import * as z from "zod/v4";
/** A model selector or an ordered fallback chain of selectors. */
export type ModelSelectorValue = string | readonly string[];
/**
 * Accept one validated selector or a non-empty ordered chain of validated selectors.
 * Element schemas own each configuration surface's selector grammar.
 */
export declare function stringOrNonEmptyArray<T extends z.ZodType<string>>(elementSchema: T): z.ZodUnion<readonly [T, z.ZodArray<T>]>;
/** Return whether a value is a non-blank selector or a non-empty selector chain. */
export declare function isModelSelectorValue(value: unknown): value is ModelSelectorValue;
/**
 * Preserve compatibility with comma-delimited selector strings while flattening
 * configured chains in their declared order.
 */
export declare function normalizeModelSelectorValue(value: ModelSelectorValue | undefined): string[];
/** Return the first configured selector for consumers that need one selector. */
export declare function selectorHead(value: ModelSelectorValue | undefined): string | undefined;