RoomKey ScopeGate for Band Agent Rooms

RoomKey ScopeGate is a prototype authority gate for regulated multi-agent work inside Band rooms. The problem is simple: teams want agents to help with finance, vendor, legal, or compliance workflows, but they cannot safely dump sensitive context into a shared agent room before the right authority exists. RoomKey puts an authority-before-disclosure layer in front of the collaboration. In the demo run, a requester starts a vendor-style review before approval exists, and ScopeGate blocks the protected payload. A narrow human grant then opens only scoped context to reviewer agents. The system records reviewer deposits, blocks late replay, revokes authority, blocks post-revocation requests, and seals the run into a receipt tied to Band message IDs, event hashes, and browser-verifiable proof checks. Band is the collaboration and witness surface; ScopeGate is the gate that decides when context can move. This submission is a receipt-backed prototype and CLI/demo proof, not a claim of production security or an independent audit.