Merge pull request 'Cite ADR 0382 in the delivery design (issue 867)' (#370) from fix/867-group-siblings into main

03-DESIGN/01-to-be/47-delivery-from-commit-to-delivered.md

@@ -2,8 +2,9 @@
 layer: to-be
 status: in-progress
 code: [mesh-controller, mesh-catalog modules/mesh-delivery]
-updated: 2026-10-13
+updated: 2026-10-16
 decisions:
+  - "ADR 0382"
   - "ADR 0350"
   - "ADR 0335"
   - "ADR 0323"
@@ -371,6 +372,12 @@ only once it is built.
   group's members puts the composed check out of date: the group reads `checking` with the reason, and the
   composed check runs again once a member is judged again. Checked by mesh-delivery's
   `TestAGroupsComposedCheckGoesOutOfDateOnAMergeThatIsNotItsMember` and `TestARebasedMemberIsComposedAgainNotHeld`.
+- **Each member's own check reads its siblings** (ADR 0382): the group's other open members into a base of
+  the same name are read beside a member's own check at their head merged onto their base, and a mesh-controller
+  sibling's merge judges it, so changes that are only consistent together pass their own checks. The controller
+  learns the siblings from mesh-delivery's `groups`; the verdict names each one. A sibling's new head, close or
+  base move puts that verdict out of date, and the merge tool merges such a member only when
+  `mesh/delivery-group` passed at the heads read and every sibling head read is reviewed.
 - **Delivering**: in order. A member waits in `published` until the one before is `delivered` or `covered`.
   A member published while its group's composed check is asked and not answered waits there for the answer;
   one held because that check had not passed is *lifted* back to `published` once it passes or warns for the