[Rust Frontend] Bump xgrammar-structural-tag and enable local extension (#49161)

Signed-off-by: Bugen Zhao <i@bugenzhao.com>

rust/Cargo.lock

@@ -6321,9 +6321,9 @@ checksum = "9edde0db4769d2dc68579893f2306b26c6ecfbe0ef499b013d731b7b9247e0b9"
 
 [[package]]
 name = "xgrammar-structural-tag"
-version = "0.1.0+xgrammar.0.2.2.4d145cc"
+version = "0.2.0+xgrammar.0.2.4.dd729e7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2436dea2393d55a3b188588aa300c5a8afe8f45a77da52c611fb4498a6c876e6"
+checksum = "d4d24c842efc3c24e9756aa426d530cbdac0980e49af223cb384e276e981ca0a"
 dependencies = [
  "auto_impl",
  "serde",

rust/Cargo.toml

@@ -143,7 +143,7 @@ vllm-server = { path = "src/server" }
 vllm-text = { path = "src/text" }
 vllm-tokenizer = { path = "src/tokenizer" }
 winnow = { version = "1.0.2", features = ["simd"] }
-xgrammar-structural-tag = "0.1.0"
+xgrammar-structural-tag = "0.2.0"
 zeromq = { version = "0.6.0", default-features = false, features = [
     "tokio-runtime",
     "all-transport",

rust/src/chat/src/output/default/mod.rs

@@ -74,7 +74,7 @@ impl DefaultChatOutputProcessor {
             Box::new(CombinedParser::new(reasoning_parser, tool_parser)) as Box<dyn UnifiedParser>
         };
 
-        apply_structural_tag_constraint(request, parser.structural_tag_model())?;
+        apply_structural_tag_constraint(request, parser.structural_tag_builder())?;
 
         if parser.preserve_special_tokens() {
             request.decode_options.skip_special_tokens = false;

rust/src/chat/src/output/default/structural_tag.rs

@@ -7,7 +7,8 @@ use thiserror_ext::AsReport;
 use vllm_engine_core_client::protocol::structured_outputs::{
     StructuredOutputBackend, StructuredOutputsParams,
 };
-use vllm_parser::tool::StructuralTagModel;
+use vllm_parser::tool::StructuralTagBuilder;
+use xgrammar_structural_tag::builders::StructuralTagOptions;
 use xgrammar_structural_tag::{
     FunctionDefinition, FunctionToolParam, ToolChoice as StructuralTagToolChoice, ToolParam,
     build_structural_tag,
@@ -20,9 +21,9 @@ use crate::{Error, Result as ChatResult};
 /// support and the request's tool choice.
 pub(super) fn apply_structural_tag_constraint(
     request: &mut ChatRequest,
-    model: Option<StructuralTagModel>,
+    builder: Option<&dyn StructuralTagBuilder>,
 ) -> ChatResult<()> {
-    let Some(model) = model else {
+    let Some(builder) = builder else {
         return Ok(());
     };
     let Some(tool_choice) = structural_tag_tool_choice(request) else {
@@ -42,11 +43,16 @@ pub(super) fn apply_structural_tag_constraint(
         })
         .collect::<Vec<_>>();
 
-    let structural_tag = build_structural_tag(model, &tools, tool_choice, false)
-        .and_then(|tag| tag.to_json_string())
-        .map_err(|error| Error::StructuralTag {
-            message: error.to_report_string(),
-        })?;
+    let structural_tag = build_structural_tag(
+        builder,
+        &tools,
+        tool_choice,
+        StructuralTagOptions::default().with_reasoning(false),
+    )
+    .and_then(|tag| tag.to_json_string())
+    .map_err(|error| Error::StructuralTag {
+        message: error.to_report_string(),
+    })?;
 
     // Overwrite any existing structured output settings with the structural tag constraint.
     request.sampling_params.structured_outputs = Some(StructuredOutputsParams {
@@ -141,7 +147,7 @@ mod tests {
         let mut request = request(ChatToolChoice::Auto, vec![chat_tool("search", Some(true))]);
         let parser = qwen3_coder_parser(&request.tools);
 
-        apply_structural_tag_constraint(&mut request, parser.structural_tag_model())
+        apply_structural_tag_constraint(&mut request, parser.structural_tag_builder())
             .expect("structural tag should build");
 
         let tag = structural_tag_value(&request);
@@ -154,7 +160,7 @@ mod tests {
         let mut request = request(ChatToolChoice::Auto, vec![chat_tool("search", None)]);
         let parser = qwen3_coder_parser(&request.tools);
 
-        apply_structural_tag_constraint(&mut request, parser.structural_tag_model())
+        apply_structural_tag_constraint(&mut request, parser.structural_tag_builder())
             .expect("structural tag decision should succeed");
 
         assert!(request.sampling_params.structured_outputs.is_none());
@@ -169,7 +175,7 @@ mod tests {
         });
         let parser = qwen3_coder_parser(&request.tools);
 
-        apply_structural_tag_constraint(&mut request, parser.structural_tag_model())
+        apply_structural_tag_constraint(&mut request, parser.structural_tag_builder())
             .expect("structural tag should build");
 
         let params = structured_outputs(&request);
@@ -184,7 +190,7 @@ mod tests {
         let mut request = request(ChatToolChoice::Required, vec![chat_tool("search", None)]);
         let parser = qwen3_coder_parser(&request.tools);
 
-        apply_structural_tag_constraint(&mut request, parser.structural_tag_model())
+        apply_structural_tag_constraint(&mut request, parser.structural_tag_builder())
             .expect("structural tag should build");
 
         let tag = structural_tag_value(&request);
@@ -201,7 +207,7 @@ mod tests {
         });
         let parser = qwen3_coder_parser(&request.tools);
 
-        apply_structural_tag_constraint(&mut request, parser.structural_tag_model())
+        apply_structural_tag_constraint(&mut request, parser.structural_tag_builder())
             .expect("structural tag should build");
 
         let params = structured_outputs(&request);
@@ -221,7 +227,7 @@ mod tests {
         );
         let parser = qwen3_coder_parser(&request.tools);
 
-        apply_structural_tag_constraint(&mut request, parser.structural_tag_model())
+        apply_structural_tag_constraint(&mut request, parser.structural_tag_builder())
             .expect("structural tag should build");
 
         let tag = structural_tag_value(&request).to_string();
@@ -234,7 +240,7 @@ mod tests {
         let mut request = request(ChatToolChoice::None, vec![chat_tool("search", Some(true))]);
         let parser = qwen3_coder_parser(&request.tools);
 
-        apply_structural_tag_constraint(&mut request, parser.structural_tag_model())
+        apply_structural_tag_constraint(&mut request, parser.structural_tag_builder())
             .expect("structural tag decision should succeed");
 
         assert!(request.sampling_params.structured_outputs.is_none());
@@ -249,7 +255,7 @@ mod tests {
         });
         let parser = qwen3_coder_parser(&request.tools);
 
-        apply_structural_tag_constraint(&mut request, parser.structural_tag_model())
+        apply_structural_tag_constraint(&mut request, parser.structural_tag_builder())
             .expect("structural tag decision should succeed");
 
         let params = structured_outputs(&request);

rust/src/parser/benches/utils/adapter.rs

@@ -4,7 +4,7 @@
 use std::sync::Arc;
 
 use vllm_parser::tool::{
-    Result, StructuralTagModel, Tool, ToolParser, ToolParserError, ToolParserOutput,
+    Result, StructuralTagBuilder, Tool, ToolParser, ToolParserError, ToolParserOutput,
 };
 use vllm_parser::unified::{
     UnifiedParser, UnifiedParserError, UnifiedParserEvent, UnifiedParserOutput,
@@ -85,8 +85,8 @@ impl<T: UnifiedParser> ToolParser for UnifiedToolParserAdapter<T> {
         self.inner.preserve_special_tokens()
     }
 
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
-        self.inner.structural_tag_model()
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
+        self.inner.structural_tag_builder()
     }
 
     fn tool_call_id(&self, tool_index: usize) -> Option<&str> {

rust/src/parser/src/tool/deepseek_dsml/deepseek_v32.rs

@@ -2,7 +2,7 @@
 // SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
 use super::{DeepSeekDsmlToolParser, DsmlTokens};
-use crate::tool::{Result, StructuralTagModel, Tool, ToolParser, ToolParserOutput};
+use crate::tool::{Result, StructuralTagBuilder, Tool, ToolParser, ToolParserOutput};
 
 /// Tool parser for DeepSeek V3.2 models.
 ///
@@ -47,8 +47,8 @@ impl ToolParser for DeepSeekV32ToolParser {
         true
     }
 
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
-        Some(StructuralTagModel::DeepSeekV32)
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
+        Some(xgrammar_structural_tag::Model::DeepSeekV32.builder())
     }
 
     fn parse_into(&mut self, chunk: &str, output: &mut ToolParserOutput) -> Result<()> {

rust/src/parser/src/tool/deepseek_dsml/deepseek_v4.rs

@@ -2,7 +2,7 @@
 // SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
 use super::{DeepSeekDsmlToolParser, DsmlTokens};
-use crate::tool::{Result, StructuralTagModel, Tool, ToolParser, ToolParserOutput};
+use crate::tool::{Result, StructuralTagBuilder, Tool, ToolParser, ToolParserOutput};
 
 /// Tool parser for DeepSeek V4 models.
 ///
@@ -50,8 +50,8 @@ impl ToolParser for DeepSeekV4ToolParser {
         true
     }
 
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
-        Some(StructuralTagModel::DeepSeekV4)
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
+        Some(xgrammar_structural_tag::Model::DeepSeekV4.builder())
     }
 
     fn parse_into(&mut self, chunk: &str, output: &mut ToolParserOutput) -> Result<()> {
@@ -73,7 +73,7 @@ mod tests {
 
     use super::DeepSeekV4ToolParser;
     use crate::tool::test_utils::{collect_stream, test_tools};
-    use crate::tool::{StructuralTagModel, ToolParser, ToolParserTestExt as _};
+    use crate::tool::{ToolParser, ToolParserTestExt as _};
 
     fn build_tool_call(function_name: &str, params: &[(&str, &str)]) -> String {
         let params = params
@@ -91,13 +91,10 @@ mod tests {
     }
 
     #[test]
-    fn deepseek_v4_exposes_structural_tag_model() {
+    fn deepseek_v4_exposes_structural_tag_builder() {
         let parser = DeepSeekV4ToolParser::new(&test_tools());
 
-        assert_eq!(
-            parser.structural_tag_model(),
-            Some(StructuralTagModel::DeepSeekV4)
-        );
+        assert!(parser.structural_tag_builder().is_some());
     }
 
     #[test]

rust/src/parser/src/tool/deepseek_json/deepseek_v3.rs

@@ -2,7 +2,7 @@
 // SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
 use super::{DeepSeekJsonFormat, DeepSeekJsonToolParser};
-use crate::tool::{Result, StructuralTagModel, Tool, ToolParser, ToolParserOutput};
+use crate::tool::{Result, StructuralTagBuilder, Tool, ToolParser, ToolParserOutput};
 
 /// Tool parser for DeepSeek V3 JSON-fenced tool calls.
 ///
@@ -35,8 +35,8 @@ impl ToolParser for DeepSeekV3ToolParser {
         Ok(Box::new(Self::new(tools)))
     }
 
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
-        Some(StructuralTagModel::DeepSeekR1)
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
+        Some(xgrammar_structural_tag::Model::DeepSeekR1.builder())
     }
 
     fn parse_into(&mut self, chunk: &str, output: &mut ToolParserOutput) -> Result<()> {

rust/src/parser/src/tool/deepseek_json/deepseek_v31.rs

@@ -2,7 +2,7 @@
 // SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
 use super::{DeepSeekJsonFormat, DeepSeekJsonToolParser};
-use crate::tool::{Result, StructuralTagModel, Tool, ToolParser, ToolParserOutput};
+use crate::tool::{Result, StructuralTagBuilder, Tool, ToolParser, ToolParserOutput};
 
 /// Tool parser for DeepSeek V3.1 raw JSON tool calls.
 ///
@@ -31,8 +31,8 @@ impl ToolParser for DeepSeekV31ToolParser {
         Ok(Box::new(Self::new(tools)))
     }
 
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
-        Some(StructuralTagModel::DeepSeekV31)
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
+        Some(xgrammar_structural_tag::Model::DeepSeekV31.builder())
     }
 
     fn parse_into(&mut self, chunk: &str, output: &mut ToolParserOutput) -> Result<()> {

rust/src/parser/src/tool/glm_xml/glm47_moe.rs

@@ -2,7 +2,7 @@
 // SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
 use super::{GlmXmlToolParser, Separator};
-use crate::tool::{Result, StructuralTagModel, Tool, ToolParser, ToolParserOutput};
+use crate::tool::{Result, StructuralTagBuilder, Tool, ToolParser, ToolParserOutput};
 
 /// Tool parser for GLM-4.7 MoE XML-style tool calls.
 ///
@@ -25,8 +25,8 @@ impl ToolParser for Glm47MoeToolParser {
         Ok(Box::new(Self::new(tools)))
     }
 
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
-        Some(StructuralTagModel::Glm47)
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
+        Some(xgrammar_structural_tag::Model::Glm47.builder())
     }
 
     fn parse_into(&mut self, chunk: &str, output: &mut ToolParserOutput) -> Result<()> {

rust/src/parser/src/tool/hy_v3.rs

@@ -10,7 +10,7 @@ use winnow::token::{literal, rest, take_until};
 use super::parameters::ToolSchemas;
 use super::utils::{MarkerScanState, parse_buffered_event, safe_text_len, take_until_marker};
 use super::{Result, ToolCallDelta, ToolParser, ToolParserOutput};
-use crate::tool::{StructuralTagModel, Tool};
+use crate::tool::{StructuralTagBuilder, Tool};
 
 const TOOL_CALLS_START: &str = "<tool_calls>";
 const TOOL_CALLS_END: &str = "</tool_calls>";
@@ -116,8 +116,8 @@ impl ToolParser for HyV3ToolParser {
         Ok(Box::new(Self::new(tools)))
     }
 
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
-        Some(StructuralTagModel::HyV3)
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
+        Some(xgrammar_structural_tag::Model::HyV3.builder())
     }
 
     fn parse_into(&mut self, chunk: &str, output: &mut ToolParserOutput) -> Result<()> {

rust/src/parser/src/tool/json/hermes.rs

@@ -2,7 +2,7 @@
 // SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
 use super::{JsonToolCallConfig, JsonToolCallParser, JsonToolCallWhitespace};
-use crate::tool::{Result, StructuralTagModel, Tool, ToolParser, ToolParserOutput};
+use crate::tool::{Result, StructuralTagBuilder, Tool, ToolParser, ToolParserOutput};
 
 const HERMES_CONFIG: JsonToolCallConfig = JsonToolCallConfig {
     parser_name: "Hermes",
@@ -48,8 +48,8 @@ impl ToolParser for HermesToolParser {
         Ok(Box::new(Self::new(tools)))
     }
 
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
-        Some(StructuralTagModel::Hermes)
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
+        Some(xgrammar_structural_tag::Model::Hermes.builder())
     }
 
     fn parse_into(&mut self, chunk: &str, output: &mut ToolParserOutput) -> Result<()> {

rust/src/parser/src/tool/json/llama.rs

@@ -12,7 +12,9 @@ use super::{
     argument_delta_event, tool_call_header_event,
 };
 use crate::tool::utils::{JsonObjectScanState, parse_buffered_event};
-use crate::tool::{Result, StructuralTagModel, Tool, ToolCallDelta, ToolParser, ToolParserOutput};
+use crate::tool::{
+    Result, StructuralTagBuilder, Tool, ToolCallDelta, ToolParser, ToolParserOutput,
+};
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 enum LlamaJsonMode {
@@ -136,8 +138,8 @@ impl ToolParser for Llama3JsonToolParser {
         Ok(Box::new(Self::new(tools)))
     }
 
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
-        Some(StructuralTagModel::Llama)
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
+        Some(xgrammar_structural_tag::Model::Llama.builder())
     }
 
     fn parse_into(&mut self, chunk: &str, output: &mut ToolParserOutput) -> Result<()> {

rust/src/parser/src/tool/json/qwen.rs

@@ -2,7 +2,7 @@
 // SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
 use super::{JsonToolCallConfig, JsonToolCallParser, JsonToolCallWhitespace};
-use crate::tool::{Result, StructuralTagModel, Tool, ToolParser, ToolParserOutput};
+use crate::tool::{Result, StructuralTagBuilder, Tool, ToolParser, ToolParserOutput};
 
 const QWEN_XML_CONFIG: JsonToolCallConfig = JsonToolCallConfig {
     parser_name: "Qwen XML",
@@ -50,8 +50,8 @@ impl ToolParser for Qwen3XmlToolParser {
         Ok(Box::new(Self::new(tools)))
     }
 
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
-        Some(StructuralTagModel::Qwen3)
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
+        Some(xgrammar_structural_tag::Model::Qwen3.builder())
     }
 
     fn parse_into(&mut self, chunk: &str, output: &mut ToolParserOutput) -> Result<()> {

rust/src/parser/src/tool/kimi_k2.rs

@@ -11,7 +11,7 @@ use winnow::token::{literal, rest, take_until, take_while};
 
 use super::utils::{JsonObjectScanState, parse_buffered_event, safe_text_len, take_json_object};
 use super::{Result, ToolCallDelta, ToolParser, ToolParserOutput};
-use crate::tool::{StructuralTagModel, Tool};
+use crate::tool::{StructuralTagBuilder, Tool};
 
 const TOOL_CALLS_START: &str = "<|tool_calls_section_begin|>";
 const TOOL_CALLS_END: &str = "<|tool_calls_section_end|>";
@@ -150,8 +150,8 @@ impl ToolParser for KimiK2ToolParser {
         true
     }
 
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
-        Some(StructuralTagModel::Kimi)
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
+        Some(xgrammar_structural_tag::Model::Kimi.builder())
     }
 
     fn tool_call_id(&self, tool_index: usize) -> Option<&str> {

rust/src/parser/src/tool/minimax_m2.rs

@@ -10,7 +10,7 @@ use winnow::token::{literal, rest, take_until};
 use super::parameters::ToolSchemas;
 use super::utils::{MarkerScanState, parse_buffered_event, safe_text_len, take_until_marker};
 use super::{Result, ToolCallDelta, ToolParser, ToolParserOutput};
-use crate::tool::{StructuralTagModel, Tool};
+use crate::tool::{StructuralTagBuilder, Tool};
 
 const TOOL_CALL_START: &str = "<minimax:tool_call>";
 const TOOL_CALL_END: &str = "</minimax:tool_call>";
@@ -115,8 +115,8 @@ impl ToolParser for MinimaxM2ToolParser {
         Ok(Box::new(Self::new(tools)))
     }
 
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
-        Some(StructuralTagModel::Minimax)
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
+        Some(xgrammar_structural_tag::Model::Minimax.builder())
     }
 
     fn parse_into(&mut self, chunk: &str, output: &mut ToolParserOutput) -> Result<()> {

rust/src/parser/src/tool/mod.rs

@@ -36,7 +36,7 @@ pub use qwen_coder::Qwen3CoderToolParser;
 pub use seed_oss::SeedOssToolParser;
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
-pub use xgrammar_structural_tag::Model as StructuralTagModel;
+pub use xgrammar_structural_tag::builders::StructuralTagBuilder;
 
 use crate::utils;
 
@@ -187,8 +187,8 @@ pub trait ToolParser: Send {
         false
     }
 
-    /// Return the xgrammar structural-tag model used for strict tool calling.
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
+    /// Return the xgrammar structural-tag builder used for strict tool calling.
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
         None
     }
 

rust/src/parser/src/tool/qwen_coder.rs

@@ -9,8 +9,8 @@ use winnow::token::{literal, take_until};
 
 use super::parameters::ToolSchemas;
 use super::utils::{MarkerScanState, parse_buffered_event, safe_text_len, take_until_marker};
-use super::{Result, StructuralTagModel, ToolCallDelta, ToolParser, ToolParserOutput};
-use crate::tool::Tool;
+use super::{Result, ToolCallDelta, ToolParser, ToolParserOutput};
+use crate::tool::{StructuralTagBuilder, Tool};
 
 const TOOL_CALL_START: &str = "<tool_call>";
 const TOOL_CALL_END: &str = "</tool_call>";
@@ -146,8 +146,8 @@ impl ToolParser for Qwen3CoderToolParser {
         Ok(Box::new(Self::new(tools)))
     }
 
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
-        Some(StructuralTagModel::Qwen3Coder)
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
+        Some(xgrammar_structural_tag::Model::Qwen3Coder.builder())
     }
 
     fn parse_into(&mut self, chunk: &str, output: &mut ToolParserOutput) -> Result<()> {
@@ -294,7 +294,7 @@ mod tests {
     use serde_json::{Value, json};
     use thiserror_ext::AsReport;
 
-    use super::{Qwen3CoderToolParser, StructuralTagModel, ToolParser};
+    use super::{Qwen3CoderToolParser, ToolParser};
     use crate::tool::test_utils::{collect_stream, split_by_chars, test_tools};
     use crate::tool::{ToolParserOutput, ToolParserTestExt as _};
 
@@ -308,13 +308,10 @@ mod tests {
     }
 
     #[test]
-    fn qwen_coder_exposes_structural_tag_model() {
+    fn qwen_coder_exposes_structural_tag_builder() {
         let parser = Qwen3CoderToolParser::new(&test_tools());
 
-        assert_eq!(
-            parser.structural_tag_model(),
-            Some(StructuralTagModel::Qwen3Coder)
-        );
+        assert!(parser.structural_tag_builder().is_some());
     }
 
     #[test]

rust/src/parser/src/unified/combined.rs

@@ -7,7 +7,7 @@ use vllm_tokenizer::DynTokenizer;
 
 use super::{Result, UnifiedParser, UnifiedParserError, UnifiedParserOutput};
 use crate::reasoning::ReasoningParser;
-use crate::tool::{StructuralTagModel, Tool, ToolParser, ToolParserOutput};
+use crate::tool::{StructuralTagBuilder, Tool, ToolParser, ToolParserOutput};
 
 /// Unified parser that composes existing reasoning and tool parsers.
 pub struct CombinedParser {
@@ -79,8 +79,8 @@ impl UnifiedParser for CombinedParser {
             || self.tool.as_ref().is_some_and(|parser| parser.preserve_special_tokens())
     }
 
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
-        self.tool.as_ref().and_then(|parser| parser.structural_tag_model())
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
+        self.tool.as_ref().and_then(|parser| parser.structural_tag_builder())
     }
 
     fn tool_call_id(&self, tool_index: usize) -> Option<&str> {
@@ -269,10 +269,7 @@ mod tests {
     fn combined_parser_emits_tool_calls_from_visible_content() {
         let tool = Qwen3XmlToolParser::create(&test_tools()).unwrap();
         let mut parser = CombinedParser::new(None, Some(tool));
-        assert!(matches!(
-            parser.structural_tag_model(),
-            Some(crate::tool::StructuralTagModel::Qwen3)
-        ));
+        assert!(parser.structural_tag_builder().is_some());
 
         let output = collect(
             &mut parser,

rust/src/parser/src/unified/mod.rs

@@ -16,7 +16,7 @@ use vllm_tokenizer::DynTokenizer;
 
 use crate::reasoning::ReasoningError;
 use crate::tool::{
-    StructuralTagModel, Tool, ToolCallDelta, ToolParserError, ToolParserEvent, ToolParserOutput,
+    StructuralTagBuilder, Tool, ToolCallDelta, ToolParserError, ToolParserEvent, ToolParserOutput,
 };
 
 /// Result alias for unified parser operations.
@@ -171,8 +171,8 @@ pub trait UnifiedParser: Send {
         false
     }
 
-    /// Return the xgrammar structural-tag model used for strict tool calling.
-    fn structural_tag_model(&self) -> Option<StructuralTagModel> {
+    /// Return the xgrammar structural-tag builder used for strict tool calling.
+    fn structural_tag_builder(&self) -> Option<&dyn StructuralTagBuilder> {
         None
     }