[Bug]: outdated / mismatched a2a.proto on grpc spec for compat-0.3

[charmaineet]

This is the Part definition in compat-0.3/spec-grpc/src/main/proto/a2a.proto. It seems to be missing the optional metadata field, according to python's a2a sdk for compat-0.3 there is a

java (compat-0.3/spec-grpc/src/main/proto/a2a.proto)
message Part {
oneof part {
string text = 1;
FilePart file = 2;
DataPart data = 3;
}
}

python (src/a2a/compat/v0_3/a2a_v0_3.proto)
message Part {
oneof part {
string text = 1;
FilePart file = 2;
DataPart data = 3;
}
// Optional metadata associated with this part.
google.protobuf.Struct metadata = 4;
}

This results in the SDK failing to parse the metadata field from responses that includes it.

[kabir]

I don't know what a2a-python has done, but the spec version of the 0.3 a2a.proto is here: https://github.com/a2aproject/A2A/blob/v0.3.0/specification/grpc/a2a.proto

This is the one implementations should be aligned with, so I think what you are describing is probably a bug in a2a-python?

[charmaineet]

I think this is the protocol definition on https://a2a-protocol.org/v0.3.0/specification/, so I think the python one should be correct? the metadata field is an optional field