[router] openai router: support grok model

sgl-router/src/protocols/spec.rs

@@ -1073,8 +1073,8 @@ fn generate_request_id() -> String {
 #[derive(Debug, Clone, Deserialize, Serialize)]
 pub struct ResponsesRequest {
     /// Run the request in the background
-    #[serde(default)]
-    pub background: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub background: Option<bool>,
 
     /// Fields to include in the response
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -1108,8 +1108,8 @@ pub struct ResponsesRequest {
     pub conversation: Option<String>,
 
     /// Whether to enable parallel tool calls
-    #[serde(default = "default_true")]
-    pub parallel_tool_calls: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub parallel_tool_calls: Option<bool>,
 
     /// ID of previous response to continue from
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -1120,40 +1120,40 @@ pub struct ResponsesRequest {
     pub reasoning: Option<ResponseReasoningParam>,
 
     /// Service tier
-    #[serde(default)]
-    pub service_tier: ServiceTier,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub service_tier: Option<ServiceTier>,
 
     /// Whether to store the response
-    #[serde(default = "default_true")]
-    pub store: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub store: Option<bool>,
 
     /// Whether to stream the response
-    #[serde(default)]
-    pub stream: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub stream: Option<bool>,
 
     /// Temperature for sampling
     #[serde(skip_serializing_if = "Option::is_none")]
     pub temperature: Option<f32>,
 
     /// Tool choice behavior
-    #[serde(default)]
-    pub tool_choice: ToolChoice,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub tool_choice: Option<ToolChoice>,
 
     /// Available tools
-    #[serde(default)]
-    pub tools: Vec<ResponseTool>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub tools: Option<Vec<ResponseTool>>,
 
     /// Number of top logprobs to return
-    #[serde(default)]
-    pub top_logprobs: u32,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub top_logprobs: Option<u32>,
 
     /// Top-p sampling parameter
     #[serde(skip_serializing_if = "Option::is_none")]
     pub top_p: Option<f32>,
 
     /// Truncation behavior
-    #[serde(default)]
-    pub truncation: Truncation,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub truncation: Option<Truncation>,
 
     /// User identifier
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -1168,12 +1168,12 @@ pub struct ResponsesRequest {
     pub priority: i32,
 
     /// Frequency penalty
-    #[serde(default)]
-    pub frequency_penalty: f32,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub frequency_penalty: Option<f32>,
 
     /// Presence penalty
-    #[serde(default)]
-    pub presence_penalty: f32,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub presence_penalty: Option<f32>,
 
     /// Stop sequences
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -1210,7 +1210,7 @@ fn default_repetition_penalty() -> f32 {
 impl Default for ResponsesRequest {
     fn default() -> Self {
         Self {
-            background: false,
+            background: None,
             include: None,
             input: ResponseInput::Text(String::new()),
             instructions: None,
@@ -1219,23 +1219,23 @@ impl Default for ResponsesRequest {
             metadata: None,
             model: None,
             conversation: None,
-            parallel_tool_calls: true,
+            parallel_tool_calls: None,
             previous_response_id: None,
             reasoning: None,
-            service_tier: ServiceTier::default(),
-            store: true,
-            stream: false,
+            service_tier: None,
+            store: None,
+            stream: None,
             temperature: None,
-            tool_choice: ToolChoice::default(),
-            tools: Vec::new(),
-            top_logprobs: 0,
+            tool_choice: None,
+            tools: None,
+            top_logprobs: None,
             top_p: None,
-            truncation: Truncation::default(),
+            truncation: None,
             user: None,
             request_id: generate_request_id(),
             priority: 0,
-            frequency_penalty: 0.0,
-            presence_penalty: 0.0,
+            frequency_penalty: None,
+            presence_penalty: None,
             stop: None,
             top_k: default_top_k(),
             min_p: 0.0,
@@ -1299,14 +1299,18 @@ impl ResponsesRequest {
             "top_p".to_string(),
             Value::Number(Number::from_f64(top_p as f64).unwrap()),
         );
-        params.insert(
-            "frequency_penalty".to_string(),
-            Value::Number(Number::from_f64(self.frequency_penalty as f64).unwrap()),
-        );
-        params.insert(
-            "presence_penalty".to_string(),
-            Value::Number(Number::from_f64(self.presence_penalty as f64).unwrap()),
-        );
+        if let Some(fp) = self.frequency_penalty {
+            params.insert(
+                "frequency_penalty".to_string(),
+                Value::Number(Number::from_f64(fp as f64).unwrap()),
+            );
+        }
+        if let Some(pp) = self.presence_penalty {
+            params.insert(
+                "presence_penalty".to_string(),
+                Value::Number(Number::from_f64(pp as f64).unwrap()),
+            );
+        }
         params.insert("top_k".to_string(), Value::Number(Number::from(self.top_k)));
         params.insert(
             "min_p".to_string(),
@@ -1337,7 +1341,7 @@ impl ResponsesRequest {
 
 impl GenerationRequest for ResponsesRequest {
     fn is_stream(&self) -> bool {
-        self.stream
+        self.stream.unwrap_or(false)
     }
 
     fn get_model(&self) -> Option<&str> {
@@ -1523,31 +1527,33 @@ impl ResponsesResponse {
             max_output_tokens: request.max_output_tokens,
             model: model_name,
             output,
-            parallel_tool_calls: request.parallel_tool_calls,
+            parallel_tool_calls: request.parallel_tool_calls.unwrap_or(true),
             previous_response_id: request.previous_response_id.clone(),
             reasoning: request.reasoning.as_ref().map(|r| ReasoningInfo {
                 effort: r.effort.as_ref().map(|e| format!("{:?}", e)),
                 summary: None,
             }),
-            store: request.store,
+            store: request.store.unwrap_or(false),
             temperature: request.temperature,
             text: Some(ResponseTextFormat {
                 format: TextFormatType {
                     format_type: "text".to_string(),
                 },
             }),
             tool_choice: match &request.tool_choice {
-                ToolChoice::Value(ToolChoiceValue::Auto) => "auto".to_string(),
-                ToolChoice::Value(ToolChoiceValue::Required) => "required".to_string(),
-                ToolChoice::Value(ToolChoiceValue::None) => "none".to_string(),
-                ToolChoice::Function { .. } => "function".to_string(),
-                ToolChoice::AllowedTools { mode, .. } => mode.clone(),
+                Some(ToolChoice::Value(ToolChoiceValue::Auto)) => "auto".to_string(),
+                Some(ToolChoice::Value(ToolChoiceValue::Required)) => "required".to_string(),
+                Some(ToolChoice::Value(ToolChoiceValue::None)) => "none".to_string(),
+                Some(ToolChoice::Function { .. }) => "function".to_string(),
+                Some(ToolChoice::AllowedTools { mode, .. }) => mode.clone(),
+                None => "auto".to_string(),
             },
-            tools: request.tools.clone(),
+            tools: request.tools.clone().unwrap_or_default(),
             top_p: request.top_p,
             truncation: match &request.truncation {
-                Truncation::Auto => Some("auto".to_string()),
-                Truncation::Disabled => Some("disabled".to_string()),
+                Some(Truncation::Auto) => Some("auto".to_string()),
+                Some(Truncation::Disabled) => Some("disabled".to_string()),
+                None => None,
             },
             usage: usage.map(ResponsesUsage::Classic),
             user: request.user.clone(),

sgl-router/src/routers/openai/mcp.rs

@@ -689,9 +689,13 @@ pub(super) async fn execute_tool_loop(
             if state.total_calls > 0 {
                 let server_label = original_body
                     .tools
-                    .iter()
-                    .find(|t| matches!(t.r#type, ResponseToolType::Mcp))
-                    .and_then(|t| t.server_label.as_deref())
+                    .as_ref()
+                    .and_then(|tools| {
+                        tools
+                            .iter()
+                            .find(|t| matches!(t.r#type, ResponseToolType::Mcp))
+                            .and_then(|t| t.server_label.as_deref())
+                    })
                     .unwrap_or("mcp");
 
                 // Build mcp_list_tools item
@@ -747,9 +751,13 @@ pub(super) fn build_incomplete_response(
     if let Some(output_array) = obj.get_mut("output").and_then(|v| v.as_array_mut()) {
         let server_label = original_body
             .tools
-            .iter()
-            .find(|t| matches!(t.r#type, ResponseToolType::Mcp))
-            .and_then(|t| t.server_label.as_deref())
+            .as_ref()
+            .and_then(|tools| {
+                tools
+                    .iter()
+                    .find(|t| matches!(t.r#type, ResponseToolType::Mcp))
+                    .and_then(|t| t.server_label.as_deref())
+            })
             .unwrap_or("mcp");
 
         // Find any function_call items and convert them to mcp_call (incomplete)

sgl-router/src/routers/openai/responses.rs

@@ -129,7 +129,10 @@ pub(super) fn patch_streaming_response_json(
             }
         }
 
-        obj.insert("store".to_string(), Value::Bool(original_body.store));
+        obj.insert(
+            "store".to_string(),
+            Value::Bool(original_body.store.unwrap_or(false)),
+        );
 
         if obj
             .get("model")
@@ -205,7 +208,7 @@ pub(super) fn rewrite_streaming_block(
 
     let mut changed = false;
     if let Some(response_obj) = parsed.get_mut("response").and_then(|v| v.as_object_mut()) {
-        let desired_store = Value::Bool(original_body.store);
+        let desired_store = Value::Bool(original_body.store.unwrap_or(false));
         if response_obj.get("store") != Some(&desired_store) {
             response_obj.insert("store".to_string(), desired_store);
             changed = true;
@@ -267,10 +270,11 @@ pub(super) fn rewrite_streaming_block(
 
 /// Mask function tools as MCP tools in response for client
 pub(super) fn mask_tools_as_mcp(resp: &mut Value, original_body: &ResponsesRequest) {
-    let mcp_tool = original_body
-        .tools
-        .iter()
-        .find(|t| matches!(t.r#type, ResponseToolType::Mcp) && t.server_url.is_some());
+    let mcp_tool = original_body.tools.as_ref().and_then(|tools| {
+        tools
+            .iter()
+            .find(|t| matches!(t.r#type, ResponseToolType::Mcp) && t.server_url.is_some())
+    });
     let Some(t) = mcp_tool else {
         return;
     };

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

@@ -148,7 +148,11 @@ impl OpenAIRouter {
         original_previous_response_id: Option<String>,
     ) -> Response {
         // Check if MCP is active for this request
-        let req_mcp_manager = mcp_manager_from_request_tools(&original_body.tools).await;
+        let req_mcp_manager = if let Some(ref tools) = original_body.tools {
+            mcp_manager_from_request_tools(tools.as_slice()).await
+        } else {
+            None
+        };
         let active_mcp = req_mcp_manager.as_ref().or(self.mcp_manager.as_ref());
 
         let mut response_json: Value;
@@ -183,6 +187,7 @@ impl OpenAIRouter {
             }
         } else {
             // No MCP - simple request
+
             let mut request_builder = self.client.post(&url).json(&payload);
             if let Some(h) = headers {
                 request_builder = apply_request_headers(h, request_builder, true);
@@ -385,6 +390,7 @@ impl crate::routers::RouterTrait for OpenAIRouter {
             }
         };
         if let Some(obj) = payload.as_object_mut() {
+            // Always remove SGLang-specific fields (unsupported by OpenAI)
             for key in [
                 "top_k",
                 "min_p",
@@ -535,7 +541,7 @@ impl crate::routers::RouterTrait for OpenAIRouter {
                 .into_response();
         }
 
-        // Clone the body and override model if needed
+        // Clone the body for validation and logic, but we'll build payload differently
         let mut request_body = body.clone();
         if let Some(model) = model_id {
             request_body.model = Some(model.to_string());
@@ -690,7 +696,7 @@ impl crate::routers::RouterTrait for OpenAIRouter {
         }
 
         // Always set store=false for upstream (we store internally)
-        request_body.store = false;
+        request_body.store = Some(false);
 
         // Convert to JSON and strip SGLang-specific fields
         let mut payload = match to_value(&request_body) {
@@ -704,14 +710,13 @@ impl crate::routers::RouterTrait for OpenAIRouter {
             }
         };
 
-        // Remove SGLang-specific fields
+        // Remove SGLang-specific fields only
         if let Some(obj) = payload.as_object_mut() {
+            // Remove SGLang-specific fields (not part of OpenAI API)
             for key in [
                 "request_id",
                 "priority",
                 "top_k",
-                "frequency_penalty",
-                "presence_penalty",
                 "min_p",
                 "min_tokens",
                 "regex",
@@ -732,10 +737,38 @@ impl crate::routers::RouterTrait for OpenAIRouter {
             ] {
                 obj.remove(key);
             }
+            // XAI doesn't support the OPENAI item type input: https://platform.openai.com/docs/api-reference/responses/create#responses-create-input-input-item-list-item
+            // To Achieve XAI compatibility, strip extra fields from input messages (id, status)
+            // XAI doesn't support output_text as type for content with role of assistant
+            // so normalize content types: output_text -> input_text
+            if let Some(input_arr) = obj.get_mut("input").and_then(Value::as_array_mut) {
+                for item_obj in input_arr.iter_mut().filter_map(Value::as_object_mut) {
+                    // Remove fields not universally supported
+                    item_obj.remove("id");
+                    item_obj.remove("status");
+
+                    // Normalize content types to input_text (xAI compatibility)
+                    if let Some(content_arr) =
+                        item_obj.get_mut("content").and_then(Value::as_array_mut)
+                    {
+                        for content_obj in content_arr.iter_mut().filter_map(Value::as_object_mut) {
+                            // Change output_text to input_text
+                            if content_obj.get("type").and_then(Value::as_str)
+                                == Some("output_text")
+                            {
+                                content_obj.insert(
+                                    "type".to_string(),
+                                    Value::String("input_text".to_string()),
+                                );
+                            }
+                        }
+                    }
+                }
+            }
         }
 
         // Delegate to streaming or non-streaming handler
-        if body.stream {
+        if body.stream.unwrap_or(false) {
             handle_streaming_response(
                 &self.client,
                 &self.circuit_breaker,