(sigil async wakeup)

Create a notification source, or #f if local socket pairs are unavailable. The caller owns it and must call wakeup-close!.

Notify a waiter without blocking. Repeated notifications coalesce: one unread byte represents every pending notification. Returns false after close; notifications sent before a wait are retained.

Wait for a notification, any socket's readability, or the optional deadline. Callers re-check their work after every return. No reader task is spawned, so repeated waits do not leave abandoned tasks.

Release both descriptors. Repeated close is safe.

(No description)