/**
 * Binary upgrade strategy for `ref upgrade` on single-binary installs.
 *
 * Downloads the latest release asset for the current platform to
 * `{dest}.tmp.{pid}`, verifies it by invoking `--version`, then atomically
 * replaces the running binary: a single overwriting `rename()` on Unix, a
 * `.old` rotation on Windows (where the running exe cannot be replaced).
 *
 * See: spec/features/self-upgrade.md §Atomic replace.
 */
import { type ReleaseInfo } from "./check.js";
export type UpgradeStatus = "success" | "already-up-to-date" | "guidance" | "error";
export interface UpgradeResult {
    status: UpgradeStatus;
    fromVersion?: string;
    toVersion?: string;
    url?: string;
    message?: string;
    error?: string;
    /** Non-fatal caveat about the applied upgrade (e.g. checksum skipped). */
    notice?: string;
}
export interface UpgradeBinaryOptions {
    /** Absolute path to the binary that should be replaced. */
    destPath: string;
    /** The version of the currently running `ref`, without leading `v`. */
    currentVersion: string;
    /** Explicit release tag (e.g. "v0.34.0" or "0.34.0"). When unset, uses `getLatest`. */
    version?: string;
    /** Report mode only: do not mutate anything. */
    check?: boolean;
    /** Defaults to `process.platform`. */
    platform?: NodeJS.Platform;
    /** Defaults to `process.arch`. */
    arch?: string;
    /** Defaults to `process.pid`. */
    pid?: number;
    /** Injection points. */
    fetch?: typeof globalThis.fetch;
    getLatest?: (options?: {
        force?: boolean;
    }) => Promise<ReleaseInfo | null>;
    /**
     * Runs the downloaded binary's `--version` command and returns the stdout
     * (or null on failure). Injected so unit tests don't execute real children.
     */
    verifyBinary?: (path: string) => Promise<string | null>;
}
export declare function computeAssetName(platform: NodeJS.Platform, arch: string): string;
export declare function upgradeBinary(options: UpgradeBinaryOptions): Promise<UpgradeResult>;
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