feat(anthropic,fireworks,openai): support langsmith gateway through env var

libs/partners/anthropic/langchain_anthropic/chat_models.py

@@ -6,6 +6,7 @@
 import datetime
 import hashlib
 import json
+import os
 import re
 import warnings
 from collections.abc import AsyncIterator, Callable, Iterator, Mapping, Sequence
@@ -76,6 +77,18 @@
 
 _MODEL_PROFILES = cast(ModelProfileRegistry, _PROFILES)
 
+_LANGSMITH_GATEWAY_DEFAULT_URL = "https://gateway.smith.langchain.com/anthropic"
+
+
+def _resolve_gateway_base_url() -> str | None:
+    raw = os.getenv("LANGSMITH_GATEWAY")
+    if raw is None or raw.lower() in ("false", "0", "no"):
+        return None
+    if raw.lower() in ("true", "1", "yes"):
+        return _LANGSMITH_GATEWAY_DEFAULT_URL
+    return raw
+
+
 _USER_AGENT: Final[str] = f"langchain-anthropic/{__version__}"
 
 
@@ -945,15 +958,18 @@ class ChatAnthropic(BaseChatModel):
 
     anthropic_api_url: str | None = Field(
         alias="base_url",
-        default_factory=from_env(
+        default_factory=lambda: _resolve_gateway_base_url()
+        or from_env(
             ["ANTHROPIC_API_URL", "ANTHROPIC_BASE_URL"],
             default="https://api.anthropic.com",
-        ),
+        )(),
     )
     """Base URL for API requests. Only specify if using a proxy or service emulator.
 
     If a value isn't passed in, will attempt to read the value first from
     `ANTHROPIC_API_URL` and if that is not set, `ANTHROPIC_BASE_URL`.
+
+    If `LANGSMITH_GATEWAY` is set, it takes precedence over both env vars.
     """
 
     anthropic_api_key: SecretStr = Field(

libs/partners/anthropic/tests/unit_tests/test_chat_models.py

@@ -3574,3 +3574,27 @@ def mock_create(_payload: Any) -> list:
     message_finish = cast("dict[str, Any]", stream_events[-1])
     assert message_finish["event"] == "message-finish"
     assert message_finish["metadata"]["stop_reason"] == "tool_use"
+
+
+def test_langsmith_gateway_true(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setenv("LANGSMITH_GATEWAY", "true")
+    monkeypatch.delenv("ANTHROPIC_API_URL", raising=False)
+    monkeypatch.delenv("ANTHROPIC_BASE_URL", raising=False)
+    llm = ChatAnthropic(model=MODEL_NAME, api_key="test")
+    assert llm.anthropic_api_url == "https://gateway.smith.langchain.com/anthropic"
+
+
+def test_langsmith_gateway_false(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setenv("LANGSMITH_GATEWAY", "false")
+    monkeypatch.delenv("ANTHROPIC_API_URL", raising=False)
+    monkeypatch.delenv("ANTHROPIC_BASE_URL", raising=False)
+    llm = ChatAnthropic(model=MODEL_NAME, api_key="test")
+    assert llm.anthropic_api_url == "https://api.anthropic.com"
+
+
+def test_langsmith_gateway_unset(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.delenv("LANGSMITH_GATEWAY", raising=False)
+    monkeypatch.delenv("ANTHROPIC_API_URL", raising=False)
+    monkeypatch.delenv("ANTHROPIC_BASE_URL", raising=False)
+    llm = ChatAnthropic(model=MODEL_NAME, api_key="test")
+    assert llm.anthropic_api_url == "https://api.anthropic.com"

libs/partners/fireworks/langchain_fireworks/chat_models.py

@@ -5,6 +5,7 @@
 import contextlib
 import json
 import logging
+import os
 from collections.abc import AsyncIterator, Callable, Iterator, Mapping, Sequence
 from operator import itemgetter
 from typing import (
@@ -108,6 +109,17 @@
 
 _MODEL_PROFILES = cast("ModelProfileRegistry", _PROFILES)
 
+_LANGSMITH_GATEWAY_DEFAULT_URL = "https://gateway.smith.langchain.com/fireworks"
+
+
+def _resolve_gateway_base_url() -> str | None:
+    raw = os.getenv("LANGSMITH_GATEWAY")
+    if raw is None or raw.lower() in ("false", "0", "no"):
+        return None
+    if raw.lower() in ("true", "1", "yes"):
+        return _LANGSMITH_GATEWAY_DEFAULT_URL
+    return raw
+
 
 def _get_default_model_profile(model_name: str) -> ModelProfile:
     default = _MODEL_PROFILES.get(model_name) or {}
@@ -771,10 +783,14 @@ def model(self) -> str:
     """
 
     fireworks_api_base: str | None = Field(
-        alias="base_url", default_factory=from_env("FIREWORKS_API_BASE", default=None)
+        alias="base_url",
+        default_factory=lambda: _resolve_gateway_base_url()
+        or from_env("FIREWORKS_API_BASE", default=None)(),
     )
     """Base URL path for API requests, leave blank if not using a proxy or service
     emulator.
+
+    If `LANGSMITH_GATEWAY` is set, it takes precedence over `FIREWORKS_API_BASE`.
     """
 
     request_timeout: float | tuple[float, float] | Any | None = Field(

libs/partners/fireworks/tests/unit_tests/test_chat_models.py

@@ -1591,3 +1591,23 @@ def test_request_timeout_tuple_normalized_to_httpx_timeout(
     assert forwarded.connect == 5.0
     assert forwarded.read == 30.0
     assert async_mock.call_args.kwargs["timeout"] == forwarded
+
+
+def test_langsmith_gateway_true(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setenv("LANGSMITH_GATEWAY", "true")
+    llm = _make_model()
+    assert llm.fireworks_api_base == "https://gateway.smith.langchain.com/fireworks"
+
+
+def test_langsmith_gateway_false(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setenv("LANGSMITH_GATEWAY", "false")
+    monkeypatch.delenv("FIREWORKS_API_BASE", raising=False)
+    llm = _make_model()
+    assert llm.fireworks_api_base is None
+
+
+def test_langsmith_gateway_unset(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.delenv("LANGSMITH_GATEWAY", raising=False)
+    monkeypatch.delenv("FIREWORKS_API_BASE", raising=False)
+    llm = _make_model()
+    assert llm.fireworks_api_base is None

libs/partners/openai/langchain_openai/chat_models/base.py

@@ -178,6 +178,17 @@ def _get_ssrf_safe_client() -> httpx.Client:
 
 _MODEL_PROFILES = cast(ModelProfileRegistry, _PROFILES)
 
+_LANGSMITH_GATEWAY_DEFAULT_URL = "https://gateway.smith.langchain.com/openai/v1"
+
+
+def _resolve_gateway_base_url() -> str | None:
+    raw = os.getenv("LANGSMITH_GATEWAY")
+    if raw is None or raw.lower() in ("false", "0", "no"):
+        return None
+    if raw.lower() in ("true", "1", "yes"):
+        return _LANGSMITH_GATEWAY_DEFAULT_URL
+    return raw
+
 
 def _get_default_model_profile(model_name: str) -> ModelProfile:
     default = _MODEL_PROFILES.get(model_name) or {}
@@ -1167,26 +1178,33 @@ def validate_environment(self) -> Self:
             or os.getenv("OPENAI_ORG_ID")
             or os.getenv("OPENAI_ORGANIZATION")
         )
-        self.openai_api_base = self.openai_api_base or os.getenv("OPENAI_API_BASE")
-
-        # Enable stream_usage by default if using default base URL and client
-        if (
-            all(
-                getattr(self, key, None) is None
-                for key in (
-                    "stream_usage",
-                    "openai_proxy",
-                    "openai_api_base",
-                    "base_url",
-                    "client",
-                    "root_client",
-                    "async_client",
-                    "root_async_client",
-                    "http_client",
-                    "http_async_client",
-                )
+        _gateway_base_url = _resolve_gateway_base_url()
+        _base_url_from_gateway = False
+        if self.openai_api_base is None:
+            if _gateway_base_url is not None:
+                self.openai_api_base = _gateway_base_url
+                _base_url_from_gateway = True
+            else:
+                self.openai_api_base = os.getenv("OPENAI_API_BASE")
+
+        # Enable stream_usage by default if using default base URL and client,
+        # or when the base URL was set by the LangSmith gateway (which proxies
+        # to OpenAI and supports streaming token usage).
+        if all(
+            getattr(self, key, None) is None
+            for key in (
+                "stream_usage",
+                "openai_proxy",
+                "client",
+                "root_client",
+                "async_client",
+                "root_async_client",
+                "http_client",
+                "http_async_client",
             )
-            and "OPENAI_BASE_URL" not in os.environ
+        ) and (
+            _base_url_from_gateway
+            or (self.openai_api_base is None and "OPENAI_BASE_URL" not in os.environ)
         ):
             self.stream_usage = True
 

libs/partners/openai/tests/unit_tests/chat_models/test_base.py

@@ -4501,3 +4501,22 @@ def test_defer_loading_in_responses_api_payload() -> None:
     assert weather_tool["defer_loading"] is True
     assert weather_tool["type"] == "function"
     assert {"type": "tool_search"} in result["tools"]
+
+
+def test_langsmith_gateway_true(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setenv("LANGSMITH_GATEWAY", "true")
+    llm = ChatOpenAI(model=OPENAI_TEST_MODEL, api_key="test")
+    assert llm.openai_api_base == "https://gateway.smith.langchain.com/openai/v1"
+    assert llm.stream_usage is True
+
+
+def test_langsmith_gateway_false(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setenv("LANGSMITH_GATEWAY", "false")
+    llm = ChatOpenAI(model=OPENAI_TEST_MODEL, api_key="test")
+    assert llm.openai_api_base is None
+
+
+def test_langsmith_gateway_unset(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.delenv("LANGSMITH_GATEWAY", raising=False)
+    llm = ChatOpenAI(model=OPENAI_TEST_MODEL, api_key="test")
+    assert llm.openai_api_base is None