/**
 * .env File Read/Write Helpers
 * Pure fs helpers for creating and upserting KEY=value lines in dotenv-style
 * files. Used by `pop init` (and available to any command that needs to
 * persist config). Deliberately NOT a dotenv wrapper — env-load.ts owns
 * LOADING; this module owns WRITING.
 *
 * Format contract:
 *   - one `KEY=value` per line, values written verbatim (no quoting) so a
 *     round-trip through readEnvFile is byte-stable for simple values
 *   - files are chmod 0600 by default (they hold private keys); the parent
 *     directory is created if missing
 *   - updateEnvVar preserves every other line INCLUDING comments and blanks,
 *     touching only the target key (or appending it when absent)
 */
/**
 * Write `vars` as KEY=value lines to `filePath`, creating the parent directory
 * if needed and chmod-ing the file to `opts.mode` (default 0600). Overwrites
 * any existing file — callers that must not clobber should check existence
 * first (see `pop init`'s --force gate).
 */
export declare function writeEnvFile(filePath: string, vars: Record<string, string>, opts?: {
    mode?: number;
}): void;
/**
 * Upsert a single `key=value` pair in `filePath`, preserving every other line
 * (comments and blanks included). Creates the file (chmod 0600) with just this
 * one line when it does not exist. Only the FIRST occurrence of the key is
 * rewritten; the value is written verbatim.
 */
export declare function updateEnvVar(filePath: string, key: string, value: string): void;
/**
 * Parse `filePath` into a plain object of KEY→value. Blank lines and comment
 * lines (leading #) are skipped; the value is everything after the first `=`,
 * with a single layer of surrounding single/double quotes stripped so files
 * written by other tools still read cleanly. Returns {} when the file is
 * absent.
 */
export declare function readEnvFile(filePath: string): Record<string, string>;