DevUI: Use metadata.entity_id for agent/workflow name instead of model field

Author: ReubenBond

dotnet/src/Microsoft.Agents.AI.Hosting.OpenAI/Responses/AgentRunResponseExtensions.cs

@@ -56,7 +56,7 @@ public static Response ToResponse(
             MaxOutputTokens = request.MaxOutputTokens,
             MaxToolCalls = request.MaxToolCalls,
             Metadata = request.Metadata is IReadOnlyDictionary<string, string> metadata ? new Dictionary<string, string>(metadata) : [],
-            Model = request.Agent?.Name ?? request.Model,
+            Model = request.Model,
             Output = output,
             ParallelToolCalls = request.ParallelToolCalls ?? true,
             PreviousResponseId = request.PreviousResponseId,

dotnet/src/Microsoft.Agents.AI.Hosting.OpenAI/Responses/AgentRunResponseUpdateExtensions.cs

@@ -165,7 +165,7 @@ Response CreateResponse(ResponseStatus status = ResponseStatus.Completed, IEnume
                 MaxOutputTokens = request.MaxOutputTokens,
                 MaxToolCalls = request.MaxToolCalls,
                 Metadata = request.Metadata != null ? new Dictionary<string, string>(request.Metadata) : [],
-                Model = request.Agent?.Name ?? request.Model,
+                Model = request.Model,
                 Output = outputs?.ToList() ?? [],
                 ParallelToolCalls = request.ParallelToolCalls ?? true,
                 PreviousResponseId = request.PreviousResponseId,

dotnet/src/Microsoft.Agents.AI.Hosting.OpenAI/Responses/HostedAgentResponseExecutor.cs

@@ -13,8 +13,9 @@
 namespace Microsoft.Agents.AI.Hosting.OpenAI.Responses;
 
 /// <summary>
-/// Response executor that routes requests to hosted AIAgent services based on the model or agent.name parameter.
+/// Response executor that routes requests to hosted AIAgent services based on agent.name or metadata["entity_id"].
 /// This executor resolves agents from keyed services registered via AddAIAgent().
+/// The model field is reserved for actual model names and is never used for entity/agent identification.
 /// </summary>
 internal sealed class HostedAgentResponseExecutor : IResponseExecutor
 {
@@ -76,17 +77,26 @@ public async IAsyncEnumerable<StreamingResponseEvent> ExecuteAsync(
 
     /// <summary>
     /// Resolves an agent from the service provider based on the request.
+    /// Checks agent.name first, then metadata["entity_id"].
     /// </summary>
     /// <param name="request">The create response request.</param>
     /// <returns>The resolved AIAgent instance.</returns>
     /// <exception cref="InvalidOperationException">Thrown when the agent cannot be resolved.</exception>
     private AIAgent ResolveAgent(CreateResponse request)
     {
-        // Extract agent name from agent.name or model parameter
-        var agentName = request.Agent?.Name ?? request.Model;
+        // Extract agent name from agent.name first (highest priority)
+        string? agentName = request.Agent?.Name;
+
+        // Fall back to metadata["entity_id"] if agent.name is not present
+        if (string.IsNullOrEmpty(agentName) && request.Metadata?.TryGetValue("entity_id", out string? entityId) == true)
+        {
+            agentName = entityId;
+        }
+
+        // Never use model field for entity ID - it's for the actual model name
         if (string.IsNullOrEmpty(agentName))
         {
-            throw new InvalidOperationException("No 'agent.name' or 'model' specified in the request.");
+            throw new InvalidOperationException("No 'agent.name' or 'metadata.entity_id' specified in the request.");
         }
 
         // Resolve the keyed agent service

dotnet/src/Microsoft.Agents.AI.Hosting.OpenAI/Responses/InMemoryResponsesService.cs

@@ -371,7 +371,7 @@ private ResponseState InitializeResponse(string responseId, CreateResponse reque
             MaxOutputTokens = request.MaxOutputTokens,
             MaxToolCalls = request.MaxToolCalls,
             Metadata = metadata,
-            Model = request.Model ?? "default",
+            Model = request.Model,
             Output = [],
             ParallelToolCalls = request.ParallelToolCalls ?? true,
             PreviousResponseId = request.PreviousResponseId,

dotnet/src/Microsoft.Agents.AI.Hosting.OpenAI/Responses/ResponsesHttpHandler.cs

@@ -82,7 +82,7 @@ public async Task<IResult> CreateResponseAsync(
                 }
             });
         }
-        catch (InvalidOperationException ex) when (ex.Message.Contains("No 'agent.name' or 'model' specified"))
+        catch (InvalidOperationException ex) when (ex.Message.Contains("No 'agent.name'"))
         {
             // Return OpenAI-style error for missing required parameters
             return Results.BadRequest(new ErrorResponse

dotnet/tests/Microsoft.Agents.AI.Hosting.OpenAI.UnitTests/OpenAIHttpApiIntegrationTests.cs

@@ -45,7 +45,7 @@ public async Task CreateConversationAndResponse_NonStreaming_NonBackground_Updat
         // Act - Create response (non-streaming, non-background)
         var createResponseRequest = new
         {
-            model = AgentName,
+            metadata = new { entity_id = AgentName },
             conversation = conversationId,
             input = UserMessage,
             stream = false
@@ -122,7 +122,7 @@ public async Task CreateConversationAndResponse_Streaming_NonBackground_UpdatesC
         // Act - Create response (streaming, non-background)
         var createResponseRequest = new
         {
-            model = AgentName,
+            metadata = new { entity_id = AgentName },
             conversation = conversationId,
             input = UserMessage,
             stream = true
@@ -196,7 +196,7 @@ public async Task CreateConversationAndResponse_NonStreaming_Background_UpdatesC
         // Act - Create response (non-streaming, background)
         var createResponseRequest = new
         {
-            model = AgentName,
+            metadata = new { entity_id = AgentName },
             conversation = conversationId,
             input = UserMessage,
             stream = false,

dotnet/tests/Microsoft.Agents.AI.Hosting.OpenAI.UnitTests/OpenAIResponsesAgentResolutionIntegrationTests.cs

@@ -168,23 +168,23 @@ public async Task CreateResponse_WithMultipleAgents_ResolvesCorrectAgentAsync()
     }
 
     /// <summary>
-    /// Verifies that agent resolution using the model property works correctly.
+    /// Verifies that agent resolution using the metadata.entity_id property works correctly.
     /// </summary>
     [Fact]
-    public async Task CreateResponse_WithModelProperty_ResolvesCorrectAgentAsync()
+    public async Task CreateResponse_WithMetadataEntityId_ResolvesCorrectAgentAsync()
     {
         // Arrange
-        const string AgentName = "model-agent";
+        const string AgentName = "metadata-agent";
         const string Instructions = "You are a helpful assistant.";
-        const string ExpectedResponse = "Response via model property";
+        const string ExpectedResponse = "Response via metadata.entity_id";
 
         this._httpClient = await this.CreateTestServerWithAgentResolutionAsync(
             (AgentName, Instructions, ExpectedResponse));
 
-        // Act - Use raw HTTP request to control the model property
+        // Act - Use raw HTTP request with metadata.entity_id
         using StringContent requestContent = new(JsonSerializer.Serialize(new
         {
-            model = AgentName,
+            metadata = new { entity_id = AgentName },
             input = new[]
             {
                 new { type = "message", role = "user", content = "Test message" }
@@ -268,7 +268,6 @@ public async Task CreateResponse_WithoutAgentOrModel_ReturnsBadRequestAsync()
 
         string responseJson = await httpResponse.Content.ReadAsStringAsync();
         Assert.Contains("agent.name", responseJson, StringComparison.OrdinalIgnoreCase);
-        Assert.Contains("model", responseJson, StringComparison.OrdinalIgnoreCase);
     }
 
     /// <summary>

python/packages/devui/agent_framework_devui/models/_openai_custom.py

@@ -139,12 +139,12 @@ class AgentFrameworkRequest(BaseModel):
     """OpenAI ResponseCreateParams with Agent Framework routing.
 
     This properly extends the real OpenAI API request format.
-    - Uses 'model' field as entity_id (agent/workflow name)
+    - Uses 'metadata.entity_id' field for entity/agent/workflow identification
     - Uses 'conversation' field for conversation context (OpenAI standard)
     """
 
     # All OpenAI fields from ResponseCreateParams
-    model: str  # Used as entity_id in DevUI!
+    model: str | None = None
     input: str | list[Any] | dict[str, Any]  # ResponseInputParam + dict for workflow structured input
     stream: bool | None = False
 
@@ -164,12 +164,13 @@ class AgentFrameworkRequest(BaseModel):
     model_config = ConfigDict(extra="allow")
 
     def get_entity_id(self) -> str:
-        """Get entity_id from model field.
+        """Get entity_id from metadata dictionary.
 
-        In DevUI, model IS the entity_id (agent/workflow name).
-        Simple and clean!
+        In DevUI, entity_id is stored in metadata["entity_id"].
         """
-        return self.model
+        if self.metadata and "entity_id" in self.metadata:
+            return str(self.metadata["entity_id"])
+        return ""
 
     def get_conversation_id(self) -> str | None:
         """Extract conversation_id from conversation parameter.

python/packages/devui/agent_framework_devui/ui/assets/index.js

@@ -549,7 +549,7 @@ class ApiClient {
     resumeResponseId?: string
   ): AsyncGenerator<ExtendedResponseStreamEvent, void, unknown> {
     const openAIRequest: AgentFrameworkRequest = {
-      model: agentId, // Model IS the entity_id (simplified routing!)
+      metadata: { entity_id: agentId },
       input: request.input, // Direct OpenAI ResponseInputParam
       stream: true,
       conversation: request.conversation_id, // OpenAI standard conversation param
@@ -573,9 +573,9 @@ class ApiClient {
     workflowId: string,
     request: RunWorkflowRequest
   ): AsyncGenerator<ExtendedResponseStreamEvent, void, unknown> {
-    // Convert to OpenAI format - use model field for entity_id (same as agents)
+    // Convert to OpenAI format - use metadata.entity_id for workflow ID
     const openAIRequest: AgentFrameworkRequest = {
-      model: workflowId, // Use workflow ID in model field (matches agent pattern)
+      metadata: { entity_id: workflowId },
       input: request.input_data || "", // Send dict directly, no stringification needed
       stream: true,
       conversation: request.conversation_id, // Include conversation if present