diff --git a/src/apps/settings/index.tsx b/src/apps/settings/index.tsx
index 8d47758..668a699 100644
--- a/src/apps/settings/index.tsx
+++ b/src/apps/settings/index.tsx
@@ -164,7 +164,9 @@ function AppearanceSection() {
 
 const MAX_WALLPAPER_FILE_BYTES = 5 * 1024 * 1024;
 const MAX_WALLPAPER_DIMENSION = 6000;
-const ALLOWED_WALLPAPER_TYPES = new Set(['image/jpeg', 'image/png', 'image/webp', 'image/gif']);
+// GIFs are excluded: the upload path always re-encodes to JPEG, which would
+// silently drop animation/transparency, so we don't advertise GIF support.
+const ALLOWED_WALLPAPER_TYPES = new Set(['image/jpeg', 'image/png', 'image/webp']);
 
 export function WallpaperSection() {
   const { config, updateConfig } = useAppContext();
@@ -237,7 +239,7 @@ export function WallpaperSection() {
     if (!file) return;
 
     if (!ALLOWED_WALLPAPER_TYPES.has(file.type)) {
-      toast({ title: 'Unsupported image type', description: 'Use JPEG, PNG, WebP, or GIF.', variant: 'destructive' });
+      toast({ title: 'Unsupported image type', description: 'Use JPEG, PNG, or WebP.', variant: 'destructive' });
       return;
     }
     if (file.size > MAX_WALLPAPER_FILE_BYTES) {
@@ -264,7 +266,10 @@ export function WallpaperSection() {
       canvas.width = bitmap.width;
       canvas.height = bitmap.height;
       const ctx = canvas.getContext('2d');
-      if (!ctx) throw new Error('This browser cannot process images.');
+      if (!ctx) {
+        bitmap.close();
+        throw new Error('This browser cannot process images.');
+      }
       ctx.drawImage(bitmap, 0, 0);
       bitmap.close();
 
@@ -355,7 +360,7 @@ export function WallpaperSection() {
           <input
             ref={fileInputRef}
             type="file"
-            accept="image/png,image/jpeg,image/webp,image/gif"
+            accept="image/png,image/jpeg,image/webp"
             className="sr-only"
             aria-label="Upload a local image to use as wallpaper"
             onChange={(event) => { void onFileSelected(event.target.files?.[0]); }}
@@ -382,6 +387,7 @@ export function WallpaperSection() {
             <img
               src={preview.url}
               alt="Wallpaper preview"
+              referrerPolicy="no-referrer"
               className={cn(
                 'h-24 w-full rounded-md border border-border bg-muted',
                 fit === 'contain' ? 'object-contain' : 'object-cover',
diff --git a/src/components/os/Desktop.tsx b/src/components/os/Desktop.tsx
index 0b05d47..76f2a5e 100644
--- a/src/components/os/Desktop.tsx
+++ b/src/components/os/Desktop.tsx
@@ -20,7 +20,7 @@ import { swapDesktopSlots, type DesktopSlot, type GridGeometry } from '@/os/icon
 import { useIconLayout } from '@/os/useIconLayout';
 import { useAppContext } from '@/hooks/useAppContext';
 import { useDecodedImage } from '@/hooks/useDecodedImage';
-import { CURATED_WALLPAPERS, DEFAULT_CURATED_ID, isSafeWallpaperUrl, resolveCurated } from '@/lib/wallpaper';
+import { CURATED_WALLPAPERS, DEFAULT_CURATED_ID, DEFAULT_PRESENTATION, isSafeWallpaperUrl, resolveCurated } from '@/lib/wallpaper';
 import { sanitizeUrl } from '@/lib/nostrUtils';
 import { cn } from '@/lib/utils';
 
@@ -73,6 +73,31 @@ export function Desktop() {
     customWallpaper && sanitizedWallpaperUrl && isSafeWallpaperUrl(sanitizedWallpaperUrl) ? sanitizedWallpaperUrl : undefined;
   const curatedId = wallpaper.source === 'curated' ? wallpaper.id : undefined;
 
+  // `decoded.url` can lag behind `customWallpaper` (a newer selection is
+  // still decoding, or failed) while the previous image keeps rendering. If
+  // we read `customWallpaper.presentation` directly in that window, a fit/dim
+  // change meant for the *new* (not-yet-visible) image would briefly apply to
+  // the still-displayed old one. This tracks (by reference, mirroring the
+  // `trackedSelection` pattern in the Settings wallpaper form) the
+  // presentation that belongs to whichever url is actually decoded, adjusted
+  // during render rather than in a useEffect body.
+  //
+  // This intentionally follows React's "adjusting state during render"
+  // pattern and relies on reference equality: `activePresentation` must keep
+  // returning the *same* `customWallpaper.presentation` object across
+  // re-renders until the selection actually changes (it does today, because
+  // it's read straight from `config` rather than freshly constructed here).
+  // Don't refactor it into a `useMemo`/derived value that produces a new
+  // object identity every render — that would break the `!==` check below
+  // and re-run `setRenderedPresentation` on every render.
+  const activePresentation = customWallpaper && decoded.url === customWallpaper.url ? customWallpaper.presentation : undefined;
+  const [trackedPresentation, setTrackedPresentation] = useState(activePresentation);
+  const [renderedPresentation, setRenderedPresentation] = useState(activePresentation ?? DEFAULT_PRESENTATION);
+  if (activePresentation !== trackedPresentation) {
+    setTrackedPresentation(activePresentation);
+    if (activePresentation) setRenderedPresentation(activePresentation);
+  }
+
   const setCuratedWallpaper = useCallback((id: string) => {
     updateConfig((current) => ({ ...current, wallpaper: { version: 1, selection: { source: 'curated', id } } }));
   }, [updateConfig]);
@@ -179,15 +204,16 @@ export function Desktop() {
                 src={safeWallpaperImageUrl}
                 alt=""
                 aria-hidden="true"
+                referrerPolicy="no-referrer"
                 className={cn(
                   'pointer-events-none absolute inset-0 h-full w-full',
-                  customWallpaper.presentation.fit === 'contain' ? 'object-contain' : 'object-cover',
+                  renderedPresentation.fit === 'contain' ? 'object-contain' : 'object-cover',
                 )}
               />
-              {customWallpaper.presentation.dim > 0 && (
+              {renderedPresentation.dim > 0 && (
                 <div
                   className="pointer-events-none absolute inset-0 bg-black"
-                  style={{ opacity: customWallpaper.presentation.dim / 100 }}
+                  style={{ opacity: renderedPresentation.dim / 100 }}
                   aria-hidden="true"
                 />
               )}
diff --git a/src/lib/wallpaper.test.ts b/src/lib/wallpaper.test.ts
index ac1d500..cc22816 100644
--- a/src/lib/wallpaper.test.ts
+++ b/src/lib/wallpaper.test.ts
@@ -69,6 +69,11 @@ describe('WallpaperPreferenceSchema', () => {
     expect(WallpaperPreferenceSchema.parse('not an object')).toEqual(DEFAULT_WALLPAPER);
   });
 
+  it('falls back to the default wallpaper for an unknown/stale curated id', () => {
+    const value = { version: 1, selection: { source: 'curated', id: 'some-removed-id' } };
+    expect(WallpaperPreferenceSchema.parse(value)).toEqual(DEFAULT_WALLPAPER);
+  });
+
   it('falls back to the default wallpaper for an out-of-range dim value', () => {
     const value = {
       version: 1,
diff --git a/src/lib/wallpaper.ts b/src/lib/wallpaper.ts
index 3f286ec..01ed9d2 100644
--- a/src/lib/wallpaper.ts
+++ b/src/lib/wallpaper.ts
@@ -67,7 +67,11 @@ export const DEFAULT_WALLPAPER: WallpaperPreference = {
 
 /** Looks up a curated wallpaper by id, falling back to the default pattern for unknown/stale ids. */
 export function resolveCurated(id: string): CuratedWallpaper {
-  return CURATED_WALLPAPERS.find((wallpaper) => wallpaper.id === id) ?? CURATED_WALLPAPERS[0];
+  return (
+    CURATED_WALLPAPERS.find((wallpaper) => wallpaper.id === id) ??
+    CURATED_WALLPAPERS.find((wallpaper) => wallpaper.id === DEFAULT_CURATED_ID) ??
+    CURATED_WALLPAPERS[0]
+  );
 }
 
 /**
@@ -98,9 +102,11 @@ const WallpaperPresentationSchema = z.object({
   dim: z.number().min(0).max(80),
 }) satisfies z.ZodType<WallpaperPresentation>;
 
+const curatedIds = CURATED_WALLPAPERS.map((wallpaper) => wallpaper.id) as [string, ...string[]];
+
 const CuratedSelectionSchema = z.object({
   source: z.literal('curated'),
-  id: z.string().min(1).max(64),
+  id: z.enum(curatedIds),
 });
 
 const UrlSelectionSchema = z.object({