diff --git a/e2e/tests/note/detail-fullscreen-note-resize.spec.ts b/e2e/tests/note/detail-fullscreen-note-resize.spec.ts
index ae13447fb1..321b96b731 100644
--- a/e2e/tests/note/detail-fullscreen-note-resize.spec.ts
+++ b/e2e/tests/note/detail-fullscreen-note-resize.spec.ts
@@ -32,8 +32,11 @@ test.describe('Detail panel fullscreen note - resize', () => {
     await expect(detailPanel).toBeVisible();
 
     // Open the fullscreen markdown editor from the notes inline-markdown.
-    await detailPanel
-      .locator('inline-markdown button')
+    // The controls are opacity:0 until the notes area is hovered.
+    const noteMarkdown = detailPanel.locator('inline-markdown').first();
+    await noteMarkdown.hover();
+    await noteMarkdown
+      .locator('button')
       .filter({ has: page.locator('mat-icon', { hasText: 'fullscreen' }) })
       .first()
       .click();
diff --git a/src/app/ui/inline-markdown/inline-markdown.component.spec.ts b/src/app/ui/inline-markdown/inline-markdown.component.spec.ts
index 1e7206d5bf..c6afe88c45 100644
--- a/src/app/ui/inline-markdown/inline-markdown.component.spec.ts
+++ b/src/app/ui/inline-markdown/inline-markdown.component.spec.ts
@@ -1,5 +1,5 @@
 import { ComponentFixture, fakeAsync, TestBed, tick } from '@angular/core/testing';
-import { MatDialog } from '@angular/material/dialog';
+import { MatDialog, MatDialogState } from '@angular/material/dialog';
 import { MarkdownModule } from 'ngx-markdown';
 import { NoopAnimationsModule } from '@angular/platform-browser/animations';
 import { InlineMarkdownComponent } from './inline-markdown.component';
@@ -1867,15 +1867,18 @@ describe('InlineMarkdownComponent', () => {
 
   describe('fullscreen editor save-and-close on navigation (#8434)', () => {
     let afterClosed$: Subject<unknown>;
+    let store: MockStore;
     let closeSpy: jasmine.Spy;
     let unsubscribeSpy: jasmine.Spy;
     let locationCb: ((value: PopStateEvent) => void) | undefined;
+    let dialogState: MatDialogState;
 
     beforeEach(() => {
       afterClosed$ = new Subject<unknown>();
       closeSpy = jasmine.createSpy('close');
       unsubscribeSpy = jasmine.createSpy('unsubscribe');
       locationCb = undefined;
+      dialogState = MatDialogState.OPEN;
 
       // Capture the Location listener so a "navigation" can be simulated.
       const location = TestBed.inject(Location);
@@ -1887,11 +1890,16 @@ describe('InlineMarkdownComponent', () => {
       mockMatDialog.open.and.returnValue({
         afterClosed: () => afterClosed$.asObservable(),
         componentInstance: { close: closeSpy },
+        getState: () => dialogState,
       } as never);
+      store = TestBed.inject(MockStore);
+      spyOn(store, 'dispatch');
       fixture.componentRef.setInput('taskId', 'task-1');
       fixture.detectChanges();
     });
 
+    const navigate = (): void => locationCb!({} as PopStateEvent);
+
     // The default closeOnNavigation disposes the overlay with no result on a
     // navigation, dropping the edit (#8434); we must opt out so we can close it
     // through the save path instead.
@@ -1909,11 +1917,52 @@ describe('InlineMarkdownComponent', () => {
       component.openFullScreen();
       expect(closeSpy).not.toHaveBeenCalled();
 
-      locationCb!({} as PopStateEvent);
+      navigate();
 
       expect(closeSpy).toHaveBeenCalledTimes(1);
     });
 
+    // A breakpoint-crossing resize can emit more than one popstate; the second
+    // must not re-trigger close() and re-run the dialog's exit animation.
+    it('does not close again once the dialog is already closing', () => {
+      component.openFullScreen();
+      navigate();
+      dialogState = MatDialogState.CLOSING;
+
+      navigate();
+
+      expect(closeSpy).toHaveBeenCalledTimes(1);
+    });
+
+    // The point of #8434: a navigation-close must PERSIST the edit, not just
+    // close. When still alive the note routes out via `changed`.
+    it('persists the edit via `changed` when a navigation closes the dialog', () => {
+      spyOn(component.changed, 'emit');
+      component.openFullScreen();
+
+      navigate();
+      // The dialog resolves through its save path with the typed content.
+      afterClosed$.next('typed before resize');
+
+      expect(component.changed.emit).toHaveBeenCalledWith('typed before resize');
+    });
+
+    // The production scenario: the breakpoint switch destroys this host while
+    // the editor is open, so the save must land via the direct dispatch (#8432).
+    it('persists directly when a navigation closes the dialog after host destroy', () => {
+      component.openFullScreen();
+      component.ngOnDestroy();
+
+      navigate();
+      afterClosed$.next('typed before resize');
+
+      expect(store.dispatch).toHaveBeenCalledWith(
+        TaskSharedActions.updateTask({
+          task: { id: 'task-1', changes: { notes: 'typed before resize' } },
+        }),
+      );
+    });
+
     it('stops listening for navigations once the dialog has closed', () => {
       component.openFullScreen();
 
diff --git a/src/app/ui/inline-markdown/inline-markdown.component.ts b/src/app/ui/inline-markdown/inline-markdown.component.ts
index d8700737fe..edfc24fc63 100644
--- a/src/app/ui/inline-markdown/inline-markdown.component.ts
+++ b/src/app/ui/inline-markdown/inline-markdown.component.ts
@@ -17,7 +17,7 @@ import {
 } from '@angular/core';
 import { FormsModule } from '@angular/forms';
 import { MatIconButton } from '@angular/material/button';
-import { MatDialog } from '@angular/material/dialog';
+import { MatDialog, MatDialogState } from '@angular/material/dialog';
 import { MatIcon } from '@angular/material/icon';
 import { MatMenu, MatMenuItem, MatMenuTrigger } from '@angular/material/menu';
 import { MatTooltip } from '@angular/material/tooltip';
@@ -382,18 +382,19 @@ export class InlineMarkdownComponent implements OnInit, OnDestroy {
       },
     });
 
-    // Reinstate close-on-navigation as a save-and-close. closeOnNavigation
-    // (above) is the overlay's `disposeOnNavigation`, which on a Location
-    // change (popstate/hashchange) DISPOSES the overlay with no result —
-    // dropping the edit. We listen to the same Location signal but close
-    // through the dialog's save path, so an Android back-button press or the
-    // involuntary navigation a breakpoint-crossing resize triggers persists
-    // the note instead of losing it. Not tied to takeUntilDestroyed so it
-    // still fires after a breakpoint switch destroys this host mid-edit; torn
-    // down in the afterClosed handler below.
-    const locationSub = this._location.subscribe(() =>
-      dialogRef.componentInstance?.close(),
-    );
+    // Reinstate close-on-navigation as a save-and-close: listen to the same
+    // Location signal closeOnNavigation uses, but route through the dialog's
+    // save path so an Android back-button press or the breakpoint-crossing
+    // resize above persists the note instead of dropping it. Not tied to
+    // takeUntilDestroyed so it still fires after a breakpoint switch destroys
+    // this host mid-edit; torn down in the afterClosed handler below.
+    const locationSub = this._location.subscribe(() => {
+      // A breakpoint-crossing resize can emit more than one popstate; only act
+      // while the dialog is still open so we don't re-run its exit animation.
+      if (dialogRef.getState() === MatDialogState.OPEN) {
+        dialogRef.componentInstance?.close();
+      }
+    });
 
     // Intentionally NOT torn down with takeUntilDestroyed: this MUST still fire
     // after the component is destroyed — see the `_isDestroyed` branch below.