Function list_relay_devices 

pub fn list_relay_devices<A: ToSocketAddrs>(
    addr: A,
    token: &str,
) -> Result<Vec<String>, AppError>

Query a relay for the device ids currently registered (bd-bc8b5c), so omni devices --relay can show operators which cross-device endpoints are connected. Bounded: a legacy relay that does not understand list sends no devices reply, so this returns an empty list (never hangs) within the read timeout. An auth rejection surfaces as a validation error.

Errors

AppError::internal on connect / I/O failure; AppError::validation when the relay rejects the token.