/**
 * Currency assessment for a single extension version.
 *
 * Compares an installed version against the versions available in an
 * ExtensionIndex, respecting an optional version constraint.
 *
 * @experimental This API is unstable and may change without notice.
 */
import * as Option from "effect/Option";
import type { Version } from "../../version-constraints/version-constraints.js";
import type { ExtensionIndex } from "../../registry/schema.js";
/**
 * Currency status for a single extension.
 *
 * - `current` — installed version matches the latest satisfying version.
 * - `update-available` — a newer version exists within the same major line.
 * - `major-update-available` — a newer major version exists.
 */
export type CurrencyStatus = "current" | "update-available" | "major-update-available";
/**
 * Result of a currency check for a single extension.
 *
 * @experimental This API is unstable and may change without notice.
 */
export interface CurrencyResult {
    readonly status: CurrencyStatus;
    readonly installedVersion: Version;
    /** Latest version satisfying the declared constraint. None when no version satisfies. */
    readonly latestMatching: Option.Option<Version>;
    /** Absolute latest version in the index (regardless of constraint). */
    readonly latestAvailable: Version;
}
/**
 * Assess version currency for a single extension.
 *
 * @param installedVersion - Currently installed version.
 * @param constraint - Optional version constraint from settings (e.g. `^1.0.0`).
 * @param index - Extension index containing all available versions (newest-first).
 */
export declare const checkCurrency: (installedVersion: Version, constraint: Option.Option<string>, index: ExtensionIndex) => CurrencyResult;
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