Add resilient Azure offline transcription backlog

MeetingAssistant/Recording/ITranscriptStore.cs

@@ -14,13 +14,30 @@ public interface ITranscriptStore
 
     Task AppendAsync(TranscriptSession session, TranscriptionSegment segment, CancellationToken cancellationToken)
     {
-        return AppendLineAsync(
+        return AppendLineAndDiscardReferenceAsync(
             session,
             TranscriptLineFormatter.Format(segment).Line,
             cancellationToken);
     }
 
-    Task AppendLineAsync(TranscriptSession session, string line, CancellationToken cancellationToken);
+    private async Task AppendLineAndDiscardReferenceAsync(
+        TranscriptSession session,
+        string line,
+        CancellationToken cancellationToken)
+    {
+        _ = await AppendLineAsync(session, line, cancellationToken);
+    }
+
+    Task<TranscriptLineReference> AppendLineAsync(
+        TranscriptSession session,
+        string line,
+        CancellationToken cancellationToken);
+
+    Task ReplaceLineAsync(
+        TranscriptSession session,
+        TranscriptLineReference lineReference,
+        string replacementLine,
+        CancellationToken cancellationToken);
 
     Task ReplaceAsync(
         TranscriptSession session,
@@ -47,11 +64,18 @@ public interface ITranscriptStore
 
 public sealed record TranscriptSession(string TranscriptPath);
 
+public sealed record TranscriptLineReference(string TranscriptPath, int BodyLineIndex, string OriginalLine);
+
 public static class TranscriptLineFormatter
 {
     public static FormattedTranscriptLine Format(TranscriptionSegment segment)
     {
         var speaker = NormalizeSpeaker(segment.Speaker);
+        if (segment.Kind == TranscriptionSegmentKind.Marker)
+        {
+            return new FormattedTranscriptLine(segment.Text, speaker);
+        }
+
         return new FormattedTranscriptLine(
             $"[{segment.Start:hh\\:mm\\:ss}] {speaker}: {segment.Text}",
             speaker);