.NET: feat: Implement message filtering to exclude non-portable content typ… (#5410)

* feat: Implement message filtering to exclude non-portable content types before forwarding Co-authored-by: Copilot <copilot@github.com> * Added unit tests to cover forwarded message filtering within AI Agent executors Co-authored-by: Copilot <copilot@github.com> * Update dotnet/src/Microsoft.Agents.AI.Workflows/Specialized/AIAgentHostExecutor.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> * Update dotnet/src/Microsoft.Agents.AI.Workflows/Specialized/AIAgentHostExecutor.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> * Update dotnet/src/Microsoft.Agents.AI.Workflows/Specialized/AIAgentHostExecutor.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> * fix: Disable forwarding of incoming messages in AIAgentHostExecutor tests Co-authored-by: Copilot <copilot@github.com> --------- Co-authored-by: Copilot <copilot@github.com> Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> Co-authored-by: Jacob Alber <jaalber@microsoft.com>
2026-06-16 21:04:09 +08:00 · 2026-05-05 07:43:45 -07:00
parent e7dc3b91f1
commit 162985f2a3
2 changed files with 291 additions and 2 deletions
@@ -181,8 +181,16 @@ internal sealed class AIAgentHostExecutor : ChatProtocolExecutor

        AgentResponse response = await this.InvokeAgentAsync(filteredMessages, context, emitEvents, cancellationToken).ConfigureAwait(false);

-        await context.SendMessageAsync(response.Messages is List<ChatMessage> list ? list : response.Messages.ToList(), cancellationToken)
-                     .ConfigureAwait(false);
+        // Filter out server-side artifacts (reasoning tokens, web search calls, etc.)
+        // that are internal to this agent. Forwarding them to other agents in the workflow
+        // causes invalid request errors when the receiving agent uses the Responses API,
+        // because these item types are not valid as input items.
+        List<ChatMessage> forwardableMessages = FilterForwardableMessages(response.Messages).ToList();
+        if (forwardableMessages.Count > 0)
+        {
+            await context.SendMessageAsync(forwardableMessages, cancellationToken)
+                         .ConfigureAwait(false);
+        }

        // If we have no outstanding requests, we can yield a turn token back to the workflow.
        if (!this.HasOutstandingRequests)
@@ -241,4 +249,60 @@ internal sealed class AIAgentHostExecutor : ChatProtocolExecutor

        return response;
    }
+
+    /// <summary>
+    /// Content types that represent meaningful conversational content portable across agents.
+    /// Messages containing only content types not in this set (e.g. reasoning tokens, web search
+    /// calls) are filtered out before forwarding, as they are output-only items that cause
+    /// schema validation errors when sent as input to the Responses API.
+    /// </summary>
+    private static readonly HashSet<Type> s_forwardableContentTypes =
+    [
+        typeof(TextContent),
+        typeof(DataContent),
+        typeof(UriContent),
+        typeof(FunctionCallContent),
+        typeof(FunctionResultContent),
+        typeof(ToolApprovalRequestContent),
+        typeof(ToolApprovalResponseContent),
+        typeof(HostedFileContent),
+        typeof(ErrorContent),
+    ];
+
+    /// <summary>
+    /// Filters response messages to only include those with portable conversational content,
+    /// and strips <see cref="ChatMessage.RawRepresentation"/> so that provider-specific output
+    /// items (e.g. <c>mcp_list_tools</c>, <c>reasoning</c>, <c>fabric_dataagent_preview_call</c>)
+    /// are not round-tripped by the M.E.AI library when the messages are sent to another agent.
+    /// </summary>
+    private static List<ChatMessage> FilterForwardableMessages(IList<ChatMessage> messages)
+    {
+        List<ChatMessage> result = [];
+
+        foreach (ChatMessage message in messages)
+        {
+            // Extract only the content items that are portable across agents.
+            List<AIContent> forwardableContents = message.Contents
+                .Where(c => s_forwardableContentTypes.Any(t => t.IsAssignableFrom(c.GetType())))
+                .ToList();
+
+            if (forwardableContents.Count == 0)
+            {
+                continue;
+            }
+
+            // Build a clean message without the provider-specific RawRepresentation,
+            // which would otherwise cause the M.E.AI library to round-trip the original
+            // output-only items (e.g. mcp_list_tools) as input to the next agent.
+            result.Add(new ChatMessage(message.Role, forwardableContents)
+            {
+                AuthorName = message.AuthorName,
+                MessageId = message.MessageId,
+                CreatedAt = message.CreatedAt,
+                AdditionalProperties = message.AdditionalProperties is null ? null : new(message.AdditionalProperties),
+            });
+        }
+
+        return result;
+    }
 }