Overly aggressive httpx client type check conflicts with opentelemetry instrumentation in some cases

[micahjsmith]

I've found that it is impossible to call client.with_options if anthropic is imported before opentelemetry httpx instrumentor is run. This is because anthropic has a reference to the original/unpatched httpx.Client via inheritance whereas at runtime the isinstance comparison happens against the instrumented client via otel.

I recognize that this error is probably a "user error" and devs can and should take care to run all of their instrumentation/patching before other imports happen.

However there are a few points I'd make to see whether you'd consider addressing within this repo.

• the fact that the problematic code only errors upon with_options() but does not error upon Anthropic() is a smell that there is something funky with anthropic sdk
• the specific type check at https://github.com/anthropics/anthropic-sdk-python/blob/main/src/anthropic/_base_client.py#L898-L901 is unreachable per the typing and has a pyright ignore statement accordingly

I believe this type check in _base_client can be removed entirely as it is the user's responsibility to ensure they pass in an http client with type that is acceptable per the type annotations.

anthropic 0.48.0
opentelemetry-instrumentation-httpx 0.48b0

this works when patching fully happens before anthropic sdk is imported

$ poetry run python
Python 3.11.11 (main, Dec  3 2024, 17:20:40) [Clang 16.0.0 (clang-1600.0.26.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from opentelemetry.instrumentation.httpx import HTTPXClientInstrumentor
>>> HTTPXClientInstrumentor().instrument()
>>> import anthropic
>>> client = anthropic.Anthropic()
>>> client = client.with_options(timeout=1.0)
>>> ^D

this fails when patching happens after anthropic sdk is imported

$ poetry run python
Python 3.11.11 (main, Dec  3 2024, 17:20:40) [Clang 16.0.0 (clang-1600.0.26.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import anthropic
>>> from opentelemetry.instrumentation.httpx import HTTPXClientInstrumentor
>>> HTTPXClientInstrumentor().instrument()
>>> client = anthropic.Anthropic()
>>> client = client.with_options(timeout=1.0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/micahsmith/workspace/.venv/lib/python3.11/site-packages/anthropic/_client.py", line 221, in copy
    return self.__class__(
           ^^^^^^^^^^^^^^^
  File "/Users/micahsmith/workspace/.venv/lib/python3.11/site-packages/anthropic/_client.py", line 110, in __init__
    super().__init__(
  File "/Users/micahsmith/workspace/.venv/lib/python3.11/site-packages/anthropic/_base_client.py", line 899, in __init__
    raise TypeError(
TypeError: Invalid `http_client` argument; Expected an instance of `httpx.Client` but got <class 'anthropic._base_client.SyncHttpxClientWrapper'>
>>> httpx.Client.mro()
[<class 'opentelemetry.instrumentation.httpx._InstrumentedClient'>, <class 'httpx.Client'>, <class 'httpx._client.BaseClient'>, <class 'object'>]
>>> type(client._client).mro()
[<class 'anthropic._base_client.SyncHttpxClientWrapper'>, <class 'anthropic._DefaultHttpxClient'>, <class 'httpx.Client'>, <class 'httpx._client.BaseClient'>, <class 'object'>]