/**
 * dsh-widgets — the rail’s measurement layer.
 *
 * Everything that reads the shell’s layout and turns it into the rail’s geometry:
 * the `--dsx-rail-top` / `--dsx-input-bottom` anchor probes, the right-bar width
 * tracking (read per frame while the user drags a width handle), the ResizeObserver
 * fan-out, and the budget / YIELD beat — which is applied straight to the DOM so it
 * cannot land a frame late behind React’s commit.
 *
 * Moved out of `client/index.ts` (Phase 2.6b) with its body unchanged. The
 * mechanism state (observers, timers, the last-published fingerprints) lives here;
 * the two values the composition root itself owns stay there and arrive through
 * accessors:
 *   - `railBudget` is part of the bridge snapshot, so `emit()` reads it;
 *   - `drawerEl` is written by the rail view’s ref.
 * `prefs` is a LIVE binding, hence `getPrefs()` at the point of use.
 */
import { type Prefs } from '../runtime/prefs';
/** What the measurement layer needs from the composition root. */
export interface RailMeasureDeps {
    /** The LIVE prefs binding — read it at the point of use, never capture it. */
    getPrefs: () => Prefs;
    /** The LIVE rail budget (px); -1 until measured. */
    getRailBudget: () => number;
    /** Publish a new rail budget (the composition root owns the binding). */
    setRailBudget: (next: number) => void;
    /** The drawer wrapper, if the rail is mounted. */
    getDrawerEl: () => HTMLDivElement | null;
    /** Rebuild + publish the bridge snapshot. */
    emit: () => void;
    /** Subscribe to the bridge (the width watcher runs on every emit). */
    subscribe: (fn: () => void) => () => void;
}
/** The measurement layer’s handle on the composition root. */
export interface RailMeasure {
    /** Start the observers/listeners; returns the disposer `ctx.effect` wants. */
    install: () => () => void;
    /** Recompute the geometry now, with an optional observer width hint. */
    scheduleMeasure: (widthHint?: number, horizontalOnly?: boolean) => void;
}
/** Build the measurement layer bound to one composition root. */
export declare function createRailMeasure(deps: RailMeasureDeps): RailMeasure;