python/typeshed

grpc.aio.ServerInterceptor is incompatible with async RPC methods

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#15495 opened on Mar 8, 2026

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help wantedstubs: false positive

Description

The grpc.aio.ServerInterceptor is currently annotated using grpc.RpcMethodHandler. However the interface for grpc.RpcMethodHandler is not compatible with async RPC methods. The correct stub for an async version would make use of Awaitable and AsyncIterator:

class RpcMethodHandler(abc.ABC, Generic[_TRequest, _TResponse]):
    request_streaming: bool
    response_streaming: bool

    # XXX: not clear from docs whether this is optional or not
    request_deserializer: _Deserializer[_TRequest] | None

    # XXX: not clear from docs whether this is optional or not
    response_serializer: _Serializer[_TResponse] | None

    unary_unary: Callable[[_TRequest, ServicerContext], Awaitable[_TResponse]] | None

    unary_stream: Callable[[_TRequest, ServicerContext], AsyncIterator[_TResponse]] | None

    stream_unary: Callable[[Iterator[_TRequest], ServicerContext], Awaitable[_TResponse]] | None

    stream_stream: Callable[[Iterator[_TRequest], ServicerContext], AsyncIterator[_TResponse]] | None

Contributor guide

Tech stack
python
Domain
tooling
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Python async/awaitgRPC conceptstype hints
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75
Research direction
Review the type stub file at stubs/grpcio/grpc/aio/ init .pyi, specifically the RpcMethodHandler class. Modify the unary unary, unary stream, stream unary, and stream stream methods to use Awaitable and AsyncIterator return types as shown in the issue body. Ensure compatibility with the existing grpc.aio.ServerInterceptor interface.