/**
 * src/extension/widget-refresh.ts — anti-flicker widget plumbing (cycle 4).
 *
 * Two defects fixed here:
 *   1. TWO independent 2s timers (HUD + FleetView) each repainting
 *      unconditionally at every tick — replaced by ONE shared ticker all
 *      widgets subscribe to (created lazily on the first subscriber, stopped
 *      when the last one detaches).
 *   2. Unconditional setWidget/setStatus calls (flicker): WidgetPainter
 *      diffs the rendered content and SKIPS the host call when nothing
 *      changed — an idle session performs ZERO repaints.
 *
 * Zero @earendil-works/* imports.
 */
import type { SessionContext, WidgetContent } from "./pi-types.js";
/** Shared refresh period (safety-net polling; event bus drives immediate refreshes). */
export declare const WIDGET_REFRESH_MS = 2000;
/** Minimal subscription surface (injectable for tests). */
export interface WidgetTicker {
    subscribe(refresh: () => void): () => void;
}
/**
 * One shared interval for every widget owner. The timer starts when the first
 * listener subscribes and stops when the last one leaves — a single 2s tick
 * for HUD + FleetView instead of two independent timers.
 */
export declare class SharedIntervalTicker implements WidgetTicker {
    private readonly intervalMs;
    private timer?;
    private readonly listeners;
    constructor(intervalMs?: number);
    subscribe(refresh: () => void): () => void;
    private fire;
}
/** Process-wide shared widget ticker (HUD + FleetView ride the same timer). */
export declare const widgetTicker: WidgetTicker;
/** True when two widget contents render identically (deep string-array equal). */
export declare function sameWidgetContent(a: WidgetContent, b: WidgetContent): boolean;
/**
 * Diffing painter for one footer widget + its status line: setWidget /
 * setStatus are called ONLY when the rendered content actually changed, so an
 * unchanged render is a zero-op (no flicker). `clear()` always forces the
 * host calls (detach path).
 */
export declare class WidgetPainter {
    private readonly ctx;
    private readonly widgetId;
    private readonly statusId;
    private lastWidget;
    private widgetPainted;
    private lastStatus;
    private statusPainted;
    constructor(ctx: SessionContext, widgetId: string, statusId: string);
    /** Paint the widget content unless it renders identically to the last paint. */
    paintWidget(content: WidgetContent): void;
    /** Paint the status text unless it is identical to the last paint. */
    paintStatus(text: string | undefined): void;
    /** Force-clear the widget + status and reset the diff state (detach). */
    clear(): void;
}