/**
 * Navigation lock for the Instant Navigation Testing API.
 *
 * This module is not meant to be used directly. It's exposed via a cookie-based
 * protocol intended to be driven by an e2e testing framework like Playwright:
 *
 *   async function instant(page, fn) {
 *     const context = page.context()
 *     const domain = new URL(page.url()).hostname
 *     await context.addCookies([{
 *       name: 'next-instant-navigation-testing',
 *       value: '1',
 *       domain,
 *       path: '/',
 *     }])
 *     try {
 *       return await fn()
 *     } finally {
 *       await context.clearCookies({
 *         name: 'next-instant-navigation-testing',
 *       })
 *     }
 *   }
 *
 *   // Usage in a test:
 *   await instant(page, async () => {
 *     await page.click('a[href="/product"]')
 *     await expect(page.locator('[data-testid="loading"]')).toBeVisible()
 *   })
 *
 * Next.js never writes to the cookie — it only reads and listens for changes
 * via the CookieStore API's `change` event.
 *
 * When the lock is acquired:
 * - Routes without a prefetch cache hit will wait for prefetch to complete
 *   before navigating.
 * - Routes with a prefetch cache hit will wait before writing dynamic data
 *   into the UI.
 *
 * For MPA navigations (page reload, full page load):
 * - The cookie tells the server to render only the static shell.
 * - When the lock is released (cookie deleted), the page reloads to fetch
 *   dynamic data (handled in app-bootstrap.ts).
 *
 * This allows tests to assert on the prefetched UI state before dynamic
 * content streams in. Network requests are not blocked — they proceed in
 * parallel while the lock is held.
 *
 * All functions in this module are wrapped in checks for the testing API,
 * which is not exposed in production builds by default. This ensures the code
 * is dead code eliminated unless explicitly enabled.
 */
/**
 * Starts listening for changes to the instant navigation test cookie via the
 * CookieStore API. When the cookie is added (by the test framework), the
 * in-memory lock is acquired. When the cookie is deleted, the lock is released.
 *
 * This should be called once during page initialization.
 */
export declare function startListeningForInstantNavigationCookie(): void;
/**
 * Returns true if the navigation lock is currently active. Checks the cookie
 * rather than in-memory lockState because the cookie survives across MPA
 * navigations (page reloads). Returns false when the testing API is disabled.
 */
export declare function isNavigationLocked(): boolean;
/**
 * Waits for the navigation lock to be released, if it's currently held.
 * No-op if the lock is not acquired.
 */
export declare function waitForNavigationLockIfActive(): Promise<void>;