Hooks reference¶

The adapters delegate to the bundled React dispatcher. Hook ordering rules, render purity and dependency identity still matter. Use them at the top level of a component or custom hook.

Hook	Result / behavior	Important boundary
`use_state(initial)`	`(value, setter)`	A callable initializer is lazy; a callable setter argument is an updater.
`use_reducer(reducer, initial, initializer=None)`	`(state, dispatch)`	Reducer receives previous state and action.
`use_context(context)`	Provider value	Create a stable context outside individual renders.
`use_ref(initial=None)`	Mutable `.current`	Ref mutation does not schedule a render.
`use_effect(effect, dependencies=None)`	Post-commit effect	Return `None` or cleanup, not a coroutine.
`use_layout_effect(effect, dependencies=None)`	Layout-phase effect	Keep work short; browser layout APIs are not present during SSR.
`use_insertion_effect(effect, dependencies=None)`	Insertion-phase effect	Intended for style-insertion integrations.
`use_memo(factory, dependencies)`	Cached result	Cache identity is not a correctness mechanism.
`use_callback(fn, dependencies)`	Callable wrapper	Wrapper exposes stable React identity in dependencies.
`use_id()`	Matching component ID	Use for DOM associations, not record keys.
`use_imperative_handle(ref, factory, dependencies=None)`	Custom ref handle	Commonly paired with a forwarded ref.
`use_sync_external_store(subscribe, get_snapshot, get_server_snapshot=None)`	Current snapshot	Subscribe returns cleanup; unchanged snapshots must remain stable.
`use_transition()`	`(pending, start)`	The start callback should do initial transition work synchronously.
`use_deferred_value(value, initial=...)`	Deferred value	Optional initial value is omitted unless supplied.
`use_optimistic(value, reducer=None)`	`(optimistic, dispatch)`	Dispatch within an action/transition.
`use_action_state(action, initial, permalink=None)`	`(state, dispatch, pending)`	Browser-local async action, not server-function transport.
`use_effect_event(fn)`	Effect event callback	Invoke only from effect logic.
`use_debug_value(value, formatter=None)`	DevTools debug value	DevTools behavior is not fully verified by this alpha suite.
`use(promise_or_context)`	Resolved/context value	Use stable resource promise holders for Python async data.
`use_form_status()`	Browser form status proxy	Must be read by a descendant of the form.

Dependency arrays¶

None omits the array, [] is an empty array and a sequence lists dependencies. Object entries preserve Python identity. Include every reactive value used by the hook rather than mutating an object to avoid a dependency change.

Python async transitions¶

Calling an async def creates a coroutine; its body starts later. If the first optimistic update is inside that coroutine, it may run after the synchronous transition context has ended. Use this shape:

def save():
    add_optimistic(1)

    async def finish():
        await send_request()
        start_transition(lambda: set_base(lambda previous: previous + 1))
    return finish()

# In a component's event handler:
html.button("Save", on_click=lambda: transition(save))

The action function does the initial update before returning the awaitable. The conformance example includes this scenario with a deterministic delay.

See effects, context and refs, forms and async data for usage.