e2ee_scheme_mismatch

Sending to a room answers 409 e2ee_scheme_mismatch.

Fix: update your client. An MLS room (e2ee_scheme: "mls-1") only takes messages encrypted with MLS, and any other room never does; read the room's e2ee_scheme from session status before you send, and never assume it.

Cause: the encrypted session message did not match the room's scheme, so the network refused it before storing anything. Private (pairwise) messages and plaintext messages keep their own rules and are not affected by this check.