import { AssistantConversationProcessing, AssistantTurnStage } from './conversation';
import { AssistantTr } from './i18n';
/**
 * The waiting copy for a live turn, derived from its processing state.
 *
 * ★★ Nothing here reads or writes message content (BOFF-7277). Everything is a
 * pure function of the processing entry and elapsed time; the clock that
 * advances it lives in the leaf that renders it, `AssistantTurnActivity`.
 */
/**
 * The step to describe, or `null` when there is nothing honest to say.
 *
 * ★ `provisioning` with no stage is the synchronous write before the runtime
 * has looked at anything. Guessing "Starting..." there would flash the wrong
 * word on every reused sandbox a moment before the real step arrives, so it
 * says nothing and the avatar and caret carry the wait.
 */
export declare function turnActivityStage(processing: AssistantConversationProcessing | null | undefined): AssistantTurnStage | null;
export interface TurnActivityCopy {
    /** For the eye. Rotates while thinking; otherwise identical to `label`. */
    readonly shown: string;
    /** For assistive tech. Changes only when the step does. */
    readonly label: string;
    /**
     * Whether this step is ELIGIBLE to rotate (thinking). The component holds it
     * still under reduced motion by passing no elapsed time — see
     * `AssistantTurnActivity`.
     */
    readonly rotating: boolean;
}
/**
 * What to show for a live turn that has produced nothing yet.
 *
 * ★ Environment steps are informative and hold still. Only `thinking` rotates:
 * a single frozen word for the length of a turn reads as a hang.
 *
 * ★★ A phrase is shown only in the SAME translation state as the thinking
 * label, as on the voice status line. The phrases are separately seeded keys; if
 * the label is translated and a phrase is not, rotating would alternate the
 * user's language with English, so the line holds on the translated label.
 *
 * Pure in `elapsedMs` — the caller owns the clock.
 */
export declare function turnActivityCopy(tr: AssistantTr, processing: AssistantConversationProcessing | null | undefined, elapsedMs: number): TurnActivityCopy | null;
/**
 * Time a rotation has run: from the stage's stored `origin` to the last tick.
 *
 * `null` origin — not rotating, or holding still for reduced motion — is 0,
 * which is the stable label. Never negative: `now` lags the real clock, so a
 * stage that began after the last tick reads as just started.
 */
export declare function elapsedSince(origin: number | null, now: number): number;
/**
 * Milliseconds until the phrase at `elapsedMs` is replaced by the next one.
 *
 * Always in (0, PHRASE_ROTATE_MS], so a tick scheduled with it lands on the
 * boundary instead of up to a whole phrase late.
 */
export declare function msUntilNextPhrase(elapsedMs: number): number;
/**
 * Call `onTick(now)` at each phrase boundary after `startedAt`, until stopped.
 *
 * ★ Boundary-aligned timeouts rather than a fixed interval: the origin is the
 * stage's stored start, which is usually well before this component mounted, so
 * an interval started at mount would change phrase at the wrong moments.
 *
 * Returns the stop function — an effect's cleanup.
 */
export declare function startPhraseTicker(startedAt: number, onTick: (now: number) => void, clock?: () => number): () => void;
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