Give ADR 0323 its place in to-be 47, to-be 45 §9 and the glossary (issue 341)

A merge check now judges the head merged into a named trunk commit and its
verdict goes out of date when the trunk moves; the designs and the glossary say
so, with the tests that hold it.

00-META/glossary.md

@@ -305,13 +305,17 @@ and the operator act. **Recorded by** the controller's `identity` and `licences`
 **Purpose.** To take one commit from its pull request to every node that should run it, and to put it
 back when it fails. **Recorded by** the `mesh-delivery` module (deliveries) and the controller (the
 planner, the walk). **Downstream of** Module, Core, Health and repair and Data.
-**Decided by** ADR 0162, 0218, 0236, 0237, 0238, 0239, 0250, 0267, 0270, 0276.
+**Decided by** ADR 0162, 0218, 0236, 0237, 0238, 0239, 0250, 0267, 0270, 0276, 0323.
 **Uses:** module, node, declaration and send (Placement), health (Health and repair), person.
 
 - **merge check** — the two statuses a pull request carries before it may merge: the **merge gate**
   (`mesh/merge-gate`, the build seat's composed check of the modules the change touches) and the
   **repository check** (`mesh/repo-check`, the repository's own `merge-check.sh`)
-  (ADR 0238).
+  (ADR 0238). Both judge the merge of the pull request's head into a named **trunk commit**, made in the
+  build seat's own clone and never pushed (ADR 0323).
+- **trunk commit** — the commit of the trunk a merge check's verdict was judged against: the trunk's head when
+  the build seat cloned it. The verdict holds for that commit only, and goes out of date when the trunk moves
+  (ADR 0323).
 - **build seat** — the seat whose holder builds modules, `node-build-agent`; its holder on a node is the
   **builder**. Any node may hold the seat, so there is no build node by nature
   (ADR 0237).