feat(frontend): dev mock-join fallback when LiveKit unconfigured

If the backend returns the placeholder LiveKit URL, skip the real connect and
screen capture and drop into the post-join state (with a DEV MODE banner) so
the connected UI is developable without LiveKit creds or HTTPS. Real joins
also guard getDisplayMedia behind isSecureContext.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/App.tsx

@@ -8,6 +8,8 @@ export default function App() {
   const team = useMemo(() => TEAMS.find((t) => t.id === teamId) ?? TEAMS[0]!, [teamId]);
   const [member, setMember] = useState(team.members[0]!);
   const [room, setRoom] = useState<Room | null>(null);
+  const [joined, setJoined] = useState(false);
+  const [devMode, setDevMode] = useState(false);
   const [error, setError] = useState<string | null>(null);
   const [connecting, setConnecting] = useState(false);
 
@@ -22,7 +24,10 @@ export default function App() {
     setConnecting(true);
     try {
       const identity = `${member}-${Math.random().toString(36).slice(2, 7)}`;
-      setRoom(await joinPod(team.id, identity, member));
+      const result = await joinPod(team.id, identity, member);
+      setRoom(result.room);
+      setDevMode(result.mode === 'dev');
+      setJoined(true);
     } catch (err) {
       setError((err as Error).message);
     } finally {
@@ -39,12 +44,20 @@ export default function App() {
         </p>
       </header>
 
-      {room ? (
+      {joined ? (
         <section className="rounded-lg border border-slate-700 bg-slate-900/50 p-4">
           <p className="font-medium text-emerald-400">
             {member} connected to “{team.name}”.
           </p>
-          <p className="mt-1 text-sm text-slate-400">Sharing screen + mic. PodMan is watching.</p>
+          <p className="mt-1 text-sm text-slate-400">
+            {room ? 'Sharing screen + mic. PodMan is watching.' : 'Pod joined.'}
+          </p>
+          {devMode && (
+            <p className="mt-3 rounded-md border border-amber-700/50 bg-amber-950/40 px-3 py-2 text-xs text-amber-300">
+              DEV MODE — LiveKit not configured, so screen capture is off. Set LIVEKIT_* in the
+              backend .env (and serve over HTTPS) for a real join.
+            </p>
+          )}
         </section>
       ) : (
         <section className="flex flex-col gap-4">

frontend/src/lib/pod.ts

@@ -2,7 +2,7 @@ import { Room, RoomEvent } from 'livekit-client';
 
 const BACKEND_URL = import.meta.env.VITE_BACKEND_URL || 'http://localhost:8787';
 
-/** Ask the backend for a LiveKit token to join a pod. */
+/** Token + LiveKit URL minted by the backend. */
 export async function fetchPodToken(
   podId: string,
   identity: string,
@@ -17,22 +17,41 @@ export async function fetchPodToken(
   return res.json();
 }
 
+/** True once a real LiveKit server is configured (not the placeholder). */
+export function isLiveKitConfigured(url: string | undefined): boolean {
+  return !!url && !url.includes('REPLACE_ME');
+}
+
+export type JoinResult = { mode: 'live'; room: Room } | { mode: 'dev'; room: null };
+
 /**
- * Join a pod: connect to the LiveKit room and publish screen + mic so PodMan
- * can watch. Returns the connected Room.
+ * Join a pod. When LiveKit is configured we connect for real and publish
+ * screen + mic. Otherwise we fall back to a dev mock join so the post-join UI
+ * is developable without LiveKit creds / HTTPS.
  */
-export async function joinPod(podId: string, identity: string, name: string): Promise<Room> {
+export async function joinPod(podId: string, identity: string, name: string): Promise<JoinResult> {
   const { token, url } = await fetchPodToken(podId, identity, name);
+
+  if (!isLiveKitConfigured(url)) {
+    console.warn('[podman] LiveKit not configured — dev mock join (no screen capture)');
+    return { mode: 'dev', room: null };
+  }
+
   const room = new Room({ adaptiveStream: true, dynacast: true });
   room.on(RoomEvent.Disconnected, () => console.log('[podman] disconnected'));
-
   await room.connect(url, token);
 
+  // Screen capture needs a secure context (HTTPS or localhost). Guard so a
+  // non-secure origin doesn't hard-crash the join.
+  if (window.isSecureContext && navigator.mediaDevices?.getDisplayMedia) {
     const screen = await navigator.mediaDevices.getDisplayMedia({ video: true });
     for (const track of screen.getTracks()) {
       await room.localParticipant.publishTrack(track);
     }
     await room.localParticipant.setMicrophoneEnabled(true);
-
-  return room;
+  } else {
+    console.warn('[podman] insecure context — screen capture skipped (needs HTTPS)');
+  }
+
+  return { mode: 'live', room };
 }