pub fn process_command(
runner: &mut SceneRunner,
command: Command,
) -> Option<Reply>Expand description
Execute ONE Command against runner and return the Reply it produces,
if any. The shared step both async drivers run: the native [thread_main]
calls it for each (post-coalescing) command on the runner thread; the wasm
WorkerRunner’s worker_entry calls it per postMessage on the worker.
Run → a Reply::Run; Query → a Reply::Query; Reset drops the delta
baseline AND the runner’s OWN kernel history cache (the resident registry lives
with the runner — thread or worker — not on main) and yields no reply.