The Claude browser extension cannot work on M1 — it links to a single
persistent interactive session, and the relay runs one-shot processes. It
drives a real visible Chrome over CDP instead, so manual intervention over
screen sharing still works and logins persist.
The marker is committed, so M1's own agent reads it too. The first version
told whichever side read it to run m1-say — on M1 that meant relaying to
itself. Now each side is told its role by a one-line check for the M1-only
token file.