feat(langchain): support Bedrock Mantle chat models in init_chat_model (#40837)

Co-authored-by: ccurme <ccurme@users.noreply.github.com>
Co-authored-by: open-swe[bot] <open-swe@users.noreply.github.com>

libs/langchain_v1/langchain/chat_models/base.py

@@ -61,6 +61,8 @@ _BUILTIN_PROVIDERS: dict[str, tuple[str, str, Callable[..., BaseChatModel]]] = {
     "baseten": ("langchain_baseten", "ChatBaseten", _call),
     "bedrock": ("langchain_aws", "ChatBedrock", _call),
     "bedrock_converse": ("langchain_aws", "ChatBedrockConverse", _call),
+    "bedrock_mantle_anthropic": ("langchain_aws", "ChatAnthropicMantle", _call),
+    "bedrock_mantle_openai": ("langchain_aws", "ChatOpenAIMantle", _call),
     "cohere": ("langchain_cohere", "ChatCohere", _call),
     "deepseek": ("langchain_deepseek", "ChatDeepSeek", _call),
     "fireworks": ("langchain_fireworks", "ChatFireworks", _call),
@@ -310,6 +312,8 @@ def init_chat_model(
             - `anthropic_bedrock`       -> [`langchain-aws`](https://docs.langchain.com/oss/python/integrations/providers/aws)
             - `bedrock`                 -> [`langchain-aws`](https://docs.langchain.com/oss/python/integrations/providers/aws)
             - `bedrock_converse`        -> [`langchain-aws`](https://docs.langchain.com/oss/python/integrations/providers/aws)
+            - `bedrock_mantle_openai`   -> [`langchain-aws[openai]`](https://docs.langchain.com/oss/python/integrations/providers/aws) — install with `pip install "langchain-aws[openai]"`
+            - `bedrock_mantle_anthropic` -> [`langchain-aws[anthropic]`](https://docs.langchain.com/oss/python/integrations/providers/aws) — install with `pip install "langchain-aws[anthropic]"`
             - `cohere`                  -> [`langchain-cohere`](https://docs.langchain.com/oss/python/integrations/providers/cohere)
             - `fireworks`               -> [`langchain-fireworks`](https://docs.langchain.com/oss/python/integrations/providers/fireworks)
             - `together`                -> [`langchain-together`](https://docs.langchain.com/oss/python/integrations/providers/together)

libs/langchain_v1/tests/unit_tests/chat_models/test_chat_models.py

@@ -155,6 +155,18 @@ def test_supported_providers_is_sorted() -> None:
     assert list(_BUILTIN_PROVIDERS) == sorted(_BUILTIN_PROVIDERS.keys())
 
 
+def test_bedrock_mantle_providers_registered() -> None:
+    """Mantle providers map to the `langchain_aws` Mantle chat model classes."""
+    assert _BUILTIN_PROVIDERS["bedrock_mantle_openai"][:2] == (
+        "langchain_aws",
+        "ChatOpenAIMantle",
+    )
+    assert _BUILTIN_PROVIDERS["bedrock_mantle_anthropic"][:2] == (
+        "langchain_aws",
+        "ChatAnthropicMantle",
+    )
+
+
 @pytest.mark.parametrize(
     ("model_name", "expected_provider"),
     [

libs/langchain_v1/uv.lock

@@ -2442,7 +2442,7 @@ typing = [
 
 [[package]]
 name = "langchain-anthropic"
-version = "1.7.2"
+version = "1.7.4"
 source = { editable = "../partners/anthropic" }
 dependencies = [
     { name = "anthropic" },
@@ -2581,7 +2581,7 @@ wheels = [
 
 [[package]]
 name = "langchain-core"
-version = "1.6.3"
+version = "1.6.5"
 source = { editable = "../core" }
 dependencies = [
     { name = "httpx" },
@@ -2785,7 +2785,7 @@ wheels = [
 
 [[package]]
 name = "langchain-openai"
-version = "1.6.2"
+version = "1.6.6"
 source = { editable = "../partners/openai" }
 dependencies = [
     { name = "certifi" },
@@ -2796,11 +2796,14 @@ dependencies = [
 
 [package.metadata]
 requires-dist = [
+    { name = "aiohttp", marker = "extra == 'azure-identity'", specifier = ">=3.11.0,<4.0.0" },
+    { name = "azure-identity", marker = "extra == 'azure-identity'", specifier = ">=1.25.0,<2.0.0" },
     { name = "certifi", specifier = ">=2024.6.2" },
     { name = "langchain-core", editable = "../core" },
     { name = "openai", specifier = ">=2.45.0,<4.0.0" },
     { name = "tiktoken", specifier = ">=0.7.0,<1.0.0" },
 ]
+provides-extras = ["azure-identity"]
 
 [package.metadata.requires-dev]
 dev = []