fix(api,frontend): render files by name without fetching, previewable share links

frontend/src/lib/api/media.ts

@@ -21,9 +21,11 @@ export type InlineMedia =
 export interface ViewerItem {
   downloaded: boolean;
   fileName: string | null;
+  fileSize: number | null;
   kind: string;
   mediaId: number | null;
   messageId: number;
+  mime: string | null;
 }
 
 export function viewerItemsFrom(
@@ -32,7 +34,15 @@ export function viewerItemsFrom(
 ): ViewerItem[] {
   if (media.length === 0) {
     return [
-      { messageId, mediaId: null, kind: "", downloaded: false, fileName: null },
+      {
+        messageId,
+        mediaId: null,
+        kind: "",
+        downloaded: false,
+        fileName: null,
+        fileSize: null,
+        mime: null,
+      },
     ];
   }
   return media.map((item) => ({
@@ -41,9 +51,31 @@ export function viewerItemsFrom(
     kind: item.kind,
     downloaded: item.downloaded,
     fileName: item.file_name,
+    fileSize: item.file_size,
+    mime: item.mime,
   }));
 }
 
+const PREVIEW_KINDS = new Set([
+  "photo",
+  "video",
+  "video_note",
+  "animation",
+  "gif",
+  "sticker",
+  "voice",
+  "audio",
+]);
+
+const PREVIEW_MIME_PREFIXES = ["image/", "video/", "audio/"];
+
+export function isPreviewable(kind: string, mime: string | null): boolean {
+  if (PREVIEW_KINDS.has(kind)) {
+    return true;
+  }
+  return PREVIEW_MIME_PREFIXES.some((prefix) => mime?.startsWith(prefix));
+}
+
 export type VisualKind = "image" | "video" | "other";
 
 const VIDEO_KINDS = new Set(["video", "video_note", "animation", "gif"]);