- /agent [filter] lists the run's agents (glyphs, elapsed, task) via the
native selector and switchSession()es to the agent's own session file
- run is restored in the agent session by deriving the run id from the
session file path (<stateDir>/runs/<runId>/sessions/...)
- main session file recorded in the run manifest so /back works even after
a reload while viewing an agent chat
- widget re-attach timer guard on session switch
