/**
 * Centralized Environment Variable Helper
 *
 * Provides safe access to environment variables with clear error messages.
 * Never crashes during build - only fails at runtime when actually needed.
 */
/**
 * Get an environment variable, returning undefined if not set
 * Safe to use during build time
 */
export declare function getEnv(key: string): string | undefined;
/**
 * Get an environment variable with a default value
 * Safe to use during build time
 */
export declare function getEnvWithDefault(key: string, defaultValue: string): string;
/**
 * Require an environment variable - throws only at runtime
 * Use this in API routes and server actions that truly need the variable
 *
 * @throws Error if variable is missing
 */
export declare function requireEnv(key: string): string;
/**
 * Check if an environment variable exists (boolean check only)
 * Safe to use during build time
 */
export declare function hasEnv(key: string): boolean;
/**
 * Get NEXTAUTH_URL safely
 * Returns undefined if not set (build-time safe)
 */
export declare function getNextAuthUrl(): string | undefined;
/**
 * Get DATABASE_URL safely
 * Returns undefined if not set (build-time safe)
 */
export declare function getDatabaseUrl(): string | undefined;
/**
 * Require DATABASE_URL - throws only at runtime
 * Use this in API routes that require database access
 *
 * @throws Error if DATABASE_URL is missing
 */
export declare function requireDatabaseUrl(): string;
/**
 * Check if database is available
 * Safe to use during build time
 */
export declare function hasDatabase(): boolean;
/**
 * Get Vercel environment info
 */
export declare function getVercelEnv(): {
    env: string | undefined;
    url: string | undefined;
    commitSha: string | undefined;
};
/**
 * Check if we're in a Vercel environment
 */
export declare function isVercel(): boolean;
/**
 * Check if we're in production (custom domain on Vercel)
 */
export declare function isProduction(): boolean;
/**
 * Check if we're in preview (Vercel preview deployment)
 */
export declare function isPreview(): boolean;
/**
 * Check if we're in development (local)
 */
export declare function isDevelopment(): boolean;
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