diff --git a/src/agents/orchestrator.py b/src/agents/orchestrator.py
index f89930e..3e0a6bc 100644
--- a/src/agents/orchestrator.py
+++ b/src/agents/orchestrator.py
@@ -865,7 +865,7 @@ class AgentOrchestrator:
 
                 if analysis:
                     sources = analysis.get("sources", [])
-                    sources_json = json.dumps(sources, ensure_ascii=False) if sources else None
+                    sources_json = json.dumps(sources, ensure_ascii=False) if sources else previous_sources_json
                     new_summary = analysis.get("summary", "") or previous_summary
 
                     await db.execute(