Fix: strip temperature/top_k/top_p for claude-opus-4+ in UiPathChatAnthropicBedrock

Claude Opus 4+ (e.g. anthropic.claude-opus-4-7) are reasoning models
that reject temperature, top_k, and top_p with a 400 Bad Request.

Override _get_request_payload in UiPathChatAnthropicBedrock to pop
those params when the model name matches the claude-opus-4 pattern.
Params are untouched for all other models.

Also add anthropic.claude-opus-4-7 to the bedrock integration test
matrix (UiPathChatAnthropicBedrock, non-thinking configs only, as
thinking cassettes are not yet recorded for this model).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: cosminacho

packages/uipath_langchain_client/CHANGELOG.md

@@ -2,6 +2,11 @@
 
 All notable changes to `uipath_langchain_client` will be documented in this file.
 
+## [1.9.10] - 2026-04-23
+
+### Fixed
+- `UiPathChatAnthropicBedrock` now strips `temperature`, `top_k`, and `top_p` from the request payload when the model name matches `claude-opus-4` (e.g. `anthropic.claude-opus-4-7`). These sampling parameters are not supported by Claude Opus 4+ reasoning models and previously caused a `400 Bad Request` from the gateway. Requests for other models (e.g. claude-haiku) are unaffected.
+
 ## [1.9.9] - 2026-04-23
 
 ### Fixed

packages/uipath_langchain_client/src/uipath_langchain_client/__version__.py

@@ -1,3 +1,3 @@
 __title__ = "UiPath LangChain Client"
 __description__ = "A Python client for interacting with UiPath's LLM services via LangChain."
-__version__ = "1.9.9"
+__version__ = "1.9.10"

packages/uipath_langchain_client/src/uipath_langchain_client/clients/bedrock/chat_models.py

@@ -1,7 +1,10 @@
+import re
 from functools import cached_property
 from typing import Any, Self
 
+from langchain_core.language_models import LanguageModelInput
 from pydantic import Field, model_validator
+from typing_extensions import override
 
 from uipath_langchain_client.base_client import UiPathBaseChatModel
 from uipath_langchain_client.settings import (
@@ -48,6 +51,16 @@ def _patched_format_data_content_block(block: dict) -> dict:
     ) from e
 
 
+# Sampling parameters that Claude Opus 4+ (reasoning models) do not support.
+# The API returns 400 if any of these are present in the request payload.
+_CLAUDE_OPUS_4_UNSUPPORTED_PARAMS: frozenset[str] = frozenset({"temperature", "top_k", "top_p"})
+
+
+def _is_claude_opus_4_or_above(model_name: str) -> bool:
+    """Return True for Claude Opus 4+ models that reject sampling parameters."""
+    return bool(re.search(r"claude-opus-4", model_name, re.IGNORECASE))
+
+
 class UiPathChatBedrockConverse(UiPathBaseChatModel, ChatBedrockConverse):  # type: ignore[override]
     api_config: UiPathAPIConfig = UiPathAPIConfig(
         api_type=ApiType.COMPLETIONS,
@@ -147,3 +160,17 @@ def _async_client(self) -> AsyncAnthropicBedrock:
             max_retries=0,  # handled by the UiPathBaseChatModel
             http_client=self.uipath_async_client,
         )
+
+    @override
+    def _get_request_payload(
+        self,
+        input_: LanguageModelInput,
+        *,
+        stop: list[str] | None = None,
+        **kwargs: Any,
+    ) -> dict:
+        payload = super()._get_request_payload(input_, stop=stop, **kwargs)
+        if _is_claude_opus_4_or_above(self.model):
+            for param in _CLAUDE_OPUS_4_UNSUPPORTED_PARAMS:
+                payload.pop(param, None)
+        return payload

tests/langchain/clients/bedrock/conftest.py

@@ -46,8 +46,18 @@
     },
 ]
 
+CLAUDE_ANTHROPIC_BEDROCK_CONFIGS_NO_THINKING = [
+    c
+    for c in CLAUDE_BEDROCK_CONFIGS
+    if c["model_class"] is UiPathChatAnthropicBedrock
+    and "thinking" not in c.get("model_kwargs", {})
+]
+
 COMPLETIONS_MODELS_WITH_CONFIGS = {
     "anthropic.claude-haiku-4-5-20251001-v1:0": CLAUDE_BEDROCK_CONFIGS,
+    # claude-opus-4-7 via Bedrock: tested with UiPathChatAnthropicBedrock only (no thinking;
+    # thinking cassettes not yet recorded for this model).
+    "anthropic.claude-opus-4-7": CLAUDE_ANTHROPIC_BEDROCK_CONFIGS_NO_THINKING,
 }
 
 

tests/langchain/clients/bedrock/test_unit.py

@@ -1,15 +1,19 @@
 """LangChain unit tests for Bedrock provider clients."""
 
 from typing import Any
+from unittest.mock import MagicMock, patch
 
 import pytest
 from langchain_core.embeddings import Embeddings
 from langchain_core.language_models.chat_models import BaseChatModel
+from langchain_core.messages import HumanMessage
 from langchain_tests.unit_tests import ChatModelUnitTests, EmbeddingsUnitTests
 from uipath_langchain_client.clients.bedrock.chat_models import (
+    _CLAUDE_OPUS_4_UNSUPPORTED_PARAMS,
     UiPathChatAnthropicBedrock,
     UiPathChatBedrock,
     UiPathChatBedrockConverse,
+    _is_claude_opus_4_or_above,
 )
 from uipath_langchain_client.clients.bedrock.embeddings import UiPathBedrockEmbeddings
 
@@ -40,6 +44,62 @@ def chat_model_params(self) -> dict[str, Any]:
     def test_serdes(self, *args: Any, **kwargs: Any) -> None: ...
 
 
+class TestClaudeOpus4SamplingParamFiltering:
+    """UiPathChatAnthropicBedrock must strip temperature/top_k/top_p for claude-opus-4+ models."""
+
+    @pytest.fixture()
+    def opus4_client(self, client_settings: UiPathBaseSettings) -> UiPathChatAnthropicBedrock:
+        return UiPathChatAnthropicBedrock(
+            model="anthropic.claude-opus-4-7",
+            settings=client_settings,
+            temperature=0.7,
+            top_k=40,
+            top_p=0.9,
+        )
+
+    def test_is_claude_opus_4_or_above(self) -> None:
+        assert _is_claude_opus_4_or_above("anthropic.claude-opus-4-7")
+        assert _is_claude_opus_4_or_above("claude-opus-4-5-20250514")
+        assert not _is_claude_opus_4_or_above("anthropic.claude-3-5-sonnet-20240620-v1:0")
+        assert not _is_claude_opus_4_or_above("anthropic.claude-haiku-4-5-20251001-v1:0")
+
+    def test_unsupported_params_stripped_from_payload(
+        self, opus4_client: UiPathChatAnthropicBedrock
+    ) -> None:
+        with patch.object(opus4_client, "_client") as mock_client:
+            mock_client.messages.create.return_value = MagicMock(
+                content=[MagicMock(type="text", text="hi")],
+                stop_reason="end_turn",
+                usage=MagicMock(input_tokens=10, output_tokens=5),
+                model="anthropic.claude-opus-4-7",
+                id="msg_123",
+            )
+            opus4_client.invoke([HumanMessage(content="hi")])
+        call_kwargs = mock_client.messages.create.call_args.kwargs
+        for param in _CLAUDE_OPUS_4_UNSUPPORTED_PARAMS:
+            assert param not in call_kwargs, f"{param} must be stripped for claude-opus-4"
+
+    def test_sampling_params_kept_for_other_models(
+        self, client_settings: UiPathBaseSettings
+    ) -> None:
+        haiku = UiPathChatAnthropicBedrock(
+            model="anthropic.claude-haiku-4-5-20251001-v1:0",
+            settings=client_settings,
+            temperature=0.5,
+        )
+        with patch.object(haiku, "_client") as mock_client:
+            mock_client.messages.create.return_value = MagicMock(
+                content=[MagicMock(type="text", text="hi")],
+                stop_reason="end_turn",
+                usage=MagicMock(input_tokens=10, output_tokens=5),
+                model="anthropic.claude-haiku-4-5-20251001-v1:0",
+                id="msg_123",
+            )
+            haiku.invoke([HumanMessage(content="hi")])
+        call_kwargs = mock_client.messages.create.call_args.kwargs
+        assert call_kwargs.get("temperature") == 0.5, "temperature must be kept for haiku"
+
+
 class TestBedrockEmbeddings(EmbeddingsUnitTests):
     @pytest.fixture(autouse=True, params=BEDROCK_EMBEDDINGS_CLASSES)
     def setup_models(self, request: pytest.FixtureRequest, client_settings: UiPathBaseSettings):