fix(immich): prune a read node against every frame the reading met

docker/frontend/src/engine/immich.ts

@@ -326,7 +326,13 @@ export async function syncImmich(
   const chosen = folder.albums ?? [];
   const root = normPath(folder.name);
 
-  const rows: LibraryPhoto[] = [];
+  // Every row this reading met, spelled the way `prunePhotos` spells one. It is
+  // the whole reading that is written down here — the foreground's pages and the
+  // pages behind them — because a node bigger than one visit is read in two
+  // passes, and a prune held against the first pass alone takes back every frame
+  // the second one filed: the node the reader is left with is the newest three
+  // pages of it, for good, and its place says the reading is done.
+  const met = new Set<string>();
   const dirs: LibraryDir[] = [];
   const counts: Record<string, number> = {};
   // The frames this reading has already filed. The keyset read stops on a frame's
@@ -411,7 +417,7 @@ export async function syncImmich(
         size: item.size ?? 0,
         addedAt: Date.now(),
       };
-      rows.push(row);
+      met.add(name.toLowerCase());
       batchRows.push(row);
       rootCount++;
     }
@@ -475,7 +481,7 @@ export async function syncImmich(
             size: item.size ?? 0,
             addedAt: Date.now(),
           };
-          rows.push(row);
+          met.add(`${normPath(label)}/${name}`.toLowerCase());
           albBatch.push(row);
           albCount++;
         }
@@ -500,14 +506,12 @@ export async function syncImmich(
 
   // A row the reading did not meet is dropped only against a reading that met all
   // of them — and only one that began at the top. A reading that carried on from
-  // where the last one stopped holds the newest pages in its own list and no older
-  // row in it at all, and pruned to that list it would take back every frame it
-  // was picking up.
+  // where the last one stopped met the older pages alone and not one of the newest,
+  // and pruned to what it met it would take back every frame it was picking up.
   // ponytail: a resumed reading therefore stops one prune short — a frame dropped
   // on the server keeps its row until some visit reads the node from the top. Read
-  // `met` out of the catalogue rather than out of `rows` if that ever shows.
+  // the catalogue rather than the reading if that ever shows.
   if (complete && !failed && !resume) {
-    const met = new Set(rows.map((r) => (r.dir ? `${normPath(r.dir)}/${r.name}` : r.name).toLowerCase()));
     await prunePhotos(root, '', met);
   }
 
@@ -544,6 +548,7 @@ export async function syncImmich(
             const name = frameName(item.name, item.id, rootTaken);
             rootTaken.add(item.name);
             rootTaken.add(name);
+            met.add(name.toLowerCase());
             bgBatchRows.push({
               id: [root, name].join('/'),
               folder: folder.name,
@@ -579,7 +584,6 @@ export async function syncImmich(
           // added since would be.
           await remember(null, 1, true);
           if (!resume) {
-            const met = new Set(rows.map((r) => (r.dir ? `${normPath(r.dir)}/${r.name}` : r.name).toLowerCase()));
             await prunePhotos(root, '', met);
           }
         }