diff --git a/src/app/app.routes.ts b/src/app/app.routes.ts
index e154ed5..4c6ae9b 100644
--- a/src/app/app.routes.ts
+++ b/src/app/app.routes.ts
@@ -1,5 +1,6 @@
 import { Routes } from '@angular/router';
 import { languageGuard } from './guards/language.guard';
+import { projectEditorDirtyGuard } from './features/project-editor/guards/project-editor-dirty.guard';
 import { environment } from '../environments/environment';
 
 // Core routes (same across all brands)
@@ -41,7 +42,8 @@ const coreRoutes: Routes = [
   },
   {
     path: 'edit/:section',
-    loadComponent: () => import('./features/project-editor/pages/project-editor-page.component').then(m => m.ProjectEditorPageComponent)
+    loadComponent: () => import('./features/project-editor/pages/project-editor-page.component').then(m => m.ProjectEditorPageComponent),
+    canDeactivate: [projectEditorDirtyGuard]
   },
   {
     path: 'edit',
diff --git a/src/app/features/project-editor/guards/project-editor-dirty.guard.ts b/src/app/features/project-editor/guards/project-editor-dirty.guard.ts
new file mode 100644
index 0000000..eacee89
--- /dev/null
+++ b/src/app/features/project-editor/guards/project-editor-dirty.guard.ts
@@ -0,0 +1,12 @@
+import { inject } from '@angular/core';
+import { CanDeactivateFn } from '@angular/router';
+import { ProjectEditorFacade } from '../facade/project-editor.facade';
+import { ProjectEditorPageComponent } from '../pages/project-editor-page.component';
+
+export const projectEditorDirtyGuard: CanDeactivateFn<ProjectEditorPageComponent> = () => {
+  const facade = inject(ProjectEditorFacade);
+  if (!facade.dirty()) {
+    return true;
+  }
+  return window.confirm('You have unsaved changes. Leave anyway?');
+};
diff --git a/src/app/features/project-editor/pages/project-editor-page.component.ts b/src/app/features/project-editor/pages/project-editor-page.component.ts
index 3dbb9a7..31e54a7 100644
--- a/src/app/features/project-editor/pages/project-editor-page.component.ts
+++ b/src/app/features/project-editor/pages/project-editor-page.component.ts
@@ -1,4 +1,4 @@
-import { ChangeDetectionStrategy, Component, effect, inject } from '@angular/core';
+import { ChangeDetectionStrategy, Component, HostListener, effect, inject } from '@angular/core';
 import { ActivatedRoute } from '@angular/router';
 import { toSignal } from '@angular/core/rxjs-interop';
 import { map } from 'rxjs/operators';
@@ -68,4 +68,12 @@ export class ProjectEditorPageComponent {
       }
     });
   }
+
+  @HostListener('window:beforeunload', ['$event'])
+  warnBeforeUnload(event: BeforeUnloadEvent): void {
+    if (this.facade.dirty()) {
+      event.preventDefault();
+      event.returnValue = '';
+    }
+  }
 }