Prevent double job assignment

- Check if job is already assigned before assigning again
- Prevents multiple active jobs for the same queue entry
- Fixes duplicate cancellation attempts

vidai/cluster_master.py

@@ -1374,6 +1374,11 @@ class ClusterMaster:
 
                 for job_row in jobs:
                     job = dict(job_row)
+                    # Check if already assigned
+                    already_assigned = any(job_info.get('queue_id') == job['id'] for job_info in self.active_jobs.values())
+                    if already_assigned:
+                        continue
+
                     # Set status to processing before assigning
                     from .database import update_queue_status
                     update_queue_status(job['id'], 'processing')