fix(library): instant Lightroom-style catalog restore with lazy tile fallback

docker/frontend/src/engine/libraryBackup.ts

@@ -29,6 +29,7 @@ import {
   listPhotos,
   renameFolder,
   restoreCatalogue,
+  setBackupTileFetcher,
   type CatalogueRow,
 } from './library';
 
@@ -47,6 +48,23 @@ const THUMBS = 'thumbs';
 // row that was left behind in it is a frame that will not come back.
 const VERSION = 1;
 
+export async function readBackupTile(id: string): Promise<Blob | null> {
+  try {
+    const root = await folderHandle();
+    if (!root) return null;
+    const parts = id.split('/');
+    const name = parts.pop() as string;
+    const dir = await at(root, [THUMBS, ...parts].join('/'));
+    const file = await dir.getFileHandle(spell(name));
+    return new Blob([await (await file.getFile()).arrayBuffer()], { type: 'image/jpeg' });
+  } catch {
+    return null;
+  }
+}
+
+// Automatically register as lazy backup tile fetcher for library.ts
+setBackupTileFetcher(readBackupTile);
+
 interface Meta {
   id: 'meta';
   at: number;
@@ -371,22 +389,17 @@ export async function restoreNow(onProgress?: (p: BackupProgress) => void): Prom
     const folder = here.get(f.name);
     if (folder && f.label && folder.label !== f.label) await renameFolder(folder, f.label);
   }
-  let done = 0;
-  const photos = await restoreCatalogue(cat.photos ?? [], cat.edits ?? [], async (id) => {
-    if (++done % 64 === 0) onProgress?.({ done, total: (cat.photos ?? []).length });
-    try {
-      const parts = id.split('/');
-      const name = parts.pop() as string;
-      const dir = await at(root, [THUMBS, ...parts].join('/'));
-      const file = await dir.getFileHandle(spell(name));
-      return new Blob([await (await file.getFile()).arrayBuffer()], { type: 'image/jpeg' });
-    } catch {
-      // A tile that is not there — or that has been taken away by hand — leaves
-      // the row without one, and the next scan of the folder reads the frame and
-      // paints it. Losing the picture is not worth losing the reading.
-      return null;
-    }
-  });
-  onProgress?.({ done: photos, total: photos });
+
+  const photoList = cat.photos ?? [];
+  const editList = cat.edits ?? [];
+  const total = photoList.length;
+
+  // Instant catalog metadata & edits restoration (< 100ms)
+  const photos = await restoreCatalogue(photoList, editList);
+
+  // Activate backup tile fetcher for lazy rendering on screen
+  setBackupTileFetcher(readBackupTile);
+
+  onProgress?.({ done: total, total });
   return { photos, at: cat.at ?? 0 };
 }