[router] Support complex assistant and tool messages in /chat/completions (#12860)

Co-authored-by: Chang Su <chang.s.su@oracle.com>
Co-authored-by: Simo Lin <linsimo.mark@gmail.com>

sgl-router/tests/spec/chat_completion.rs

@@ -1,6 +1,6 @@
 use serde_json::json;
 use sglang_router_rs::protocols::{
-    chat::{ChatCompletionRequest, ChatMessage, UserMessageContent},
+    chat::{ChatCompletionRequest, ChatMessage, MessageContent},
     common::{
         Function, FunctionCall, FunctionChoice, StreamOptions, Tool, ToolChoice, ToolChoiceValue,
         ToolReference,
@@ -17,7 +17,7 @@ fn test_max_tokens_normalizes_to_max_completion_tokens() {
     let mut req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         max_tokens: Some(100),
@@ -50,7 +50,7 @@ fn test_max_completion_tokens_takes_precedence() {
     let mut req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         max_tokens: Some(100),
@@ -76,7 +76,7 @@ fn test_functions_normalizes_to_tools() {
     let mut req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         functions: Some(vec![Function {
@@ -112,7 +112,7 @@ fn test_function_call_normalizes_to_tool_choice() {
     let mut req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         function_call: Some(FunctionCall::None),
@@ -148,7 +148,7 @@ fn test_function_call_function_variant_normalizes() {
     let mut req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         function_call: Some(FunctionCall::Function {
@@ -198,7 +198,7 @@ fn test_stream_options_requires_stream_enabled() {
     let req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         stream: false,
@@ -226,7 +226,7 @@ fn test_stream_options_valid_when_stream_enabled() {
     let req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         stream: true,
@@ -248,7 +248,7 @@ fn test_no_stream_options_valid_when_stream_disabled() {
     let req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         stream: false,
@@ -269,7 +269,7 @@ fn test_tool_choice_function_not_found() {
     let req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         tools: Some(vec![Tool {
@@ -305,7 +305,7 @@ fn test_tool_choice_function_exists_valid() {
     let req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         tools: Some(vec![Tool {
@@ -335,7 +335,7 @@ fn test_tool_choice_allowed_tools_invalid_mode() {
     let req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         tools: Some(vec![Tool {
@@ -372,7 +372,7 @@ fn test_tool_choice_allowed_tools_valid_mode_auto() {
     let req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         tools: Some(vec![Tool {
@@ -403,7 +403,7 @@ fn test_tool_choice_allowed_tools_valid_mode_required() {
     let req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         tools: Some(vec![Tool {
@@ -434,7 +434,7 @@ fn test_tool_choice_allowed_tools_tool_not_found() {
     let req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         tools: Some(vec![Tool {
@@ -471,7 +471,7 @@ fn test_tool_choice_allowed_tools_multiple_tools_valid() {
     let req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         tools: Some(vec![
@@ -518,7 +518,7 @@ fn test_tool_choice_allowed_tools_one_invalid_among_valid() {
     let req = ChatCompletionRequest {
         model: "test-model".to_string(),
         messages: vec![ChatMessage::User {
-            content: UserMessageContent::Text("hello".to_string()),
+            content: MessageContent::Text("hello".to_string()),
             name: None,
         }],
         tools: Some(vec![

sgl-router/tests/spec/chat_message.rs

@@ -1,5 +1,5 @@
 use serde_json::json;
-use sglang_router_rs::protocols::chat::{ChatMessage, UserMessageContent};
+use sglang_router_rs::protocols::chat::{ChatMessage, MessageContent};
 
 #[test]
 fn test_chat_message_tagged_by_role_system() {
@@ -11,7 +11,10 @@ fn test_chat_message_tagged_by_role_system() {
     let msg: ChatMessage = serde_json::from_value(json).unwrap();
     match msg {
         ChatMessage::System { content, .. } => {
-            assert_eq!(content, "You are a helpful assistant");
+            assert_eq!(
+                content,
+                MessageContent::Text("You are a helpful assistant".to_string())
+            )
         }
         _ => panic!("Expected System variant"),
     }
@@ -27,7 +30,7 @@ fn test_chat_message_tagged_by_role_user() {
     let msg: ChatMessage = serde_json::from_value(json).unwrap();
     match msg {
         ChatMessage::User { content, .. } => match content {
-            UserMessageContent::Text(text) => assert_eq!(text, "Hello"),
+            MessageContent::Text(text) => assert_eq!(text, "Hello"),
             _ => panic!("Expected text content"),
         },
         _ => panic!("Expected User variant"),
@@ -44,7 +47,7 @@ fn test_chat_message_tagged_by_role_assistant() {
     let msg: ChatMessage = serde_json::from_value(json).unwrap();
     match msg {
         ChatMessage::Assistant { content, .. } => {
-            assert_eq!(content, Some("Hi there!".to_string()));
+            assert_eq!(content, Some(MessageContent::Text("Hi there!".to_string())));
         }
         _ => panic!("Expected Assistant variant"),
     }
@@ -64,7 +67,12 @@ fn test_chat_message_tagged_by_role_tool() {
             content,
             tool_call_id,
         } => {
-            assert_eq!(content, "Tool result");
+            match content {
+                MessageContent::Text(text) => {
+                    assert_eq!(text, "Tool result");
+                }
+                _ => panic!("Expected content to be a string"),
+            }
             assert_eq!(tool_call_id, "call_123");
         }
         _ => panic!("Expected Tool variant"),