fix ProjectResponsesClient endpoint bug

Author: trrwilson

sdk/ai/Azure.AI.Projects.OpenAI/CHANGELOG.md

@@ -1,5 +1,11 @@
 # Release History
 
+## 1.0.0-beta.2 (Unreleased)
+
+### Bugs fixed
+
+- Addressed a problem where not supplying an options instance to the `ProjectResponsesClient` constructor resulted in fallback to the `https://api.openai.com/v1` endpoint
+
 ## 1.0.0-beta.1 (2025-11-14)
 
 This is the first release of the `Azure.AI.Projects.OpenAI` library, a new extension package for the official `OpenAI` .NET library that facilitates and simplifies use of Microsoft Foundry extensions to OpenAI APIs.

sdk/ai/Azure.AI.Projects.OpenAI/src/Custom/OpenAI/ProjectOpenAIClient.cs

@@ -49,7 +49,7 @@ public ProjectOpenAIClient(AuthenticationPolicy authenticationPolicy, ProjectOpe
     {
         Argument.AssertNotNull(authenticationPolicy, nameof(authenticationPolicy));
         Argument.AssertNotNull(options, nameof(options));
-        Argument.AssertNotNull(options.Endpoint, nameof(options.Endpoint));
+        Argument.AssertNotNull(options.Endpoint, $"{nameof(options)}.{nameof(options.Endpoint)}");
 
         _options = options;
     }
@@ -157,6 +157,7 @@ internal static ProjectOpenAIClientOptions GetMergedOptions(Uri projectEndpoint,
             throw new InvalidOperationException(
                 $"Cannot supply both a constructor '{nameof(projectEndpoint)}' and {nameof(options)}.{nameof(options.Endpoint)}.");
         }
+        options ??= new();
         options?.Endpoint ??= new Uri(rawTargetOpenAIEndpoint);
         return options;
     }

sdk/ai/Azure.AI.Projects.OpenAI/tests/ResponsesSmokeTests.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT License.
 
 using System;
+using System.ClientModel;
 using System.ClientModel.Primitives;
 using System.Linq;
 using Microsoft.ClientModel.TestFramework;
@@ -166,4 +167,43 @@ public void TestResponseCreationOptionsExtensions()
         Assert.That(options.StructuredInputs.Keys, Has.Count.EqualTo(2));
         Assert.That(options.StructuredInputs["direct_value_2"].ToString(), Is.EqualTo("42"));
     }
+
+    [Test]
+    public void ResponsesEndpointsSetCorrectly()
+    {
+        Uri mockProjectEndpoint = new("https://microsoft.com/mock/endpoint");
+        Uri mockOpenAIEndpoint = new($"{mockProjectEndpoint.AbsoluteUri}/openai");
+        AuthenticationTokenProvider mockCredential = new MockCredential();
+        AuthenticationPolicy mockAuthPolicy = new BearerTokenPolicy(mockCredential, "https://ai.azure.com/.default");
+
+        ProjectOpenAIClientOptions GetOptions(Uri endpoint = null) => new() { Endpoint = endpoint };
+
+        // Not specifying options should use the constructed /openai endpoint from the project Uri
+        ProjectOpenAIClient client = new(mockProjectEndpoint, new MockCredential());
+        Assert.That(client.Endpoint?.AbsoluteUri, Is.EqualTo(mockOpenAIEndpoint));
+        client = new(new Uri(mockProjectEndpoint.AbsoluteUri + "/"), mockCredential);
+        Assert.That(client.Endpoint?.AbsoluteUri, Is.EqualTo(mockOpenAIEndpoint));
+
+        // Providing no endpoint anywhere should throw
+        Assert.Throws<ArgumentNullException>(() => client = new(mockAuthPolicy, GetOptions()));
+
+        // Supplying in options should use the literal value with no construction
+        client = new(mockAuthPolicy, GetOptions(mockProjectEndpoint));
+        Assert.That(client.Endpoint?.AbsoluteUri, Is.EqualTo(mockProjectEndpoint.AbsoluteUri));
+
+        // Supplying in both should be OK if they match correctly
+        client = new(mockProjectEndpoint, mockCredential, GetOptions(mockOpenAIEndpoint));
+        Assert.That(client.Endpoint?.AbsoluteUri, Is.EqualTo(mockOpenAIEndpoint));
+
+        // Supplying in both should throw if they don't match
+        Assert.Throws<InvalidOperationException>(() => client = new(mockProjectEndpoint, mockCredential, GetOptions(mockProjectEndpoint)));
+
+        // Clients retrieved from ProjectOpenAIClient should handle construction
+        ProjectOpenAIClient openAIClient = new(mockProjectEndpoint, mockCredential);
+        Assert.That(openAIClient.Responses.Endpoint, Is.EqualTo(mockOpenAIEndpoint));
+        Assert.That(openAIClient.GetOpenAIResponseClient("model").Endpoint, Is.EqualTo(mockOpenAIEndpoint));
+        Assert.That(openAIClient.GetProjectResponsesClient().Endpoint, Is.EqualTo(mockOpenAIEndpoint));
+        Assert.That(openAIClient.GetProjectResponsesClientForModel("model").Endpoint, Is.EqualTo(mockOpenAIEndpoint));
+        Assert.That(openAIClient.GetProjectResponsesClientForAgent(new AgentReference("agent")).Endpoint, Is.EqualTo(mockOpenAIEndpoint));
+    }
 }