Users of grpc-web clients that want to support streaming are currently required to use the grpc-web-text wire format (https://github.com/grpc/grpc-web?tab=readme-ov-file#streaming-support).

On the server side this format is supported by proxies like Envoy or Improbable's grpcwebproxy.

If Vanguard supported this format it would make it easier for grpc-web users to gradually transition to Connect by allowing them to first switch their proxy to Vanguard and then incrementally update their frontend clients, without losing server side streaming support for clients that aren't yet migrated.

Request originated in this slack thread: https://bufbuild.slack.com/archives/CRZ680FUH/p1729008888312809