This crate is the storage boundary used by the future Linux AppImage shell. Settings writes only server_address and username to the client settings.json. Session credentials are stored under the Linux kernel keyring service trixie.server.session, scoped by server address and username. load_session returns None when the keyring is unavailable; callers must return to credential entry and must not create a plaintext fallback.

The crate uses keyctl with argument arrays, never a shell command. It does not log or serialize session values.