Three amendments from review, now that zit#151 has shipped.

The fold's DAG-based reading applied only to protected targets, so adding or deleting a protection row re-judged every landing on that branch — the thing Disposability forbids. It is now unconditional: a DAG fact is the same fact under any policy. The merge is identified structurally (non-primary parent on the proposed branch, bounded by the open date), not by tip ancestry, which breaks for a branch merged and then continued.

zit#151 shipped with an absent header meaning no rule. Correct for a bare server; behind a front it means a gate bug silently disables protection. The RFC now records that and places three obligations on the gate: always set the header, strip the inbound one, prove both.

Test matrix gains the missing rows; What-this-is-not records the supersede interaction; build order marks phase 0 done. closed check-in: 2eff0c5d61 user: dmestas tags: rfc-0007-review