fix(viewer): make recorded layers deterministic

apps/control-station/src/workspaces/Workspaces.tsx

@@ -336,10 +336,13 @@ function SpatialWorkspace({
     (source) => source.capabilities.overlay && source.modality !== "point-cloud",
   );
   const recordedPerceptionSupported = recordedSource && perceptionAvailability !== "unavailable";
-  // Keep one stable original-video + world composition for every admitted
-  // perception recording. Layer buttons then only change entity visibility;
-  // they never reparent the 3D view or invalidate the operator's camera.
-  const unifiedPerception = recordedPerceptionSupported;
+  const recordedPerceptionEnabled =
+    showDetections2d || showSegmentation || showCuboids3d;
+  // The native recorded camera remains the authoritative original. Only 2D
+  // image-space overlays need Rerun's paired camera/world composition; 3D
+  // cuboids are added directly to the stable spatial view.
+  const unifiedPerception = recordedPerceptionSupported &&
+    (showDetections2d || showSegmentation);
   const livePerceptionAvailable = !recordedSource && streamActive;
   const detections2dActive = recordedSource
     ? showDetections2d
@@ -354,6 +357,16 @@ function SpatialWorkspace({
     observationLayout.visibleSourceIds.has(source.id) &&
     !source.id.startsWith("recorded.perception."),
   );
+  const initialRecordedPlaybackStartSeconds = recordedSource
+    ? mediaSources.reduce<number | undefined>((earliest, source) => {
+        if (
+          source.id.startsWith("recorded.perception.") ||
+          source.delivery?.kind !== "recorded-fmp4-manifest"
+        ) return earliest;
+        const start = source.delivery.timelineStartSeconds;
+        return earliest === undefined ? start : Math.min(earliest, start);
+      }, undefined)
+    : undefined;
   const presentedMediaSourceCount = unifiedPerception ? 0 : visibleMediaSources.length;
   const pointCloudFocused = Boolean(
     pointCloudSource && observationLayout.focusedSourceId === pointCloudSource.id,
@@ -574,10 +587,11 @@ function SpatialWorkspace({
               expectedTimelineEndSeconds={recordedSource
                 ? state?.observationTimeline?.range?.endSeconds
                 : undefined}
+              initialPlaybackStartSeconds={initialRecordedPlaybackStartSeconds}
               sceneSettings={sceneSettings}
               recordedViewResetGeneration={recordedViewResetGeneration}
               recordedPerceptionLayers={{
-                enabled: unifiedPerception,
+                enabled: recordedPerceptionSupported && recordedPerceptionEnabled,
                 detections2d: showDetections2d,
                 segmentation: showSegmentation,
                 cuboids3d: showCuboids3d,