export declare class ConfigurationError extends Error {
    constructor(keyName: string);
}
/**
 * Resolve an API key by name. Tries environment variables first, then
 * ~/.luminus/keys.json. Throws ConfigurationError if not found.
 * Resolved values are cached in memory for the process lifetime.
 */
export declare function resolveApiKey(name: string): Promise<string>;
/** Constant-time string comparison. Reserved for future client authentication. */
export declare function timingSafeCompare(a: string, b: string): boolean;
/**
 * Map of tool name to required API key names.
 * Empty array = public API, no key needed.
 */
export declare const TOOL_KEY_REQUIREMENTS: Readonly<Record<string, readonly string[]>>;
/**
 * Check whether all API keys for a tool are resolvable right now.
 * Checks environment variables and the cached key file synchronously.
 * Returns true for tools with no key requirements.
 */
export declare function hasRequiredKeys(toolName: string): boolean;
/** Check whether a specific API key name is available (env or key file). */
export declare function isKeyConfigured(keyName: string): boolean;
/** Pre-load keys.json so hasRequiredKeys works immediately. */
export declare function preloadKeyFile(): Promise<void>;