/**
 * Keeps agent shells out of the user's shell history.
 *
 * Crewly used to type `export GEMINI_API_KEY=…` into agent shells, and bash
 * wrote those lines to ~/.bash_history hundreds of times. Secrets now travel
 * only in the spawn env (utils/secret-env), and on top of that agent shells
 * never write a history file at all:
 *
 * - historyOffSpawnEnv() goes into every PTY's spawn environment;
 * - shellHistoryDisableLine() is typed first by the runtime init sequence,
 *   after the rc files ran (they may set HISTFILE themselves);
 * - quietShellLine() prefixes every other typed line with a space, which
 *   bash (HISTCONTROL=ignorespace) and zsh (HIST_IGNORE_SPACE) skip.
 *
 * See SHELL_HISTORY_CONSTANTS for why HISTSIZE/HISTFILESIZE are not touched.
 *
 * @module utils/shell-history
 */
/**
 * Env vars that keep a freshly spawned bash/zsh from writing history.
 *
 * @returns A fresh copy (callers may spread or mutate it)
 */
export declare function historyOffSpawnEnv(): Record<string, string>;
/**
 * Prefixes a line typed into a shell with a space so it is not recorded.
 * Already-prefixed lines are returned unchanged.
 *
 * @param line - Shell command line
 * @returns The line, space-prefixed
 */
export declare function quietShellLine(line: string): string;
/**
 * The (space-prefixed) line that turns history off inside a running shell.
 *
 * @param shell - Shell binary path (defaults to $SHELL, then /bin/bash — what
 *   agent PTYs are spawned with)
 * @returns The line to type, or null for a shell we do not know how to quiet
 */
export declare function shellHistoryDisableLine(shell?: string | undefined): string | null;
/**
 * Quotes a value for a POSIX shell word (single quotes).
 *
 * @param value - Raw value
 * @returns Single-quoted value safe for `sh -c`
 */
export declare function shellQuote(value: string): string;
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