Reserve shutdown time for actionable alerts behind informational sends

When an actionable callback alert waits behind an informational transfer alert, giving both the same timeout can let the first send exhaust a shared shutdown deadline before the callback even starts. A bounded drain alone does not fix this starvation. Limit the informational wait to a smaller portion of the total window, preserve ordering for prompt completion, and cancel unfinished informational work without retrying ambiguous requests. Test both a hanging predecessor and the final actionable send under one deadline. This improves opportunity to deliver, not guaranteed receipt; parent termination and noncooperative cancellation remain separate limits.

Applies when: ordered notification tasks share a finite worker shutdown window. Keywords: notification callback transfer starvation timeout shutdown asyncio deadline ordering