[router] Fix tool_choice normalization in ChatCompletionRequest and fix ut (#11731)

sgl-router/src/protocols/chat.rs

@@ -531,13 +531,14 @@ impl Normalizable for ChatCompletionRequest {
 
         // Apply tool_choice defaults
         if self.tool_choice.is_none() {
-            let has_tools = self.tools.as_ref().is_some_and(|t| !t.is_empty());
-
-            self.tool_choice = if has_tools {
-                Some(ToolChoice::Value(ToolChoiceValue::Auto))
-            } else {
-                Some(ToolChoice::Value(ToolChoiceValue::None))
-            };
+            if let Some(tools) = &self.tools {
+                self.tool_choice = if !tools.is_empty() {
+                    Some(ToolChoice::Value(ToolChoiceValue::Auto))
+                } else {
+                    Some(ToolChoice::Value(ToolChoiceValue::None))
+                };
+            }
+            // If tools is None, leave tool_choice as None (don't set it)
         }
     }
 }

sgl-router/tests/spec/rerank.rs

@@ -230,45 +230,6 @@ fn test_rerank_response_serialization() {
     assert_eq!(deserialized.object, response.object);
 }
 
-#[test]
-fn test_rerank_response_sort_by_score() {
-    let results = vec![
-        RerankResult {
-            score: 0.6,
-            document: Some("doc2".to_string()),
-            index: 1,
-            meta_info: None,
-        },
-        RerankResult {
-            score: 0.8,
-            document: Some("doc1".to_string()),
-            index: 0,
-            meta_info: None,
-        },
-        RerankResult {
-            score: 0.4,
-            document: Some("doc3".to_string()),
-            index: 2,
-            meta_info: None,
-        },
-    ];
-
-    let mut response = RerankResponse::new(
-        results,
-        "test-model".to_string(),
-        Some(StringOrArray::String("req-123".to_string())),
-    );
-
-    response.sort_by_score();
-
-    assert_eq!(response.results[0].score, 0.8);
-    assert_eq!(response.results[0].index, 0);
-    assert_eq!(response.results[1].score, 0.6);
-    assert_eq!(response.results[1].index, 1);
-    assert_eq!(response.results[2].score, 0.4);
-    assert_eq!(response.results[2].index, 2);
-}
-
 #[test]
 fn test_rerank_response_apply_top_k() {
     let results = vec![
@@ -589,9 +550,6 @@ fn test_full_rerank_workflow() {
     // Create response
     let mut response = RerankResponse::new(results, request.model.clone(), request.rid.clone());
 
-    // Sort by score
-    response.sort_by_score();
-
     // Apply top_k
     response.apply_top_k(request.effective_top_k());