feat: Add hardened error handling and retries (#2451)

- Closes #1830
 - Closes #2099

src/view/target-id.ts

@@ -0,0 +1,27 @@
+import { getStreamCameraID } from '../utils/substream';
+import { View } from './view';
+
+// Synthetic target ID used for the image view. The image view has no natural
+// per-display identifier (unlike live, which has a camera ID, or the viewer,
+// which has a media ID), so a sentinel string is used as its universal key in
+// the target-ID namespace. Must not collide with real camera IDs or media IDs.
+export const IMAGE_VIEW_TARGET_ID_SENTINEL = '__IMAGE_VIEW__';
+
+// Returns a universal target identifier for the current view — the single key
+// used by PTZ/zoom state and media retry epochs to identify "what is currently
+// being displayed." Distinct from a raw camera ID because it accounts for
+// substreams (live) and the image view sentinel. Media IDs, camera IDs, and
+// the image sentinel inhabit distinct namespaces so there are no collisions
+// across view types.
+export const getViewTargetID = (view: View): string | null => {
+  if (view.isViewerView()) {
+    return view.queryResults?.getSelectedResult()?.getID() ?? null;
+  }
+  if (view.is('live')) {
+    return getStreamCameraID(view);
+  }
+  if (view.is('image')) {
+    return IMAGE_VIEW_TARGET_ID_SENTINEL;
+  }
+  return null;
+};