[router] harmony responses api streaming support (#12395)

sgl-router/src/routers/grpc/harmony/mod.rs

@@ -43,7 +43,9 @@ pub use builder::HarmonyBuilder;
 pub use detector::HarmonyDetector;
 pub use parser::HarmonyParserAdapter;
 pub use processor::{HarmonyResponseProcessor, ResponsesIterationResult};
-pub use responses::{serve_harmony_responses, HarmonyResponsesContext};
+pub use responses::{
+    serve_harmony_responses, serve_harmony_responses_stream, HarmonyResponsesContext,
+};
 pub use stages::{
     HarmonyPreparationStage, HarmonyRequestBuildingStage, HarmonyResponseProcessingStage,
 };

sgl-router/src/routers/grpc/harmony/parser.rs

@@ -103,7 +103,7 @@ impl HarmonyParserAdapter {
     /// # Returns
     ///
     /// Tuple of (analysis, commentary, final_text)
-    fn parse_messages(
+    pub fn parse_messages(
         messages: &[openai_harmony::chat::Message],
     ) -> (Option<String>, Option<Vec<ToolCall>>, String) {
         let mut analysis = None;
@@ -260,6 +260,51 @@ impl HarmonyParserAdapter {
         self.parser.messages().to_vec()
     }
 
+    /// Extract incomplete commentary content from parser state
+    ///
+    /// When the stream ends, there may be incomplete commentary content in the parser
+    /// that hasn't been finalized into a completed message. This method extracts
+    /// such content and converts it to tool calls.
+    ///
+    /// # Returns
+    ///
+    /// Optional vector of ToolCall if incomplete commentary is found
+    pub fn extract_incomplete_commentary(&self) -> Option<Vec<ToolCall>> {
+        // Check if current channel is commentary
+        let current_channel = self.parser.current_channel();
+        if current_channel.as_deref() != Some("commentary") {
+            return None;
+        }
+
+        // Get current recipient (should be "functions.{name}")
+        let recipient = self.parser.current_recipient()?;
+        if !recipient.starts_with("functions.") {
+            return None;
+        }
+
+        // Get current incomplete content
+        let content = self.parser.current_content().ok()?;
+        if content.is_empty() {
+            return None;
+        }
+
+        // Extract function name from recipient
+        let function_name = recipient.strip_prefix("functions.").unwrap();
+
+        // Create tool call from incomplete content
+        let call_id = format!("call_{}", Uuid::new_v4());
+        let tool_call = ToolCall {
+            id: call_id,
+            tool_type: "function".to_string(),
+            function: FunctionCallResponse {
+                name: function_name.to_string(),
+                arguments: Some(content),
+            },
+        };
+
+        Some(vec![tool_call])
+    }
+
     /// Parse streaming chunk
     ///
     /// Parses incremental token IDs and returns a delta with any new content

sgl-router/src/routers/grpc/harmony/stages/response_processing.rs

@@ -40,6 +40,11 @@ impl Default for HarmonyResponseProcessingStage {
 #[async_trait]
 impl PipelineStage for HarmonyResponseProcessingStage {
     async fn execute(&self, ctx: &mut RequestContext) -> Result<Option<Response>, Response> {
+        let is_streaming = ctx.is_streaming();
+
+        // Check request type to determine which processor method to call
+        match &ctx.input.request_type {
+            RequestType::Chat(_) => {
                 // Get execution result (output tokens from model)
                 let execution_result = ctx
                     .state
@@ -48,7 +53,6 @@ impl PipelineStage for HarmonyResponseProcessingStage {
                     .take()
                     .ok_or_else(|| utils::internal_error_static("No execution result"))?;
 
-        let is_streaming = ctx.is_streaming();
                 let dispatch = ctx
                     .state
                     .dispatch
@@ -56,9 +60,6 @@ impl PipelineStage for HarmonyResponseProcessingStage {
                     .cloned()
                     .ok_or_else(|| utils::internal_error_static("Dispatch metadata not set"))?;
 
-        // Check request type to determine which processor method to call
-        match &ctx.input.request_type {
-            RequestType::Chat(_) => {
                 // For streaming, delegate to streaming processor and return SSE response
                 if is_streaming {
                     return Ok(Some(
@@ -83,14 +84,28 @@ impl PipelineStage for HarmonyResponseProcessingStage {
                 Ok(None)
             }
             RequestType::Responses(_) => {
-                // For Responses API, process iteration and store result
-                // Streaming not yet supported for Responses API
+                // For streaming Responses API, leave execution_result in context
+                // for external streaming processor (serve_harmony_responses_stream)
                 if is_streaming {
-                    return Err(utils::internal_error_static(
-                        "Streaming not yet supported for Responses API",
-                    ));
+                    // Don't take execution_result - let the caller handle it
+                    return Ok(None);
                 }
 
+                // For non-streaming, process normally
+                let execution_result = ctx
+                    .state
+                    .response
+                    .execution_result
+                    .take()
+                    .ok_or_else(|| utils::internal_error_static("No execution result"))?;
+
+                let dispatch = ctx
+                    .state
+                    .dispatch
+                    .as_ref()
+                    .cloned()
+                    .ok_or_else(|| utils::internal_error_static("Dispatch metadata not set"))?;
+
                 let responses_request = ctx.responses_request_arc();
                 let iteration_result = self
                     .processor

sgl-router/src/routers/grpc/pipeline.rs

@@ -454,4 +454,53 @@ impl RequestPipeline {
                 utils::internal_error_static("No ResponsesIterationResult produced by pipeline")
             })
     }
+
+    /// Execute Harmony Responses pipeline iteration with streaming support
+    ///
+    /// This version executes the pipeline up to the dispatch stage and returns
+    /// the raw ExecutionResult (with stream) for token-level streaming processing.
+    pub async fn execute_harmony_responses_streaming(
+        &self,
+        request: &crate::protocols::responses::ResponsesRequest,
+        harmony_ctx: &harmony::responses::HarmonyResponsesContext,
+    ) -> Result<ExecutionResult, Response> {
+        // Create RequestContext for this Responses request
+        let mut ctx = RequestContext::for_responses(
+            Arc::new(request.clone()),
+            None,
+            None,
+            harmony_ctx.components.clone(),
+        );
+
+        // Execute pipeline stages up to dispatch (which creates the stream)
+        for (idx, stage) in self.stages.iter().enumerate() {
+            match stage.execute(&mut ctx).await {
+                Ok(Some(response)) => {
+                    error!(
+                        "Stage {} ({}) returned unexpected response during streaming Responses",
+                        idx + 1,
+                        stage.name()
+                    );
+                    return Err(response);
+                }
+                Ok(None) => continue,
+                Err(response) => {
+                    error!(
+                        "Stage {} ({}) failed with status {}",
+                        idx + 1,
+                        stage.name(),
+                        response.status()
+                    );
+                    return Err(response);
+                }
+            }
+        }
+
+        // Extract execution_result (the raw stream from workers)
+        ctx.state
+            .response
+            .execution_result
+            .take()
+            .ok_or_else(|| utils::internal_error_static("No ExecutionResult produced by pipeline"))
+    }
 }

sgl-router/src/routers/grpc/responses/streaming.rs

@@ -9,7 +9,7 @@ use uuid::Uuid;
 
 use crate::protocols::chat::ChatCompletionStreamResponse;
 
-pub(super) enum OutputItemType {
+pub enum OutputItemType {
     Message,
     McpListTools,
     McpCall,
@@ -53,9 +53,9 @@ struct OutputItemState {
 /// - response.mcp_call_arguments.done
 /// - response.mcp_call.completed
 /// - response.mcp_call.failed
-pub(super) struct ResponseStreamEventEmitter {
+pub struct ResponseStreamEventEmitter {
     sequence_number: u64,
-    response_id: String,
+    pub response_id: String,
     model: String,
     created_at: u64,
     message_id: String,
@@ -74,7 +74,7 @@ pub(super) struct ResponseStreamEventEmitter {
 }
 
 impl ResponseStreamEventEmitter {
-    pub(super) fn new(response_id: String, model: String, created_at: u64) -> Self {
+    pub fn new(response_id: String, model: String, created_at: u64) -> Self {
         let message_id = format!("msg_{}", Uuid::new_v4());
 
         Self {
@@ -102,7 +102,7 @@ impl ResponseStreamEventEmitter {
         seq
     }
 
-    pub(super) fn emit_created(&mut self) -> serde_json::Value {
+    pub fn emit_created(&mut self) -> serde_json::Value {
         self.has_emitted_created = true;
         json!({
             "type": "response.created",
@@ -118,7 +118,7 @@ impl ResponseStreamEventEmitter {
         })
     }
 
-    pub(super) fn emit_in_progress(&mut self) -> serde_json::Value {
+    pub fn emit_in_progress(&mut self) -> serde_json::Value {
         self.has_emitted_in_progress = true;
         json!({
             "type": "response.in_progress",
@@ -131,7 +131,7 @@ impl ResponseStreamEventEmitter {
         })
     }
 
-    pub(super) fn emit_content_part_added(
+    pub fn emit_content_part_added(
         &mut self,
         output_index: usize,
         item_id: &str,
@@ -151,7 +151,7 @@ impl ResponseStreamEventEmitter {
         })
     }
 
-    pub(super) fn emit_text_delta(
+    pub fn emit_text_delta(
         &mut self,
         delta: &str,
         output_index: usize,
@@ -169,7 +169,7 @@ impl ResponseStreamEventEmitter {
         })
     }
 
-    pub(super) fn emit_text_done(
+    pub fn emit_text_done(
         &mut self,
         output_index: usize,
         item_id: &str,
@@ -185,7 +185,7 @@ impl ResponseStreamEventEmitter {
         })
     }
 
-    pub(super) fn emit_content_part_done(
+    pub fn emit_content_part_done(
         &mut self,
         output_index: usize,
         item_id: &str,
@@ -204,10 +204,7 @@ impl ResponseStreamEventEmitter {
         })
     }
 
-    pub(super) fn emit_completed(
-        &mut self,
-        usage: Option<&serde_json::Value>,
-    ) -> serde_json::Value {
+    pub fn emit_completed(&mut self, usage: Option<&serde_json::Value>) -> serde_json::Value {
         let mut response = json!({
             "type": "response.completed",
             "sequence_number": self.next_sequence(),
@@ -240,10 +237,7 @@ impl ResponseStreamEventEmitter {
     // MCP Event Emission Methods
     // ========================================================================
 
-    pub(super) fn emit_mcp_list_tools_in_progress(
-        &mut self,
-        output_index: usize,
-    ) -> serde_json::Value {
+    pub fn emit_mcp_list_tools_in_progress(&mut self, output_index: usize) -> serde_json::Value {
         json!({
             "type": "response.mcp_list_tools.in_progress",
             "sequence_number": self.next_sequence(),
@@ -251,7 +245,7 @@ impl ResponseStreamEventEmitter {
         })
     }
 
-    pub(super) fn emit_mcp_list_tools_completed(
+    pub fn emit_mcp_list_tools_completed(
         &mut self,
         output_index: usize,
         tools: &[crate::mcp::Tool],
@@ -275,7 +269,7 @@ impl ResponseStreamEventEmitter {
         })
     }
 
-    pub(super) fn emit_mcp_call_in_progress(
+    pub fn emit_mcp_call_in_progress(
         &mut self,
         output_index: usize,
         item_id: &str,
@@ -288,7 +282,7 @@ impl ResponseStreamEventEmitter {
         })
     }
 
-    pub(super) fn emit_mcp_call_arguments_delta(
+    pub fn emit_mcp_call_arguments_delta(
         &mut self,
         output_index: usize,
         item_id: &str,
@@ -309,7 +303,7 @@ impl ResponseStreamEventEmitter {
         })
     }
 
-    pub(super) fn emit_mcp_call_arguments_done(
+    pub fn emit_mcp_call_arguments_done(
         &mut self,
         output_index: usize,
         item_id: &str,
@@ -324,7 +318,7 @@ impl ResponseStreamEventEmitter {
         })
     }
 
-    pub(super) fn emit_mcp_call_completed(
+    pub fn emit_mcp_call_completed(
         &mut self,
         output_index: usize,
         item_id: &str,
@@ -357,7 +351,7 @@ impl ResponseStreamEventEmitter {
     // ========================================================================
 
     /// Emit response.output_item.added event
-    pub(super) fn emit_output_item_added(
+    pub fn emit_output_item_added(
         &mut self,
         output_index: usize,
         item: &serde_json::Value,
@@ -371,7 +365,7 @@ impl ResponseStreamEventEmitter {
     }
 
     /// Emit response.output_item.done event
-    pub(super) fn emit_output_item_done(
+    pub fn emit_output_item_done(
         &mut self,
         output_index: usize,
         item: &serde_json::Value,
@@ -390,7 +384,7 @@ impl ResponseStreamEventEmitter {
     }
 
     /// Allocate next output index and track item
-    pub(super) fn allocate_output_index(&mut self, item_type: OutputItemType) -> (usize, String) {
+    pub fn allocate_output_index(&mut self, item_type: OutputItemType) -> (usize, String) {
         let index = self.next_output_index;
         self.next_output_index += 1;
 
@@ -412,7 +406,7 @@ impl ResponseStreamEventEmitter {
     }
 
     /// Mark output item as completed
-    pub(super) fn complete_output_item(&mut self, output_index: usize) {
+    pub fn complete_output_item(&mut self, output_index: usize) {
         if let Some(item) = self
             .output_items
             .iter_mut()
@@ -426,7 +420,7 @@ impl ResponseStreamEventEmitter {
     ///
     /// Reasoning items in OpenAI format are simple placeholders emitted between tool iterations.
     /// They don't have streaming content - just wrapper events with empty/null content.
-    pub(super) fn emit_reasoning_item(
+    pub fn emit_reasoning_item(
         &mut self,
         tx: &mpsc::UnboundedSender<Result<Bytes, std::io::Error>>,
         reasoning_content: Option<String>,
@@ -550,7 +544,7 @@ impl ResponseStreamEventEmitter {
         Ok(())
     }
 
-    pub(super) fn send_event(
+    pub fn send_event(
         &self,
         event: &serde_json::Value,
         tx: &mpsc::UnboundedSender<Result<Bytes, std::io::Error>>,
@@ -558,13 +552,38 @@ impl ResponseStreamEventEmitter {
         let event_json = serde_json::to_string(event)
             .map_err(|e| format!("Failed to serialize event: {}", e))?;
 
-        if tx
-            .send(Ok(Bytes::from(format!("data: {}\n\n", event_json))))
-            .is_err()
-        {
+        // Extract event type from the JSON for SSE event field
+        let event_type = event
+            .get("type")
+            .and_then(|v| v.as_str())
+            .unwrap_or("message");
+
+        // Format as SSE with event: field
+        let sse_message = format!("event: {}\ndata: {}\n\n", event_type, event_json);
+
+        if tx.send(Ok(Bytes::from(sse_message))).is_err() {
             return Err("Client disconnected".to_string());
         }
 
         Ok(())
     }
+
+    /// Send event and log any errors (typically client disconnect)
+    ///
+    /// This is a convenience method for streaming scenarios where client
+    /// disconnection is expected and should be logged but not fail the operation.
+    /// Returns true if sent successfully, false if client disconnected.
+    pub fn send_event_best_effort(
+        &self,
+        event: &serde_json::Value,
+        tx: &mpsc::UnboundedSender<Result<Bytes, std::io::Error>>,
+    ) -> bool {
+        match self.send_event(event, tx) {
+            Ok(()) => true,
+            Err(e) => {
+                tracing::debug!("Failed to send event (likely client disconnect): {}", e);
+                false
+            }
+        }
+    }
 }

sgl-router/src/routers/grpc/router.rs

@@ -13,7 +13,10 @@ use tracing::debug;
 
 use super::{
     context::SharedComponents,
-    harmony::{serve_harmony_responses, HarmonyDetector, HarmonyResponsesContext},
+    harmony::{
+        serve_harmony_responses, serve_harmony_responses_stream, HarmonyDetector,
+        HarmonyResponsesContext,
+    },
     pipeline::RequestPipeline,
     responses,
 };
@@ -192,8 +195,8 @@ impl GrpcRouter {
         model_id: Option<&str>,
     ) -> Response {
         debug!(
-            "Processing Harmony responses request for model: {:?}",
-            model_id
+            "Processing Harmony responses request for model: {:?}, streaming: {:?}",
+            model_id, body.stream
         );
 
         // Create HarmonyResponsesContext from existing responses context
@@ -204,12 +207,17 @@ impl GrpcRouter {
             self.harmony_responses_context.response_storage.clone(),
         );
 
-        // Use serve_harmony_responses for multi-turn MCP tool orchestration
+        // Check if streaming is requested
+        if body.stream.unwrap_or(false) {
+            serve_harmony_responses_stream(&harmony_ctx, body.clone()).await
+        } else {
+            // Use non-streaming version for standard JSON responses
             match serve_harmony_responses(&harmony_ctx, body.clone()).await {
                 Ok(response) => axum::Json(response).into_response(),
                 Err(error_response) => error_response,
             }
         }
+    }
 }
 
 impl std::fmt::Debug for GrpcRouter {