feat(profile): preserve animation on GIF/APNG/animated-WebP avatar uploads

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/desktop/src/lib/avatarUpload.ts

@@ -43,19 +43,86 @@ async function resizeToSquare(file: File): Promise<Blob> {
   }
 }
 
+const MAX_ANIMATED_BYTES = 2 * 1024 * 1024; // 2 MB hard cap on animated uploads
+const ANIMATED_MIMES = new Set(['image/gif', 'image/apng', 'image/webp', 'image/png']);
+
 export async function uploadAvatar(userId: string, file: File): Promise<string> {
   if (!file.type.startsWith('image/')) {
     throw new Error('only image files are accepted');
   }
+  // Animated formats bypass the canvas re-encode (which would strip
+  // animation by sampling the first frame). We still validate dimensions
+  // and size so a 40-MB animated WebP can't slip through.
+  if (ANIMATED_MIMES.has(file.type) && (await isAnimated(file))) {
+    if (file.size > MAX_ANIMATED_BYTES) {
+      throw new Error('animated avatar too large (max 2 MB)');
+    }
+    const dims = await readDimensions(file);
+    if (dims.width > MAX_DIM || dims.height > MAX_DIM) {
+      throw new Error('animated avatar exceeds ' + MAX_DIM + 'px (got ' + dims.width + 'x' + dims.height + ')');
+    }
+    return uploadAvatarBlob(userId, file);
+  }
   const blob = await resizeToSquare(file);
   return uploadAvatarBlob(userId, blob);
 }
 
+async function readDimensions(file: File): Promise<{ width: number; height: number }> {
+  const url = URL.createObjectURL(file);
+  try {
+    const img = await new Promise<HTMLImageElement>((resolve, reject) => {
+      const i = new Image();
+      i.onload = () => resolve(i);
+      i.onerror = () => reject(new Error('image load failed'));
+      i.src = url;
+    });
+    return { width: img.naturalWidth, height: img.naturalHeight };
+  } finally {
+    URL.revokeObjectURL(url);
+  }
+}
+
+async function isAnimated(file: File): Promise<boolean> {
+  // GIF: any GIF89a/GIF87a header is treated as potentially animated. The
+  // static-GIF case (one image-descriptor block) is rare enough that
+  // re-encoding wouldn't save much, so we accept the false-positives.
+  if (file.type === 'image/gif') return true;
+  // APNG: presence of an 'acTL' chunk inside the PNG stream. Scan the
+  // first 64 KB — APNGs put acTL near the front, before IDAT.
+  if (file.type === 'image/apng' || file.type === 'image/png') {
+    const head = await file.slice(0, 65536).arrayBuffer();
+    return containsBytes(head, [0x61, 0x63, 0x54, 0x4c]); // 'acTL'
+  }
+  // Animated WebP: 'ANIM' chunk in the RIFF container.
+  if (file.type === 'image/webp') {
+    const head = await file.slice(0, 65536).arrayBuffer();
+    return containsBytes(head, [0x41, 0x4e, 0x49, 0x4d]); // 'ANIM'
+  }
+  return false;
+}
+
+function containsBytes(buf: ArrayBuffer, needle: number[]): boolean {
+  const view = new Uint8Array(buf);
+  const len = view.length;
+  const nlen = needle.length;
+  outer: for (let i = 0; i + nlen <= len; i++) {
+    for (let j = 0; j < nlen; j++) {
+      if (view[i + j] !== needle[j]) continue outer;
+    }
+    return true;
+  }
+  return false;
+}
+
 // Upload an already-cropped Blob (e.g. from ImageCropDialog) without going
 // through the legacy center-crop. Caller is responsible for sizing — the
 // dialog already clamps to MAX_DIM via its outputWidth.
 export async function uploadAvatarBlob(userId: string, blob: Blob): Promise<string> {
-  const ext = blob.type === 'image/webp' ? 'webp' : 'jpg';
+  const ext =
+    blob.type === 'image/webp' ? 'webp' :
+    blob.type === 'image/gif' ? 'gif' :
+    blob.type === 'image/apng' || blob.type === 'image/png' ? 'png' :
+    'jpg';
   // Random filename so old uploads don't get overwritten before we update
   // the profile row — Supabase Storage CDN caches by URL, so a fresh path
   // also forces clients to fetch the new image.