separate chunks: sent []; composer ""; status "takeover: transferred"
  order: interrupt start -> interrupt end -> takeover start -> takeover end
one chunk after Ctrl-G: sent []; composer ""; status "takeover: transferred"
  order: interrupt start -> interrupt end -> takeover start -> takeover end
control: no earlier action: sent ["hi"]; composer ""; status "prompt: admitted"
  order: takeover start -> takeover end -> prompt hi
