/**
 * Colours an elapsed-time string by how close the current step is to its
 * timeout ceiling (`stepTimeoutMs`), so a watcher sees at a glance that a step
 * is taking unusually long — green well within budget, yellow past halfway, red
 * once it is about to be killed. Pure (no I/O): the caller passes the already-
 * formatted text, the raw elapsed ms, and the ceiling.
 *
 * Bands (fraction of the ceiling): < 0.5 green · 0.5–0.8 yellow · > 0.8 red.
 * The thresholds and the ceiling are parameters, not constants, because
 * `stepTimeoutMs` is configurable. When `colour` is false (non-TTY / NO_COLOR /
 * --plain) the text is returned unstyled. A non-positive ceiling means there is
 * no deadline to approach, so the text stays green rather than dividing by zero.
 */
export declare function colourByElapsed(text: string, elapsedMs: number, ceilingMs: number, colour: boolean): string;