export type RuntimeSystemPhase = "input" | "fixed" | "update" | "late" | "presentation";
/** All durations use milliseconds, matching the session's animation clock. */
export interface RuntimeTickContext {
    readonly phase: RuntimeSystemPhase;
    readonly deltaMs: number;
    readonly unscaledDeltaMs: number;
    readonly elapsedMs: number;
    readonly frame: number;
    readonly fixed?: Readonly<{
        index: number;
        count: number;
        elapsedMs: number;
        interpolation: number;
        droppedMs: number;
    }>;
}
export interface RuntimeSystem {
    readonly id: string;
    readonly phase: RuntimeSystemPhase;
    readonly order?: number;
    run(context: RuntimeTickContext): void;
}
/** Opt-in host systems; no document writes, timers, engine or render-loop ownership. */
export interface RuntimeLoop {
    addSystem(system: RuntimeSystem): () => void;
    paused: boolean;
    timeScale: number;
    configureFixedStep(options: {
        stepMs: number;
        maxSubsteps: number;
    }): void;
    getState(): RuntimeLoopState;
    /** Simulated milliseconds. Each repeating timer runs at most once per frame. */
    schedule(delayMs: number, callback: () => void, options?: {
        repeatMs?: number;
    }): () => void;
}
export interface RuntimeLoopState {
    readonly paused: boolean;
    readonly timeScale: number;
    readonly elapsedMs: number;
    readonly fixedElapsedMs: number;
    readonly frame: number;
    readonly stepMs: number;
    readonly maxSubsteps: number;
    readonly interpolation: number;
    readonly droppedMs: number;
    readonly totalDroppedMs: number;
    readonly timers: number;
    readonly systems: readonly {
        id: string;
        phase: RuntimeSystemPhase;
        order: number;
    }[];
}
interface LoopHost {
    transaction(action: () => void): void;
    advanceClock(deltaMs: number): void;
    reportError(error: unknown, systemId: string): void;
}
/** Internal driver. Only RuntimeSession supplies frame timestamps and lifecycle. */
export declare class RuntimeLoopController implements RuntimeLoop {
    #private;
    readonly host: LoopHost;
    constructor(host: LoopHost);
    get paused(): boolean;
    set paused(value: boolean);
    get timeScale(): number;
    set timeScale(value: number);
    addSystem(system: RuntimeSystem): () => void;
    configureFixedStep(options: {
        stepMs: number;
        maxSubsteps: number;
    }): void;
    getState(): RuntimeLoopState;
    schedule(delayMs: number, callback: () => void, options?: {
        repeatMs?: number;
    }): () => void;
    advance(now: number, active: boolean): void;
    resetInterval(): void;
    reset(): void;
    dispose(): void;
}
export {};
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