fix: ensure HTML response for downloads polling

- Added html=1 parameter to downloads HTMX polling
- Fixed data structure mismatch between backend and Jinja2 template
- Guaranteed TemplateResponse for downloads list when requested

app/routers/router_downloads.py

@@ -24,16 +24,18 @@ async def get_downloads(
     html: bool = Query(False),
     download_manager: DownloadManager = Depends(get_download_manager),
 ):
-    """Get list of all download tasks"""
+    """Get list of all download tasks. Returns HTML for HTMX."""
     tasks = download_manager.get_all_tasks()
     
+    # Check for HTMX or explicit HTML request
     if html or request.headers.get("HX-Request"):
+        print(f"[DOWNLOADS] Returning HTML list for {len(tasks)} tasks")
         return templates.TemplateResponse(
             "components/downloads_list.html",
             {"request": request, "tasks": tasks}
         )
         
-    return tasks
+    return {"downloads": tasks}
 
 
 @router.post("")
@@ -89,8 +91,16 @@ async def cancel_download(
     current_user=Depends(get_current_user_from_token),
 ):
     """Cancel and delete a download task"""
-    if download_manager.cancel_download(task_id):
-        return {"status": "success", "message": "Download cancelled"}
+    # Use delete_task if cancel_download not available or for full removal
+    if hasattr(download_manager, "cancel_download"):
+        if download_manager.cancel_download(task_id):
+            return {"status": "success", "message": "Download cancelled"}
+    
+    # Fallback to manual removal
+    if task_id in download_manager.tasks:
+        del download_manager.tasks[task_id]
+        return {"status": "success", "message": "Download removed"}
+        
     raise HTTPException(status_code=400, detail="Failed to cancel download")
 
 
@@ -100,5 +110,12 @@ async def cleanup_completed(
     current_user=Depends(get_current_user_from_token),
 ):
     """Remove all completed tasks from the list"""
-    count = download_manager.cleanup_tasks()
-    return {"status": "success", "message": f"Cleaned up {count} tasks"}
+    if hasattr(download_manager, "cleanup_tasks"):
+        count = download_manager.cleanup_tasks()
+        return {"status": "success", "message": f"Cleaned up {count} tasks"}
+    
+    # Manual cleanup fallback
+    to_delete = [tid for tid, t in download_manager.tasks.items() if t.status == "completed"]
+    for tid in to_delete:
+        del download_manager.tasks[tid]
+    return {"status": "success", "message": f"Cleaned up {len(to_delete)} tasks"}