[WIP] support MiniMax M2 model (#12129)

Signed-off-by: Xinyuan Tong <xinyuantong.cs@gmail.com>
Signed-off-by: xuebi <xuebi@minimaxi.com>
Co-authored-by: Xinyuan Tong <xinyuantong.cs@gmail.com>
Co-authored-by: Xinyuan Tong <115166877+JustinTong0323@users.noreply.github.com>
Co-authored-by: Roger Young <42564206+rogeryoungh@users.noreply.github.com>
Co-authored-by: xuebi <xuebi@minimaxi.com>

python/sglang/srt/parser/reasoning_parser.py

@@ -249,6 +249,31 @@ class GptOssDetector(BaseReasoningFormatDetector):
         )
 
 
+class MiniMaxAppendThinkDetector(BaseReasoningFormatDetector):
+    """
+    Append `<think>` token to the beginning of the text.
+    """
+
+    def __init__(self, stream_reasoning: bool = True, force_reasoning: bool = False):
+        # scheduler.py need `reasoning_parser.detector.think_end_token`
+        super().__init__(
+            "<think>",
+            "</think>",
+            force_reasoning=force_reasoning,
+            stream_reasoning=stream_reasoning,
+        )
+        self.is_first_chunk = False
+
+    def parse_streaming_increment(self, new_text: str) -> StreamingParseResult:
+        if not self.is_first_chunk:
+            self.is_first_chunk = True
+            new_text = self.think_start_token + new_text
+        return StreamingParseResult(normal_text=new_text)
+
+    def detect_and_parse(self, text: str) -> StreamingParseResult:
+        return StreamingParseResult(normal_text=self.think_start_token + text)
+
+
 class ReasoningParser:
     """
     Parser that handles both streaming and non-streaming scenarios for extracting
@@ -268,6 +293,8 @@ class ReasoningParser:
         "kimi": KimiDetector,
         "qwen3": Qwen3Detector,
         "qwen3-thinking": Qwen3Detector,
+        "minimax": Qwen3Detector,
+        "minimax-append-think": MiniMaxAppendThinkDetector,
         "step3": DeepSeekR1Detector,
     }
 
@@ -285,7 +312,7 @@ class ReasoningParser:
             raise ValueError(f"Unsupported model type: {model_type}")
 
         # Special cases where we override force_reasoning
-        if model_type.lower() in {"qwen3-thinking", "gpt-oss"}:
+        if model_type.lower() in {"qwen3-thinking", "gpt-oss", "minimax"}:
             force_reasoning = True
 
         # Only pass force_reasoning if explicitly set, let detectors use their defaults