Rename setups and add provider reauthentication

SUBAGENTS.md

@@ -9,7 +9,7 @@ card and readable in the same transcript view the session has. Designed
 
 **A subagent is a second transcript owned by a session, in the same event
 model, with no process and no controls.** It is not a session: it cannot be
-messaged, stopped or started, and it has no setup, model or usage of its
+messaged, stopped or started, and it has no machine, model or usage of its
 own. Everything it shares with a session -- the transcript file format, the
 paging routes, the SSE stream, the phone's cache and rendering -- is reused
 by addressing, not by copying.