fix(seg): prevent segmentations from spreading to all viewports before hydration confirmation in 3D four-up (#5967)

platform/core/src/services/HangingProtocolService/HangingProtocolService.ts

@@ -661,6 +661,12 @@ export default class HangingProtocolService extends PubSubService {
     if (displaySet?.unsupported) {
       throw new Error('Unsupported displaySet');
     }
+    // Overlays (SEG, RTSTRUCT) share selectors with referenced volumes but must not
+    // sync to every matched viewport before hydration (would replace e.g. 3D primary).
+    if (displaySet?.isOverlayDisplaySet) {
+      return defaultReturn;
+    }
+
     const protocol = this.protocol;
     const protocolStage = protocol.stages[this.stageIndex];
     const protocolViewports = protocolStage.viewports;

platform/core/src/types/HangingProtocol.ts

@@ -24,6 +24,13 @@ export type DisplaySetAndViewportOptions = {
   displaySetOptions: DisplaySetOptions;
 };
 
+export interface ViewportUpdate {
+  viewportId?: string;
+  displaySetInstanceUIDs: string[];
+  viewportOptions?: ViewportOptions;
+  displaySetOptions?: DisplaySetOptions[];
+}
+
 export type DisplayArea = {
   type?: 'SCALE' | 'FIT';
   scale?: number;