chore: import upstream snapshot with attribution

dotnet/tests/Foundry.IntegrationTests/ResponsesAgentServedModelTests.cs

@@ -0,0 +1,85 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+using AgentConformance.IntegrationTests.Support;
+using Azure.AI.Projects;
+using Microsoft.Agents.AI;
+using Microsoft.Extensions.AI;
+using Shared.IntegrationTests;
+
+namespace Foundry.IntegrationTests;
+
+/// <summary>
+/// Integration tests validating that the <c>x-ms-served-model</c> response header
+/// returned by the Azure OpenAI Responses API is surfaced on <see cref="ChatResponse.ModelId"/>.
+/// </summary>
+public class ResponsesAgentServedModelTests
+{
+    // Matches a dated served-model snapshot, e.g. "gpt-5-nano-2025-08-07".
+    private static readonly Regex s_snapshotRegex = new(@"-\d{4}-\d{2}-\d{2}$", RegexOptions.Compiled);
+
+    private static Uri Endpoint => new(TestConfiguration.GetRequiredValue(TestSettings.AzureAIProjectEndpoint));
+
+    private static string DeploymentName => TestConfiguration.GetRequiredValue(TestSettings.AzureAIModelDeploymentName);
+
+    private readonly AIProjectClient _client = new(Endpoint, TestAzureCliCredentials.CreateAzureCliCredential());
+
+    [Fact]
+    public async Task GetResponseAsync_ReturnsServedModelSnapshotOnModelIdAsync()
+    {
+        // Arrange
+        ChatClientAgent agent = this._client.AsAIAgent(
+            model: DeploymentName,
+            instructions: "You are a helpful assistant. Reply with a single short word.",
+            name: "ServedModelTest");
+
+        IChatClient chatClient = agent.ChatClient;
+
+        // Act
+        ChatResponse response = await chatClient.GetResponseAsync(
+            [new ChatMessage(ChatRole.User, "Say hi.")],
+            new ChatOptions { ModelId = DeploymentName });
+
+        // Assert
+        AssertServedModel(response.ModelId);
+    }
+
+    [Fact]
+    public async Task RunAsync_AgentResponseRawRepresentationCarriesServedModelAsync()
+    {
+        // Arrange
+        ChatClientAgent agent = this._client.AsAIAgent(
+            model: DeploymentName,
+            instructions: "You are a helpful assistant. Reply with a single short word.",
+            name: "ServedModelTestRun");
+
+        // Act
+        AgentResponse agentResponse = await agent.RunAsync("Say hi.");
+
+        // Assert
+        ChatResponse? chatResponse = agentResponse.RawRepresentation as ChatResponse;
+        Assert.NotNull(chatResponse);
+        AssertServedModel(chatResponse!.ModelId);
+    }
+
+    private static void AssertServedModel(string? modelId)
+    {
+        Assert.False(string.IsNullOrWhiteSpace(modelId), "ChatResponse.ModelId must be populated.");
+
+        // Primary invariant: the served-model value must look like a dated snapshot
+        // (e.g. "gpt-5-nano-2025-08-07"). This is what the x-ms-served-model header carries.
+        // Only when the configured deployment name itself already matches the snapshot pattern
+        // do we fall back to permitting equality with the deployment alias.
+        bool aliasIsSnapshot = s_snapshotRegex.IsMatch(DeploymentName);
+
+        if (aliasIsSnapshot)
+        {
+            return;
+        }
+
+        Assert.Matches(s_snapshotRegex, modelId!);
+        Assert.NotEqual(DeploymentName, modelId);
+    }
+}