test(frontend): cover deepseek-v3/v4 thinking opt-in

Add a direct unit test for resolve_request_force_reasoning asserting that
deepseek-v3 and deepseek-v4 both opt into reasoning via
chat_template_kwargs.thinking and stay off by default. The behavior already
lives in main (deepseek-v4 in _THINKING_OPT_IN); this adds the focused
default-off assertion that ai-dynamo#10163 carried, as a test-only change.

Signed-off-by: Gavin.Zhu <gavin.z@gmicloud.ai>

Author: GavinZhu-GMI

components/src/dynamo/frontend/tests/test_sglang_processor_unit.py

@@ -632,6 +632,27 @@ def test_minimax_m3_force_reasoning_uses_thinking_mode():
     )
 
 
+@pytest.mark.parametrize("parser_name", ["deepseek-v3", "deepseek-v4"])
+def test_deepseek_v3_v4_thinking_opt_in(parser_name):
+    """deepseek-v3/v4 opt into reasoning via chat_template_kwargs.thinking.
+
+    deepseek-v4 maps to the same _DeepSeekV3Detector as deepseek-v3 in sglang,
+    so both honor the ``thinking`` kwarg and stay off by default.
+    """
+    assert (
+        resolve_request_force_reasoning(
+            {"chat_template_kwargs": {"thinking": True}},
+            parser_name,
+            template_default=False,
+        )
+        is True
+    )
+    assert (
+        resolve_request_force_reasoning({}, parser_name, template_default=False)
+        is False
+    )
+
+
 class _CapturingReasoningParser:
     def __init__(self, *, model_type, stream_reasoning, force_reasoning):
         self.model_type = model_type