fix(k1): stabilize live recovery and media admission

apps/control-station/src/components/MseFmp4WebSocketPlayer.tsx

@@ -41,7 +41,9 @@ export interface CameraStartupWatchdog {
  * Supervise only the disposable browser transport. One fixed first-media
  * deadline covers both an MSE that never opens and an open-but-silent socket.
  * The first non-empty fragment then starts a separate first-playable-frame
- * deadline; later fragments deliberately do not extend it.
+ * deadline. Every subsequent fragment extends that deadline: a browser that is
+ * still receiving the authoritative stream must not destroy its partial MSE
+ * decode solely because the main thread or decoder needed longer to start.
  */
 export function createCameraStartupWatchdog({
   schedule,
@@ -83,7 +85,7 @@ export function createCameraStartupWatchdog({
       arm("first-media", firstMediaTimeoutMs);
     },
     markMediaReceived() {
-      if (mediaReceived || playing) return;
+      if (playing) return;
       mediaReceived = true;
       arm("first-playable-frame", firstPlayableFrameTimeoutMs);
     },
@@ -189,6 +191,7 @@ export function MseFmp4WebSocketPlayer({
   const leaseRetryRef = useRef(resetCameraLeaseRetryBudget(delivery.id));
   const activeAuthorityRef = useRef(recoveryAuthorityIdentity);
   const recoveryPendingAuthorityRef = useRef<string | null>(null);
+  const transportHealthyRef = useRef(false);
   const transportEpochRef = useRef(0);
   const transportAuthorityRef = useRef(recoveryAuthorityIdentity);
   const activeTransportDisposeRef = useRef<(() => void) | null>(null);
@@ -243,6 +246,7 @@ export function MseFmp4WebSocketPlayer({
     let receivedMedia = false;
     let failed = false;
     let startupWatchdog: CameraStartupWatchdog | null = null;
+    transportHealthyRef.current = false;
     const recovering = Boolean(
       activeAuthorityRef.current
       && recoveryPendingAuthorityRef.current === activeAuthorityRef.current,
@@ -254,6 +258,7 @@ export function MseFmp4WebSocketPlayer({
       if (!transportIsCurrent() || failed) return;
       startupWatchdog?.clear();
       failed = true;
+      transportHealthyRef.current = false;
       recoveryPendingAuthorityRef.current = null;
       setStatus("error");
       setMessage(copy);
@@ -280,6 +285,7 @@ export function MseFmp4WebSocketPlayer({
       }
       startupWatchdog?.clear();
       failed = true;
+      transportHealthyRef.current = false;
       queue.length = 0;
       queuedBytes = 0;
       const retry = consumeCameraLeaseRetry(leaseRetryRef.current, delivery.id);
@@ -320,6 +326,7 @@ export function MseFmp4WebSocketPlayer({
     const onPlaying = () => {
       if (!transportIsCurrent() || failed) return;
       startupWatchdog?.markPlaying();
+      transportHealthyRef.current = true;
       leaseRetryRef.current = resetCameraLeaseRetryBudget(delivery.id);
       recoveryPendingAuthorityRef.current = null;
       setStatus("playing");
@@ -464,6 +471,7 @@ export function MseFmp4WebSocketPlayer({
     const disposeTransport = () => {
       if (disposed) return;
       disposed = true;
+      transportHealthyRef.current = false;
       startupWatchdog?.clear();
       if (retryTimer !== undefined) window.clearTimeout(retryTimer);
       queue.length = 0;
@@ -518,6 +526,7 @@ export function MseFmp4WebSocketPlayer({
         now: Date.now(),
         documentVisible: document.visibilityState === "visible",
         networkOnline: navigator.onLine !== false,
+        transportHealthy: transportHealthyRef.current,
       });
       recovery = decision.state;
       if (!decision.reopen) return;