Add meeting workflow automation

MeetingAssistant/Summary/MeetingSummaryTools.cs

@@ -106,6 +106,7 @@ public sealed class MeetingSummaryTools
             meetingNote,
             string.IsNullOrWhiteSpace(summaryTitle) ? "Meeting Summary" : summaryTitle,
             artifacts.SummaryPath);
+        frontmatter.Attendees = await ResolveSummaryAttendeesAsync(meetingNote);
         await File.WriteAllTextAsync(
             artifacts.SummaryPath,
             MeetingArtifactFrontmatterRenderer.Render(frontmatter, markdown));
@@ -571,6 +572,37 @@ public sealed class MeetingSummaryTools
             .Replace(Path.AltDirectorySeparatorChar.ToString(), "/", StringComparison.Ordinal);
     }
 
+    private async Task<List<string>?> ResolveSummaryAttendeesAsync(MeetingNote meetingNote)
+    {
+        var existingAttendees = await ReadExistingSummaryAttendeesAsync();
+        if (existingAttendees is not null)
+        {
+            return existingAttendees;
+        }
+
+        return meetingNote.Frontmatter.Attendees.Count == 0
+            ? null
+            : meetingNote.Frontmatter.Attendees.ToList();
+    }
+
+    private async Task<List<string>?> ReadExistingSummaryAttendeesAsync()
+    {
+        if (!File.Exists(artifacts.SummaryPath))
+        {
+            return null;
+        }
+
+        var content = await File.ReadAllTextAsync(artifacts.SummaryPath);
+        var document = MarkdownDocumentParser.SplitOptional(content);
+        if (!document.HasFrontmatter)
+        {
+            return null;
+        }
+
+        var yaml = YamlDeserializer.Deserialize<SummaryFrontmatterYaml>(document.Frontmatter);
+        return yaml?.Attendees;
+    }
+
     private sealed record ProjectFileTarget(BoundMeetingProject Project, string Path);
 
     private sealed record FileLineEditMode(
@@ -633,6 +665,12 @@ public sealed class MeetingSummaryTools
         public string? Summary { get; set; }
     }
 
+    private sealed class SummaryFrontmatterYaml
+    {
+        [YamlDotNet.Serialization.YamlMember(Alias = "attendees")]
+        public List<string>? Attendees { get; set; }
+    }
+
     private static DateTimeOffset? ParseDateTime(string? value)
     {
         return DateTimeOffset.TryParse(value, out var parsed)