/**
 * Creator-initials presentation for rail rows. Derives a 1–2 letter monogram
 * plus a stable per-subject hue from a session's frozen `createdBy` fact.
 * Display-only: never an authorization input.
 */
export type CreatorRef = {
    kind: "subject" | "service";
    subjectId: string;
    label?: string | undefined;
};
/**
 * 1–2 letter monogram for a human creator; null for service/system creators
 * and unattributed legacy rows (the rail shows people, not machinery).
 */
export declare function creatorInitials(createdBy: CreatorRef): string | null;
/**
 * The creator a rail row should show a monogram for, or null.
 *
 * Top-level rows only. A spawned session inherits its parent's creator, so
 * repeating the chip down a subtree is noise that costs title width on exactly
 * the rows with the least of it. `parentSessionId` is the session's own lineage
 * fact, which is why it beats the row's render depth: a collapsed channel
 * section renders the selected session at depth 0 even when it is nested.
 */
export declare function railRowCreator(session: {
    parentSessionId: string | null;
    createdBy: CreatorRef;
}): CreatorRef | null;
/** Human-readable creator name for a tooltip or screen-reader announcement. */
export declare function creatorLabel(createdBy: CreatorRef): string;
/**
 * How a rail row announces its creator, or null when it shows no chip.
 *
 * The chip is `aria-hidden` and the row's own `aria-label` replaces
 * name-from-content, so the row's accessible name is the only place a screen
 * reader can hear this. Gate it on exactly the facts that decide whether the
 * chip renders, so a row never announces a creator it does not show.
 */
export declare function creatorAnnouncement(createdBy: CreatorRef | null): string | null;
/** Stable hue (0–359) hashed from the subject id, for the monogram chip. */
export declare function creatorHue(subjectId: string): number;