[router][grpc] Remove `continue_final_message` in `ChatTemplateParams` and add...

[router][grpc] Remove `continue_final_message` in `ChatTemplateParams` and add `minijinja-contrib` (#11882)

sgl-router/Cargo.toml

@@ -64,6 +64,7 @@ anyhow = "1.0"
 tokenizers = { version = "0.22.0" }
 tiktoken-rs = { version = "0.7.0" }
 minijinja = { version = "2.0", features = ["unstable_machinery", "json", "builtins"] }
+minijinja-contrib = { version = "2.0", features = ["pycompat"] }
 rustls = { version = "0.23", default-features = false, features = ["ring", "std"] }
 hf-hub = { version = "0.4.3", features = ["tokio"] }
 rmcp = { version = "0.6.3", features = ["client", "server",

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

@@ -382,7 +382,6 @@ pub fn process_chat_messages(
 
         let params = ChatTemplateParams {
             add_generation_prompt: true,
-            continue_final_message: request.continue_final_message,
             tools: tools_json.as_deref(),
             template_kwargs: final_template_kwargs,
             ..Default::default()

sgl-router/src/tokenizer/chat_template.rs

@@ -3,12 +3,16 @@
 //! This module provides functionality to apply chat templates to messages,
 //! similar to HuggingFace transformers' apply_chat_template method.
 
-use std::collections::HashMap;
+use std::{collections::HashMap, fs};
 
 use anyhow::{anyhow, Result};
 use minijinja::{
     context,
-    machinery::ast::{Expr, Stmt},
+    machinery::{
+        ast::{Expr, Stmt},
+        parse, WhitespaceConfig,
+    },
+    syntax::SyntaxConfig,
     Environment, Value,
 };
 use serde_json;
@@ -323,11 +327,6 @@ impl<'a> Detector<'a> {
 /// AST-based detection using minijinja's unstable machinery
 /// Single-pass detector with scope tracking
 fn detect_format_with_ast(template: &str) -> Option<ChatTemplateContentFormat> {
-    use minijinja::{
-        machinery::{parse, WhitespaceConfig},
-        syntax::SyntaxConfig,
-    };
-
     let ast = match parse(
         template,
         "template",
@@ -350,7 +349,6 @@ fn detect_format_with_ast(template: &str) -> Option<ChatTemplateContentFormat> {
 #[derive(Default)]
 pub struct ChatTemplateParams<'a> {
     pub add_generation_prompt: bool,
-    pub continue_final_message: bool,
     pub tools: Option<&'a [serde_json::Value]>,
     pub documents: Option<&'a [serde_json::Value]>,
     pub template_kwargs: Option<&'a HashMap<String, serde_json::Value>>,
@@ -377,16 +375,15 @@ impl ChatTemplateProcessor {
         messages: &[serde_json::Value],
         params: ChatTemplateParams,
     ) -> Result<String> {
-        // Validate incompatible options
-        if params.continue_final_message && params.add_generation_prompt {
-            return Err(anyhow!("continue_final_message and add_generation_prompt are not compatible. Use continue_final_message when you want the model to continue the final message, and add_generation_prompt when you want to add a header that will prompt it to start a new assistant message instead."));
-        }
         let mut env = Environment::new();
 
         // Register the template
         env.add_template("chat", &self.template)
             .map_err(|e| anyhow!("Failed to add template: {}", e))?;
 
+        // Enable Python method compatibility (e.g., str.startswith, str.endswith)
+        env.set_unknown_method_callback(minijinja_contrib::pycompat::unknown_method_callback);
+
         // Get the template
         let tmpl = env
             .get_template("chat")
@@ -423,8 +420,6 @@ impl ChatTemplateProcessor {
 
 /// Load chat template from tokenizer config JSON
 pub fn load_chat_template_from_config(config_path: &str) -> Result<Option<String>> {
-    use std::fs;
-
     let content = fs::read_to_string(config_path)?;
     let config: serde_json::Value = serde_json::from_str(&content)?;