diff --git a/app/plugins/builtins/ai_assistant/services.py b/app/plugins/builtins/ai_assistant/services.py
index bb8aeb6..e4ca90c 100644
--- a/app/plugins/builtins/ai_assistant/services.py
+++ b/app/plugins/builtins/ai_assistant/services.py
@@ -274,8 +274,9 @@ async def build_litellm_params(
         provider = await get_default_provider(db, tenant_id)
 
     # Build litellm model string with provider prefix
+    # LiteLLM always needs a provider prefix, even for OpenAI-compatible APIs
     litellm_model = model_id
-    if provider and provider.provider_type != "openai":
+    if provider:
         litellm_model = f"{provider.provider_type}/{model_id}"
 
     # Build messages with system prompt