cleanup

src/server/api/download.py

@@ -44,8 +44,11 @@ async def get_queue_status(
         queue_status = await download_service.get_queue_status()
         queue_stats = await download_service.get_queue_stats()
 
-        # Provide a legacy-shaped status payload expected by older clients
-        # and integration tests. Map internal model fields to the older keys.
+    # Preserve the legacy response contract expected by the original CLI
+    # client and existing integration tests. Those consumers rely on the
+    # field names ``active``/``pending``/``completed``/``failed`` and raw
+    # dict payloads rather than Pydantic models, so we emit JSON-friendly
+    # dictionaries that mirror the historic structure.
         status_payload = {
             "is_running": queue_status.is_running,
             "is_paused": queue_status.is_paused,
@@ -55,7 +58,9 @@ async def get_queue_status(
             "failed": [it.model_dump(mode="json") for it in queue_status.failed_downloads],
         }
 
-        # Add success_rate to statistics for backward compatibility
+    # Add the derived ``success_rate`` metric so dashboards built against
+    # the previous API continue to function without recalculating it
+    # client-side.
         completed = queue_stats.completed_count
         failed = queue_stats.failed_count
         success_rate = None