Prevent duplicate Twitch session prompts

app/agent/orchestrator.py

@@ -88,6 +88,47 @@ class AgentOrchestrator:
         logger.info(f"Started session {session_id} for {channel_name}")
         return session_id
 
+    async def ensure_single_active_session_for_channel(self, channel_name: str) -> str:
+        """Return one active session for a channel and end duplicate active sessions."""
+        normalized_channel = channel_name.lower()
+        matching_sessions = [
+            (session_id, session)
+            for session_id, session in self.active_sessions.items()
+            if session.get("channel_name", "").lower() == normalized_channel
+        ]
+
+        if not matching_sessions:
+            return await self.start_session(channel_name)
+
+        keep_session_id, _ = max(
+            matching_sessions,
+            key=lambda item: item[1].get("started_at", datetime.min),
+        )
+        duplicate_session_ids = [
+            session_id
+            for session_id, _ in matching_sessions
+            if session_id != keep_session_id
+        ]
+
+        if duplicate_session_ids:
+            async for db_session in get_session():
+                repo = Repository(db_session)
+                for session_id in duplicate_session_ids:
+                    await repo.end_session(session_id)
+
+            for session_id in duplicate_session_ids:
+                self.active_sessions.pop(session_id, None)
+                self.chat_activity.clear_activity(session_id)
+
+            logger.warning(
+                "Ended %s duplicate active session(s) for channel %s; keeping %s",
+                len(duplicate_session_ids),
+                channel_name,
+                keep_session_id,
+            )
+
+        return keep_session_id
+
     async def restore_active_sessions(self) -> int:
         """Restore active sessions from the database after app startup."""
         restored_count = 0