/**
 * Wire 0.2 Extension Key Grammar Validator
 *
 * Validates that extension keys conform to the Wire 0.2 reverse-DNS
 * extension key grammar: `<domain>/<segment>`.
 *
 * Extracted from the monolithic wire-02-extensions.ts for maintainability.
 */
/**
 * Validate that an extension key conforms to the Wire 0.2 extension key
 * grammar: `<domain>/<segment>`.
 *
 * Domain rules:
 *   - At least one dot (distinguishes from single-label paths)
 *   - Each label matches [a-z0-9]([a-z0-9-]*[a-z0-9])? (lowercase only)
 *   - No uppercase letters anywhere in the domain
 *
 * Segment rules:
 *   - Matches [a-z0-9][a-z0-9_-]* (lowercase only)
 *   - Underscores are permitted (for extension names like credential_event)
 *
 * @param key - Extension key to validate
 * @returns true if valid extension key grammar; false otherwise
 */
export declare function isValidExtensionKey(key: string): boolean;
/**
 * Escape a single path segment per RFC 6901.
 * '~' -> '~0', '/' -> '~1'
 */
export declare function escapePointerSegment(s: string): string;
/**
 * Build a leaf-precise RFC 6901 JSON Pointer from a group key and Zod
 * issue path.
 *
 * @param groupKey - Extension group key (e.g., 'org.peacprotocol/commerce')
 * @param zodPath - Path array from the first Zod issue
 * @returns RFC 6901 pointer string
 */
export declare function zodPathToPointer(groupKey: string, zodPath: readonly PropertyKey[]): string;
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