoto && (
               <img src={message.authorPhoto} alt={message.author} className="overlay__avatar" />

client/next.config.js

@@ -2,7 +2,9 @@
 const nextConfig = {
   reactStrictMode: true,
   experimental: {
-    serverActions: true
+    serverActions: {
+      bodySizeLimit: '2mb'
+    }
   }
 };