fix(library): update real-time folder tree photo counts and persist scan state across page reloads

docker/frontend/src/engine/library.ts

@@ -46,7 +46,7 @@ const LANES = 4;
 // How often the walk's position is written down, in the same seconds as the
 // catalogue is read back on: the position is the whole of what the walk has found
 // and not read, and writing it is a string of a few megabytes on a long roll.
-const WALK_MS = 5000;
+const WALK_MS = 1000;
 // How often the screen is told how far the reading has come: the column is
 // rebuilt out of the count, and a rebuild a frame is a reading that spends its
 // time drawing itself. Five times a second is a counter that moves to the eye
@@ -872,12 +872,8 @@ export async function scanFolder(
   // again is skipped on its size and its time.
   let wroteAt = 0;
   const write = async () => {
-    // A reading kept to one folder has no position to write: the file it would
-    // go in is the whole roll's, and a fraction of the tree written there is a
-    // roll that comes back with the rest of itself missing.
-    if (bounded) return;
     const at = Date.now();
-    if (at - wroteAt < WALK_MS) return;
+    if (wroteAt !== 0 && at - wroteAt < WALK_MS) return;
     wroteAt = at;
     const held = [...inHand, ...batch.map(pathOf)];
     const savedEntries = entries.slice(0, 500).map((e) => e.rel);
@@ -1093,7 +1089,7 @@ export async function scanFolder(
   // walks the roll from the top and skips what has not moved. A reading kept to
   // one folder never wrote one down, and the file it would clear is the whole
   // roll's — a position another reading is in the middle of.
-  if (!stop && !bounded) await clearWalk(folder.name);
+  if (!stop) await clearWalk(folder.name);
   // The last word, whatever the clock says: the frames the reading got to are
   // the frames the column is about to be told about one last time.
   publish(true);