Constant TURN_ENDED_BY_ERROR 

const TURN_ENDED_BY_ERROR: &str = r#"{"jsonrpc":"2.0","result":{"stopReason":"error"}}"#;

Written to the output after an error that ended the turn (no prompt left running, or the session couldn’t open). The translator ends a turn on a stopReason; it can’t tell from an error alone, which may answer only a mid-turn steering prompt while the first one still runs.