Add attendee transformation workflows

MeetingAssistant/Recording/MeetingRecordingCoordinator.cs

@@ -213,7 +213,12 @@ public sealed class MeetingRecordingCoordinator
             currentMeetingNote = await meetingNoteStore.ReadAsync(currentMeetingNote.Path, cancellationToken);
             if (suppliedMetadata is not null)
             {
-                await ApplyMeetingMetadataAsync(currentMeetingNote, suppliedMetadata, runOptions, cancellationToken);
+                await ApplyMeetingMetadataAsync(
+                    currentArtifacts,
+                    currentMeetingNote,
+                    suppliedMetadata,
+                    runOptions,
+                    cancellationToken);
                 currentMeetingNote = await meetingNoteStore.SaveAsync(
                     currentMeetingNote,
                     runOptions,
@@ -1030,7 +1035,7 @@ public sealed class MeetingRecordingCoordinator
                 }
 
                 var meetingNote = await meetingNoteStore.ReadAsync(run.MeetingNotePath, CancellationToken.None);
-                await ApplyMeetingMetadataAsync(meetingNote, metadata, run.Options, CancellationToken.None);
+                await ApplyMeetingMetadataAsync(run.Artifacts, meetingNote, metadata, run.Options, CancellationToken.None);
                 meetingNote = await meetingNoteStore.SaveAsync(meetingNote, run.Options, CancellationToken.None);
                 if (currentMeetingNote?.Path == meetingNote.Path)
                 {
@@ -1082,6 +1087,7 @@ public sealed class MeetingRecordingCoordinator
     }
 
     private async Task ApplyMeetingMetadataAsync(
+        MeetingSessionArtifacts artifacts,
         MeetingNote meetingNote,
         MeetingMetadata metadata,
         MeetingAssistantOptions options,
@@ -1104,10 +1110,39 @@ public sealed class MeetingRecordingCoordinator
                 return;
             }
 
-            meetingNote.Frontmatter.Attendees = await CanonicalizeAttendeesAsync(metadata.Attendees, cancellationToken);
+            var canonicalized = await CanonicalizeAttendeesAsync(metadata.Attendees, cancellationToken);
+            meetingNote.Frontmatter.Attendees = await TransformAttendeesAsync(
+                artifacts,
+                canonicalized,
+                options,
+                cancellationToken);
         }
     }
 
+    private async Task<List<string>> TransformAttendeesAsync(
+        MeetingSessionArtifacts artifacts,
+        IReadOnlyList<string> attendees,
+        MeetingAssistantOptions options,
+        CancellationToken cancellationToken)
+    {
+        var transformed = new List<string>();
+        foreach (var attendee in attendees)
+        {
+            var value = await TransformAttendeeAsync(artifacts, attendee, options, cancellationToken);
+            var storageValue = string.Equals(value, attendee, StringComparison.Ordinal)
+                ? attendee.Trim()
+                : NormalizeAttendeeName(value);
+            var normalized = NormalizeAttendeeName(storageValue);
+            if (!string.IsNullOrWhiteSpace(normalized) &&
+                !transformed.Contains(normalized, StringComparer.OrdinalIgnoreCase))
+            {
+                transformed.Add(storageValue);
+            }
+        }
+
+        return transformed;
+    }
+
     private async Task<List<string>> CanonicalizeAttendeesAsync(
         IReadOnlyList<string> attendees,
         CancellationToken cancellationToken)
@@ -1422,8 +1457,17 @@ public sealed class MeetingRecordingCoordinator
                 continue;
             }
 
+            var transformedDisplayName = await TransformAttendeeAsync(
+                artifacts,
+                match.DisplayName.Trim(),
+                runOptions,
+                cancellationToken);
+            var displayName = string.Equals(transformedDisplayName, match.DisplayName.Trim(), StringComparison.Ordinal)
+                ? match.DisplayName.Trim()
+                : NormalizeAttendeeName(transformedDisplayName);
             var acceptedNames = match.AcceptedNames
                 .Append(match.DisplayName)
+                .Append(displayName)
                 .Select(NormalizeAttendeeName)
                 .Where(name => !string.IsNullOrWhiteSpace(name))
                 .Distinct(StringComparer.OrdinalIgnoreCase)
@@ -1442,7 +1486,6 @@ public sealed class MeetingRecordingCoordinator
                 continue;
             }
 
-            var displayName = match.DisplayName.Trim();
             meetingNote.Frontmatter.Attendees.Add(displayName);
             existingNames.Add(NormalizeAttendeeName(displayName));
             changed = true;
@@ -1502,6 +1545,18 @@ public sealed class MeetingRecordingCoordinator
         return MeetingAttendeeNames.NormalizeDisplayName(attendee);
     }
 
+    private async Task<string> TransformAttendeeAsync(
+        MeetingSessionArtifacts artifacts,
+        string attendee,
+        MeetingAssistantOptions options,
+        CancellationToken cancellationToken)
+    {
+        return await meetingWorkflowEngine.TransformAttendeeAsync(
+            MeetingWorkflowEvent.AttendeeAdded(artifacts, attendee),
+            options,
+            cancellationToken);
+    }
+
     private static bool RemoveDuplicateAcceptedAliases(
         List<string> attendees,
         string displayName,

MeetingAssistant/Screenshots/MeetingScreenshotService.cs

@@ -5,6 +5,7 @@ using System.Runtime.InteropServices;
 using System.Text.RegularExpressions;
 using MeetingAssistant.MeetingNotes;
 using MeetingAssistant.Speakers;
+using MeetingAssistant.Workflow;
 
 namespace MeetingAssistant.Screenshots;
 
@@ -149,6 +150,7 @@ public sealed partial class MeetingScreenshotService :
     private readonly IMeetingArtifactStore artifactStore;
     private readonly IMeetingNoteStore meetingNoteStore;
     private readonly ISpeakerIdentityAttendeeCanonicalizer attendeeCanonicalizer;
+    private readonly IMeetingWorkflowEngine meetingWorkflowEngine;
     private readonly IScreenshotOcrClient ocrClient;
     private readonly ILogger<MeetingScreenshotService> logger;
     private readonly ConcurrentDictionary<string, List<PendingOcrTask>> pendingOcrByContext = new(StringComparer.OrdinalIgnoreCase);
@@ -160,12 +162,14 @@ public sealed partial class MeetingScreenshotService :
         IMeetingNoteStore meetingNoteStore,
         ISpeakerIdentityAttendeeCanonicalizer attendeeCanonicalizer,
         IScreenshotOcrClient ocrClient,
-        ILogger<MeetingScreenshotService> logger)
+        ILogger<MeetingScreenshotService> logger,
+        IMeetingWorkflowEngine? meetingWorkflowEngine = null)
     {
         this.screenshotCapture = screenshotCapture;
         this.artifactStore = artifactStore;
         this.meetingNoteStore = meetingNoteStore;
         this.attendeeCanonicalizer = attendeeCanonicalizer;
+        this.meetingWorkflowEngine = meetingWorkflowEngine ?? NoopMeetingWorkflowEngine.Instance;
         this.ocrClient = ocrClient;
         this.logger = logger;
     }
@@ -434,6 +438,7 @@ public sealed partial class MeetingScreenshotService :
                 await AddOcrAttendeesAsync(
                     artifacts,
                     result.Attendees,
+                    options,
                     CancellationToken.None);
             }
         }
@@ -477,6 +482,7 @@ public sealed partial class MeetingScreenshotService :
     private async Task AddOcrAttendeesAsync(
         MeetingSessionArtifacts artifacts,
         IReadOnlyList<string> attendees,
+        MeetingAssistantOptions options,
         CancellationToken cancellationToken)
     {
         var additions = MeetingAttendeeNames.NormalizeDistinct(attendees);
@@ -488,8 +494,13 @@ public sealed partial class MeetingScreenshotService :
         try
         {
             var meetingNote = await meetingNoteStore.ReadAsync(artifacts.MeetingNotePath, cancellationToken);
+            var transformedAdditions = await TransformAttendeesAsync(
+                artifacts,
+                additions,
+                options,
+                cancellationToken);
             var canonicalized = await attendeeCanonicalizer.CanonicalizeAsync(
-                meetingNote.Frontmatter.Attendees.Concat(additions).ToList(),
+                meetingNote.Frontmatter.Attendees.Concat(transformedAdditions).ToList(),
                 cancellationToken);
             if (meetingNote.Frontmatter.Attendees.SequenceEqual(canonicalized, StringComparer.Ordinal))
             {
@@ -512,6 +523,30 @@ public sealed partial class MeetingScreenshotService :
         }
     }
 
+    private async Task<IReadOnlyList<string>> TransformAttendeesAsync(
+        MeetingSessionArtifacts artifacts,
+        IReadOnlyList<string> attendees,
+        MeetingAssistantOptions options,
+        CancellationToken cancellationToken)
+    {
+        var transformed = new List<string>();
+        foreach (var attendee in attendees)
+        {
+            var value = await meetingWorkflowEngine.TransformAttendeeAsync(
+                MeetingWorkflowEvent.AttendeeAdded(artifacts, attendee),
+                options,
+                cancellationToken);
+            var normalized = MeetingAttendeeNames.NormalizeDisplayName(value);
+            if (!string.IsNullOrWhiteSpace(normalized) &&
+                !transformed.Contains(normalized, StringComparer.OrdinalIgnoreCase))
+            {
+                transformed.Add(normalized);
+            }
+        }
+
+        return transformed;
+    }
+
     private async Task<bool> ReplaceOcrPlaceholderAsync(
         string assistantContextPath,
         string screenshotId,

MeetingAssistant/Summary/MeetingSummaryTools.cs

@@ -1,6 +1,7 @@
 using MeetingAssistant.MeetingNotes;
 using MeetingAssistant.Speakers;
 using MeetingAssistant.Transcription;
+using MeetingAssistant.Workflow;
 using YamlDotNet.Serialization;
 
 namespace MeetingAssistant.Summary;
@@ -13,6 +14,7 @@ public sealed class MeetingSummaryTools
     private readonly MeetingAssistantOptions options;
     private readonly IDictationWordStore? dictationWordStore;
     private readonly SummaryAgentWriteAudit? writeAudit;
+    private readonly IMeetingWorkflowEngine meetingWorkflowEngine;
     private readonly BoundMeetingProjectResolver projectResolver;
 
     public MeetingSummaryTools(MeetingSessionArtifacts artifacts)
@@ -24,12 +26,14 @@ public sealed class MeetingSummaryTools
         MeetingSessionArtifacts artifacts,
         MeetingAssistantOptions options,
         IDictationWordStore? dictationWordStore = null,
-        SummaryAgentWriteAudit? writeAudit = null)
+        SummaryAgentWriteAudit? writeAudit = null,
+        IMeetingWorkflowEngine? meetingWorkflowEngine = null)
     {
         this.artifacts = artifacts;
         this.options = options;
         this.dictationWordStore = dictationWordStore;
         this.writeAudit = writeAudit;
+        this.meetingWorkflowEngine = meetingWorkflowEngine ?? NoopMeetingWorkflowEngine.Instance;
         projectResolver = new BoundMeetingProjectResolver(options);
     }
 
@@ -98,7 +102,11 @@ public sealed class MeetingSummaryTools
             return "Refused: attendee must not be empty.";
         }
 
-        var displayName = attendee.Trim();
+        var displayName = await meetingWorkflowEngine.TransformAttendeeAsync(
+            MeetingWorkflowEvent.AttendeeAdded(artifacts, attendee.Trim()),
+            options,
+            CancellationToken.None);
+        displayName = displayName.Trim();
         var normalized = MeetingAttendeeNames.NormalizeDisplayName(displayName);
         if (string.IsNullOrWhiteSpace(normalized))
         {

MeetingAssistant/Summary/OpenAiMeetingSummaryAgentPipeline.cs

@@ -1,5 +1,6 @@
 using MeetingAssistant.MeetingNotes;
 using MeetingAssistant.Transcription;
+using MeetingAssistant.Workflow;
 using Microsoft.Agents.AI;
 using Microsoft.Agents.AI.Compaction;
 using Microsoft.Extensions.AI;
@@ -17,6 +18,7 @@ public sealed class OpenAiMeetingSummaryAgentPipeline : IMeetingSummaryPipeline
     private readonly IMeetingSummaryFailureWriter failureWriter;
     private readonly IMeetingSummaryInstructionBuilder instructionBuilder;
     private readonly IDictationWordStore dictationWordStore;
+    private readonly IMeetingWorkflowEngine meetingWorkflowEngine;
 
     public OpenAiMeetingSummaryAgentPipeline(
         IOptions<MeetingAssistantOptions> options,
@@ -25,7 +27,8 @@ public sealed class OpenAiMeetingSummaryAgentPipeline : IMeetingSummaryPipeline
         IServiceProvider services,
         IMeetingSummaryFailureWriter failureWriter,
         IMeetingSummaryInstructionBuilder instructionBuilder,
-        IDictationWordStore dictationWordStore)
+        IDictationWordStore dictationWordStore,
+        IMeetingWorkflowEngine meetingWorkflowEngine)
     {
         this.options = options.Value;
         this.loggerFactory = loggerFactory;
@@ -34,6 +37,7 @@ public sealed class OpenAiMeetingSummaryAgentPipeline : IMeetingSummaryPipeline
         this.failureWriter = failureWriter;
         this.instructionBuilder = instructionBuilder;
         this.dictationWordStore = dictationWordStore;
+        this.meetingWorkflowEngine = meetingWorkflowEngine;
     }
 
     public async Task<MeetingSummaryRunResult> RunAsync(
@@ -51,7 +55,12 @@ public sealed class OpenAiMeetingSummaryAgentPipeline : IMeetingSummaryPipeline
         var agentOptions = options.Agent;
         var key = ResolveApiKey(agentOptions);
         var writeAudit = new SummaryAgentWriteAudit(artifacts);
-        var meetingTools = new MeetingSummaryTools(artifacts, options, dictationWordStore, writeAudit);
+        var meetingTools = new MeetingSummaryTools(
+            artifacts,
+            options,
+            dictationWordStore,
+            writeAudit,
+            meetingWorkflowEngine);
         var tools = CreateTools(meetingTools);
         var instructions = await instructionBuilder.BuildAsync(artifacts, options, cancellationToken);
         using var compactionSummaryClient = new LiteLlmResponsesChatClient(

MeetingAssistant/Workflow/MeetingWorkflowEngine.cs

@@ -17,6 +17,14 @@ public interface IMeetingWorkflowEngine
         MeetingWorkflowEvent workflowEvent,
         MeetingAssistantOptions options,
         CancellationToken cancellationToken);
+
+    Task<string> TransformAttendeeAsync(
+        MeetingWorkflowEvent workflowEvent,
+        MeetingAssistantOptions options,
+        CancellationToken cancellationToken)
+    {
+        return Task.FromResult(workflowEvent.AttendeeName ?? "");
+    }
 }
 
 public sealed class NoopMeetingWorkflowEngine : IMeetingWorkflowEngine
@@ -38,6 +46,14 @@ public sealed class NoopMeetingWorkflowEngine : IMeetingWorkflowEngine
     {
         return Task.FromResult(workflowEvent.TranscriptLineText ?? "");
     }
+
+    public Task<string> TransformAttendeeAsync(
+        MeetingWorkflowEvent workflowEvent,
+        MeetingAssistantOptions options,
+        CancellationToken cancellationToken)
+    {
+        return Task.FromResult(workflowEvent.AttendeeName ?? "");
+    }
 }
 
 public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
@@ -54,7 +70,8 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
         "state.to",
         "speaker.name",
         MeetingWorkflowRuleSchema.PropertyTranscriptLine,
-        MeetingWorkflowRuleSchema.ParameterTranscriptSpeaker
+        MeetingWorkflowRuleSchema.ParameterTranscriptSpeaker,
+        MeetingWorkflowRuleSchema.PropertyAttendeeName
     ];
 
     private readonly IMeetingWorkflowRulesProvider rulesProvider;
@@ -98,6 +115,21 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
             ?? "";
     }
 
+    public async Task<string> TransformAttendeeAsync(
+        MeetingWorkflowEvent workflowEvent,
+        MeetingAssistantOptions options,
+        CancellationToken cancellationToken)
+    {
+        if (workflowEvent.Type != MeetingWorkflowEventType.AttendeeAdded)
+        {
+            throw new ArgumentException("Workflow event must be an attendee added event.", nameof(workflowEvent));
+        }
+
+        return await RunCoreAsync(workflowEvent, options, cancellationToken)
+            ?? workflowEvent.AttendeeName
+            ?? "";
+    }
+
     private async Task<string?> RunCoreAsync(
         MeetingWorkflowEvent workflowEvent,
         MeetingAssistantOptions options,
@@ -107,7 +139,7 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
         var context = new MeetingWorkflowExecutionContext(workflowEvent);
         if (rules.Count == 0)
         {
-            return context.TranscriptLine;
+            return context.ResultValue;
         }
 
         var meeting = await meetingNoteStore.ReadAsync(
@@ -134,10 +166,18 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
                 var model = CreateTemplateModel(meeting, context);
                 foreach (var step in rule.Steps)
                 {
+                    if (workflowEvent.Type == MeetingWorkflowEventType.AttendeeAdded &&
+                        !IsAttendeeTransformStep(step))
+                    {
+                        throw new InvalidOperationException(
+                            "attendee_added workflow rules can only transform attendee.name with set_property.");
+                    }
+
                     var stepChanged = await ApplyStepAsync(
                         step,
                         meeting,
                         context,
+                        options,
                         model,
                         cancellationToken);
                     ruleNoteChanged |= stepChanged;
@@ -176,7 +216,7 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
                 cancellationToken);
         }
 
-        return context.TranscriptLine;
+        return context.ResultValue;
     }
 
     private static bool MatchesTrigger(
@@ -229,9 +269,41 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
                         StringComparison.OrdinalIgnoreCase));
         }
 
+        if (trigger.AttendeeAdded is not null)
+        {
+            return workflowEvent.Type == MeetingWorkflowEventType.AttendeeAdded &&
+                MatchesAttendeeAddedTrigger(trigger.AttendeeAdded, workflowEvent.AttendeeName);
+        }
+
         return false;
     }
 
+    private static bool MatchesAttendeeAddedTrigger(
+        MeetingWorkflowAttendeeAddedTrigger trigger,
+        string? attendeeName)
+    {
+        var attendee = attendeeName ?? "";
+        if (!string.IsNullOrWhiteSpace(trigger.EqualsValue) &&
+            !string.Equals(attendee, trigger.EqualsValue.Trim(), StringComparison.OrdinalIgnoreCase))
+        {
+            return false;
+        }
+
+        if (!string.IsNullOrWhiteSpace(trigger.Contains) &&
+            !attendee.Contains(trigger.Contains.Trim(), StringComparison.OrdinalIgnoreCase))
+        {
+            return false;
+        }
+
+        if (!string.IsNullOrWhiteSpace(trigger.Regex) &&
+            !Regex.IsMatch(attendee, trigger.Regex, RegexOptions.IgnoreCase))
+        {
+            return false;
+        }
+
+        return true;
+    }
+
     private bool EvaluateConditions(
         IReadOnlyList<MeetingWorkflowCondition> conditions,
         MeetingNote meeting,
@@ -298,6 +370,7 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
         MeetingWorkflowStep step,
         MeetingNote meeting,
         MeetingWorkflowExecutionContext context,
+        MeetingAssistantOptions options,
         MeetingWorkflowTemplateModel model,
         CancellationToken cancellationToken)
     {
@@ -305,7 +378,11 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
         switch (step.Uses.Trim().ToLowerInvariant())
         {
             case MeetingWorkflowRuleSchema.StepAddAttendee:
-                return AddUnique(meeting.Frontmatter.Attendees, value, MeetingAttendeeNames.NormalizeDisplayName);
+                var attendee = await TransformAttendeeAsync(
+                    MeetingWorkflowEvent.AttendeeAdded(context.Event.Artifacts, value),
+                    options,
+                    cancellationToken);
+                return AddUnique(meeting.Frontmatter.Attendees, attendee, MeetingAttendeeNames.NormalizeDisplayName);
             case MeetingWorkflowRuleSchema.StepRemoveAttendee:
                 return RemoveValue(meeting.Frontmatter.Attendees, value);
             case MeetingWorkflowRuleSchema.StepAddProject:
@@ -319,6 +396,9 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
             case MeetingWorkflowRuleSchema.StepSetProperty when IsTranscriptLineProperty(step.Property ?? step.Name):
                 SetTranscriptLine(context, value);
                 return false;
+            case MeetingWorkflowRuleSchema.StepSetProperty when IsAttendeeNameProperty(step.Property ?? step.Name):
+                SetAttendeeName(context, value);
+                return false;
             case MeetingWorkflowRuleSchema.StepSetProperty:
                 return SetProperty(meeting, step.Property ?? step.Name, value);
             default:
@@ -370,11 +450,39 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
         context.TranscriptLine = value;
     }
 
+    private static void SetAttendeeName(
+        MeetingWorkflowExecutionContext context,
+        string value)
+    {
+        if (context.Event.Type != MeetingWorkflowEventType.AttendeeAdded)
+        {
+            throw new InvalidOperationException("The attendee.name property can only be set during attendee_added events.");
+        }
+
+        if (string.Equals(context.AttendeeName, value, StringComparison.Ordinal))
+        {
+            return;
+        }
+
+        context.AttendeeName = value;
+    }
+
     private static bool IsTranscriptLineProperty(string? property)
     {
         return MeetingWorkflowRuleSchema.IsProperty(property, MeetingWorkflowRuleSchema.PropertyTranscriptLine);
     }
 
+    private static bool IsAttendeeNameProperty(string? property)
+    {
+        return MeetingWorkflowRuleSchema.IsProperty(property, MeetingWorkflowRuleSchema.PropertyAttendeeName);
+    }
+
+    private static bool IsAttendeeTransformStep(MeetingWorkflowStep step)
+    {
+        return MeetingWorkflowRuleSchema.IsStep(step.Uses, MeetingWorkflowRuleSchema.StepSetProperty) &&
+            IsAttendeeNameProperty(step.Property ?? step.Name);
+    }
+
     private static bool AddUnique(
         List<string> values,
         string value,
@@ -456,7 +564,8 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
             ["state.to"] = workflowEvent.ToState is { } to ? MeetingWorkflowStateNames.ToRuleName(to) : "",
             ["speaker.name"] = workflowEvent.SpeakerName,
             [MeetingWorkflowRuleSchema.PropertyTranscriptLine] = context.TranscriptLine ?? "",
-            [MeetingWorkflowRuleSchema.ParameterTranscriptSpeaker] = workflowEvent.SpeakerName ?? ""
+            [MeetingWorkflowRuleSchema.ParameterTranscriptSpeaker] = workflowEvent.SpeakerName ?? "",
+            [MeetingWorkflowRuleSchema.PropertyAttendeeName] = context.AttendeeName ?? ""
         };
     }
 
@@ -480,7 +589,10 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
                 : new MeetingWorkflowSpeakerModel(workflowEvent.SpeakerName),
             new MeetingWorkflowTranscriptModel(
                 context.TranscriptLine ?? "",
-                workflowEvent.SpeakerName ?? ""));
+                workflowEvent.SpeakerName ?? ""),
+            string.IsNullOrWhiteSpace(context.AttendeeName)
+                ? null
+                : new MeetingWorkflowAttendeeModel(context.AttendeeName));
     }
 
     private sealed class MeetingWorkflowExecutionContext
@@ -489,10 +601,23 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
         {
             Event = workflowEvent;
             TranscriptLine = workflowEvent.TranscriptLineText;
+            AttendeeName = workflowEvent.AttendeeName;
         }
 
         public MeetingWorkflowEvent Event { get; }
 
         public string? TranscriptLine { get; set; }
+
+        public string? AttendeeName { get; set; }
+
+        public string? ResultValue
+        {
+            get
+            {
+                return Event.Type == MeetingWorkflowEventType.AttendeeAdded
+                    ? AttendeeName
+                    : TranscriptLine;
+            }
+        }
     }
 }

MeetingAssistant/Workflow/MeetingWorkflowEvent.cs

@@ -7,7 +7,8 @@ public enum MeetingWorkflowEventType
     Created,
     StateTransition,
     SpeakerIdentified,
-    TranscriptLine
+    TranscriptLine,
+    AttendeeAdded
 }
 
 public sealed record MeetingWorkflowEvent(
@@ -16,7 +17,8 @@ public sealed record MeetingWorkflowEvent(
     AssistantContextState? FromState = null,
     AssistantContextState? ToState = null,
     string? SpeakerName = null,
-    string? TranscriptLineText = null)
+    string? TranscriptLineText = null,
+    string? AttendeeName = null)
 {
     public static MeetingWorkflowEvent Created(MeetingSessionArtifacts artifacts)
     {
@@ -49,4 +51,14 @@ public sealed record MeetingWorkflowEvent(
             SpeakerName: speakerName,
             TranscriptLineText: line);
     }
+
+    public static MeetingWorkflowEvent AttendeeAdded(
+        MeetingSessionArtifacts artifacts,
+        string attendeeName)
+    {
+        return new MeetingWorkflowEvent(
+            MeetingWorkflowEventType.AttendeeAdded,
+            artifacts,
+            AttendeeName: attendeeName);
+    }
 }

MeetingAssistant/Workflow/MeetingWorkflowModels.cs

@@ -37,6 +37,9 @@ public sealed class MeetingWorkflowTrigger
 
     [YamlMember(Alias = "transcript_line")]
     public MeetingWorkflowTranscriptLineTrigger? TranscriptLine { get; set; }
+
+    [YamlMember(Alias = "attendee_added")]
+    public MeetingWorkflowAttendeeAddedTrigger? AttendeeAdded { get; set; }
 }
 
 public sealed class MeetingWorkflowStateTransitionTrigger
@@ -60,6 +63,18 @@ public sealed class MeetingWorkflowTranscriptLineTrigger
     public string? Speaker { get; set; }
 }
 
+public sealed class MeetingWorkflowAttendeeAddedTrigger
+{
+    [YamlMember(Alias = "equals")]
+    public string? EqualsValue { get; set; }
+
+    [YamlMember(Alias = "contains")]
+    public string? Contains { get; set; }
+
+    [YamlMember(Alias = "regex")]
+    public string? Regex { get; set; }
+}
+
 public sealed class MeetingWorkflowCondition
 {
     [YamlMember(Alias = "condition")]
@@ -94,7 +109,8 @@ public sealed record MeetingWorkflowTemplateModel(
     MeetingWorkflowMeetingModel Meeting,
     MeetingWorkflowEventModel Event,
     MeetingWorkflowSpeakerModel? Speaker,
-    MeetingWorkflowTranscriptModel? Transcript);
+    MeetingWorkflowTranscriptModel? Transcript,
+    MeetingWorkflowAttendeeModel? Attendee);
 
 public sealed record MeetingWorkflowMeetingModel(
     string Title,
@@ -111,6 +127,8 @@ public sealed record MeetingWorkflowSpeakerModel(string Name);
 
 public sealed record MeetingWorkflowTranscriptModel(string Line, string Speaker);
 
+public sealed record MeetingWorkflowAttendeeModel(string Name);
+
 internal static class MeetingWorkflowStateNames
 {
     public static string ToRuleName(AssistantContextState state)

MeetingAssistant/Workflow/MeetingWorkflowRuleSchema.cs

@@ -12,13 +12,15 @@ internal static class MeetingWorkflowRuleSchema
     public const string PropertyMeetingTitle = "meeting.title";
     public const string PropertyTranscriptLine = "transcript.line";
     public const string ParameterTranscriptSpeaker = "transcript.speaker";
+    public const string PropertyAttendeeName = "attendee.name";
 
     public static readonly string[] SupportedTriggerKeys =
     [
         "created",
         "state_transition",
         "speaker_identified",
-        "transcript_line"
+        "transcript_line",
+        "attendee_added"
     ];
 
     public static readonly string[] SupportedConditionKeys =
@@ -42,7 +44,8 @@ internal static class MeetingWorkflowRuleSchema
     [
         PropertyTitle,
         PropertyMeetingTitle,
-        PropertyTranscriptLine
+        PropertyTranscriptLine,
+        PropertyAttendeeName
     ];
 
     public static bool IsStep(string? value, string step)

MeetingAssistant/Workflow/MeetingWorkflowRulesValidator.cs

@@ -59,7 +59,8 @@ internal static class MeetingWorkflowRulesValidator
             trigger.Created is not null,
             trigger.StateTransition is not null,
             trigger.SpeakerIdentified is not null,
-            trigger.TranscriptLine is not null);
+            trigger.TranscriptLine is not null,
+            trigger.AttendeeAdded is not null);
         if (configuredCount == 0)
         {
             errors.Add($"{ruleName} on[{triggerIndex + 1}] must contain one supported trigger: {JoinAllowed(MeetingWorkflowRuleSchema.SupportedTriggerKeys)}.");
@@ -137,6 +138,12 @@ internal static class MeetingWorkflowRulesValidator
             return;
         }
 
+        if (HasAttendeeAddedTrigger(rule) &&
+            !IsAttendeeNameSetPropertyStep(step))
+        {
+            errors.Add($"{stepPath} on attendee_added rules can only transform the attendee with 'set_property' property 'attendee.name'.");
+        }
+
         if (MeetingWorkflowRuleSchema.IsStep(uses, MeetingWorkflowRuleSchema.StepSetProperty))
         {
             var property = step.Property ?? step.Name;
@@ -153,6 +160,11 @@ internal static class MeetingWorkflowRulesValidator
             {
                 errors.Add($"{stepPath} can set 'transcript.line' only on rules with a transcript_line trigger.");
             }
+            else if (MeetingWorkflowRuleSchema.IsProperty(property, MeetingWorkflowRuleSchema.PropertyAttendeeName) &&
+                !HasAttendeeAddedTrigger(rule))
+            {
+                errors.Add($"{stepPath} can set 'attendee.name' only on rules with an attendee_added trigger.");
+            }
         }
 
         if (step.Value is { } value &&
@@ -181,6 +193,17 @@ internal static class MeetingWorkflowRulesValidator
         return rule.On.Any(static trigger => trigger.TranscriptLine is not null);
     }
 
+    private static bool HasAttendeeAddedTrigger(MeetingWorkflowRule rule)
+    {
+        return rule.On.Any(static trigger => trigger.AttendeeAdded is not null);
+    }
+
+    private static bool IsAttendeeNameSetPropertyStep(MeetingWorkflowStep step)
+    {
+        return MeetingWorkflowRuleSchema.IsStep(step.Uses, MeetingWorkflowRuleSchema.StepSetProperty) &&
+            MeetingWorkflowRuleSchema.IsProperty(step.Property ?? step.Name, MeetingWorkflowRuleSchema.PropertyAttendeeName);
+    }
+
     private static int CountConfigured(params bool[] values)
     {
         return values.Count(static value => value);
@@ -206,7 +229,8 @@ internal static class MeetingWorkflowRulesValidator
             new MeetingWorkflowSpeakerModel("Ada Lovelace"),
             new MeetingWorkflowTranscriptModel(
                 "[00:00:01] Ada Lovelace: Validation line.",
-                "Ada Lovelace"));
+                "Ada Lovelace"),
+            new MeetingWorkflowAttendeeModel("Ada Lovelace"));
     }
 
     private static string FormatRazorValidationMessage(Exception exception)