fix: track pending folder reservations

lib/folder-monitor.js

@@ -30,6 +30,7 @@ class FolderMonitor extends EventEmitter {
     this._settings = null;
     this._seenFiles = new Set();
     this._batchBuffer = [];
+    this._batchSeenReservations = new Set();
     this._batchTimer = null;
     this._initialScopes = new Set();
     this._reconcileTimer = null;
@@ -189,8 +190,9 @@ class FolderMonitor extends EventEmitter {
   _invalidateLifecycle(paused) {
     this._generation++;
     if (paused) {
-      for (const filePath of this._batchBuffer) this._seenFiles.delete(this._normalizePath(filePath));
+      for (const normalized of this._batchSeenReservations) this._seenFiles.delete(normalized);
     }
+    this._batchSeenReservations.clear();
     this._paused = paused;
     this._scanning = false;
     this._followUpRequested = false;
@@ -213,7 +215,11 @@ class FolderMonitor extends EventEmitter {
 
   _onNewFile(filePath, generation) {
     if (!this._acceptCallback(generation)) return;
-    if (!this._classifyPath(filePath, this._settings).allowed || !this._acceptPath(filePath)) return;
+    if (!this._classifyPath(filePath, this._settings).allowed) return;
+    const normalized = this._normalizePath(filePath);
+    const ownsSeenReservation = !!this._settings?.skipDuplicates && !this._seenFiles.has(normalized);
+    if (!this._acceptPath(filePath)) return;
+    if (ownsSeenReservation) this._batchSeenReservations.add(normalized);
     this._batchBuffer.push(filePath);
     if (this._batchTimer) this._clearTimeout(this._batchTimer);
     this._batchTimer = this._setTimeout(() => {
@@ -222,6 +228,11 @@ class FolderMonitor extends EventEmitter {
       this._batchTimer = null;
       if (files.length === 0) return;
       const listenerError = this._emitEvent('new-files', [files], generation);
+      for (const emittedPath of files) {
+        const emittedNormalized = this._normalizePath(emittedPath);
+        if (!this._batchSeenReservations.delete(emittedNormalized)) continue;
+        if (listenerError) this._seenFiles.delete(emittedNormalized);
+      }
       if (listenerError && this._acceptCallback(generation)) {
         this._lastError = 'Ordnerüberwachung fehlgeschlagen';
         this._emitStatus(generation);

tests/folder-monitor.test.js

@@ -374,6 +374,42 @@ test('watcher add paused before batch timeout is emitted exactly once by resume
   assert.equal(monitor.status().seenCount, 1);
 });
 
+test('pause rollback never deletes historical seen state from a dedupe-off batch', async () => {
+  const timers = createManualTimers();
+  const watchers = [];
+  const newFiles = [];
+  const filePath = 'C:\\watch\\historical.mkv';
+  let discoverExisting = false;
+  const monitor = new FolderMonitor({
+    watch: () => {
+      const watcher = new EventEmitter();
+      watcher.close = async () => {};
+      watchers.push(watcher);
+      return watcher;
+    },
+    access: async () => {},
+    walkFolder: async () => discoverExisting ? [{ path: filePath, name: 'historical.mkv', size: 1 }] : [],
+    stat: async () => ({ mtimeMs: 1 }),
+    ...timers
+  });
+  monitor.on('new-files', (files) => newFiles.push(files));
+  const dedupeOn = { folderPath: 'C:\\watch', extensions: 'mkv', skipDuplicates: true, reconcileIntervalMinutes: 5 };
+  const dedupeOff = { ...dedupeOn, skipDuplicates: false };
+  monitor.start(dedupeOn);
+  watchers[0].emit('add', filePath);
+  await timers.runTimeouts();
+  assert.deepEqual(newFiles, [[filePath]]);
+  await monitor.pause();
+  await monitor.resume(dedupeOff);
+  watchers[1].emit('add', filePath);
+  assert.deepEqual(newFiles, [[filePath]]);
+  await monitor.pause();
+  discoverExisting = true;
+  await monitor.resume(dedupeOn);
+  assert.deepEqual(newFiles, [[filePath]]);
+  assert.equal(monitor.status().seenCount, 1);
+});
+
 test('dry scan leaves the public status byte-identical and does not consume reconnect state', async () => {
   let reachable = false;
   const timers = createManualTimers();