[router] add chat_template_kwargs in ChatCompletionRequest (#9958)

Signed-off-by: Tony Lu <tonylu@linux.alibaba.com>

sgl-router/benches/request_processing.rs

@@ -91,6 +91,7 @@ fn default_chat_completion_request() -> ChatCompletionRequest {
         session_params: None,
         separate_reasoning: true,
         stream_reasoning: true,
+        chat_template_kwargs: None,
         return_hidden_states: false,
     }
 }

sgl-router/src/protocols/spec.rs

@@ -330,6 +330,10 @@ pub struct ChatCompletionRequest {
     #[serde(default = "default_true")]
     pub stream_reasoning: bool,
 
+    /// Chat template kwargs
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub chat_template_kwargs: Option<HashMap<String, serde_json::Value>>,
+
     /// Return model hidden states
     #[serde(default)]
     pub return_hidden_states: bool,

sgl-router/src/protocols/validation.rs

@@ -916,6 +916,7 @@ mod tests {
                 session_params: None,
                 separate_reasoning: true,
                 stream_reasoning: true,
+                chat_template_kwargs: None,
                 return_hidden_states: false,
             }
         }