buf 1.62.1 generated client is incompatible with connect-python>=0.6.0

[SpencerWhitehead7]

Sorry if this is the wrong place to open this issue, but https://connectrpc.com/ has a big banner that says "CREATED BY BUF" so I hope it's alright. If this is something that should be addressed by the buf cli, just redirect me to where I can file an issue with them instead.

When I use the buf cli@1.62.1 (latest at time of writing) with buf generate to create python service files from protobuf definitions, I get a pyright error in the generated code for XXXServiceASGIApplication

Argument missing for parameter "service"Pylance[reportCallIssue](https://github.com/microsoft/pylance-release/blob/main/docs/diagnostics/reportCallIssue.md)
(method) def __init__(
    *,
    service: Unknown | AsyncGenerator[Unknown, None],
    endpoints: (Unknown) -> Mapping[str, Endpoint[Unknown, Unknown]],
    interceptors: Iterable[Interceptor] = (),
    read_max_bytes: int | None = None
) -> None
Initialize the ASGI application.

The attached zip file is a uv repo that shows the issue. You should be able to run uv sync to download the dependencies and create a fresh .venv.

Then you can run pyright to see the error, or look at gen/ping/v1/ping_service_connect.py in an editor with pyright integration.

If you downgrade connect-python to ==0.5.0 in pyproject.toml, then run uv sync and pyright again, the error goes away.

I can hand-patch the error away by adding service=service to the __init__'s arguments, but that reveals another pyright error

Argument of type "dict[str, EndpointUnary[PingRequest, PingResponse]]" cannot be assigned to parameter "endpoints" of type "(Unknown) -> Mapping[str, Endpoint[Unknown, Unknown]]" in function "__init__"Pylance[reportArgumentType](https://github.com/microsoft/pylance-release/blob/main/docs/diagnostics/reportArgumentType.md)

which I did not try and patch.

buf_1.62.1_generated_client_is_incompatible_with_connect-python_0.6.0.zip

[anuraaga]

Hi @SpencerWhitehead7 - until we release v1.0, we may need to make some breaking changes to generated code. This means it is best to use the same version of the codegen as the library. Currently your buf.gen.yaml is using buf.build/connectrpc/python:v0.5.0 which is why it only works with connect-python==0.5.0 - it's not just a type error but would fail completely at runtime too. I verified bumping it to 0.6.0 fixes it (or you could bump both to the latest version).

Sorry for the confusing behavior there, hopefully we will reach a point where we can have more drift between those versions in the future as we stabilize.

[SpencerWhitehead7]

Thank you, it would be nice if there was better backward compat, but it is a pre 1.0 release and the behavior really isn't that confusing, I just wasn't paying much attention to that version string in config file.