Function is_deadline_abort 

pub fn is_deadline_abort(err: &EvalAltResult) -> bool

True when err was produced by the per-render wallclock deadline aborting the script (the engine’s on_progress callback). Lets the consumer-side segment wrapper distinguish a host-imposed timeout from a script-issued throw/runtime error without reaching for the host-only marker type directly.

A plugin cannot forge this classification: the marker is a host-only Rust type that’s never registered with the rhai engine, so a throw "..." payload — even one carrying an identical string message — won’t satisfy the inner type-id check.