Add resilient Azure offline transcription backlog

MeetingAssistant/Recording/TemporaryRecordedAudioStore.cs

@@ -7,13 +7,16 @@ public sealed class TemporaryRecordedAudioStore : IRecordedAudioStore
 {
     private readonly MeetingAssistantOptions options;
     private readonly ILogger<TemporaryRecordedAudioStore> logger;
+    private readonly IOfflineTranscriptionBacklog offlineTranscriptionBacklog;
 
     public TemporaryRecordedAudioStore(
         IOptions<MeetingAssistantOptions> options,
-        ILogger<TemporaryRecordedAudioStore> logger)
+        ILogger<TemporaryRecordedAudioStore> logger,
+        IOfflineTranscriptionBacklog? offlineTranscriptionBacklog = null)
     {
         this.options = options.Value;
         this.logger = logger;
+        this.offlineTranscriptionBacklog = offlineTranscriptionBacklog ?? NoopOfflineTranscriptionBacklog.Instance;
     }
 
     public Task<IRecordedAudioSink> CreateSessionAsync(CancellationToken cancellationToken)
@@ -35,21 +38,28 @@ public sealed class TemporaryRecordedAudioStore : IRecordedAudioStore
         return Task.FromResult<IRecordedAudioSink>(new TemporaryRecordedAudioSink(path, format, logger));
     }
 
-    public Task DeleteStaleRecordingsAsync(CancellationToken cancellationToken)
+    public async Task DeleteStaleRecordingsAsync(CancellationToken cancellationToken)
     {
         var folder = GetTemporaryRecordingsFolder(options);
         if (!Directory.Exists(folder))
         {
-            return Task.CompletedTask;
+            return;
         }
 
+        var queuedAudioPaths = (await offlineTranscriptionBacklog.ListAsync(cancellationToken))
+            .Select(item => item.AudioPath)
+            .ToHashSet(StringComparer.OrdinalIgnoreCase);
         foreach (var path in Directory.EnumerateFiles(folder, "*.wav", SearchOption.TopDirectoryOnly))
         {
             cancellationToken.ThrowIfCancellationRequested();
+            if (queuedAudioPaths.Contains(path))
+            {
+                logger.LogInformation("Keeping queued offline transcription recording file {RecordingPath}", path);
+                continue;
+            }
+
             DeleteFile(path);
         }
-
-        return Task.CompletedTask;
     }
 
     private static string GetTemporaryRecordingsFolder(MeetingAssistantOptions options)