/**
 * Merge a built-in chain registry with a caller-supplied custom list,
 * deduped by `caip2`. Custom entries win on collision so a consumer can
 * shadow a built-in (e.g. override Ethereum's `name` or `blockExplorer`).
 *
 * Chain-agnostic — works for any entry shape that carries a `caip2`
 * discriminator. Insertion order is preserved (built-ins first, then
 * unseen custom entries) so list-style CLI output stays stable.
 */
export declare function mergeChains<T extends {
    caip2: string;
}>(builtIn: readonly T[], custom?: readonly T[]): T[];