feat(F-059): completed feature

project/apps/admin/src/app/api/upload/route.ts

@@ -16,6 +16,14 @@ const PEER_UPLOAD_DIRS = [
 
 /** Thumbnail widths pre-generated for lists (40px) and previews (200px). */
 const THUMBNAIL_WIDTHS = [40, 200];
+/**
+ * Maximum height ratio (h/w) for cached thumbnails. The thumbnail is scaled
+ * to fit inside a `width × width * MAX_HEIGHT_RATIO` bounding box without
+ * cropping. A non-square source produces a non-square thumbnail that preserves
+ * the original aspect ratio, so the frontend can render it with
+ * `object-contain` inside a matching box.
+ */
+const MAX_HEIGHT_RATIO = 1.4;
 
 async function mirrorToPeers(filePath: string): Promise<void> {
   await Promise.allSettled(
@@ -47,7 +55,10 @@ async function generateThumbnails(buffer: Buffer, filename: string): Promise<voi
       THUMBNAIL_WIDTHS.map(async (width) => {
         const thumbDir = path.join(dir, String(width));
         await mkdir(thumbDir, { recursive: true });
-        const resized = await sharp(buffer).resize({ width, withoutEnlargement: true }).toBuffer();
+        const maxHeight = Math.round(width * MAX_HEIGHT_RATIO);
+        const resized = await sharp(buffer)
+          .resize({ width, height: maxHeight, fit: 'inside', withoutEnlargement: true })
+          .toBuffer();
         await writeFile(path.join(thumbDir, filename), resized);
       }),
     ),