diff --git a/src/main/services/agents/services/SessionMessageService.ts b/src/main/services/agents/services/SessionMessageService.ts
index df9cf0a69f..8ae405e8ee 100644
--- a/src/main/services/agents/services/SessionMessageService.ts
+++ b/src/main/services/agents/services/SessionMessageService.ts
@@ -334,7 +334,7 @@ export class SessionMessageService extends BaseService {
     const insertData: InsertSessionMessageRow = {
       session_id: sessionId,
       role: 'user',
-      content: prompt,
+      content: JSON.stringify({ role: 'user', content: prompt }),
       agent_session_id: agentSessionId,
       created_at: now,
       updated_at: now