fix: finalize streamed agent responses

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

sidecar/src/Kopaya.AgentHost/Services/CopilotWorkflowRunner.cs

@@ -138,10 +138,21 @@ public sealed class CopilotWorkflowRunner : ITurnWorkflowRunner
             {
                 List<ChatMessage> allMessages = outputEvent.As<List<ChatMessage>>() ?? [];
                 List<ChatMessage> newMessages = allMessages.Skip(inputMessages.Count).ToList();
-                completedMessages = ConvertOutputMessages(command, newMessages, segments);
+                completedMessages = ProjectCompletedMessages(
+                    command,
+                    newMessages,
+                    segments.Select(segment => (segment.MessageId, segment.AuthorName, segment.Content.ToString())).ToList());
             }
         }
 
+        if (completedMessages.Count == 0 && segments.Count > 0)
+        {
+            completedMessages = ProjectCompletedMessages(
+                command,
+                [],
+                segments.Select(segment => (segment.MessageId, segment.AuthorName, segment.Content.ToString())).ToList());
+        }
+
         return completedMessages;
     }
 
@@ -291,17 +302,18 @@ public sealed class CopilotWorkflowRunner : ITurnWorkflowRunner
         return created;
     }
 
-    private static List<ChatMessageDto> ConvertOutputMessages(
+    internal static List<ChatMessageDto> ProjectCompletedMessages(
         RunTurnCommandDto command,
         IReadOnlyList<ChatMessage> newMessages,
-        IReadOnlyList<StreamingSegment> segments)
+        IReadOnlyList<(string MessageId, string AuthorName, string Content)> segments)
     {
         List<ChatMessageDto> mapped = [];
         int segmentIndex = 0;
 
         foreach (ChatMessage message in newMessages.Where(message => message.Role != ChatRole.User))
         {
-            StreamingSegment? segment = segmentIndex < segments.Count ? segments[segmentIndex] : null;
+            (string MessageId, string AuthorName, string Content)? segment =
+                segmentIndex < segments.Count ? segments[segmentIndex] : null;
             segmentIndex++;
 
             mapped.Add(new ChatMessageDto
@@ -312,7 +324,7 @@ public sealed class CopilotWorkflowRunner : ITurnWorkflowRunner
                     command.Pattern,
                     message.AuthorName,
                     segment?.AuthorName),
-                Content = message.Text ?? segment?.Content.ToString() ?? string.Empty,
+                Content = message.Text ?? segment?.Content ?? string.Empty,
                 CreatedAt = DateTimeOffset.UtcNow.ToString("O"),
             });
         }
@@ -324,7 +336,7 @@ public sealed class CopilotWorkflowRunner : ITurnWorkflowRunner
                 Id = segment.MessageId,
                 Role = "assistant",
                 AuthorName = AgentIdentityResolver.ResolveDisplayAuthorName(command.Pattern, segment.AuthorName),
-                Content = segment.Content.ToString(),
+                Content = segment.Content,
                 CreatedAt = DateTimeOffset.UtcNow.ToString("O"),
             }));
         }

sidecar/tests/Kopaya.AgentHost.Tests/CopilotWorkflowRunnerTests.cs

@@ -0,0 +1,102 @@
+using Kopaya.AgentHost.Contracts;
+using Kopaya.AgentHost.Services;
+using Microsoft.Extensions.AI;
+
+namespace Kopaya.AgentHost.Tests;
+
+public sealed class CopilotWorkflowRunnerTests
+{
+    [Fact]
+    public void ProjectCompletedMessages_FallsBackToStreamingSegmentsWhenWorkflowOutputIsMissing()
+    {
+        RunTurnCommandDto command = new()
+        {
+            RequestId = "turn-1",
+            SessionId = "session-1",
+            Pattern = new PatternDefinitionDto
+            {
+                Id = "pattern-concurrent",
+                Name = "Concurrent Brainstorm",
+                Mode = "concurrent",
+                Availability = "available",
+                Agents =
+                [
+                    CreateAgent(id: "agent-concurrent-architect", name: "Architect"),
+                    CreateAgent(id: "agent-concurrent-implementer", name: "Implementer"),
+                ],
+            },
+        };
+
+        IReadOnlyList<ChatMessageDto> messages = CopilotWorkflowRunner.ProjectCompletedMessages(
+            command,
+            [],
+            [
+                ("msg-1", "Architect", "Architecture reply"),
+                ("msg-2", "Implementer", "Implementation reply"),
+            ]);
+
+        Assert.Collection(
+            messages,
+            architect =>
+            {
+                Assert.Equal("msg-1", architect.Id);
+                Assert.Equal("Architect", architect.AuthorName);
+                Assert.Equal("Architecture reply", architect.Content);
+            },
+            implementer =>
+            {
+                Assert.Equal("msg-2", implementer.Id);
+                Assert.Equal("Implementer", implementer.AuthorName);
+                Assert.Equal("Implementation reply", implementer.Content);
+            });
+    }
+
+    [Fact]
+    public void ProjectCompletedMessages_CanonicalizesWorkflowOutputAuthorNames()
+    {
+        RunTurnCommandDto command = new()
+        {
+            RequestId = "turn-1",
+            SessionId = "session-1",
+            Pattern = new PatternDefinitionDto
+            {
+                Id = "pattern-single",
+                Name = "Single Agent",
+                Mode = "single",
+                Availability = "available",
+                Agents =
+                [
+                    CreateAgent(id: "agent-single-primary", name: "Primary Agent"),
+                ],
+            },
+        };
+
+        IReadOnlyList<ChatMessageDto> messages = CopilotWorkflowRunner.ProjectCompletedMessages(
+            command,
+            [
+                new ChatMessage(ChatRole.Assistant, "Hello")
+                {
+                    AuthorName = "assistant",
+                },
+            ],
+            [
+                ("msg-1", "Primary Agent", "Hello"),
+            ]);
+
+        ChatMessageDto message = Assert.Single(messages);
+        Assert.Equal("msg-1", message.Id);
+        Assert.Equal("Primary Agent", message.AuthorName);
+        Assert.Equal("Hello", message.Content);
+    }
+
+    private static PatternAgentDefinitionDto CreateAgent(string id, string name)
+    {
+        return new PatternAgentDefinitionDto
+        {
+            Id = id,
+            Name = name,
+            Model = "gpt-5.4",
+            Instructions = "Help with the request.",
+        };
+    }
+}