Add TTS OpenTelemetry exception logging and changelog entry

Copilot · stephentoub · Copilot · commit fdedf6540e4b · 2026-03-12T02:33:25.000Z
Co-authored-by: stephentoub &lt;2642209+stephentoub@users.noreply.github.com&gt;
diff --git a/src/Libraries/Microsoft.Extensions.AI/CHANGELOG.md b/src/Libraries/Microsoft.Extensions.AI/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## NOT YET RELEASED
 
+- Added `gen_ai.client.operation.exception` log event emission via `ILogger` across all OpenTelemetry instrumentation classes.
 - Added `time_to_first_chunk` and `time_per_output_chunk` streaming metrics to `OpenTelemetryChatClient`.
 - Fixed `OpenTelemetryChatClient` to emit tool definitions even when EnableSensitiveData is false.
 - Updated the OpenTelemetry instrumentation to conform to the latest 1.49 draft specification of the Semantic Conventions for Generative AI systems.
diff --git a/src/Libraries/Microsoft.Extensions.AI/TextToSpeech/OpenTelemetryTextToSpeechClient.cs b/src/Libraries/Microsoft.Extensions.AI/TextToSpeech/OpenTelemetryTextToSpeechClient.cs
@@ -38,17 +38,19 @@ public sealed class OpenTelemetryTextToSpeechClient : DelegatingTextToSpeechClie
     private readonly string? _serverAddress;
     private readonly int _serverPort;
 
+    private readonly ILogger? _logger;
+
     /// <summary>Initializes a new instance of the <see cref="OpenTelemetryTextToSpeechClient"/> class.</summary>
     /// <param name="innerClient">The underlying <see cref="ITextToSpeechClient"/>.</param>
     /// <param name="logger">The <see cref="ILogger"/> to use for emitting any logging data from the client.</param>
     /// <param name="sourceName">An optional source name that will be used on the telemetry data.</param>
-#pragma warning disable IDE0060 // Remove unused parameter; it exists for consistency with IChatClient and future use
     public OpenTelemetryTextToSpeechClient(ITextToSpeechClient innerClient, ILogger? logger = null, string? sourceName = null)
-#pragma warning restore IDE0060
         : base(innerClient)
     {
         Debug.Assert(innerClient is not null, "Should have been validated by the base ctor");
 
+        _logger = logger;
+
         if (innerClient!.GetService<TextToSpeechClientMetadata>() is TextToSpeechClientMetadata metadata)
         {
             _defaultModelId = metadata.DefaultModelId;
@@ -287,6 +289,11 @@ private void TraceResponse(
             _ = activity?
                 .AddTag(OpenTelemetryConsts.Error.Type, error.GetType().FullName)
                 .SetStatus(ActivityStatusCode.Error, error.Message);
+
+            if (_logger is not null)
+            {
+                OpenTelemetryLog.OperationException(_logger, error);
+            }
         }
 
         if (response is not null && activity is not null)
diff --git a/test/Libraries/Microsoft.Extensions.AI.Tests/TextToSpeech/OpenTelemetryTextToSpeechClientTests.cs b/test/Libraries/Microsoft.Extensions.AI.Tests/TextToSpeech/OpenTelemetryTextToSpeechClientTests.cs
@@ -7,6 +7,8 @@
 using System.Runtime.CompilerServices;
 using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Testing;
 using OpenTelemetry.Trace;
 using Xunit;
 
@@ -127,4 +129,64 @@ static async IAsyncEnumerable<TextToSpeechResponseUpdate> TestClientStreamAsync(
 
         Assert.True(activity.Duration.TotalMilliseconds > 0);
     }
+
+    [Theory]
+    [InlineData(false)]
+    [InlineData(true)]
+    public async Task ExceptionLogged_Async(bool streaming)
+    {
+        var sourceName = Guid.NewGuid().ToString();
+        var activities = new List<Activity>();
+        using var tracerProvider = OpenTelemetry.Sdk.CreateTracerProviderBuilder()
+            .AddSource(sourceName)
+            .AddInMemoryExporter(activities)
+            .Build();
+
+        var collector = new FakeLogCollector();
+        using var loggerFactory = LoggerFactory.Create(b => b.AddProvider(new FakeLoggerProvider(collector)));
+
+        var expectedException = new InvalidOperationException("test exception message");
+
+        using var innerClient = new TestTextToSpeechClient
+        {
+            GetAudioAsyncCallback = (text, options, cancellationToken) => throw expectedException,
+            GetStreamingAudioAsyncCallback = (text, options, cancellationToken) => throw expectedException,
+            GetServiceCallback = (serviceType, serviceKey) =>
+                serviceType == typeof(TextToSpeechClientMetadata) ? new TextToSpeechClientMetadata("testservice", new Uri("http://localhost:12345"), "testmodel") :
+                null,
+        };
+
+        using var client = innerClient
+            .AsBuilder()
+            .UseOpenTelemetry(loggerFactory, sourceName)
+            .Build();
+
+        if (streaming)
+        {
+            await Assert.ThrowsAsync<InvalidOperationException>(async () =>
+            {
+                await foreach (var update in client.GetStreamingAudioAsync("Hello"))
+                {
+                    _ = update;
+                }
+            });
+        }
+        else
+        {
+            await Assert.ThrowsAsync<InvalidOperationException>(() =>
+                client.GetAudioAsync("Hello"));
+        }
+
+        var activity = Assert.Single(activities);
+
+        // Existing error behavior is preserved
+        Assert.Equal(expectedException.GetType().FullName, activity.GetTagItem("error.type"));
+        Assert.Equal(ActivityStatusCode.Error, activity.Status);
+
+        // Exception is logged via ILogger
+        var logEntry = Assert.Single(collector.GetSnapshot());
+        Assert.Equal("gen_ai.client.operation.exception", logEntry.Id.Name);
+        Assert.Equal(LogLevel.Warning, logEntry.Level);
+        Assert.Same(expectedException, logEntry.Exception);
+    }
 }
