Function prepare_thread_switch 

pub unsafe fn prepare_thread_switch<'switch>(
    pin: &'switch CpuPin<'_>,
    previous: Pin<&CurrentThreadHeader>,
    next: Pin<&CurrentThreadHeader>,
) -> Result<(PreparedThreadSwitch<'switch>, PreviousThreadBinding), ThreadSwitchError>

Validates and binds a complete scheduler thread switch transaction.

All fallible validation occurs before the returned prepared token can be committed. Dropping the prepared token automatically rolls back next.

Safety

The caller must own the IRQ-disabled scheduler switch path. Both headers must remain pinned and alive through the raw switch and incoming tail.