type CleanupFn = () => void;
type MountFn = (() => CleanupFn | undefined | void) | (() => Promise<void>);
/**
 * Runs `fn` once after the component's DOM is attached and ready
 * (fires on the internal `DOMReadyEvent`).
 *
 * Accepts both sync and async functions.
 *
 * **Sync behaviour:**
 * `fn` runs after the component's DOM is ready. If `fn` returns a function,
 * that function is registered as a cleanup and called when the component unmounts.
 *
 * **Async behaviour — client:**
 * `fn` is called after `DOMReadyEvent` fires (same timing as sync).
 * State updates inside `fn` trigger reactive re-renders normally.
 * Cleanup return values are not supported for async functions (a `Promise`
 * is returned, not a `CleanupFn`).
 *
 * **Async behaviour — SSR:**
 * `DOMReadyEvent` is a no-op on the server's fake host, so async functions
 * would otherwise never run. Instead, when `isSSR()` is `true`, async functions
 * are pushed onto `host._asyncMountQueue`. The renderer drains this queue
 * (`await Promise.all`) **before** calling the template function, so by the
 * time the HTML is serialized the state is already populated.
 * Sync functions are silently ignored on the server (same as before —
 * `DOMReadyEvent.__subscribe` is a no-op on the fake host).
 *
 * Must be called in the component outer function (guarded by `safetyCheck`).
 *
 * @example
 * // Sync — return a cleanup function to run on unmount:
 * onMount(() => {
 *   console.log("component mounted");
 *   return () => console.log("component unmounted");
 * });
 *
 * // Async — no cleanup return value supported:
 * onMount(async () => {
 *   const data = await fetch("/api/init").then(r => r.json());
 *   myAtom.set(data);
 * });
 */
export declare const onMount: (fn: MountFn) => void;
/**
 * Runs `fn` after each paint of the current component and all its children,
 * during both the initial mount and every subsequent update cycle.
 *
 * If `fn` returns a function, that function is registered as a cleanup and
 * called before the next paint or when the component unmounts.
 *
 * Must be called in the component outer function (guarded by `safetyCheck`).
 *
 * @example
 * onPaint(() => {
 *   console.log("painted");
 *   return () => console.log("paint cleanup");
 * });
 */
export declare const onPaint: (fn: () => CleanupFn | undefined) => void;
/**
 * Runs `fn` once, after the current component **and all its children** have
 * mounted, before the next paint.
 *
 * Uses `globalScheduler.onceIdle` — `fn` fires when the scheduler becomes idle,
 * guaranteeing that the entire component subtree is fully mounted.
 *
 * If `fn` returns a function, that function is registered as a cleanup and
 * called when the component unmounts.
 *
 * Must be called in the component outer function (guarded by `safetyCheck`).
 *
 * @example
 * onAllMount(() => {
 *   console.log("current component and all children are mounted");
 * });
 */
export declare const onAllMount: (fn: () => CleanupFn | undefined) => void;
/**
 * Registers `fn` to run when the component is unmounted (removed from the DOM).
 *
 * Equivalent to returning a cleanup function from `onMount`, but can be called
 * independently at any point in the component outer function.
 *
 * Must be called in the component outer function (guarded by `safetyCheck`).
 *
 * @example
 * onCleanup(() => {
 *   console.log("component unmounted — cleaning up");
 *   subscription.unsubscribe();
 * });
 */
export declare const onCleanup: (fn: () => void) => void;
export {};
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