/**
 * Wire 0.2 Extension Validation (envelope-level superRefine helper)
 *
 * Validates the extensions record inside Wire02ClaimsSchema.superRefine():
 *   1. Extension key grammar validation
 *   2. Recursive plain-JSON-value guard (rejects non-JSON-safe values)
 *   3. Known extension group schema validation
 *   4. Byte-budget enforcement
 *
 * NORMATIVE: Extension group values MUST be plain JSON values all the
 * way down (objects, arrays, strings, finite numbers, booleans, null).
 * Arbitrary JavaScript objects (functions, Symbols, Dates, BigInt,
 * objects with toJSON(), circular references, non-finite numbers, etc.)
 * are not a supported input class and are rejected at the validation
 * boundary via E_EXTENSION_NON_JSON_VALUE. This ensures cross-language
 * portability and reproducible byte-budget measurement.
 *
 * MEASUREMENT BASIS: Byte budgets are measured as the UTF-8 byte length
 * of ECMAScript JSON.stringify() output on plain JSON data. This is
 * explicitly ECMAScript-defined, not language-neutral canonical JSON.
 * Equivalent objects with different member order can yield different
 * byte counts; if cross-language reproducibility is needed in the
 * future, a canonical JSON profile (e.g., JCS / RFC 8785) can be
 * adopted via a future DD without changing the budget constants.
 * See EXTENSION_BUDGET in @peac/kernel for the full specification.
 *
 * Schema does NOT emit warnings (unknown_extension_preserved belongs
 * in @peac/protocol.verifyLocal(), Layer 3).
 *
 * Layer 1 (@peac/schema): pure Zod validation, zero I/O.
 */
import { z } from 'zod';
/**
 * Check whether a value is a plain JSON value all the way down.
 *
 * This is the public entry point for the recursive guard. It initializes
 * the depth counter and circular-reference detection set.
 *
 * @param value - Value to check
 * @returns true if the entire value tree is plain JSON
 */
declare function isPlainJsonValue(value: unknown): boolean;
/**
 * Validate extensions record in Wire02ClaimsSchema.superRefine().
 *
 * Steps:
 *   1. Validate extension key grammar
 *   2. Recursive guard: reject non-plain-JSON values (E_EXTENSION_NON_JSON_VALUE)
 *   3. Validate known extension groups against their Zod schemas
 *   4. Unconditional byte-budget enforcement
 *
 * @param extensions - The extensions record from Wire 0.2 claims
 * @param ctx - Zod refinement context
 */
export declare function validateKnownExtensions(extensions: Record<string, unknown> | undefined, ctx: z.RefinementCtx): void;
export { isPlainJsonValue as _isPlainJsonValue };
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