PythonNative starts one standard asyncio event loop on a dedicated application thread. Component rendering, effects, event handlers, and async tasks run on that thread. UIKit and Android retain their own UI threads; native bridge calls marshal view operations there and queue events back to Python.

Ordinary asyncio networking, TaskGroup, timeouts, synchronization primitives, and third-party async libraries run on this loop. A synchronous Python callback can still delay other Python work, so use asyncio.to_thread for blocking I/O and cooperative async work for long operations.

Component effects and async event handlers have component lifetimes. Unmounting cancels their tasks. Use runtime.run_application_task() when work must survive the initiating component, and TaskScope for explicitly owned services. Native promises can register cancellation handlers; late results are ignored.

Headless tests can use run_blocking() and drain(). Don't call run_blocking() from the running application loop; await the operation instead.

::: pythonnative.runtime