Hardcode Python default empty response

app/services/config_service.py

@@ -7,21 +7,20 @@ from __future__ import annotations
 
 import logging
 
+from app.config import DEFAULT_EMPTY_RESPONSE
 from app.database import get_conn, get_write_conn
 from app.models import ConfigResponse
 
 logger = logging.getLogger(__name__)
 
 _SETTING_KEYS = {"default_wait_seconds", "default_empty_response", "agent_stale_after_seconds"}
-
-
 def get_config() -> ConfigResponse:
     with get_conn() as conn:
         rows = conn.execute("SELECT key, value FROM settings").fetchall()
     data = {r["key"]: r["value"] for r in rows}
     return ConfigResponse(
         default_wait_seconds=int(data.get("default_wait_seconds", 10)),
-        default_empty_response=data.get("default_empty_response", ""),
+        default_empty_response=data.get("default_empty_response") or DEFAULT_EMPTY_RESPONSE,
         agent_stale_after_seconds=int(data.get("agent_stale_after_seconds", 30)),
     )