/**
 * Process-wide error type and exit-code contract.
 *
 * Extracted from http.ts so the auth gateway (auth/ensure.ts) can throw the same
 * error type without creating an import cycle (http.ts → ensure.ts → http.ts).
 * `SkillError` is still re-exported from http.ts, so existing imports are unchanged.
 *
 * Exit codes are a CONTRACT with hosts (Claude Code / Codex / ab-agent): an agent
 * reads the code to decide whether to guide the user through authorization, retry
 * later, or surface a hard failure. Never reuse a code for a different meaning.
 */
export declare const EXIT: {
    /** Success. */
    readonly OK: 0;
    /** Generic runtime failure. */
    readonly ERROR: 1;
    /** Usage error — unknown skill / unknown option. */
    readonly USAGE: 2;
    /** No usable credential, or the credential was rejected. Host should offer to authorize. */
    readonly NOT_AUTHENTICATED: 4;
    /** Backend unreachable / timed out. Distinct from 4 so "log in" isn't suggested for an outage. */
    readonly BACKEND_UNREACHABLE: 5;
    /** Failed to spawn the underlying interpreter. */
    readonly SPAWN_FAILED: 127;
};
export declare class SkillError extends Error {
    readonly exitCode: number;
    constructor(message: string, exitCode?: number);
}