Make meeting lifecycle stateful

MeetingAssistant/Transcription/AzureSpeechStreamingTranscriptionProvider.cs

@@ -25,7 +25,9 @@ public sealed class AzureSpeechStreamingTranscriptionProvider : IStreamingTransc
         SpeechRecognitionPipelineOptions pipelineOptions,
         [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken)
     {
-        await using var enumerator = audio.GetAsyncEnumerator(cancellationToken);
+        var enumerator = audio.GetAsyncEnumerator(cancellationToken);
+        try
+        {
         if (!await enumerator.MoveNextAsync())
         {
             yield break;
@@ -94,6 +96,18 @@ public sealed class AzureSpeechStreamingTranscriptionProvider : IStreamingTransc
         }
 
         await pumpTask.WaitAsync(cancellationToken);
+        }
+        finally
+        {
+            try
+            {
+                await enumerator.DisposeAsync();
+            }
+            catch (NotSupportedException)
+            {
+                // Some diagnostic async enumerable sources expose DisposeAsync but throw after the stream has been read.
+            }
+        }
     }
 
     internal ConversationTranscriber CreateTranscriber(SpeechConfig speechConfig, AudioConfig audioConfig)
@@ -150,7 +164,7 @@ public sealed class AzureSpeechStreamingTranscriptionProvider : IStreamingTransc
                 $"Azure Speech key is not configured. Set AzureSpeech:Key or environment variable {azure.KeyEnv}.");
         }
 
-        var speechConfig = SpeechConfig.FromEndpoint(GetEndpoint(azure), key);
+        var speechConfig = CreateSpeechConfig(azure, key);
         var autoDetectLanguages = GetAutoDetectLanguages(azure);
         if (autoDetectLanguages.Count == 0)
         {
@@ -167,6 +181,13 @@ public sealed class AzureSpeechStreamingTranscriptionProvider : IStreamingTransc
         speechConfig.SetProperty(
             PropertyId.SpeechServiceResponse_DiarizeIntermediateResults,
             azure.DiarizeIntermediateResults ? "true" : "false");
+        if (!string.IsNullOrWhiteSpace(azure.PostProcessingOption))
+        {
+            logger.LogWarning(
+                "Azure Speech post-processing option {PostProcessingOption} is configured but skipped because the live Azure backend uses ConversationTranscriber; Speech SDK post-processing is documented for SpeechRecognizer.",
+                azure.PostProcessingOption.Trim());
+        }
+
         return speechConfig;
     }
 
@@ -185,10 +206,17 @@ public sealed class AzureSpeechStreamingTranscriptionProvider : IStreamingTransc
     }
 
     internal static Uri GetEndpoint(AzureSpeechOptions options)
+    {
+        return string.IsNullOrWhiteSpace(options.Endpoint)
+            ? throw new InvalidOperationException("Azure Speech endpoint must be configured.")
+            : new Uri(options.Endpoint);
+    }
+
+    internal static SpeechConfig CreateSpeechConfig(AzureSpeechOptions options, string key)
     {
         if (!string.IsNullOrWhiteSpace(options.Endpoint))
         {
-            return new Uri(options.Endpoint);
+            return SpeechConfig.FromEndpoint(GetEndpoint(options), key);
         }
 
         if (string.IsNullOrWhiteSpace(options.Region))
@@ -196,7 +224,7 @@ public sealed class AzureSpeechStreamingTranscriptionProvider : IStreamingTransc
             throw new InvalidOperationException("Azure Speech region or endpoint must be configured.");
         }
 
-        return new Uri($"wss://{options.Region}.stt.speech.microsoft.com/speech/universal/v2");
+        return SpeechConfig.FromSubscription(key, options.Region.Trim());
     }
 
     internal static string NormalizeLanguageIdMode(string? value)