Function kernel_variant_tracing_enabled 

pub fn kernel_variant_tracing_enabled() -> bool

Whether kernel-variant trace annotations would currently be recorded.

This is true only when an enabled executor op-span is active on the current thread, so callers can guard shape-dependent reason formatting behind it and keep the disabled dispatch path allocation-free. It is the cheap thread-local check that closes the “dead write” gap: without a live span, an annotation has nothing to attach to, so there is no point formatting a reason.