diff --git a/litellm/constants.py b/litellm/constants.py
index 334ef8d48a..177fb024d6 100644
--- a/litellm/constants.py
+++ b/litellm/constants.py
@@ -399,6 +399,16 @@ BEDROCK_MAX_POLICY_SIZE = int(os.getenv("BEDROCK_MAX_POLICY_SIZE", 75))
 BEDROCK_MIN_THINKING_BUDGET_TOKENS = int(
     os.getenv("BEDROCK_MIN_THINKING_BUDGET_TOKENS", 1024)
 )
+# Anthropic's Messages API rejects ``thinking.budget_tokens < 1024`` with a
+# 400. ``reasoning_effort='minimal'`` historically mapped to 128 (the global
+# default) which always 400'd against direct Anthropic, Azure AI Anthropic,
+# Vertex AI Anthropic, and Bedrock Invoke. Use the provider minimum so
+# ``minimal`` is a usable tier on all Anthropic-backed routes; Bedrock
+# Converse already clamped to 1024 server-side, so this just unifies the
+# behavior.
+ANTHROPIC_MIN_THINKING_BUDGET_TOKENS = int(
+    os.getenv("ANTHROPIC_MIN_THINKING_BUDGET_TOKENS", 1024)
+)
 REPLICATE_POLLING_DELAY_SECONDS = float(
     os.getenv("REPLICATE_POLLING_DELAY_SECONDS", 0.5)
 )
diff --git a/litellm/llms/anthropic/chat/transformation.py b/litellm/llms/anthropic/chat/transformation.py
index 35624c93b3..7b07a96ca5 100644
--- a/litellm/llms/anthropic/chat/transformation.py
+++ b/litellm/llms/anthropic/chat/transformation.py
@@ -7,6 +7,7 @@ import httpx
 
 import litellm
 from litellm.constants import (
+    ANTHROPIC_MIN_THINKING_BUDGET_TOKENS,
     ANTHROPIC_WEB_SEARCH_TOOL_MAX_USES,
     DEFAULT_ANTHROPIC_CHAT_MAX_TOKENS,
     DEFAULT_REASONING_EFFORT_HIGH_THINKING_BUDGET,
@@ -819,9 +820,16 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
                 budget_tokens=DEFAULT_REASONING_EFFORT_HIGH_THINKING_BUDGET,
             )
         elif reasoning_effort == "minimal":
+            # Anthropic Messages API rejects ``budget_tokens < 1024`` with a
+            # 400. Floor at the provider minimum so ``minimal`` is a usable
+            # tier on Anthropic / Azure AI Anthropic / Vertex AI Anthropic /
+            # Bedrock Invoke. Bedrock Converse already clamps server-side.
             return AnthropicThinkingParam(
                 type="enabled",
-                budget_tokens=DEFAULT_REASONING_EFFORT_MINIMAL_THINKING_BUDGET,
+                budget_tokens=max(
+                    DEFAULT_REASONING_EFFORT_MINIMAL_THINKING_BUDGET,
+                    ANTHROPIC_MIN_THINKING_BUDGET_TOKENS,
+                ),
             )
         else:
             raise ValueError(f"Unmapped reasoning effort: {reasoning_effort}")
@@ -1088,9 +1096,21 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
             elif param == "thinking":
                 optional_params["thinking"] = value
             elif param == "reasoning_effort" and isinstance(value, str):
-                mapped_thinking = AnthropicConfig._map_reasoning_effort(
-                    reasoning_effort=value, model=model
-                )
+                # Wrap the ``ValueError`` ``_map_reasoning_effort`` raises on
+                # unmapped efforts (``disabled`` / ``invalid`` / ``""`` /
+                # ``xhigh``/``max`` on budget-mode Claude 4.5) into a clean
+                # 400 ``BadRequestError`` instead of letting it surface as
+                # 500.
+                try:
+                    mapped_thinking = AnthropicConfig._map_reasoning_effort(
+                        reasoning_effort=value, model=model
+                    )
+                except ValueError as e:
+                    raise litellm.exceptions.BadRequestError(
+                        message=str(e),
+                        model=model,
+                        llm_provider=self.custom_llm_provider or "anthropic",
+                    )
                 if mapped_thinking is None:
                     optional_params.pop("thinking", None)
                     optional_params.pop("output_config", None)
@@ -1526,18 +1546,31 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
     def _apply_output_config(
         self, data: dict, model: str, optional_params: dict
     ) -> None:
-        """Validate and apply output_config to the request data."""
+        """Validate and apply output_config to the request data.
+
+        Validation errors raise ``BadRequestError`` (clean 400) so callers
+        passing ``effort="disabled"`` / ``effort=""`` / unsupported tiers
+        for the model see a client-side error rather than a 500.
+        """
         if "output_config" not in optional_params:
             return
         output_config = optional_params.get("output_config")
         if not output_config or not isinstance(output_config, dict):
             return
         effort = output_config.get("effort")
+        # ``effort=""`` (empty string) and unmapped strings should be treated
+        # as invalid, not silently passed through. We use ``effort is not None``
+        # here so empty string fails the membership check below. (The legacy
+        # ``if effort and ...`` short-circuit silently accepted ``""``.)
         valid_efforts = ["high", "medium", "low", "xhigh", "max"]
-        if effort and effort not in valid_efforts:
-            raise ValueError(
-                f"Invalid effort value: {effort}. Must be one of: "
-                f"'high', 'medium', 'low', 'xhigh', 'max'"
+        if effort is not None and effort not in valid_efforts:
+            raise litellm.exceptions.BadRequestError(
+                message=(
+                    f"Invalid effort value: {effort!r}. Must be one of: "
+                    f"'high', 'medium', 'low', 'xhigh', 'max'"
+                ),
+                model=model,
+                llm_provider=self.custom_llm_provider or "anthropic",
             )
         # ``max`` is for Opus 4.6+ output effort (not Sonnet 4.6, not Opus 4.5).
         # Accept known Opus 4.6/4.7 id patterns and/or ``supports_max_reasoning_effort``
@@ -1547,14 +1580,24 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
             or self._is_opus_4_7_model(model)
             or self._supports_effort_level(model, "max")
         ):
-            raise ValueError(
-                f"effort='max' is not supported by this model. Got model: {model}"
+            raise litellm.exceptions.BadRequestError(
+                message=(
+                    f"effort='max' is not supported by this model. "
+                    f"Got model: {model}"
+                ),
+                model=model,
+                llm_provider=self.custom_llm_provider or "anthropic",
             )
         # ``xhigh`` is data-driven via ``supports_xhigh_reasoning_effort`` so
         # enabling it for a new model is a pure model-map change.
         if effort == "xhigh" and not self._supports_effort_level(model, "xhigh"):
-            raise ValueError(
-                f"effort='xhigh' is not supported by this model. Got model: {model}"
+            raise litellm.exceptions.BadRequestError(
+                message=(
+                    f"effort='xhigh' is not supported by this model. "
+                    f"Got model: {model}"
+                ),
+                model=model,
+                llm_provider=self.custom_llm_provider or "anthropic",
             )
         data["output_config"] = output_config
 
diff --git a/litellm/llms/bedrock/chat/converse_transformation.py b/litellm/llms/bedrock/chat/converse_transformation.py
index 8b8500ac06..9e46a5f2ae 100644
--- a/litellm/llms/bedrock/chat/converse_transformation.py
+++ b/litellm/llms/bedrock/chat/converse_transformation.py
@@ -415,6 +415,15 @@ class AmazonConverseConfig(BaseConfig):
         - Nova 2 models: Transform to reasoningConfig structure
         - Other models (Anthropic, etc.): Convert to thinking parameter
 
+        For Claude 4.6 / 4.7 (adaptive thinking) the tier is carried via
+        ``output_config.effort`` rather than ``thinking.budget_tokens``. We
+        validate the effort with the same rules ``AnthropicConfig._apply_output_config``
+        uses (low/medium/high/xhigh/max + per-model gating) and stage the
+        validated dict on ``optional_params["output_config"]`` so it rides
+        along to ``additionalModelRequestFields`` on the Anthropic-on-Bedrock
+        wire path. Without this the silent strip in ``_prepare_request_params``
+        collapsed every adaptive tier to identical behavior.
+
         Args:
             model: The model identifier
             reasoning_effort: The reasoning effort value
@@ -448,14 +457,115 @@ class AmazonConverseConfig(BaseConfig):
             )
             optional_params.update(reasoning_config)
         else:
-            # Anthropic and other models: convert to thinking parameter
-            mapped_thinking = AnthropicConfig._map_reasoning_effort(
-                reasoning_effort=reasoning_effort, model=model
-            )
+            # Anthropic and other models: convert to thinking parameter.
+            # Wrap the ``ValueError`` ``_map_reasoning_effort`` raises on
+            # unmapped efforts (``disabled`` / ``invalid`` / ``""`` /
+            # ``xhigh``/``max`` on budget-mode Claude 4.5) into a clean 400
+            # ``BadRequestError`` instead of letting it surface as 500.
+            try:
+                mapped_thinking = AnthropicConfig._map_reasoning_effort(
+                    reasoning_effort=reasoning_effort, model=model
+                )
+            except ValueError as e:
+                raise litellm.exceptions.BadRequestError(
+                    message=str(e),
+                    model=model,
+                    llm_provider="bedrock_converse",
+                )
             if mapped_thinking is None:
                 optional_params.pop("thinking", None)
+                optional_params.pop("output_config", None)
             else:
                 optional_params["thinking"] = mapped_thinking
+                # Adaptive-thinking models (Claude 4.6 / 4.7) take the tier
+                # via output_config.effort. Mirror the mapping used by
+                # AnthropicConfig.map_openai_params and apply the same
+                # validation rules so unmapped/garbage efforts surface as a
+                # 400 instead of being silently flattened on the wire.
+                if AnthropicConfig._is_claude_4_6_model(
+                    model
+                ) or AnthropicConfig._is_claude_4_7_model(model):
+                    effort_map = {
+                        "low": "low",
+                        "minimal": "low",
+                        "medium": "medium",
+                        "high": "high",
+                        "xhigh": "xhigh",
+                        "max": "max",
+                    }
+                    mapped_effort = effort_map.get(reasoning_effort, reasoning_effort)
+                    self._validate_anthropic_adaptive_effort(
+                        model=model, effort=mapped_effort
+                    )
+                    optional_params["output_config"] = {"effort": mapped_effort}
+
+    @staticmethod
+    def _supports_effort_level_on_bedrock(model: str, level: str) -> bool:
+        """Look up ``supports_{level}_reasoning_effort`` for a Bedrock-routed
+        model id directly in ``litellm.model_cost`` so the bedrock provider
+        prefix is irrelevant to the lookup. ``AnthropicConfig._supports_effort_level``
+        hard-codes ``custom_llm_provider="anthropic"`` and returns False for
+        the same effort level on a Bedrock model id.
+        """
+        try:
+            base_model = BedrockModelInfo.get_base_model(model)
+            for key in (model, base_model, f"bedrock/{base_model}"):
+                if key and key in litellm.model_cost:
+                    if (
+                        litellm.model_cost[key].get(
+                            f"supports_{level}_reasoning_effort"
+                        )
+                        is True
+                    ):
+                        return True
+        except Exception:
+            pass
+        return False
+
+    @staticmethod
+    def _validate_anthropic_adaptive_effort(model: str, effort: str) -> None:
+        """Validate ``output_config.effort`` for adaptive-thinking Claude 4.6/4.7
+        on Bedrock. Raises ``BadRequestError`` (clean 400) instead of letting
+        a downstream ``ValueError`` surface as 500.
+        """
+        valid_efforts = {"high", "medium", "low", "xhigh", "max"}
+        if effort not in valid_efforts:
+            raise litellm.exceptions.BadRequestError(
+                message=(
+                    f"Invalid reasoning_effort/output_config.effort value: "
+                    f"{effort!r}. Must be one of: 'low', 'medium', 'high', "
+                    f"'xhigh', 'max', or 'none'."
+                ),
+                model=model,
+                llm_provider="bedrock_converse",
+            )
+        if effort == "max" and not (
+            AnthropicConfig._is_opus_4_6_model(model)
+            or AnthropicConfig._is_opus_4_7_model(model)
+            or AmazonConverseConfig._supports_effort_level_on_bedrock(model, "max")
+        ):
+            raise litellm.exceptions.BadRequestError(
+                message=(
+                    f"effort='max' is not supported by this model. "
+                    f"Got model: {model}"
+                ),
+                model=model,
+                llm_provider="bedrock_converse",
+            )
+        if (
+            effort == "xhigh"
+            and not AmazonConverseConfig._supports_effort_level_on_bedrock(
+                model, "xhigh"
+            )
+        ):
+            raise litellm.exceptions.BadRequestError(
+                message=(
+                    f"effort='xhigh' is not supported by this model. "
+                    f"Got model: {model}"
+                ),
+                model=model,
+                llm_provider="bedrock_converse",
+            )
 
     @staticmethod
     def _clamp_thinking_budget_tokens(optional_params: dict) -> None:
@@ -1196,9 +1306,15 @@ class AmazonConverseConfig(BaseConfig):
             + supported_config_params
         )
         inference_params.pop("json_mode", None)  # used for handling json_schema
-        # Anthropic-only key. Bedrock expects `outputConfig` (camelCase) and
-        # will reject `output_config` if it leaks through pass-through routes.
-        inference_params.pop("output_config", None)
+
+        # Anthropic-only ``output_config`` (snake_case) is the adaptive-
+        # thinking effort payload (e.g. ``{"effort": "max"}``) for Claude
+        # 4.6/4.7. On Bedrock Converse it must ride along inside
+        # ``additionalModelRequestFields`` so the model actually sees the
+        # tier; stripping it (the prior behavior) silently flattened every
+        # adaptive tier to identical thinking. Only the Bedrock-native
+        # ``outputConfig`` (camelCase) goes at the top level.
+        anthropic_output_config = inference_params.pop("output_config", None)
 
         # Extract requestMetadata before processing other parameters
         request_metadata = inference_params.pop("requestMetadata", None)
@@ -1208,9 +1324,6 @@ class AmazonConverseConfig(BaseConfig):
         output_config: Optional[OutputConfigBlock] = inference_params.pop(
             "outputConfig", None
         )
-        inference_params.pop(
-            "output_config", None
-        )  # Bedrock Converse doesn't support it
 
         # keep supported params in 'inference_params', and set all model-specific params in 'additional_request_params'
         additional_request_params = {
@@ -1253,6 +1366,20 @@ class AmazonConverseConfig(BaseConfig):
             additional_request_params
         )
 
+        # Re-attach the Anthropic ``output_config`` (e.g. adaptive thinking
+        # ``{"effort": "max"}``) onto additional_request_params for Anthropic
+        # Bedrock models so the wire request carries the requested tier. Other
+        # model families (Nova, GPT-OSS, ...) don't accept it; drop it for them.
+        if anthropic_output_config is not None and isinstance(
+            anthropic_output_config, dict
+        ):
+            base_model = BedrockModelInfo.get_base_model(model)
+            if base_model.startswith("anthropic"):
+                effort = anthropic_output_config.get("effort")
+                if effort is not None:
+                    self._validate_anthropic_adaptive_effort(model=model, effort=effort)
+                additional_request_params["output_config"] = anthropic_output_config
+
         return (
             inference_params,
             additional_request_params,
diff --git a/litellm/llms/bedrock/chat/invoke_transformations/anthropic_claude3_transformation.py b/litellm/llms/bedrock/chat/invoke_transformations/anthropic_claude3_transformation.py
index cff415d49e..7de05c977c 100644
--- a/litellm/llms/bedrock/chat/invoke_transformations/anthropic_claude3_transformation.py
+++ b/litellm/llms/bedrock/chat/invoke_transformations/anthropic_claude3_transformation.py
@@ -169,7 +169,11 @@ class AmazonAnthropicClaudeConfig(AmazonInvokeConfig, AnthropicConfig):
         anthropic_request.pop("model", None)
         anthropic_request.pop("stream", None)
         anthropic_request.pop("output_format", None)
-        anthropic_request.pop("output_config", None)
+        # ``output_config`` (e.g. ``{"effort": "max"}``) is the adaptive-thinking
+        # tier payload for Claude 4.6 / 4.7. Bedrock Invoke accepts it for
+        # those models — stripping it (the prior behavior) silently flattened
+        # every adaptive tier on this route. Forward it; if the model rejects
+        # it the surfaced error is correct, vs. swallowing the user's knob.
         if "anthropic_version" not in anthropic_request:
             anthropic_request["anthropic_version"] = self.anthropic_version
 
diff --git a/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/experimental_pass_through/transformation.py b/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/experimental_pass_through/transformation.py
index d450f7a463..714877457f 100644
--- a/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/experimental_pass_through/transformation.py
+++ b/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/experimental_pass_through/transformation.py
@@ -159,10 +159,11 @@ class VertexAIPartnerModelsAnthropicMessagesConfig(AnthropicMessagesConfig, Vert
             "model", None
         )  # do not pass model in request body to vertex ai
 
-        # Vertex AI Claude accepts ``output_config.format`` (structured outputs)
-        # and ``output_format``, but rejects ``output_config.effort`` with 400
-        # "Extra inputs are not permitted". Sanitize in place so the supported
-        # bits flow through.
+        # Vertex AI Claude accepts ``output_config.format`` (structured outputs),
+        # ``output_format``, and ``output_config.effort`` (adaptive-thinking
+        # tier on Claude 4.6 / 4.7, verified end-to-end). The shared sanitize
+        # helper now no-ops for ``effort`` and remains the single hook for any
+        # future Vertex-only key drift.
         sanitize_vertex_anthropic_output_params(anthropic_messages_request)
 
         return anthropic_messages_request
diff --git a/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/output_params_utils.py b/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/output_params_utils.py
index 982d8edbf2..891c8e4d05 100644
--- a/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/output_params_utils.py
+++ b/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/output_params_utils.py
@@ -11,11 +11,12 @@ keeps the parent module's import surface narrow.
 """
 
 # Keys inside ``output_config`` that Vertex AI Claude does not accept.
-# Today only ``effort`` triggers "Extra inputs are not permitted"; add new
-# entries here as Vertex parity drifts. Keep this list narrow — anything
-# Vertex DOES accept (e.g. ``format`` for structured outputs) must be
-# preserved so callers can rely on Anthropic-native features.
-VERTEX_UNSUPPORTED_OUTPUT_CONFIG_KEYS: frozenset = frozenset({"effort"})
+# Vertex now accepts ``output_config.effort`` for the adaptive-thinking
+# Claude 4.6 / 4.7 models on direct ``:rawPredict`` (verified end-to-end
+# against ``us-east5`` for ``opus-4-6`` and ``global`` for ``opus-4-7``).
+# Keep this set narrow and only add a key here once a 400 "Extra inputs are
+# not permitted" is reproducible against the live Vertex endpoint.
+VERTEX_UNSUPPORTED_OUTPUT_CONFIG_KEYS: frozenset = frozenset()
 
 
 def sanitize_vertex_anthropic_output_params(data: dict) -> None:
diff --git a/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/transformation.py b/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/transformation.py
index 914c7e92e5..48920402e2 100644
--- a/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/transformation.py
+++ b/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/transformation.py
@@ -106,11 +106,10 @@ class VertexAIAnthropicConfig(AnthropicConfig):
 
         data.pop("model", None)  # vertex anthropic doesn't accept 'model' parameter
 
-        # Vertex AI Claude accepts ``output_config.format`` (structured outputs /
-        # JSON Schema) but NOT ``output_config.effort`` — sending ``effort`` to
-        # Vertex returns 400 "Extra inputs are not permitted". Sanitize in place:
-        # forward the structured-output bits, drop the unsupported keys.
-        # Same treatment for the legacy top-level ``output_format`` field.
+        # Sanitize ``output_config`` / ``output_format`` for Vertex parity.
+        # Vertex now accepts ``output_config.effort`` for adaptive-thinking Claude
+        # 4.6 / 4.7 models, so the helper is a no-op for ``effort``; it remains
+        # the single hook for future Vertex-only sanitization.
         sanitize_vertex_anthropic_output_params(data)
 
         tools = optional_params.get("tools")
diff --git a/litellm/types/llms/bedrock.py b/litellm/types/llms/bedrock.py
index 9ffb52ef88..72e509d178 100644
--- a/litellm/types/llms/bedrock.py
+++ b/litellm/types/llms/bedrock.py
@@ -1041,3 +1041,12 @@ class BedrockInvokeAnthropicMessagesRequest(TypedDict, total=False):
     # `metadata` is part of the common Anthropic Messages API shape.
     thinking: dict
     metadata: dict
+
+    # ``output_config`` is the adaptive-thinking effort payload for
+    # Claude 4.6 / 4.7 (e.g. ``{"effort": "max"}``). Bedrock Invoke
+    # accepts it for these models when ``thinking={"type": "adaptive"}``.
+    # Without this field in the allowlist, the runtime filter in
+    # ``AmazonAnthropicClaudeMessagesConfig.transform_anthropic_messages_request``
+    # silently drops it and every adaptive tier collapses to identical
+    # behavior on /v1/messages.
+    output_config: dict
diff --git a/model_prices_and_context_window.json b/model_prices_and_context_window.json
index 76dcfc55c1..cc34446be0 100644
--- a/model_prices_and_context_window.json
+++ b/model_prices_and_context_window.json
@@ -9491,7 +9491,6 @@
             "us": 1.1,
             "fast": 6.0
         },
-        "supports_max_reasoning_effort": true,
         "supports_minimal_reasoning_effort": true
     },
     "claude-opus-4-7-20260416": {
@@ -9526,7 +9525,6 @@
             "us": 1.1,
             "fast": 6.0
         },
-        "supports_max_reasoning_effort": true,
         "supports_minimal_reasoning_effort": true
     },
     "claude-sonnet-4-20250514": {
diff --git a/tests/test_litellm/llms/anthropic/chat/test_anthropic_chat_transformation.py b/tests/test_litellm/llms/anthropic/chat/test_anthropic_chat_transformation.py
index cbb9b21d62..0381b850d6 100644
--- a/tests/test_litellm/llms/anthropic/chat/test_anthropic_chat_transformation.py
+++ b/tests/test_litellm/llms/anthropic/chat/test_anthropic_chat_transformation.py
@@ -8,6 +8,7 @@ sys.path.insert(
 )  # Adds the parent directory to the system path
 from unittest.mock import MagicMock, patch
 
+import litellm
 from litellm.constants import RESPONSE_FORMAT_TOOL_NAME
 from litellm.llms.anthropic.chat.transformation import AnthropicConfig
 from litellm.llms.anthropic.experimental_pass_through.messages.transformation import (
@@ -1631,8 +1632,10 @@ def test_effort_validation():
         )
         assert result["output_config"]["effort"] == effort
 
-    # Invalid value should raise error
-    with pytest.raises(ValueError, match="Invalid effort value"):
+    # Invalid value should raise BadRequestError (clean 400, not a 500).
+    with pytest.raises(
+        litellm.exceptions.BadRequestError, match="Invalid effort value"
+    ):
         optional_params = {"output_config": {"effort": "invalid"}}
         config.transform_request(
             model="claude-opus-4-5-20251101",
@@ -1682,12 +1685,18 @@ def test_effort_validation_with_opus_46():
 
 
 def test_max_effort_rejected_for_opus_45():
-    """Test that effort='max' is rejected when using Claude Opus 4.5."""
+    """Test that effort='max' is rejected when using Claude Opus 4.5.
+
+    Surfaces as a clean 400 BadRequestError, not a 500 ValueError.
+    """
     config = AnthropicConfig()
 
     messages = [{"role": "user", "content": "Test"}]
 
-    with pytest.raises(ValueError, match="effort='max' is not supported by this model"):
+    with pytest.raises(
+        litellm.exceptions.BadRequestError,
+        match="effort='max' is not supported by this model",
+    ):
         optional_params = {"output_config": {"effort": "max"}}
         config.transform_request(
             model="claude-opus-4-5-20251101",
@@ -2153,12 +2162,14 @@ def test_reasoning_effort_maps_to_budget_thinking_for_non_opus_4_6():
     """
     config = AnthropicConfig()
 
-    # Test with Claude Sonnet 4.5 (non-Opus 4.6 model)
+    # Test with Claude Sonnet 4.5 (non-Opus 4.6 model).
+    # ``minimal`` floors at the Anthropic provider minimum (1024) because
+    # Anthropic / Azure / Vertex / Bedrock Invoke 400 below that.
     test_cases = [
         ("low", 1024),  # DEFAULT_REASONING_EFFORT_LOW_THINKING_BUDGET
         ("medium", 2048),  # DEFAULT_REASONING_EFFORT_MEDIUM_THINKING_BUDGET
         ("high", 4096),  # DEFAULT_REASONING_EFFORT_HIGH_THINKING_BUDGET
-        ("minimal", 128),  # DEFAULT_REASONING_EFFORT_MINIMAL_THINKING_BUDGET
+        ("minimal", 1024),  # ANTHROPIC_MIN_THINKING_BUDGET_TOKENS (provider floor)
     ]
 
     for effort, expected_budget in test_cases:
@@ -2245,11 +2256,17 @@ def test_reasoning_effort_does_not_set_output_config_for_older_models():
 
 
 def test_max_effort_rejected_for_sonnet_46():
-    """Test that effort='max' is rejected for Sonnet 4.6 (Opus-only effort level)."""
+    """Test that effort='max' is rejected for Sonnet 4.6 (Opus-only effort level).
+
+    Surfaces as a clean 400 BadRequestError, not a 500 ValueError.
+    """
     config = AnthropicConfig()
     messages = [{"role": "user", "content": "Test"}]
 
-    with pytest.raises(ValueError, match="effort='max' is not supported by this model"):
+    with pytest.raises(
+        litellm.exceptions.BadRequestError,
+        match="effort='max' is not supported by this model",
+    ):
         config.transform_request(
             model="claude-sonnet-4-6-20260219",
             messages=messages,
@@ -2335,6 +2352,81 @@ def test_reasoning_effort_none_omits_thinking_and_output_config(model):
     assert "output_config" not in result
 
 
+@pytest.mark.parametrize(
+    "effort",
+    ["disabled", "invalid", ""],
+)
+def test_reasoning_effort_garbage_raises_bad_request(effort):
+    """Unmapped / garbage / empty-string reasoning_effort surfaces as a clean
+    400 ``BadRequestError`` instead of letting ``ValueError`` propagate as 500.
+    """
+    config = AnthropicConfig()
+
+    with pytest.raises(litellm.exceptions.BadRequestError):
+        config.map_openai_params(
+            non_default_params={"reasoning_effort": effort},
+            optional_params={},
+            model="claude-sonnet-4-5-20250929",
+            drop_params=False,
+        )
+
+
+@pytest.mark.parametrize(
+    "effort",
+    ["xhigh", "max"],
+)
+def test_reasoning_effort_unsupported_tier_on_budget_model_raises_bad_request(
+    effort,
+):
+    """``xhigh`` / ``max`` aren't defined for budget-mode (4.5) Claude models;
+    surface as a clean 400 instead of 500.
+    """
+    config = AnthropicConfig()
+
+    with pytest.raises(litellm.exceptions.BadRequestError):
+        config.map_openai_params(
+            non_default_params={"reasoning_effort": effort},
+            optional_params={},
+            model="claude-sonnet-4-5-20250929",
+            drop_params=False,
+        )
+
+
+def test_output_config_effort_empty_string_raises_bad_request():
+    """``output_config={"effort": ""}`` must be rejected with a 400 — the
+    legacy ``if effort and ...`` short-circuit silently let it pass
+    through (verified end-to-end on the QA sweep for PR #27039).
+    """
+    config = AnthropicConfig()
+
+    with pytest.raises(litellm.exceptions.BadRequestError, match="Invalid effort"):
+        config.transform_request(
+            model="claude-opus-4-7",
+            messages=[{"role": "user", "content": "hi"}],
+            optional_params={"output_config": {"effort": ""}, "max_tokens": 32},
+            litellm_params={},
+            headers={},
+        )
+
+
+def test_reasoning_effort_minimal_floors_at_anthropic_provider_minimum():
+    """Anthropic Messages API rejects ``budget_tokens < 1024``. ``minimal``
+    must floor at the provider minimum so it's a usable tier on direct
+    Anthropic / Azure AI Anthropic / Vertex AI Anthropic / Bedrock Invoke.
+    """
+    config = AnthropicConfig()
+
+    result = config.map_openai_params(
+        non_default_params={"reasoning_effort": "minimal"},
+        optional_params={},
+        model="claude-sonnet-4-5-20250929",
+        drop_params=False,
+    )
+
+    assert result["thinking"]["type"] == "enabled"
+    assert result["thinking"]["budget_tokens"] >= 1024
+
+
 def test_effort_beta_header_still_injected_for_older_models():
     """
     Test that is_effort_used still returns True for pre-4.6 models
diff --git a/tests/test_litellm/llms/bedrock/chat/invoke_transformations/test_bedrock_chat_invoke_transformations_anthropic_claude3_transformation.py b/tests/test_litellm/llms/bedrock/chat/invoke_transformations/test_bedrock_chat_invoke_transformations_anthropic_claude3_transformation.py
index 80d6d26e7e..8689a05e8e 100644
--- a/tests/test_litellm/llms/bedrock/chat/invoke_transformations/test_bedrock_chat_invoke_transformations_anthropic_claude3_transformation.py
+++ b/tests/test_litellm/llms/bedrock/chat/invoke_transformations/test_bedrock_chat_invoke_transformations_anthropic_claude3_transformation.py
@@ -406,36 +406,37 @@ def test_opus_4_5_model_detection():
 #         f"computer-use beta should be kept, got: {anthropic_beta}"
 
 
-def test_output_config_removed_from_bedrock_chat_invoke_request():
+def test_output_config_forwarded_for_bedrock_chat_invoke_request():
     """
-    Test that output_config parameter is stripped from Bedrock Chat Invoke requests.
+    Bedrock Invoke (chat/completions route) must forward
+    ``output_config`` for Anthropic adaptive-thinking models. The earlier
+    behavior stripped it unconditionally, which silently flattened every
+    adaptive tier (``low``/``medium``/``high``/``xhigh``/``max``) to identical
+    behavior on the wire.
 
-    Bedrock Invoke API doesn't support the output_config parameter (Anthropic-only).
-    Ensures the chat/invoke path mirrors the messages/invoke path fix.
-
-    Fixes: https://github.com/BerriAI/litellm/issues/22797
+    The wire QA at https://github.com/BerriAI/litellm/pull/27039 showed
+    ``thinking.type: adaptive`` was forwarded but ``output_config.effort``
+    was always missing, even though direct curls to Anthropic's Bedrock
+    Invoke endpoint accept it.
     """
     config = AmazonAnthropicClaudeConfig()
 
     messages = [{"role": "user", "content": "test"}]
 
-    # Inject output_config into optional_params (simulates Anthropic SDK forwarding it)
     optional_params = {
         "max_tokens": 100,
         "output_config": {"effort": "high"},
     }
 
     result = config.transform_request(
-        model="anthropic.claude-sonnet-4-20250514-v1:0",
+        model="anthropic.claude-opus-4-7",
         messages=messages,
         optional_params=optional_params,
         litellm_params={},
         headers={},
     )
 
-    assert (
-        "output_config" not in result
-    ), f"output_config should be stripped for Bedrock Chat Invoke, got keys: {list(result.keys())}"
+    assert result.get("output_config") == {"effort": "high"}
     # Verify normal params survive
     assert result["max_tokens"] == 100
 
diff --git a/tests/test_litellm/llms/bedrock/chat/test_converse_transformation.py b/tests/test_litellm/llms/bedrock/chat/test_converse_transformation.py
index 5bb51ac619..01dbc81fbb 100644
--- a/tests/test_litellm/llms/bedrock/chat/test_converse_transformation.py
+++ b/tests/test_litellm/llms/bedrock/chat/test_converse_transformation.py
@@ -310,6 +310,111 @@ def test_reasoning_effort_none_omits_thinking_for_anthropic_converse(model):
     assert "thinking" not in optional_params
 
 
+@pytest.mark.parametrize(
+    "model,effort,expected_effort",
+    [
+        ("bedrock/converse/us.anthropic.claude-opus-4-7", "low", "low"),
+        ("bedrock/converse/us.anthropic.claude-opus-4-7", "medium", "medium"),
+        ("bedrock/converse/us.anthropic.claude-opus-4-7", "high", "high"),
+        ("bedrock/converse/us.anthropic.claude-opus-4-7", "xhigh", "xhigh"),
+        ("bedrock/converse/us.anthropic.claude-opus-4-7", "max", "max"),
+        ("bedrock/converse/us.anthropic.claude-opus-4-6-v1", "max", "max"),
+        ("bedrock/converse/us.anthropic.claude-sonnet-4-6", "high", "high"),
+        ("bedrock/converse/us.anthropic.claude-sonnet-4-6", "minimal", "low"),
+    ],
+)
+def test_reasoning_effort_sets_output_config_for_adaptive_models_converse(
+    model, effort, expected_effort
+):
+    """Adaptive-thinking Claude 4.6 / 4.7 on Bedrock Converse must carry the
+    requested tier via ``output_config.effort``. The prior strip silently
+    flattened every adaptive tier on the wire (verified in the PR #27039
+    QA sweep)."""
+    config = AmazonConverseConfig()
+
+    optional_params = config.map_openai_params(
+        non_default_params={"reasoning_effort": effort},
+        optional_params={},
+        model=model,
+        drop_params=False,
+    )
+
+    assert optional_params["thinking"]["type"] == "adaptive"
+    assert optional_params["output_config"] == {"effort": expected_effort}
+
+
+@pytest.mark.parametrize(
+    "model",
+    [
+        "bedrock/converse/us.anthropic.claude-opus-4-7",
+        "bedrock/converse/us.anthropic.claude-opus-4-6-v1",
+        "bedrock/converse/us.anthropic.claude-sonnet-4-6",
+    ],
+)
+def test_output_config_effort_forwarded_into_additional_request_fields(model):
+    """``output_config`` must ride along inside ``additionalModelRequestFields``
+    so the Anthropic-on-Bedrock wire request actually carries the effort
+    tier. The prior ``inference_params.pop("output_config")`` dropped it
+    on the floor for every adaptive tier."""
+    config = AmazonConverseConfig()
+    messages = [{"role": "user", "content": "hi"}]
+
+    result = config._transform_request(
+        model=model,
+        messages=messages,
+        optional_params={
+            "maxTokens": 256,
+            "thinking": {"type": "adaptive"},
+            "output_config": {"effort": "high"},
+        },
+        litellm_params={},
+        headers={},
+    )
+
+    additional = result.get("additionalModelRequestFields", {})
+    assert additional.get("output_config") == {"effort": "high"}
+
+
+@pytest.mark.parametrize(
+    "effort",
+    ["disabled", "invalid", ""],
+)
+def test_reasoning_effort_garbage_raises_bad_request_converse(effort):
+    """Garbage / empty-string reasoning_effort on Bedrock Converse Anthropic
+    must surface as a clean 400 ``BadRequestError`` instead of 500. The
+    earlier ``ValueError`` from ``_map_reasoning_effort`` propagated up as
+    a generic 500 in the proxy and ate the request."""
+    config = AmazonConverseConfig()
+
+    with pytest.raises(litellm.exceptions.BadRequestError):
+        config.map_openai_params(
+            non_default_params={"reasoning_effort": effort},
+            optional_params={},
+            model="bedrock/converse/us.anthropic.claude-opus-4-7",
+            drop_params=False,
+        )
+
+
+def test_output_config_effort_unsupported_max_on_sonnet_46_raises_bad_request():
+    """``effort='max'`` is Opus-only. On Sonnet 4.6 the explicit-output_config
+    path must surface a 400 (matching the chat-completion validation), not
+    silently forward an unsupported tier to Bedrock."""
+    config = AmazonConverseConfig()
+    messages = [{"role": "user", "content": "hi"}]
+
+    with pytest.raises(litellm.exceptions.BadRequestError):
+        config._transform_request(
+            model="bedrock/converse/us.anthropic.claude-sonnet-4-6",
+            messages=messages,
+            optional_params={
+                "maxTokens": 256,
+                "output_config": {"effort": "max"},
+            },
+            litellm_params={},
+            headers={},
+        )
+
+
 def test_get_supported_openai_params():
     config = AmazonConverseConfig()
     supported_params = config.get_supported_openai_params(
diff --git a/tests/test_litellm/llms/bedrock/messages/invoke_transformations/test_anthropic_claude3_transformation.py b/tests/test_litellm/llms/bedrock/messages/invoke_transformations/test_anthropic_claude3_transformation.py
index 93d56d4cd0..725bc9503b 100644
--- a/tests/test_litellm/llms/bedrock/messages/invoke_transformations/test_anthropic_claude3_transformation.py
+++ b/tests/test_litellm/llms/bedrock/messages/invoke_transformations/test_anthropic_claude3_transformation.py
@@ -592,12 +592,16 @@ def test_remove_scope_from_cache_control():
     assert request["messages"][0]["content"][0]["cache_control"]["type"] == "ephemeral"
 
 
-def test_bedrock_messages_strips_output_config():
+def test_bedrock_messages_forwards_output_config():
     """
-    Ensure output_config is stripped from the request before sending to
-    Bedrock Invoke, which doesn't support this Anthropic-specific parameter.
+    ``output_config`` is the adaptive-thinking effort payload for Claude
+    4.6 / 4.7 (e.g. ``{"effort": "max"}``). Bedrock Invoke accepts it for
+    those models — the prior behavior of stripping it silently flattened
+    every adaptive tier on /v1/messages so ``low`` / ``medium`` / ``high`` /
+    ``xhigh`` / ``max`` all collapsed to identical thinking with no tier
+    differentiation.
 
-    Regression test for: https://github.com/BerriAI/litellm/issues/22797
+    Regression coverage for the QA bug listed on PR #27039.
     """
     from litellm.types.router import GenericLiteLLMParams
 
@@ -611,25 +615,24 @@ def test_bedrock_messages_strips_output_config():
     }
 
     result = cfg.transform_anthropic_messages_request(
-        model="anthropic.claude-3-haiku-20240307-v1:0",
+        model="anthropic.claude-opus-4-7",
         messages=messages,
         anthropic_messages_optional_request_params=optional_params,
         litellm_params=GenericLiteLLMParams(),
         headers={},
     )
 
-    assert (
-        "output_config" not in result
-    ), "output_config should be stripped — Bedrock Invoke rejects it"
+    assert result.get("output_config") == {"effort": "high"}
     # Other params should be preserved
     assert result.get("max_tokens") == 4096
 
 
-def test_bedrock_messages_strips_output_config_with_output_format():
+def test_bedrock_messages_forwards_output_config_with_output_format():
     """
-    When both output_config and output_format are present, both should be
-    stripped (output_format is converted to inline schema, output_config
-    is simply dropped).
+    When both output_config and output_format are present, output_format is
+    converted to inline schema (Bedrock Invoke doesn't accept output_format
+    natively), and output_config is forwarded for Claude 4.6/4.7 adaptive
+    thinking.
     """
     from litellm.types.router import GenericLiteLLMParams
 
@@ -648,14 +651,14 @@ def test_bedrock_messages_strips_output_config_with_output_format():
     }
 
     result = cfg.transform_anthropic_messages_request(
-        model="anthropic.claude-3-haiku-20240307-v1:0",
+        model="anthropic.claude-opus-4-7",
         messages=messages,
         anthropic_messages_optional_request_params=optional_params,
         litellm_params=GenericLiteLLMParams(),
         headers={},
     )
 
-    assert "output_config" not in result
+    assert result.get("output_config") == {"effort": "low"}
     assert "output_format" not in result
 
 
@@ -728,13 +731,18 @@ def test_bedrock_messages_allowlist_filters_anthropic_only_fields():
         "mcp_servers",
         "container",
         "inference_geo",
-        "output_config",
         "context_management",
         "model",
         "stream",
     ):
         assert bad not in result, f"{bad} should be stripped by the allowlist"
 
+    # ``output_config`` rides along — Bedrock Invoke accepts it for Claude
+    # 4.6/4.7 adaptive thinking and stripping it silently flattens every
+    # adaptive tier. (Bedrock will reject it for non-adaptive models, which
+    # is the correct behavior — surface the model error rather than swallow
+    # the knob.)
+    assert result.get("output_config") == {"effort": "low"}
     # Supported fields pass through.
     assert result["max_tokens"] == 4096
     assert result["temperature"] == 0.5
@@ -882,7 +890,10 @@ async def test_promote_message_start_cache_when_message_stop_omits_cache_fields(
             "delta": {"stop_reason": "end_turn", "stop_sequence": None},
             "usage": {"input_tokens": 10, "output_tokens": 181},
         }
-        yield {"type": "message_stop", "usage": {"input_tokens": 10, "output_tokens": 181}}
+        yield {
+            "type": "message_stop",
+            "usage": {"input_tokens": 10, "output_tokens": 181},
+        }
 
     merged: list[dict] = []
     async for chunk in cfg._promote_message_stop_usage(_stream()):
@@ -936,7 +947,11 @@ async def test_unified_bedrock_messages_cache_on_start_only_never_negative_cost(
                 },
             },
         }
-        yield {"type": "content_block_start", "index": 0, "content_block": {"type": "text", "text": ""}}
+        yield {
+            "type": "content_block_start",
+            "index": 0,
+            "content_block": {"type": "text", "text": ""},
+        }
         yield {
             "type": "content_block_delta",
             "index": 0,
@@ -948,7 +963,10 @@ async def test_unified_bedrock_messages_cache_on_start_only_never_negative_cost(
             "delta": {"stop_reason": "end_turn", "stop_sequence": None},
             "usage": {"output_tokens": 181, "input_tokens": 10},
         }
-        yield {"type": "message_stop", "usage": {"input_tokens": 10, "output_tokens": 181}}
+        yield {
+            "type": "message_stop",
+            "usage": {"input_tokens": 10, "output_tokens": 181},
+        }
 
     logging_obj = LiteLLMLoggingObj(
         model="bedrock/anthropic.claude-3-5-sonnet-20240620-v1:0",
diff --git a/tests/test_litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/test_vertex_ai_partner_models_anthropic_transformation.py b/tests/test_litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/test_vertex_ai_partner_models_anthropic_transformation.py
index d0be476d72..0a5ba12f18 100644
--- a/tests/test_litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/test_vertex_ai_partner_models_anthropic_transformation.py
+++ b/tests/test_litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/test_vertex_ai_partner_models_anthropic_transformation.py
@@ -498,11 +498,14 @@ def test_vertex_ai_partner_models_anthropic_remove_prompt_caching_scope_beta_hea
     ), "Header should be removed if no supported values remain"
 
 
-def test_vertex_ai_anthropic_output_config_effort_only_dropped():
+def test_vertex_ai_anthropic_output_config_effort_only_forwarded():
     """
-    ``output_config`` containing only ``effort`` (an Anthropic-only key Vertex
-    rejects with "Extra inputs are not permitted") is dropped entirely so the
-    request body has no empty dict.
+    Vertex AI Claude 4.6 / 4.7 accept ``output_config.effort`` on direct
+    ``:rawPredict`` (verified end-to-end against ``us-east5`` for
+    ``claude-opus-4-6`` and ``global`` for ``claude-opus-4-7``). The earlier
+    strip silently flattened every adaptive tier on Vertex, so ``low`` /
+    ``medium`` / ``high`` / ``xhigh`` / ``max`` all produced identical
+    thinking with no tier differentiation.
     """
     config = VertexAIAnthropicConfig()
 
@@ -515,16 +518,14 @@ def test_vertex_ai_anthropic_output_config_effort_only_dropped():
     }
 
     result = config.transform_request(
-        model="claude-3-5-sonnet-20241022",
+        model="claude-opus-4-6",
         messages=messages,
         optional_params=optional_params,
         litellm_params={},
         headers=headers,
     )
 
-    assert (
-        "output_config" not in result
-    ), "output_config containing only effort must be dropped"
+    assert result["output_config"] == {"effort": "high"}
     assert result["max_tokens"] == 1024
     assert "messages" in result
 
@@ -566,13 +567,15 @@ def test_vertex_ai_anthropic_output_config_format_passes_through():
     assert result["output_config"] == output_config
 
 
-def test_vertex_ai_anthropic_output_config_format_plus_effort_strips_only_effort():
+def test_vertex_ai_anthropic_output_config_format_plus_effort_preserved():
     """
-    Greptile P1 on PR #23396: when ``output_config`` contains BOTH ``format``
-    and ``effort``, the prior conditional-passthrough logic forwarded the
-    full dict including the unsupported ``effort`` key, reproducing the
-    400 error the fix was meant to resolve. Only ``effort`` (and any future
-    Vertex-unsupported keys) should be filtered; ``format`` must survive.
+    Vertex AI Claude 4.6 / 4.7 accept ``output_config.effort`` on direct
+    ``:rawPredict`` (verified end-to-end against ``us-east5`` for
+    ``claude-opus-4-6`` and ``global`` for ``claude-opus-4-7``). Since the
+    strip was unjustified, ``effort`` must now ride along with ``format``.
+
+    We use a Claude 4.6 model id here because ``_apply_output_config`` only
+    accepts ``effort`` on adaptive-thinking 4.6/4.7 model ids.
     """
     config = VertexAIAnthropicConfig()
     messages = [{"role": "user", "content": "Return a person object."}]
@@ -591,7 +594,7 @@ def test_vertex_ai_anthropic_output_config_format_plus_effort_strips_only_effort
     optional_params = {"max_tokens": 1024, "output_config": output_config}
 
     result = config.transform_request(
-        model="claude-3-5-sonnet-20241022",
+        model="claude-opus-4-6",
         messages=messages,
         optional_params=optional_params,
         litellm_params={},
@@ -599,9 +602,7 @@ def test_vertex_ai_anthropic_output_config_format_plus_effort_strips_only_effort
     )
 
     assert "output_config" in result
-    assert (
-        "effort" not in result["output_config"]
-    ), "effort must be stripped — Vertex returns 400 on unknown keys"
+    assert result["output_config"]["effort"] == "high"
     assert result["output_config"]["format"] == output_config["format"]
 
 
@@ -623,14 +624,14 @@ def test_vertex_ai_anthropic_output_config_non_dict_dropped():
     assert "output_config" not in result
 
 
-def test_vertex_ai_anthropic_output_format_preserved_output_config_effort_dropped():
+def test_vertex_ai_anthropic_output_format_and_output_config_effort_preserved():
     """
-    When the request carries both ``output_format`` (top-level structured
-    outputs) AND an ``output_config`` whose only useful key for Vertex is
-    ``effort``: ``output_format`` must be forwarded (Vertex accepts it),
-    while ``output_config`` is dropped because Vertex returns 400 on
-    ``effort``. This replaces the old "drop both" behavior, which was the
-    silent strip the bug report flagged.
+    Vertex AI Claude 4.6 / 4.7 accept ``output_config.effort`` on direct
+    ``:rawPredict`` (verified end-to-end). When both ``output_format`` and
+    ``output_config: {effort}`` are present, both must be forwarded — the
+    earlier ``effort`` strip caused silent loss of the requested adaptive
+    thinking tier on Vertex routes (``low``/``medium``/``high``/``xhigh``/``max``
+    all collapsed to identical adaptive thinking with no tier differentiation).
     """
     config = VertexAIAnthropicConfig()
     messages = [{"role": "user", "content": "Extract structured data"}]
@@ -653,7 +654,7 @@ def test_vertex_ai_anthropic_output_format_preserved_output_config_effort_droppe
     }
 
     test_data = {
-        "model": "claude-3-5-sonnet-20241022",
+        "model": "claude-opus-4-6",
         "messages": messages,
         "max_tokens": 2048,
         "output_format": output_format,
@@ -671,7 +672,7 @@ def test_vertex_ai_anthropic_output_format_preserved_output_config_effort_droppe
 
     try:
         result = config.transform_request(
-            model="claude-3-5-sonnet-20241022",
+            model="claude-opus-4-6",
             messages=messages,
             optional_params=optional_params,
             litellm_params={},
@@ -680,9 +681,8 @@ def test_vertex_ai_anthropic_output_format_preserved_output_config_effort_droppe
 
         # output_format flows through unchanged — Vertex AI Claude accepts it.
         assert result["output_format"] == output_format
-        # output_config containing only ``effort`` is dropped to avoid the
-        # 400 "Extra inputs are not permitted" the silent strip used to mask.
-        assert "output_config" not in result
+        # output_config.effort now flows through (Vertex accepts it on 4.6/4.7).
+        assert result["output_config"] == {"effort": "high"}
         assert result["max_tokens"] == 2048
         assert "model" not in result, "model is still stripped (Vertex routes by URL)"
     finally:
@@ -702,10 +702,10 @@ def test_sanitize_vertex_anthropic_output_params_unit():
     sanitize_vertex_anthropic_output_params(data)
     assert data == {"max_tokens": 8}
 
-    # Effort-only → dropped entirely.
+    # Effort-only → preserved (Vertex 4.6/4.7 accept it on rawPredict).
     data = {"output_config": {"effort": "high"}}
     sanitize_vertex_anthropic_output_params(data)
-    assert "output_config" not in data
+    assert data["output_config"] == {"effort": "high"}
 
     # Format-only → preserved unchanged.
     fmt = {"format": {"type": "json_schema", "schema": {"type": "object"}}}
@@ -713,10 +713,10 @@ def test_sanitize_vertex_anthropic_output_params_unit():
     sanitize_vertex_anthropic_output_params(data)
     assert data["output_config"] == fmt
 
-    # Mixed → effort filtered, format kept.
+    # Mixed → both effort and format kept (no current Vertex-unsupported keys).
     data = {"output_config": {"format": fmt["format"], "effort": "high"}}
     sanitize_vertex_anthropic_output_params(data)
-    assert data["output_config"] == fmt
+    assert data["output_config"] == {"format": fmt["format"], "effort": "high"}
 
     # Non-dict → dropped defensively.
     data = {"output_config": "garbage"}