Merge 2b3cde3526 into e32d8a4d03

litellm/llms/anthropic/chat/transformation.py

@@ -376,6 +376,8 @@ def _build_anthropic_tool_name_maps(
     return forward, reverse
 
 
+_CLAUDE_MAJOR_VERSION: Final = re.compile(r"claude-[a-z]+-(\d+)")
+
 REASONING_EFFORT_TO_OUTPUT_CONFIG_EFFORT: Final[dict[str, str]] = {
     "low": "low",
     "minimal": "low",
@@ -1565,7 +1567,23 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
         llm_provider: str = "anthropic",
     ) -> AnthropicThinkingParam | None:
         """Capability probes read the cost map under ``custom_llm_provider``; ``llm_provider`` only tags raised exceptions."""
-        if reasoning_effort is None or reasoning_effort == "none":
+        if reasoning_effort is None:
+            return None
+        if reasoning_effort == "none":
+            # An explicit "none" asks for thinking off. On Claude 5-generation
+            # models that default thinking on (Opus 5, Sonnet 5, Haiku 5.5),
+            # omission leaves the model's default in effect, so translate
+            # "none" to thinking.type="disabled", which those models accept.
+            # Models that default thinking off keep omission, which already
+            # honors "none"; always-on-thinking models reject "disabled" and
+            # are handled downstream by maybe_drop_disabled_thinking.
+            major: Final = _CLAUDE_MAJOR_VERSION.search(model)
+            if (
+                major is not None
+                and int(major.group(1)) >= 5
+                and AnthropicConfig._is_adaptive_thinking_model(model, custom_llm_provider)
+            ):
+                return AnthropicThinkingParam(type="disabled")
             return None
         if AnthropicConfig._is_adaptive_thinking_model(model, custom_llm_provider):
             # without display, Anthropic defaults adaptive thinking to
@@ -1962,7 +1980,10 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
                     optional_params.pop("output_config", None)
                 else:
                     optional_params["thinking"] = mapped_thinking
-                    if AnthropicConfig._is_adaptive_thinking_model(model, self._resolved_provider):
+                    # "none" disables thinking outright; there is no matching output_config effort.
+                    if effort_value != "none" and AnthropicConfig._is_adaptive_thinking_model(
+                        model, self._resolved_provider
+                    ):
                         mapped_effort = REASONING_EFFORT_TO_OUTPUT_CONFIG_EFFORT.get(effort_value)
                         if mapped_effort is None:
                             AnthropicConfig._raise_invalid_reasoning_effort(

litellm/llms/bedrock/chat/converse_transformation.py

@@ -552,7 +552,8 @@ class AmazonConverseConfig(BaseConfig):
                 optional_params.pop("output_config", None)
             else:
                 optional_params["thinking"] = mapped_thinking
-                if AnthropicConfig.is_adaptive_thinking_model(model, "bedrock"):
+                # "none" disables thinking outright; there is no matching output_config effort.
+                if reasoning_effort != "none" and AnthropicConfig.is_adaptive_thinking_model(model, "bedrock"):
                     mapped_effort = REASONING_EFFORT_TO_OUTPUT_CONFIG_EFFORT.get(reasoning_effort)
                     if mapped_effort is None:
                         AnthropicConfig.raise_invalid_reasoning_effort(

tests/unit/llms/anthropic/test_anthropic_reasoning_effort.py

@@ -74,3 +74,58 @@ class TestMapReasoningEffort:
             reasoning_effort="none", model="claude-4-sonnet-20250514", custom_llm_provider="anthropic"
         )
         assert result is None
+
+    def test_none_string_returns_disabled_for_haiku_5_5(self):
+        """reasoning_effort='none' must explicitly disable thinking on Claude
+        models that default thinking on (Haiku 5.5); omission leaves the
+        model's default in effect."""
+        result = AnthropicConfig.map_reasoning_effort(
+            reasoning_effort="none", model="claude-haiku-5-5", custom_llm_provider="anthropic"
+        )
+        assert result == {"type": "disabled"}
+
+    def test_none_string_returns_disabled_for_opus_5(self):
+        result = AnthropicConfig.map_reasoning_effort(
+            reasoning_effort="none", model="claude-opus-5", custom_llm_provider="anthropic"
+        )
+        assert result == {"type": "disabled"}
+
+    def test_none_string_returns_disabled_for_always_on_model(self):
+        """Always-on models map to 'disabled' too; transform_request drops it
+        via maybe_drop_disabled_thinking (the API-documented remedy)."""
+        result = AnthropicConfig.map_reasoning_effort(
+            reasoning_effort="none", model="claude-sonnet-5-5", custom_llm_provider="anthropic"
+        )
+        assert result == {"type": "disabled"}
+
+    def test_none_string_map_openai_params_sets_thinking_without_output_config(self):
+        params = AnthropicConfig().map_openai_params(
+            non_default_params={"reasoning_effort": "none"},
+            optional_params={},
+            model="claude-haiku-5-5",
+            drop_params=False,
+        )
+        assert params.get("thinking") == {"type": "disabled"}
+        assert "output_config" not in params
+
+    def test_disabled_thinking_dropped_for_always_on_model(self):
+        from litellm.llms.anthropic.common_utils import AnthropicModelInfo
+
+        optional_params = {"thinking": {"type": "disabled"}}
+        AnthropicModelInfo.maybe_drop_disabled_thinking(
+            model="claude-sonnet-5-5",
+            optional_params=optional_params,
+            custom_llm_provider="anthropic",
+        )
+        assert "thinking" not in optional_params
+
+    def test_disabled_thinking_kept_for_haiku_5_5(self):
+        from litellm.llms.anthropic.common_utils import AnthropicModelInfo
+
+        optional_params = {"thinking": {"type": "disabled"}}
+        AnthropicModelInfo.maybe_drop_disabled_thinking(
+            model="claude-haiku-5-5",
+            optional_params=optional_params,
+            custom_llm_provider="anthropic",
+        )
+        assert optional_params["thinking"] == {"type": "disabled"}