revert(admin): remove MediaThumbnailCell — crashes admin list view

src/collections/Media.ts

@@ -43,17 +43,5 @@ export const Media: CollectionConfig = {
     update: isAdminOrEditor,
     delete: isAdminOrEditor,
   },
-  fields: [
-    {
-      name: 'alt',
-      type: 'text',
-      required: true,
-      label: 'Alt text',
-      admin: {
-        components: {
-          Cell: '@/components/admin/MediaThumbnailCell',
-        },
-      },
-    },
-  ],
+  fields: [{ name: 'alt', type: 'text', required: true, label: 'Alt text' }],
 }

src/components/admin/MediaThumbnailCell.tsx

@@ -2,22 +2,37 @@
 
 interface Props {
   cellData?: string
-  rowData?: Record<string, unknown>
+  // Payload v3 passes the full document as rowData
+  rowData?: {
+    url?: string
+    filename?: string
+    mimeType?: string
+    alt?: string
+    sizes?: { tablet?: { url?: string }; mobile?: { url?: string } }
+    [key: string]: unknown
+  }
 }
 
 export default function MediaThumbnailCell({ cellData, rowData }: Props) {
-  const url = (rowData as { url?: string })?.url
+  const text = cellData ?? rowData?.alt ?? ''
+  const imgUrl =
+    rowData?.sizes?.tablet?.url ??
+    rowData?.sizes?.mobile?.url ??
+    rowData?.url ??
+    (rowData?.filename ? `/api/media/file/${rowData.filename}` : undefined)
+  const isImage = rowData?.mimeType?.startsWith('image/') ?? !!imgUrl
+
   return (
     <div style={{ display: 'flex', alignItems: 'center', gap: 8 }}>
-      {url && (
+      {imgUrl && isImage && (
         // eslint-disable-next-line @next/next/no-img-element
         <img
-          src={url}
+          src={imgUrl}
           alt=""
           style={{ width: 40, height: 40, objectFit: 'cover', borderRadius: 4, flexShrink: 0 }}
         />
       )}
-      <span>{cellData}</span>
+      <span>{text}</span>
     </div>
   )
 }