This package provides a minimal-dependency client for the Matrix Client-Server HTTP API <https://spec.matrix.org/>, suitable for talking to a Synapse <https://element-hq.github.io/synapse/> or Conduit <https://conduit.rs/> homeserver. Covers login, room management, message send and history, media upload or download, and the transport endpoints needed to coordinate end-to-end encryption (device-key and one-time-key publication, key query and claim, to-device events). Encryption itself is out of scope; pair with a separate crypto package.