release: v2.0.6

Redesign the desktop workspace with task sidebars, live filters, clearer settings, and an accessible update dialog.

Harden encrypted backup imports, configuration persistence, history retention, queue snapshots, shutdown recovery, and update installation ordering.

Publish verified Windows artifacts and refreshed English documentation.

lib/semaphore.js

@@ -0,0 +1,73 @@
+/**
+ * FIFO Semaphore for per-hoster concurrency control.
+ * acquire(signal?) blocks until a slot is available or the signal aborts.
+ * release() frees a slot.
+ */
+class Semaphore {
+  constructor(limit) {
+    this.limit = Math.max(1, limit || 1);
+    this.active = 0;
+    this.queue = []; // { resolve, reject, signal?, onAbort? }
+  }
+
+  acquire(signal) {
+    return new Promise((resolve, reject) => {
+      if (signal && signal.aborted) {
+        reject(new Error('Aborted'));
+        return;
+      }
+
+      if (this.active < this.limit) {
+        this.active++;
+        resolve();
+        return;
+      }
+
+      const entry = { resolve, reject };
+
+      if (signal) {
+        entry.signal = signal;
+        entry.onAbort = () => {
+          const idx = this.queue.indexOf(entry);
+          if (idx !== -1) this.queue.splice(idx, 1);
+          reject(new Error('Aborted'));
+        };
+        signal.addEventListener('abort', entry.onAbort, { once: true });
+      }
+
+      this.queue.push(entry);
+    });
+  }
+
+  _cleanupEntry(entry) {
+    if (entry.signal && entry.onAbort) {
+      entry.signal.removeEventListener('abort', entry.onAbort);
+    }
+  }
+
+  release() {
+    if (this.queue.length > 0) {
+      const entry = this.queue.shift();
+      this._cleanupEntry(entry);
+      entry.resolve();
+    } else {
+      this.active = Math.max(0, this.active - 1);
+    }
+  }
+
+  updateLimit(newLimit) {
+    this.limit = Math.max(1, newLimit || 1);
+    while (this.active < this.limit && this.queue.length > 0) {
+      this.active++;
+      const entry = this.queue.shift();
+      this._cleanupEntry(entry);
+      entry.resolve();
+    }
+  }
+
+  get pending() {
+    return this.queue.length;
+  }
+}
+
+module.exports = Semaphore;