Supervise quarantined Remote input helpers and block uncertain replacement

docs/tentacle-remote-keyboard.md

@@ -110,8 +110,10 @@ An unconnected [destination-key prerequisite](testing/remote-key-target.md) now
 retains native codes through layout changes and uncertain effects, with a
 quarantined Xorg resolver/backend. It is not attached to this mailbox and supplies
 no physical collision guarantee. A subsequent [source-built helper](testing/remote-input-helper.md)
-now supplies private process-lifetime/EOF/watchdog cleanup, but no production
-reader launch or mailbox owner is attached.
+now supplies private process-lifetime/EOF/watchdog cleanup. A quarantined
+reader-side Supervisor now launches it with serialized heartbeats and an
+original-epoch cleanup/process-exit barrier; unconfirmed retirement blocks
+replacement. No production reader launch or mailbox owner is attached.
 
 No capture event API, production Xorg input owner, supervised helper attachment,
 core escape/bypass integration or installed Remote keyboard command is