Function plg_rt_b_write_1 

#[unsafe(no_mangle)]
pub extern "C" fn plg_rt_b_write_1(m: *mut Machine, term: u64) -> i32

write/1: print the term (v1 term_to_string), no trailing newline. Output goes through the Machine’s sink (stdout for CLI/WASI, a capture buffer for the reactor) so an isolate with no stdout loses nothing.