fix(auxiliary): preserve named provider on custom endpoint

agent/auxiliary_client.py

@@ -3983,8 +3983,13 @@ def _resolve_task_provider_model(
     if task:
         # Config.yaml is the primary source for per-task overrides.
         if cfg_base_url and cfg_api_key:
-            # Both base_url and api_key explicitly set → custom endpoint.
-            return "custom", resolved_model, cfg_base_url, cfg_api_key, resolved_api_mode
+            # Both base_url and api_key explicitly set. Preserve an explicit
+            # provider so downstream provider-specific logic still applies
+            # (e.g. transport quirks / parameter guards) on custom endpoints.
+            effective_provider = (
+                cfg_provider if cfg_provider and cfg_provider != "auto" else "custom"
+            )
+            return effective_provider, resolved_model, cfg_base_url, cfg_api_key, resolved_api_mode
         if cfg_base_url and cfg_provider and cfg_provider != "auto":
             # base_url set without api_key but with a known provider — use
             # the provider so it can resolve credentials from env vars

tests/agent/test_vision_resolved_args.py

@@ -62,3 +62,48 @@ def test_vision_base_url_override_keeps_explicit_provider():
     assert model == "glm-4v"
     assert mock_resolve.call_args.args[0] == "zai"
     assert mock_resolve.call_args.kwargs["explicit_base_url"] == "https://open.bigmodel.cn/api/paas/v4"
+
+
+def test_resolve_task_provider_model_preserves_provider_with_custom_endpoint():
+    """auxiliary.<task>.provider must survive when base_url+api_key are both configured."""
+    from agent.auxiliary_client import _resolve_task_provider_model
+
+    with patch(
+        "agent.auxiliary_client._get_auxiliary_task_config",
+        return_value={
+            "provider": "zai",
+            "model": "glm-4v-flash",
+            "base_url": "https://open.bigmodel.cn/api/paas/v4/",
+            "api_key": "sk-test",
+            "api_mode": "chat_completions",
+        },
+    ):
+        provider, model, base_url, api_key, api_mode = _resolve_task_provider_model(task="vision")
+
+    assert provider == "zai"
+    assert model == "glm-4v-flash"
+    assert base_url == "https://open.bigmodel.cn/api/paas/v4/"
+    assert api_key == "sk-test"
+    assert api_mode == "chat_completions"
+
+
+def test_resolve_task_provider_model_uses_custom_when_provider_is_auto():
+    """When provider is auto, base_url+api_key should still resolve to custom."""
+    from agent.auxiliary_client import _resolve_task_provider_model
+
+    with patch(
+        "agent.auxiliary_client._get_auxiliary_task_config",
+        return_value={
+            "provider": "auto",
+            "model": "gpt-4o-mini",
+            "base_url": "https://example.com/v1",
+            "api_key": "sk-test",
+        },
+    ):
+        provider, model, base_url, api_key, api_mode = _resolve_task_provider_model(task="vision")
+
+    assert provider == "custom"
+    assert model == "gpt-4o-mini"
+    assert base_url == "https://example.com/v1"
+    assert api_key == "sk-test"
+    assert api_mode is None