Accept injected httpx2 clients

pyproject.toml

@@ -86,6 +86,7 @@ dev = [
     "inline-snapshot>=0.28.0",
     "griffe>=1",
     "http-snapshot[httpx]==0.1.8",
+    "httpx2 ; python_version >= '3.10'",
 ]
 pydantic-v1 = [
     "pydantic>=1.9.0,<2",
@@ -159,6 +160,7 @@ exclude = [
     ".venv",
     ".nox",
     "examples/mcp_tool_runner.py",  # mcp requires Python 3.10+, lint runs on 3.9
+    "tests/test_httpx2_client.py",  # httpx2 requires Python 3.10+, lint runs on 3.9
 ]
 
 reportImplicitOverride = true

requirements-dev.lock

@@ -7,6 +7,7 @@ anyio==4.12.1
     # via
     #   anthropic
     #   httpx
+    #   httpx2
 asttokens==3.0.1
     # via inline-snapshot
 backports-asyncio-runner==1.2.0 ; python_full_version < '3.11'
@@ -45,19 +46,29 @@ griffelib==2.0.0 ; python_full_version >= '3.10'
     #   griffe
     #   griffecli
 h11==0.16.0
-    # via httpcore
+    # via
+    #   httpcore
+    #   httpcore2
 http-snapshot==0.1.8
 httpcore==1.0.9
     # via httpx
+httpcore2==2.7.0 ; python_full_version >= '3.10'
+    # via httpx2
 httpx==0.28.1
     # via
     #   anthropic
     #   http-snapshot
     #   respx
-idna==3.11
+httpx2==2.7.0 ; python_full_version >= '3.10'
+idna==3.11 ; python_full_version < '3.10'
+    # via
+    #   anyio
+    #   httpx
+idna==3.18 ; python_full_version >= '3.10'
     # via
     #   anyio
     #   httpx
+    #   httpx2
 importlib-metadata==8.7.1
 iniconfig==2.1.0 ; python_full_version < '3.10'
     # via pytest
@@ -123,6 +134,10 @@ tomli==2.4.0 ; python_full_version < '3.11'
     #   inline-snapshot
     #   mypy
     #   pytest
+truststore==0.10.4 ; python_full_version >= '3.10'
+    # via
+    #   httpcore2
+    #   httpx2
 types-awscrt==0.31.3
     # via botocore-stubs
 types-s3transfer==0.16.0
@@ -133,6 +148,7 @@ typing-extensions==4.15.0
     #   anyio
     #   boto3-stubs
     #   exceptiongroup
+    #   httpx2
     #   inline-snapshot
     #   mypy
     #   pydantic

src/anthropic/_base_client.py

@@ -134,6 +134,20 @@
         HTTPX_DEFAULT_TIMEOUT = Timeout(5.0)
 
 
+# httpx2 (https://github.com/pydantic/httpx2) is an API-compatible fork of httpx that
+# lives in a separate import namespace, so `httpx2.Client` & co. are distinct classes
+# that fail `isinstance(..., httpx.Client)`. Accept an injected httpx2 client when the
+# package is installed.
+try:
+    import httpx2  # type: ignore
+except ImportError:
+    httpx2 = None
+
+_SYNC_HTTP_CLIENT_TYPES = (httpx.Client,) if httpx2 is None else (httpx.Client, httpx2.Client)
+_ASYNC_HTTP_CLIENT_TYPES = (httpx.AsyncClient,) if httpx2 is None else (httpx.AsyncClient, httpx2.AsyncClient)
+_TIMEOUT_EXCEPTIONS = (httpx.TimeoutException,) if httpx2 is None else (httpx.TimeoutException, httpx2.TimeoutException)
+
+
 class PageInfo:
     """Stores the necessary information to build the request to retrieve the next page.
 
@@ -599,12 +613,20 @@ def _build_request(
             headers.pop("Content-Type", None)
             kwargs.pop("data", None)
 
+        # httpx2's `build_request` rejects a classic `httpx.URL`, so pass the URL as a
+        # string for httpx2 clients while leaving classic httpx clients untouched.
+        url = (
+            str(prepared_url)
+            if httpx2 is not None and isinstance(self._client, (httpx2.Client, httpx2.AsyncClient))
+            else prepared_url
+        )
+
         # TODO: report this error to httpx
         return self._client.build_request(  # pyright: ignore[reportUnknownMemberType]
             headers=headers,
             timeout=self.timeout if isinstance(options.timeout, NotGiven) else options.timeout,
             method=options.method,
-            url=prepared_url,
+            url=url,
             # the `Query` type that we use is incompatible with qs'
             # `Params` type as it needs to be typed as `Mapping[str, object]`
             # so that passing a `TypedDict` doesn't cause an error.
@@ -1007,7 +1029,7 @@ def __init__(
             else:
                 timeout = DEFAULT_TIMEOUT
 
-        if http_client is not None and not isinstance(http_client, httpx.Client):  # pyright: ignore[reportUnnecessaryIsInstance]
+        if http_client is not None and not isinstance(http_client, _SYNC_HTTP_CLIENT_TYPES):  # pyright: ignore[reportUnnecessaryIsInstance]
             raise TypeError(
                 f"Invalid `http_client` argument; Expected an instance of `httpx.Client` but got {type(http_client)}"
             )
@@ -1297,7 +1319,7 @@ def _attempt_request(
                 stream=stream or self._should_stream_response_body(request=request),
                 **kwargs,
             )
-        except httpx.TimeoutException as err:
+        except _TIMEOUT_EXCEPTIONS as err:
             log.debug("Encountered httpx.TimeoutException", exc_info=True)
             raise APITimeoutError(request=request) from err
         except Exception as err:
@@ -1749,7 +1771,7 @@ def __init__(
             else:
                 timeout = DEFAULT_TIMEOUT
 
-        if http_client is not None and not isinstance(http_client, httpx.AsyncClient):  # pyright: ignore[reportUnnecessaryIsInstance]
+        if http_client is not None and not isinstance(http_client, _ASYNC_HTTP_CLIENT_TYPES):  # pyright: ignore[reportUnnecessaryIsInstance]
             raise TypeError(
                 f"Invalid `http_client` argument; Expected an instance of `httpx.AsyncClient` but got {type(http_client)}"
             )
@@ -2049,7 +2071,7 @@ async def _attempt_request(
                 stream=stream or self._should_stream_response_body(request=request),
                 **kwargs,
             )
-        except httpx.TimeoutException as err:
+        except _TIMEOUT_EXCEPTIONS as err:
             log.debug("Encountered httpx.TimeoutException", exc_info=True)
             raise APITimeoutError(request=request) from err
         except Exception as err:

src/anthropic/_response.py

@@ -37,6 +37,19 @@
     from ._base_client import BaseClient
 
 
+# httpx2 (https://github.com/pydantic/httpx2) raises its own `StreamConsumed` from a
+# distinct import namespace, so an injected httpx2 client's double-read would escape an
+# `except httpx.StreamConsumed`. Catch both when the package is installed.
+try:
+    import httpx2  # type: ignore
+except ImportError:
+    httpx2 = None
+
+_STREAM_CONSUMED_EXCEPTIONS = (
+    (httpx.StreamConsumed,) if httpx2 is None else (httpx.StreamConsumed, httpx2.StreamConsumed)
+)
+
+
 P = ParamSpec("P")
 R = TypeVar("R")
 _T = TypeVar("_T")
@@ -361,7 +374,7 @@ def read(self) -> bytes:
         """Read and return the binary response content."""
         try:
             return self.http_response.read()
-        except httpx.StreamConsumed as exc:
+        except _STREAM_CONSUMED_EXCEPTIONS as exc:
             # The default error raised by httpx isn't very
             # helpful in our case so we re-raise it with
             # a different error message.
@@ -468,7 +481,7 @@ async def read(self) -> bytes:
         """Read and return the binary response content."""
         try:
             return await self.http_response.aread()
-        except httpx.StreamConsumed as exc:
+        except _STREAM_CONSUMED_EXCEPTIONS as exc:
             # the default error raised by httpx isn't very
             # helpful in our case so we re-raise it with
             # a different error message

tests/test_httpx2_client.py

@@ -0,0 +1,63 @@
+from __future__ import annotations
+
+import httpx
+import pytest
+
+from anthropic import Anthropic, AsyncAnthropic
+
+httpx2 = pytest.importorskip("httpx2")
+
+base_url = "http://127.0.0.1:4010"
+api_key = "my-anthropic-api-key"
+
+
+def test_accepts_httpx2_sync_client() -> None:
+    with httpx2.Client() as http_client:
+        client = Anthropic(
+            base_url=base_url,
+            api_key=api_key,
+            _strict_response_validation=True,
+            http_client=http_client,
+        )
+        assert isinstance(client._client, httpx2.Client)
+
+
+async def test_accepts_httpx2_async_client() -> None:
+    async with httpx2.AsyncClient() as http_client:
+        client = AsyncAnthropic(
+            base_url=base_url,
+            api_key=api_key,
+            _strict_response_validation=True,
+            http_client=http_client,
+        )
+        assert isinstance(client._client, httpx2.AsyncClient)
+
+
+def test_httpx2_sync_round_trip() -> None:
+    def handler(_request: httpx2.Request) -> httpx2.Response:
+        return httpx2.Response(200, json={"ok": True})
+
+    with httpx2.Client(transport=httpx2.MockTransport(handler)) as http_client:
+        with Anthropic(
+            base_url=base_url,
+            api_key=api_key,
+            _strict_response_validation=True,
+            http_client=http_client,
+        ) as client:
+            response = client.get("/foo", cast_to=httpx.Response)
+            assert response.status_code == 200
+
+
+async def test_httpx2_async_round_trip() -> None:
+    def handler(_request: httpx2.Request) -> httpx2.Response:
+        return httpx2.Response(200, json={"ok": True})
+
+    async with httpx2.AsyncClient(transport=httpx2.MockTransport(handler)) as http_client:
+        async with AsyncAnthropic(
+            base_url=base_url,
+            api_key=api_key,
+            _strict_response_validation=True,
+            http_client=http_client,
+        ) as client:
+            response = await client.get("/foo", cast_to=httpx.Response)
+            assert response.status_code == 200