[Inference] Make the tool-call implicit reasoning end opt-in

megatron/core/tokenizers/text/parsers/__init__.py

@@ -5,11 +5,15 @@
 from megatron.core.tokenizers.text.parsers.nemotron_v3_reasoning_parser import (
     NemotronV3ReasoningParser,
 )
-from megatron.core.tokenizers.text.parsers.qwen3_coder_tool_parser import Qwen3CoderToolParser
+from megatron.core.tokenizers.text.parsers.qwen3_coder_tool_parser import (
+    Qwen3CoderToolCombinedParser,
+    Qwen3CoderToolParser,
+)
 
 PARSER_MAPPING = {
     "deepseek-r1-reasoning": DeepSeekR1ReasoningParser,
     "qwen3-coder-tool": Qwen3CoderToolParser,
+    "qwen3-coder-tool-combined": Qwen3CoderToolCombinedParser,
     "nemotron-v3-reasoning": NemotronV3ReasoningParser,
 }
 

megatron/core/tokenizers/text/parsers/qwen3_coder_tool_parser.py

@@ -266,7 +266,6 @@ def extract_tool_calls(
 class Qwen3CoderToolParser(BaseParser):
     """Parser for Qwen3 Coder style tool calls."""
 
-    implicit_reasoning_end_markers = ("<tool_call>",)
     streaming_markers = ("<tool_call>", "<function=")
 
     @staticmethod
@@ -290,3 +289,15 @@ def parse(text: str, **kwargs) -> tuple[str, dict[str, list[dict]]]:
             return information.get("content", ""), {"tool_calls": information.get("tool_calls", [])}
         else:
             return text, {}
+
+
+class Qwen3CoderToolCombinedParser(Qwen3CoderToolParser):
+    """Qwen3 Coder tool parser where <tool_call> also ends an open reasoning block.
+
+    `qwen3-coder-tool` leaves a tool call emitted before `</think>` inside the
+    reasoning text, like vLLM's standalone reasoning parsers paired with the
+    qwen3_coder tool parser. This variant treats `<tool_call>` as an implicit
+    end of reasoning and parses it, like vLLM's combined qwen3 parser.
+    """
+
+    implicit_reasoning_end_markers = ("<tool_call>",)

megatron/training/arguments.py

@@ -3025,7 +3025,9 @@ def _add_rl_args(parser):
                         help='Directory to write RL profiling data. Defaults to {save}/profiles.')
     group.add_argument('--rl-inference-parsers', nargs='*', default=[],
                        help='List of response parsers to enable for RL inference '
-                            '(e.g. --rl-inference-parsers deepseek-r1-reasoning qwen3-coder-tool).')
+                            '(e.g. --rl-inference-parsers deepseek-r1-reasoning qwen3-coder-tool). '
+                            'qwen3-coder-tool-combined additionally treats <tool_call> as the end of '
+                            'an unterminated reasoning block, like vLLM\'s combined qwen3 parser.')
     return parser
 
 def _add_training_args(parser):

tests/unit_tests/tokenizers/test_text_parsers.py

@@ -98,12 +98,12 @@ def test_parser_mapping_registers_nemotron_v3_reasoning():
     assert PARSER_MAPPING["nemotron-v3-reasoning"] is NemotronV3ReasoningParser
 
 
-def test_tool_call_marker_implicitly_ends_reasoning_for_downstream_parser():
+def test_tool_call_marker_implicitly_ends_reasoning_for_combined_parser():
     tool_text = (
         "<tool_call><function=bash><parameter=command>echo hi</parameter>" "</function></tool_call>"
     )
     model_output = f"I should inspect this first.\n{tool_text}"
-    tool_parser = PARSER_MAPPING["qwen3-coder-tool"]
+    tool_parser = PARSER_MAPPING["qwen3-coder-tool-combined"]
 
     content, reasoning_info = DeepSeekR1ReasoningParser.parse(
         model_output, implicit_reasoning_end_markers=tool_parser.implicit_reasoning_end_markers
@@ -133,3 +133,30 @@ def test_tool_call_marker_does_not_end_reasoning_unless_configured():
     model_output = "reasoning<tool_call>not enabled</tool_call>"
 
     assert DeepSeekR1ReasoningParser.parse(model_output) == ("", {"reasoning": model_output})
+
+
+def test_strict_tool_parser_keeps_unterminated_reasoning_intact():
+    tool_text = (
+        "<tool_call><function=bash><parameter=command>echo hi</parameter>" "</function></tool_call>"
+    )
+    model_output = f"I should inspect this first.\n{tool_text}"
+    tool_parser = PARSER_MAPPING["qwen3-coder-tool"]
+
+    assert getattr(tool_parser, "implicit_reasoning_end_markers", ()) == ()
+
+    content, reasoning_info = DeepSeekR1ReasoningParser.parse(
+        model_output,
+        implicit_reasoning_end_markers=getattr(tool_parser, "implicit_reasoning_end_markers", ()),
+    )
+
+    assert content == ""
+    assert reasoning_info == {"reasoning": model_output}
+
+
+def test_parser_mapping_registers_both_qwen3_coder_tool_parsers():
+    strict = PARSER_MAPPING["qwen3-coder-tool"]
+    combined = PARSER_MAPPING["qwen3-coder-tool-combined"]
+
+    assert issubclass(combined, strict)
+    assert combined.implicit_reasoning_end_markers == ("<tool_call>",)
+    assert combined.streaming_markers == strict.streaming_markers