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fix: align protocol version negotiation (#855)

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* fix: align protocol version negotiation

* ci: relax semver-checks to allow minor changes
This commit is contained in:
Dale Seo 2026-05-18 16:54:08 -04:00 • committed by GitHub
commit d328751dc9
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1 changed files with 108 additions and 12 deletions
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35
crates/rmcp/src/service/server.rs
View file

@ -69,6 +69,10 @@ pub enum ServerInitializeError {
#[error("initialize failed: {0}")]
InitializeFailed(ErrorData),
#[deprecated(
since = "1.8.0",
note = "Negotiation now falls back to the server-configured version. This variant is never constructed and will be removed in a future major release."
)]
#[error("unsupported protocol version: {0}")]
UnsupportedProtocolVersion(ProtocolVersion),
@ -155,6 +159,23 @@ where
}
}
/// Echoes the client-requested version if known; otherwise returns `server_fallback`.
fn negotiate_protocol_version(
client_requested: &ProtocolVersion,
server_fallback: ProtocolVersion,
) -> ProtocolVersion {
if ProtocolVersion::KNOWN_VERSIONS.contains(client_requested) {
client_requested.clone()
} else {
tracing::warn!(
client_requested = %client_requested,
server_fallback = %server_fallback,
"client requested unsupported protocol version; falling back to server default"
);
server_fallback
}
}
async fn serve_server_with_ct_inner<S, T>(
service: S,
transport: T,
@ -227,16 +248,10 @@ where
return Err(ServerInitializeError::InitializeFailed(e));
}
};
let peer_protocol_version = peer_info.params.protocol_version.clone();
let protocol_version = match peer_protocol_version
.partial_cmp(&init_response.protocol_version)
.ok_or(ServerInitializeError::UnsupportedProtocolVersion(
peer_protocol_version,
))? {
std::cmp::Ordering::Less => peer_info.params.protocol_version.clone(),
_ => init_response.protocol_version,
};
init_response.protocol_version = protocol_version;
init_response.protocol_version = negotiate_protocol_version(
&peer_info.params.protocol_version,
init_response.protocol_version,
);
transport
.send(ServerJsonRpcMessage::response(
ServerResult::InitializeResult(init_response),