add support for custom AI api base url and Agent Router integrations

app/config.py

@@ -55,6 +55,9 @@ class Settings(BaseSettings):
     # Leave blank for Ollama (local, no key needed).
     ai_api_key: str | None = None
 
+    # AI_API_BASE: Custom API base URL (e.g. for Agent Router or custom OpenAI-compatible proxies)
+    ai_api_base: str | None = None
+
     # -------------------------------------------------------------------------
     # Legacy Gemini key — kept for backward compatibility.
     # If AI_API_KEY is not set but GEMINI_API_KEY is, we use that automatically.

app/services/ai.py

@@ -74,6 +74,9 @@ async def call_ai(
         "api_key": api_key,
     }
 
+    if settings.ai_api_base:
+        kwargs["api_base"] = settings.ai_api_base
+
     # JSON mode: supported natively by OpenAI and LiteLLM proxied Gemini.
     # For providers that don't support it, LiteLLM silently ignores the flag.
     if json_mode: