fix scroll top in firefox

apps/browser/src/vault/popup/components/vault-v2/view-v2/view-v2.component.ts

@@ -266,6 +266,7 @@ export class ViewV2Component {
     }
 
     this.popupScrollPositionService.stop(true);
+    this.popupScrollPositionService.forceTopOnNextVaultStart();
     await this.popupRouterCacheService.back();
 
     this.toastService.showToast({

apps/browser/src/vault/popup/services/vault-popup-scroll-position.service.spec.ts

@@ -108,6 +108,28 @@ describe("VaultPopupScrollPositionService", () => {
         });
         expect((scrollElement as any).scrollTop).toBe(500);
       }));
+
+      it("forces scroll to top on next start when requested", fakeAsync(() => {
+        service["scrollPosition"] = 500;
+        service.forceTopOnNextVaultStart();
+
+        service.start(scrollElement);
+
+        tick();
+        expect((scrollElement as any).scrollTo).toHaveBeenCalledWith({
+          behavior: "instant",
+          top: 0,
+        });
+        expect((scrollElement as any).scrollTop).toBe(0);
+
+        // A follow-up scroll is scheduled to defeat Firefox scroll restoration.
+        ((scrollElement as any).scrollTo as jest.Mock).mockClear();
+        tick(50);
+        expect((scrollElement as any).scrollTo).toHaveBeenCalledWith({
+          behavior: "instant",
+          top: 0,
+        });
+      }));
     });
 
     describe("scroll listener", () => {

apps/browser/src/vault/popup/services/vault-popup-scroll-position.service.ts

@@ -18,6 +18,9 @@ export class VaultPopupScrollPositionService {
   /** Subscription associated with the virtual scroll element. */
   private scrollSubscription: Subscription | null = null;
 
+  /** When true, the next call to `start()` will force scroll position back to the top. */
+  private forceTopOnNextStart = false;
+
   constructor() {
     this.router.events
       .pipe(
@@ -31,8 +34,22 @@ export class VaultPopupScrollPositionService {
 
   /** Scrolls the user to the stored scroll position and starts tracking scroll of the page. */
   start(scrollElement: HTMLElement) {
-    if (this.hasScrollPosition()) {
-      // Use `setTimeout` to scroll after rendering is complete
+    // Use `setTimeout` to scroll after rendering is complete.
+    // Firefox can sometimes restore scroll position on history navigation (back/forward)
+    // after our initial scroll call. When we explicitly want to reset to the top (e.g. after
+    // deleting an item), we schedule an extra follow-up scroll to ensure the final position is 0.
+    if (this.forceTopOnNextStart) {
+      this.forceTopOnNextStart = false;
+      this.scrollPosition = 0;
+      // try to set scroll to top immediately
+      setTimeout(() => {
+        scrollElement.scrollTo({ top: 0, behavior: "instant" });
+      }, 0);
+      // wait for FF to possibly restore scroll position after UI settles, then enforce top=0
+      setTimeout(() => {
+        scrollElement.scrollTo({ top: 0, behavior: "instant" });
+      }, 250);
+    } else if (this.hasScrollPosition()) {
       setTimeout(() => {
         scrollElement.scrollTo({ top: this.scrollPosition!, behavior: "instant" });
       });
@@ -66,6 +83,14 @@ export class VaultPopupScrollPositionService {
     return this.scrollPosition !== null;
   }
 
+  /**
+   * Forces the next vault list render to start at scroll position 0.
+   * Useful for flows where we don't want browser back/forward scroll restoration (e.g. after delete).
+   */
+  forceTopOnNextVaultStart() {
+    this.forceTopOnNextStart = true;
+  }
+
   /** Conditionally resets the scroll listeners based on the ending path of the navigation */
   private resetListenerForNavigation(event: NavigationEnd): void {
     // The vault page is the target of the scroll listener, return early