Client Roots

If the client wants to expose filesystem roots, declare the roots capability and handle the request:

let client_details = InitializeRequestParams {
    capabilities: ClientCapabilities {
        roots: Some(ClientRoots::default()),
        ..Default::default()
    },
    // client_info: Implementation { name: "my-client".into(), version: "0.1.0".into(), .. },
    // protocol_version: "2025-11-25".into(),
    ..Default::default()
};

async fn handle_list_roots_request(
    &self, params: Option<RequestParams>, _runtime: &dyn McpClient,
) -> Result<ListRootsResult, RpcError> {
    Ok(ListRootsResult {
        roots: vec![Root {
            uri: "file:///home/user/projects".into(),
            name: Some("My Projects".into()),
            meta: None,
        }],
        meta: None,
    })
}

Notify the server when roots change with client.notify_roots_list_changed().await?.