Design 47: a pull request that no longer merges cleanly is told, not checked (ADR 0395 §2)

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

@@ -395,7 +395,9 @@ them.
 
 *ADR 0395, changing ADR 0323 §4.* When the forge's holder hears a repository's trunk move, mesh-delivery asks the
 check of every active open pull request into that trunk against its new head at once, so a verdict is current by
-the time anyone looks. A pull request has at most one check at a time: a check against an older trunk commit,
+the time anyone looks. A pull request whose head no longer merges cleanly into the new head is not checked: the
+forge says so without a builder, its statuses fail naming the conflict, and it is told once on the pull request;
+its author's next push asks its check. A pull request has at most one check at a time: a check against an older trunk commit,
 waiting or running, is dropped or ended when a newer one is asked for it, as a new head already ends its old head's
 check (issue 726). The build queue keeps delivery builds first; then checks of pull requests marked ready, then the
 rest, the most recently pushed first. A pull request with no push and no ready mark for 7 days is left out until a