Function exit_code_is_retryable 

pub fn exit_code_is_retryable(code: i32) -> bool

Sysexits mapping: which process exits agents may re-invoke with backoff.

Only exit_codes::EX_IOERR (74) is network/SSH-IO retryable. Auth (77), usage (64), data (65), no-input (66), remote command (1), signals and pipe are permanent for the same argv.