/**
 * Environment variables configuration source
 */
import type { ConfigSource } from '../types/index.js';
export interface EnvConfigOptions {
    prefix?: string;
    separator?: string;
    transform?: {
        keys?: 'camelCase' | 'kebabCase' | 'snakeCase' | 'none';
        values?: 'auto' | 'string';
    };
    includeProcessEnv?: boolean;
}
export declare class EnvConfigSource implements ConfigSource {
    readonly name: string;
    readonly priority: number;
    private readonly options;
    private readonly envVars;
    constructor(options?: EnvConfigOptions, priority?: number);
    load(): Record<string, unknown>;
    save(): void;
    watch(): () => void;
    private transformKey;
    private transformValue;
    private capitalize;
}
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