Reasoning parser (#4000)

Co-authored-by: Lucas Pickup <lupickup@microsoft.com>

python/sglang/srt/server_args.py

@@ -23,6 +23,7 @@ from typing import List, Optional
 import torch
 
 from sglang.srt.hf_transformers_utils import check_gguf_file
+from sglang.srt.reasoning_parser import ReasoningParser
 from sglang.srt.utils import (
     get_amdgpu_memory_capacity,
     get_hpu_memory_capacity,
@@ -97,6 +98,7 @@ class ServerArgs:
     api_key: Optional[str] = None
     file_storage_path: str = "sglang_storage"
     enable_cache_report: bool = False
+    reasoning_parser: Optional[str] = None
 
     # Data parallelism
     dp_size: int = 1
@@ -631,6 +633,13 @@ class ServerArgs:
             action="store_true",
             help="Return number of cached tokens in usage.prompt_tokens_details for each openai request.",
         )
+        parser.add_argument(
+            "--reasoning-parser",
+            type=str,
+            choices=list(ReasoningParser.DetectorMap.keys()),
+            default=ServerArgs.reasoning_parser,
+            help=f"Specify the parser for reasoning models, supported parsers are: {list(ReasoningParser.DetectorMap.keys())}.",
+        )
 
         # Data parallelism
         parser.add_argument(