Archive meeting workflow and screenshot changes

MeetingAssistant/Workflow/MeetingWorkflowEngine.cs

@@ -30,6 +30,10 @@ public sealed class NoopMeetingWorkflowEngine : IMeetingWorkflowEngine
 
 public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
 {
+    private static readonly Regex EmailAddressPattern = new(
+        @"(?<![A-Za-z0-9.!#$%&'*+/=?^_`{|}~-])(?<local>[A-Za-z0-9.!#$%&'*+/=?^_`{|}~-]+)@(?<domain>(?:[A-Za-z0-9](?:[A-Za-z0-9-]{0,61}[A-Za-z0-9])?\.)+[A-Za-z]{2,63})(?![A-Za-z0-9-])",
+        RegexOptions.Compiled | RegexOptions.CultureInvariant | RegexOptions.IgnoreCase);
+
     private static readonly string[] ParameterNames =
     [
         "meeting.attendees.count",
@@ -252,17 +256,65 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
         string template,
         MeetingWorkflowTemplateModel model)
     {
-        if (!template.Contains('@', StringComparison.Ordinal))
+        if (!ContainsRazorTemplateSyntax(template))
         {
             return template;
         }
 
         return await razorEngine.CompileRenderStringAsync(
             Guid.NewGuid().ToString("N"),
-            template,
+            EscapeEmailAddressAtSigns(template),
             model);
     }
 
+    private static bool ContainsRazorTemplateSyntax(string value)
+    {
+        if (!value.Contains('@', StringComparison.Ordinal))
+        {
+            return false;
+        }
+
+        var emailAtSigns = EmailAddressPattern
+            .Matches(value)
+            .Select(match => match.Index + match.Value.IndexOf('@', StringComparison.Ordinal))
+            .ToHashSet();
+
+        for (var index = 0; index < value.Length; index++)
+        {
+            if (value[index] != '@')
+            {
+                continue;
+            }
+
+            if (index + 1 < value.Length && value[index + 1] == '@')
+            {
+                index++;
+                continue;
+            }
+
+            if (emailAtSigns.Contains(index))
+            {
+                continue;
+            }
+
+            return true;
+        }
+
+        return false;
+    }
+
+    private static string EscapeEmailAddressAtSigns(string value)
+    {
+        if (!value.Contains('@', StringComparison.Ordinal))
+        {
+            return value;
+        }
+
+        return EmailAddressPattern.Replace(
+            value,
+            match => match.Value.Replace("@", "@@", StringComparison.Ordinal));
+    }
+
     private static bool SetProperty(
         MeetingNote meeting,
         string? property,