/**
 * Kill-switch checker for Tier-3 merge-ritual steps.
 *
 * Provides a lightweight, fs.watch-backed cache of the `killSwitch` field in
 * `.cleo/sentient-state.json`. Every Tier-3 step-transition calls
 * {@link checkKillSwitch} to abort the ritual immediately if the operator has
 * activated the kill switch.
 *
 * Design notes:
 * - A module-level cache (`cachedKillSwitch`) is updated by the watcher so that
 *   synchronous read pressure on the state file is near-zero during a running
 *   ritual. The watcher fires on file change events and re-reads the JSON.
 * - Debounce of 100 ms is applied so rapid successive writes (e.g. atomic
 *   tmp-rename) don't cause thundering re-reads.
 * - `startKillSwitchWatcher` is idempotent — calling it multiple times
 *   replaces the previous watcher. The returned function closes the watcher.
 * - `__setKillSwitchForTest` bypasses disk entirely for unit tests.
 *
 * State-file shape:
 * ```json
 * {
 *   "killSwitch": true,
 *   "activatedAt": "2026-04-20T00:00:00.000Z",  // optional
 *   "activatedBy": "operator"                    // optional
 * }
 * ```
 *
 * @see ADR-054 — Sentient Loop Tier-1/Tier-3
 * @task T1027
 */
/**
 * Labels for each transition point in the Tier-3 10-step merge ritual.
 *
 * The ritual steps are:
 *   1. pre-pick      — before cherry-pick selection
 *   2. post-pick     — after cherry-pick selection
 *   3. pre-spawn     — before worker agent is spawned
 *   4. post-spawn    — after worker agent completes
 *   5. pre-verify    — before evidence gates are checked
 *   6. post-verify   — after all gates pass
 *   7. pre-sign      — before Ed25519 receipt is signed
 *   8. post-sign     — after signing completes
 *   9. pre-merge     — before `git merge --ff-only`
 *  10. post-merge    — after merge succeeds (operator must manually revert if
 *                      the kill switch fires here)
 */
export type StepLabel = 'pre-pick' | 'post-pick' | 'pre-spawn' | 'post-spawn' | 'pre-verify' | 'post-verify' | 'pre-sign' | 'post-sign' | 'pre-merge' | 'post-merge';
/**
 * Thrown by {@link checkKillSwitch} when the kill switch is active.
 *
 * Callers in the Tier-3 ritual should propagate this error up to the ritual
 * runner, which logs the abort and exits cleanly.
 */
export declare class KillSwitchActivatedError extends Error {
    /** The step at which the kill switch was detected. */
    readonly step: StepLabel;
    /** ISO-8601 timestamp at which the kill was detected (now). */
    readonly killedAt: string;
    /**
     * @param step - The ritual step where the kill switch was detected.
     * @param killedAt - ISO-8601 timestamp of detection.
     */
    constructor(step: StepLabel, killedAt: string);
}
/**
 * Check the kill switch at a ritual step boundary.
 *
 * Reads the cached value set by the watcher. If no watcher is running (cache
 * is `undefined`), falls back to a one-shot file read. Throws
 * {@link KillSwitchActivatedError} immediately if the flag is `true`.
 *
 * Call this at EVERY step-transition in the Tier-3 merge ritual.
 *
 * @param step - The ritual step at which the check is performed.
 * @param stateFile - Optional absolute path to `sentient-state.json`.
 *   Defaults to `<cwd>/.cleo/sentient-state.json`.
 * @throws {KillSwitchActivatedError} When the kill switch is active.
 */
export declare function checkKillSwitch(step: StepLabel, stateFile?: string): Promise<void>;
/**
 * Start the fs.watch singleton watcher on `sentient-state.json`.
 *
 * The watcher keeps {@link cachedKillSwitch} up to date so that
 * {@link checkKillSwitch} never needs to hit the disk mid-ritual. Changes
 * are debounced by 100 ms to handle atomic tmp-then-rename writes.
 *
 * Calling this function replaces any previously registered watcher (the old
 * watcher is closed first).
 *
 * @param stateFile - Absolute path to `sentient-state.json`.
 *   Defaults to `<cwd>/.cleo/sentient-state.json`.
 * @returns An unsubscribe function that closes the watcher and resets the
 *   cache. Call this during process shutdown or test teardown.
 */
export declare function startKillSwitchWatcher(stateFile?: string): () => void;
/**
 * Override the cached kill-switch value for unit tests.
 *
 * Bypasses disk I/O and the fs.watch watcher entirely. Call with `false`
 * in `afterEach` to restore a clean state between test cases.
 *
 * @param value - The kill-switch value to inject into the cache.
 *
 * @internal
 */
export declare function __setKillSwitchForTest(value: boolean): void;
/**
 * Reset the module-level kill-switch cache to `undefined`.
 *
 * Used in test teardown when tests exercise the disk-read fallback path and
 * need to ensure subsequent tests start with a clean (uncached) state.
 * Distinct from {@link __setKillSwitchForTest} which sets a concrete value.
 *
 * @internal
 */
export declare function __resetKillSwitchCacheForTest(): void;
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