REST /feedback: thumbs up/down affordances on answers and tool results.
Reserved-name HITL folding (request_approval/ask_user); off = spec-standard interrupts only.
REST /sessions history: the menu, auto-resume, and the list API.
Welcome starters via the ephemeral init run (Cavell shared-state suggestions).
Capability profiles (ADR 0006 D4): the Cavell convention layer (sessions/feedback/starters/native HITL) is host-visible configuration so the kit degrades gracefully against generic AG-UI agents.