import type { ExistsOptions, ExistsResult } from './npm.js';
interface PurlObject {
    name: string;
    namespace?: string | undefined;
    qualifiers?: Record<string, string> | undefined;
    subpath?: string | undefined;
    type?: string | undefined;
    version?: string | undefined;
}
/**
 * Normalize VSCode extension package URL.
 * Lowercases namespace (publisher), name (extension), and version per spec.
 * Spec: namespace, name, and version are all case-insensitive.
 */
export declare function normalize(purl: PurlObject): PurlObject;
/**
 * Validate VSCode extension package URL.
 * Checks namespace (publisher) and name (extension) for injection characters,
 * and validates version as semver when present.
 */
export declare function validate(purl: PurlObject, throws: boolean): boolean;
/**
 * Check if a VSCode extension exists in the Visual Studio Marketplace.
 *
 * Queries the VS Marketplace API to verify extension existence and optionally
 * validate a specific version. Returns the latest version from extension metadata.
 *
 * **Note:** VS Marketplace requires specific headers for API access.
 *
 * **Caching:** Responses can be cached using a TTL cache to reduce registry
 * requests. Pass `{ cache }` option with a cache instance from `createTtlCache()`.
 *
 * @param name - Extension name (e.g., 'vscode-eslint')
 * @param namespace - Publisher name (e.g., 'dbaeumer')
 * @param version - Optional version to validate (e.g., '2.4.2')
 * @param options - Optional configuration including cache
 * @returns Promise resolving to existence result with latest version
 *
 * @example
 * ```typescript
 * // Check if extension exists
 * const result = await vscodeExtensionExists('vscode-eslint', 'dbaeumer')
 * // -> { exists: true, latestVersion: '2.4.2' }
 *
 * // Validate specific version
 * const result = await vscodeExtensionExists('vscode-eslint', 'dbaeumer', '2.4.0')
 * // -> { exists: true, latestVersion: '2.4.2' }
 *
 * // With caching
 * import { createTtlCache } from '@socketsecurity/lib/cache-with-ttl'
 * const cache = createTtlCache({ ttl: 5 * 60 * 1000, prefix: 'vscode' })
 * const result = await vscodeExtensionExists('vscode-eslint', 'dbaeumer', undefined, { cache })
 *
 * // Non-existent extension
 * const result = await vscodeExtensionExists('non-existent', 'publisher')
 * // -> { exists: false, error: 'Extension not found' }
 * ```
 */
export declare function vscodeExtensionExists(name: string, namespace?: string, version?: string, options?: ExistsOptions): Promise<ExistsResult>;
export {};