diff --git a/src/apps/settings/WallpaperSection.test.tsx b/src/apps/settings/WallpaperSection.test.tsx
index 7f540af..5ed0afc 100644
--- a/src/apps/settings/WallpaperSection.test.tsx
+++ b/src/apps/settings/WallpaperSection.test.tsx
@@ -1,4 +1,4 @@
-import { beforeEach, describe, expect, it } from 'vitest';
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
 import { fireEvent, render, screen, waitFor } from '@testing-library/react';
 import { TestApp } from '@/test/TestApp';
 import { WallpaperSection } from './index';
@@ -13,9 +13,45 @@ class StubResizeObserver {
   disconnect() {}
 }
 
+// A controllable stand-in for the browser's `Image` constructor, mirroring
+// the one in useDecodedImage.test.ts, so a preview can be resolved on demand.
+class FakeImage {
+  decoding = '';
+  src = '';
+  naturalWidth = 40;
+  naturalHeight = 30;
+  private resolveDecode!: () => void;
+  readonly decodePromise = new Promise<void>((resolve) => {
+    this.resolveDecode = resolve;
+  });
+
+  constructor() {
+    instances.push(this);
+  }
+
+  decode() {
+    return this.decodePromise;
+  }
+
+  finish() {
+    this.resolveDecode();
+  }
+}
+
+let instances: FakeImage[] = [];
+
 describe('WallpaperSection', () => {
+  let originalImage: typeof Image;
+
   beforeEach(() => {
     global.ResizeObserver = StubResizeObserver as unknown as typeof ResizeObserver;
+    instances = [];
+    originalImage = globalThis.Image;
+    globalThis.Image = FakeImage as unknown as typeof Image;
+  });
+
+  afterEach(() => {
+    globalThis.Image = originalImage;
   });
 
   it('shows the dot-grid curated wallpaper selected by default', async () => {
@@ -52,4 +88,24 @@ describe('WallpaperSection', () => {
     expect(saveButton).toBeDisabled();
     expect(screen.queryByAltText('Wallpaper preview')).not.toBeInTheDocument();
   });
+
+  it('previews and saves a valid https custom URL, switching off the curated selection', async () => {
+    render(<WallpaperSection />, { wrapper: TestApp });
+
+    const urlInput = await screen.findByLabelText('Custom image');
+    fireEvent.change(urlInput, { target: { value: 'https://example.com/wallpaper.jpg' } });
+    fireEvent.click(screen.getByRole('button', { name: 'Preview' }));
+
+    await waitFor(() => expect(instances).toHaveLength(1));
+    instances[0].finish();
+
+    const previewImg = await screen.findByAltText('Wallpaper preview');
+    expect(previewImg).toHaveAttribute('src', 'https://example.com/wallpaper.jpg');
+
+    const saveButton = screen.getByRole('button', { name: 'Save wallpaper' });
+    await waitFor(() => expect(saveButton).not.toBeDisabled());
+    fireEvent.click(saveButton);
+
+    await waitFor(() => expect(screen.getByRole('radio', { name: 'Dot grid' })).not.toBeChecked());
+  });
 });
diff --git a/src/apps/settings/index.tsx b/src/apps/settings/index.tsx
index fc0f9d1..1b5b643 100644
--- a/src/apps/settings/index.tsx
+++ b/src/apps/settings/index.tsx
@@ -179,6 +179,22 @@ export function WallpaperSection() {
   const [pendingPreviewUrl, setPendingPreviewUrl] = useState<string | undefined>(undefined);
   const preview = useDecodedImage(pendingPreviewUrl);
 
+  // Keep the draft/presentation fields in sync if the saved selection changes
+  // from elsewhere (e.g. the desktop context menu's curated shortcut, or
+  // another open Settings window), so this form never shows a stale value.
+  // Adjusted during render (mirroring useLocalStorage's "key changed" reset
+  // pattern) rather than in a useEffect, since setState synchronously at the
+  // top of an effect body is flagged by react-hooks/set-state-in-effect.
+  const [trackedSelection, setTrackedSelection] = useState(selection);
+  if (trackedSelection !== selection) {
+    setTrackedSelection(selection);
+    setUrlDraft(selection.source === 'url' ? selection.url : '');
+    setFit(selection.source === 'url' ? selection.presentation.fit : 'cover');
+    setDim(selection.source === 'url' ? selection.presentation.dim : 0);
+    setPendingPreviewUrl(undefined);
+  }
+
+
   const applyCurated = (id: string) => {
     updateConfig((current) => ({ ...current, wallpaper: { version: 1, selection: { source: 'curated', id } } }));
     setPendingPreviewUrl(undefined);
@@ -269,7 +285,7 @@ export function WallpaperSection() {
       description="Personalize the desktop background. Curated patterns recolor with your theme and never leave the device; a custom image is saved only in this browser."
     >
       <RadioGroup
-        value={selection.source === 'curated' ? selection.id : undefined}
+        value={selection.source === 'curated' ? selection.id : ''}
         onValueChange={applyCurated}
         aria-label="Curated wallpapers"
         className="grid grid-cols-2 gap-3 sm:grid-cols-3"