Support GLM-4.7 function calling via structural tags (#28149)

Co-authored-by: Xinyuan Tong <115166877+JustinTong0323@users.noreply.github.com>
Co-authored-by: Xinyuan Tong <xinyuantong.cs@gmail.com>

python/sglang/srt/function_call/glm47_moe_detector.py

@@ -3,10 +3,15 @@ import json
 import logging
 import re
 from enum import Enum
-from typing import Any, Dict, List, Optional, Tuple
+from functools import lru_cache
+from typing import Any, Dict, List, Literal, Optional, Tuple, Union
 
-from sglang.srt.entrypoints.openai.protocol import Tool
-from sglang.srt.function_call.base_format_detector import BaseFormatDetector
+from sglang.srt.entrypoints.openai.protocol import Tool, ToolChoice
+from sglang.srt.function_call.base_format_detector import (
+    BaseFormatDetector,
+    StructuralTag,
+    get_model_structural_tag,
+)
 from sglang.srt.function_call.core_types import (
     StreamingParseResult,
     ToolCallItem,
@@ -17,6 +22,21 @@ from sglang.srt.function_call.utils import infer_type_from_json_schema
 logger = logging.getLogger(__name__)
 
 
+@lru_cache(maxsize=1)
+def _glm47_native_structural_tag_available() -> bool:
+    # "glm_4_7" is only registered in newer xgrammar, so the import can succeed
+    # while the model name stays unknown. Probe once and fall back if absent.
+    if get_model_structural_tag is None:
+        return False
+    try:
+        get_model_structural_tag(
+            model="glm_4_7", tools=[], tool_choice="auto", reasoning=False
+        )
+        return True
+    except Exception:
+        return False
+
+
 class StreamState(str, Enum):
     """State machine states for XML to JSON streaming conversion."""
 
@@ -781,7 +801,22 @@ class Glm47MoeDetector(BaseFormatDetector):
         return arguments
 
     def supports_structural_tag(self) -> bool:
-        return False
+        return _glm47_native_structural_tag_available()
+
+    def get_structural_tag(
+        self,
+        tools: Union[List[Tool], None] = None,
+        tool_choice: Union[ToolChoice, Literal["auto", "required"]] = "auto",
+        thinking_mode: bool = False,
+    ) -> Optional[StructuralTag]:
+        if not self.supports_structural_tag():
+            return None
+        return super().get_structural_tag(
+            tools=tools, tool_choice=tool_choice, thinking_mode=thinking_mode
+        )
 
     def structure_info(self) -> _GetInfoFunc:
-        raise NotImplementedError()
+        raise NotImplementedError
+
+    def get_structural_tag_name(self) -> str:
+        return "glm_4_7"