fix(azure): preserve /v1/ path in _prepare_url for v1 API

When azure_deployment is passed with v1/preview/latest API, the
_prepare_url method was rewriting URLs and dropping the /v1/ prefix,
causing 404 errors for non-deployment endpoints like /responses.

Now _prepare_url skips URL rewriting entirely for v1 API since the
base_url already contains /openai/v1/.

Author: Chesars

src/openai/lib/azure.py

@@ -76,6 +76,10 @@ def _prepare_url(self, url: str) -> httpx.URL:
         and the API feature being called is **not** a deployments-based endpoint
         (i.e. requires /deployments/deployment-name in the URL path).
         """
+        # v1 API doesn't need URL rewriting - base_url already has /openai/v1/
+        if getattr(self, '_is_v1_api', False):
+            return super()._prepare_url(url)
+
         if self._azure_deployment and self._azure_endpoint and url not in _deployments_endpoints:
             merge_url = httpx.URL(url)
             if merge_url.is_relative_url:

tests/lib/test_azure.py

@@ -887,3 +887,24 @@ def test_v1_api_ignores_azure_deployment_param(self, api_version: str) -> None:
         # base_url should still be /openai/v1, not /openai/deployments/ignored-deployment
         assert "/openai/v1" in str(client.base_url)
         assert "/deployments/" not in str(client.base_url)
+
+    @pytest.mark.parametrize("api_version", ["v1", "latest", "preview"])
+    @pytest.mark.parametrize("client_cls", [AzureOpenAI, AsyncAzureOpenAI])
+    def test_v1_api_non_deployment_endpoints_keep_v1_path(self, api_version: str, client_cls: type[Client]) -> None:
+        """v1 API should keep /v1/ path for non-deployment endpoints like /responses."""
+        client = client_cls(
+            api_version=api_version,
+            api_key="test",
+            azure_endpoint="https://example.azure.openai.com",
+            azure_deployment="some-deployment",  # Even with deployment param
+        )
+        req = client._build_request(
+            FinalRequestOptions.construct(
+                method="post",
+                url="/responses",
+                json_data={"model": "gpt-4o", "input": "hi"},
+            )
+        )
+        # Should be /openai/v1/responses, NOT /openai/responses
+        assert "/openai/v1/responses" in str(req.url)
+        assert "/deployments/" not in str(req.url)