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fix: remove server_info from DiscoverResult #1065

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fix: remove server_info from DiscoverResult #1065

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100 changes: 40 additions & 60 deletions crates/rmcp/src/model.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1120,9 +1120,9 @@ impl schemars::JsonSchema for DiscoverRequestParams {
pub type DiscoverRequest = Request<DiscoverRequestMethod, DiscoverRequestParams>;

/// The server's response to a [`DiscoverRequest`].
#[derive(Debug, Serialize, Clone, PartialEq)]
#[serde(rename_all = "camelCase")]
#[derive(Debug, Serialize, Deserialize, Clone, PartialEq)]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
#[serde(rename_all = "camelCase")]
#[non_exhaustive]
pub struct DiscoverResult {
/// Identifies how the result should be parsed.
Expand All @@ -1131,8 +1131,6 @@ pub struct DiscoverResult {
pub supported_versions: Vec<ProtocolVersion>,
/// Capabilities provided by this server.
pub capabilities: ServerCapabilities,
/// Information about the server implementation.
pub server_info: Implementation,
/// Optional guidance for using the server.
#[serde(skip_serializing_if = "Option::is_none")]
pub instructions: Option<String>,
Expand All @@ -1145,72 +1143,47 @@ pub struct DiscoverResult {
pub meta: Option<MetaObject>,
}

impl<'de> Deserialize<'de> for DiscoverResult {
fn deserialize<__D>(deserializer: __D) -> Result<Self, __D::Error>
where
__D: serde::Deserializer<'de>,
{
#[derive(Deserialize)]
#[serde(rename_all = "camelCase")]
struct Helper {
result_type: ResultType,
supported_versions: Vec<ProtocolVersion>,
capabilities: ServerCapabilities,
server_info: Option<Implementation>,
instructions: Option<String>,
ttl_ms: u64,
cache_scope: CacheScope,
#[serde(rename = "_meta")]
meta: Option<MetaObject>,
}

let helper = Helper::deserialize(deserializer)?;
let server_info = match helper.server_info {
Some(server_info) => server_info,
None => {
let metadata_server_info = helper
.meta
.as_ref()
.and_then(|metadata| metadata.0.get("io.modelcontextprotocol/serverInfo"))
.ok_or_else(|| serde::de::Error::missing_field("serverInfo"))?;

serde_json::from_value(metadata_server_info.clone())
.map_err(serde::de::Error::custom)?
}
};

Ok(Self {
result_type: helper.result_type,
supported_versions: helper.supported_versions,
capabilities: helper.capabilities,
server_info,
instructions: helper.instructions,
ttl_ms: helper.ttl_ms,
cache_scope: helper.cache_scope,
meta: helper.meta,
})
}
}

impl DiscoverResult {
const SERVER_INFO_META_KEY: &str = "io.modelcontextprotocol/serverInfo";

/// Create a non-cacheable private discovery result.
pub fn new(
supported_versions: Vec<ProtocolVersion>,
capabilities: ServerCapabilities,
server_info: Implementation,
) -> Self {
pub fn new(supported_versions: Vec<ProtocolVersion>, capabilities: ServerCapabilities) -> Self {
Self {
result_type: ResultType::COMPLETE,
supported_versions,
capabilities,
server_info,
instructions: None,
ttl_ms: 0,
cache_scope: CacheScope::Private,
meta: None,
}
}

/// Return the server implementation information stored in result metadata.
pub fn server_info(&self) -> Option<Implementation> {
self.meta
.as_ref()?
.0
.get(Self::SERVER_INFO_META_KEY)
.and_then(|value| serde_json::from_value(value.clone()).ok())
}

/// Store server implementation information in result metadata.
pub fn set_server_info(&mut self, server_info: Implementation) {
let server_info =
serde_json::to_value(server_info).expect("Implementation serialization cannot fail");
self.meta
.get_or_insert_default()
.0
.insert(Self::SERVER_INFO_META_KEY.to_owned(), server_info);
}

/// Store server implementation information in result metadata.
pub fn with_server_info(mut self, server_info: Implementation) -> Self {
self.set_server_info(server_info);
self
}

/// Create a discovery result from the server's initialization information.
pub fn from_server_info(
supported_versions: Vec<ProtocolVersion>,
Expand All @@ -1223,9 +1196,16 @@ impl DiscoverResult {
meta,
..
} = server_info;
let mut result = Self::new(supported_versions, capabilities, server_info);
result.instructions = instructions;
result.meta = meta;
let mut result = Self {
result_type: ResultType::COMPLETE,
supported_versions,
capabilities,
instructions,
ttl_ms: 0,
cache_scope: CacheScope::Private,
meta,
};
result.set_server_info(server_info);
result
}

Expand Down
27 changes: 13 additions & 14 deletions crates/rmcp/src/service/client.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -846,13 +846,15 @@ where
server_supported: result.supported_versions,
});
};
peer.set_peer_info(ServerInfo {
protocol_version: selected.clone(),
capabilities: result.capabilities,
server_info: result.server_info,
instructions: result.instructions,
meta: result.meta,
});
if let Some(server_info) = result.server_info() {
peer.set_peer_info(ServerInfo {
protocol_version: selected.clone(),
capabilities: result.capabilities,
server_info,
instructions: result.instructions,
meta: result.meta,
});
}
peer.set_client_request_metadata(ClientRequestMetadata {
protocol_version: selected,
client_info: client_info.client_info.clone(),
Expand Down Expand Up @@ -2197,13 +2199,10 @@ mod tests {
let peer = disconnected_peer();
let meta = RequestMetaObject::default();
let key = discover_cache_key();
let expected = DiscoverResult::new(
vec![ProtocolVersion::default()],
Default::default(),
crate::model::Implementation::from_build_env(),
)
.with_ttl_ms(5_000)
.with_cache_scope(CacheScope::Public);
let expected = DiscoverResult::new(vec![ProtocolVersion::default()], Default::default())
.with_server_info(crate::model::Implementation::from_build_env())
.with_ttl_ms(5_000)
.with_cache_scope(CacheScope::Public);
peer.cache_response(
key,
ServerResult::DiscoverResult(expected.clone()),
Expand Down
103 changes: 83 additions & 20 deletions crates/rmcp/tests/test_client_lifecycle_modes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -36,11 +36,13 @@ async fn discover_startup_accepts_stringified_numeric_response_id() {
};
server
.send(ServerJsonRpcMessage::response(
ServerResult::DiscoverResult(DiscoverResult::new(
vec![ProtocolVersion::V_2026_07_28],
ServerCapabilities::default(),
Implementation::new("discover-server", "1.0.0"),
)),
ServerResult::DiscoverResult(
DiscoverResult::new(
vec![ProtocolVersion::V_2026_07_28],
ServerCapabilities::default(),
)
.with_server_info(Implementation::new("discover-server", "1.0.0")),
),
RequestId::String(response_id.to_string().into()),
))
.await
Expand All @@ -60,6 +62,61 @@ async fn discover_startup_accepts_stringified_numeric_response_id() {
server_task.await.expect("server task");
}

#[tokio::test]
async fn discover_startup_accepts_missing_optional_server_info() {
let (server_transport, client_transport) = tokio::io::duplex(4096);
let mut server = IntoTransport::<rmcp::RoleServer, _, _>::into_transport(server_transport);
let server_task = tokio::spawn(async move {
let ClientJsonRpcMessage::Request(discover_request) =
server.receive().await.expect("expected discover request")
else {
panic!("expected discover request");
};
let result = DiscoverResult::new(
vec![ProtocolVersion::V_2026_07_28],
ServerCapabilities::default(),
);
server
.send(ServerJsonRpcMessage::response(
ServerResult::DiscoverResult(result),
discover_request.id,
))
.await
.expect("send discover response");

let ClientJsonRpcMessage::Request(request) =
server.receive().await.expect("expected normal request")
else {
panic!("expected normal request");
};
assert_eq!(
request.request.get_meta().protocol_version(),
Some(ProtocolVersion::V_2026_07_28)
);
server
.send(ServerJsonRpcMessage::response(
ServerResult::ListToolsResult(Default::default()),
request.id,
))
.await
.expect("send list tools response");
});

let client = DiscoverClient
.serve_with_lifecycle(
client_transport,
ClientLifecycleMode::Discover {
preferred_versions: vec![ProtocolVersion::V_2026_07_28],
},
)
.await
.expect("missing optional server info should not fail discovery");
assert!(client.peer_info().is_none());
client.list_tools(None).await.expect("list tools");
client.cancel().await.expect("cancel client");
server_task.await.expect("server task");
}

#[tokio::test]
async fn high_level_server_accepts_discover_startup_without_initialize() {
let (server_transport, client_transport) = tokio::io::duplex(4096);
Expand Down Expand Up @@ -103,11 +160,13 @@ async fn discover_startup_omits_initialize() {

server
.send(ServerJsonRpcMessage::response(
ServerResult::DiscoverResult(DiscoverResult::new(
vec![ProtocolVersion::V_2026_07_28],
ServerCapabilities::default(),
Implementation::new("discover-server", "1.0.0"),
)),
ServerResult::DiscoverResult(
DiscoverResult::new(
vec![ProtocolVersion::V_2026_07_28],
ServerCapabilities::default(),
)
.with_server_info(Implementation::new("discover-server", "1.0.0")),
),
request.id,
))
.await
Expand Down Expand Up @@ -267,11 +326,13 @@ async fn discover_startup_retries_a_mutually_supported_version() {
);
server
.send(ServerJsonRpcMessage::response(
ServerResult::DiscoverResult(DiscoverResult::new(
vec![ProtocolVersion::V_2026_07_28],
ServerCapabilities::default(),
Implementation::new("discover-server", "1.0.0"),
)),
ServerResult::DiscoverResult(
DiscoverResult::new(
vec![ProtocolVersion::V_2026_07_28],
ServerCapabilities::default(),
)
.with_server_info(Implementation::new("discover-server", "1.0.0")),
),
second.id,
))
.await
Expand Down Expand Up @@ -326,11 +387,13 @@ async fn discover_startup_retries_current_version_once_when_server_reports_it_su
);
server
.send(ServerJsonRpcMessage::response(
ServerResult::DiscoverResult(DiscoverResult::new(
vec![ProtocolVersion::V_2026_07_28],
ServerCapabilities::default(),
Implementation::new("discover-server", "1.0.0"),
)),
ServerResult::DiscoverResult(
DiscoverResult::new(
vec![ProtocolVersion::V_2026_07_28],
ServerCapabilities::default(),
)
.with_server_info(Implementation::new("discover-server", "1.0.0")),
),
second.id,
))
.await
Expand Down
7 changes: 7 additions & 0 deletions crates/rmcp/tests/test_message_schema.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -121,6 +121,13 @@ mod tests {
let schema = settings
.into_generator()
.into_root_schema_for::<ServerJsonRpcMessage>();
let schema_value =
serde_json::to_value(&schema).expect("Failed to serialize server schema");
let discover_result = &schema_value["definitions"]["DiscoverResult"];
assert!(
discover_result["properties"].get("serverInfo").is_none(),
"DiscoverResult serverInfo belongs in namespaced _meta"
);
let schema_str = serde_json::to_string_pretty(&schema).expect("Failed to serialize schema");

compare_schemas(
Expand Down
9 changes: 0 additions & 9 deletions crates/rmcp/tests/test_message_schema/server_json_rpc_message_schema.json
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Original file line number Diff line number Diff line change
Expand Up @@ -759,14 +759,6 @@
}
]
},
"serverInfo": {
"description": "Information about the server implementation.",
"allOf": [
{
"$ref": "#/definitions/Implementation"
}
]
},
"supportedVersions": {
"description": "Protocol versions implemented by this server.",
"type": "array",
Expand All @@ -785,7 +777,6 @@
"resultType",
"supportedVersions",
"capabilities",
"serverInfo",
"ttlMs",
"cacheScope"
]
Expand Down
9 changes: 0 additions & 9 deletions crates/rmcp/tests/test_message_schema/server_json_rpc_message_schema_current.json
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Original file line number Diff line number Diff line change
Expand Up @@ -759,14 +759,6 @@
}
]
},
"serverInfo": {
"description": "Information about the server implementation.",
"allOf": [
{
"$ref": "#/definitions/Implementation"
}
]
},
"supportedVersions": {
"description": "Protocol versions implemented by this server.",
"type": "array",
Expand All @@ -785,7 +777,6 @@
"resultType",
"supportedVersions",
"capabilities",
"serverInfo",
"ttlMs",
"cacheScope"
]
Expand Down
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