To-be 47: a merge whose walk said its modules unchanged is delivered (issue 611)

Names the walk record's delivery.unchanged, decided under the operator's standing rule on small design limits,
and how mesh-delivery reads it.

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

@@ -2,7 +2,7 @@
 layer: to-be
 status: in-progress
 code: [mesh-controller, mesh-catalog modules/mesh-delivery]
-updated: 2026-10-12
+updated: 2026-10-13
 decisions:
   - "ADR 0323"
   - "ADR 0313"
@@ -132,6 +132,15 @@ delivery merged with no walk answering it within ten minutes is held too, with t
   says `covered: a later merge that contains it was delivered` as a success. A module that runs on one
   machine only is covered too: its walk records the empty rest as sent once its first machine passes
   (ADR 0270, as corrected 2026-10-12);
+- *a merge whose walk said its modules unchanged* moves nothing too, and is `delivered` when that walk ends,
+  whichever commit the walk carried (issue 611). A delivery plan made while another walk built a module reads
+  that module whole and names it; the walk, cut later, reads the build source that build recorded (ADR 0267) and
+  may find none of the changed files in it. The walk's record then says so in `delivery.unchanged`: each such
+  module with why, "its build source holds none of the changed files", and not in its modules, which keep
+  meaning what the walk builds. A delivery whose every module the walk built or said unchanged is delivered,
+  saying which matched what runs. One with a module the walk neither built nor said unchanged is read as below.
+  Checked by the controller's `TestAWalkThatMovedNothingSaysWhichModulesMatchedWhatRuns` and mesh-delivery's
+  `TestAMergeWhoseModulesMatchWhatRunsIsDelivered`;
 - *a stop whose walk ended without building its modules* (issue 474) stays `stopped`, a final state, and
   is read as covered once a later merge covers it by the same test: `mesh/delivery` then says `covered after
   its stop` with the covering merge, once, as a success. No state or transition is added (issue 480);