Optionalcolumn: numberRequest the main thread to pause at the next safepoint.
Non-blocking pop from the main->worker queue.
Resume a paused main thread, optionally with a step mode (STEP_*).
Optionalstep: numberSend an inspect request; the reply arrives via recv() with the same id.
Read the current DebugControlBlock.state (STATE_*).
Release this ref.
Timed-wait until a main->worker message arrives (default 1ms).
OptionaltimeoutMs: number
Worker-thread channel handle (reconstructed from the transferred handle).