fix(k1): harden live handoff and camera recovery

apps/control-station/test/observationSources.test.mjs

@@ -16,6 +16,7 @@ let cameraTransportRecoveryIsCurrent;
 let cameraTransportCanOpen;
 let cameraPendingQueueCanAccept;
 let cameraTransportCloseRecoveryMessage;
+let cameraPlaybackRecoveryFailureStage;
 let createCameraStartupWatchdog;
 let cameraStartupWatchdogRecoveryMessage;
 let CAMERA_FIRST_MEDIA_TIMEOUT_MS;
@@ -69,6 +70,7 @@ before(async () => {
     cameraTransportCanOpen,
     cameraPendingQueueCanAccept,
     cameraTransportCloseRecoveryMessage,
+    cameraPlaybackRecoveryFailureStage,
     createCameraStartupWatchdog,
     cameraStartupWatchdogRecoveryMessage,
     CAMERA_FIRST_MEDIA_TIMEOUT_MS,
@@ -1297,6 +1299,25 @@ test("server slow-reader close is an automatic browser-only camera recovery", ()
   assert.match(cameraTransportCloseRecoveryMessage(1_011), /восстанавливаем/);
 });
 
+test("camera transport recovery events keep exact diagnostic causes", () => {
+  assert.equal(
+    cameraPlaybackRecoveryFailureStage({ type: "heartbeat" }),
+    "camera-heartbeat-reopen",
+  );
+  assert.equal(
+    cameraPlaybackRecoveryFailureStage({ type: "document-visible" }),
+    "camera-visibility-reopen",
+  );
+  assert.equal(
+    cameraPlaybackRecoveryFailureStage({ type: "network-online" }),
+    "camera-network-online-reopen",
+  );
+  assert.equal(
+    cameraPlaybackRecoveryFailureStage({ type: "page-restore", persisted: true }),
+    "camera-page-restore-reopen",
+  );
+});
+
 test("a laptop sleep gap reopens only the exact authoritative live camera transport", () => {
   const source = xgridsK1ObservationSources(
     cameraStreamingState("sensor.camera.right"),