/**
 * Pure state for the streaming text node. Text that has already been shown
 * lives in `settled`; every append while streaming becomes its own segment so
 * several chunks can fade in at once instead of the newest one cutting the
 * previous fade short. Segments are folded back into `settled` once they have
 * been on screen for the fade duration, keeping the DOM small.
 */
/** How long a streamed chunk takes to fade in. Mirrored to CSS via a custom property. */
export declare const STREAMING_TEXT_FADE_MS = 320;
/** Upper bound on live segments so a paused animation clock cannot grow the DOM forever. */
export declare const STREAMING_TEXT_MAX_SEGMENTS = 48;
export interface StreamingTextSegment {
    id: number;
    text: string;
    startedAt: number;
}
export interface StreamingTextState {
    settled: string;
    segments: readonly StreamingTextSegment[];
    nextId: number;
}
export declare function renderedStreamingText(state: StreamingTextState): string;
/**
 * Initial state for a node. Content that was already rendered by a previous
 * instance of the same node (markstream persists it per index key while it
 * re-parses inline markup) stays settled; only the unseen tail animates.
 */
export declare function createStreamingTextState(content: string, options: {
    persisted?: string;
    now: number;
    animate: boolean;
}): StreamingTextState;
/**
 * Apply the next content snapshot. A pure append becomes a new segment; any
 * other change (rewrite, shrink, animation disabled) settles everything so
 * the text never lags behind the parser.
 */
export declare function applyStreamingTextContent(state: StreamingTextState, content: string, options: {
    now: number;
    animate: boolean;
}): StreamingTextState;
/** Fold segments that finished fading into `settled`. Order is preserved, so only a settled head can be folded. */
export declare function settleStreamingTextSegments(state: StreamingTextState, now: number, durationMs?: number): StreamingTextState;
/** Fold the oldest segments until at most `max` remain live. */
export declare function capStreamingTextSegments(state: StreamingTextState, max: number): StreamingTextState;
/** Time at which the oldest live segment finishes fading, or null when nothing is animating. */
export declare function nextStreamingTextSettleAt(state: StreamingTextState, durationMs?: number): number | null;