//! Client-side ObjectiveAI MCP envelopes — the shapes the API pushes
//! down the reverse-attach channel from #193 (stage 2+).
//!
//! Four surfaces, two pairs:
//!
//! - [`client_request::Request`] — addressed to the client-app layer
//! (e.g. notify a running agent completion). Carries a correlation `id`.
//! - [`client_response::Response`] — client-app layer's reply to a
//! `client_request::Request`. Echoes the request's `id`.
//! - [`server_request::Request`] — addressed to the MCP-server layer
//! (standard MCP `tools/list`, `tools/call`). Carries a correlation `id`.
//! - [`server_response::Response`] — MCP-server layer's reply to a
//! `server_request::Request`. Echoes the request's `id`.
pub use McpKind;