import type { SchemaUpdateStrategy } from './types.js';
/** Allow any schema change. Explicit blind / back-compat. */
export declare function blindUpdate(): SchemaUpdateStrategy;
/** Allow additive changes; reject non-additive ones. The safety backstop. */
export declare function additiveOnly(): SchemaUpdateStrategy;
/**
 * Reject schema changes. With `fields`, reject only when one of those
 * fields is added/removed/changed; otherwise reject any non-`none` delta.
 */
export declare function lockSchema(opts?: {
    readonly fields?: readonly string[];
}): SchemaUpdateStrategy;