PASS both results and overlapping virtual subtasks
PASS failure cancels sibling and waits for cleanup
PASS timeout has typed cause and waits for started-task cleanup
PASS scope cannot return while interrupted sibling still runs
PASS owner interruption cancels children
PASS immutable scoped context inherited and unbound afterward
PASS first success tolerates earlier failure
PASS first success interrupts losing task before return
PASS all read replicas failing produces failure
PASS nonpositive budgets rejected
10 tests passed
