feat: conversation active_count test

- verify active_count increments on send_message, decrements on reset

src/integration_test.rs

@@ -4802,6 +4802,27 @@ mod conversation_extended_tests {
         assert!(registry.get_conversation_id(&room_b).await.is_none());
     }
 
+    #[tokio::test]
+    async fn test_conversation_active_count() {
+        let Some(api_key) = load_env() else { eprintln!("Skipping: no API key"); return; };
+        let mistral = Arc::new(
+            mistralai_client::v1::client::Client::new(Some(api_key), None, None, None).unwrap(),
+        );
+        let store = Arc::new(Store::open_memory().unwrap());
+        let registry = ConversationRegistry::new("mistral-medium-latest".into(), 118000, store);
+
+        assert_eq!(registry.active_count().await, 0);
+
+        let room = format!("test-count-{}", uuid::Uuid::new_v4());
+        let input = mistralai_client::v1::conversations::ConversationInput::Text("hi".into());
+        registry.send_message(&room, input, true, &mistral, None).await.unwrap();
+
+        assert_eq!(registry.active_count().await, 1);
+
+        registry.reset(&room).await;
+        assert_eq!(registry.active_count().await, 0);
+    }
+
     #[tokio::test]
     async fn test_conversation_with_context_hint() {
         let Some(api_key) = load_env() else { eprintln!("Skipping: no API key"); return; };