diff --git a/03-DESIGN/01-to-be/47-milestones/G-20-lead-answers.md b/03-DESIGN/01-to-be/47-milestones/G-20-lead-answers.md
index 6830bea5..43da4f84 100644
--- a/03-DESIGN/01-to-be/47-milestones/G-20-lead-answers.md
+++ b/03-DESIGN/01-to-be/47-milestones/G-20-lead-answers.md
@@ -612,3 +612,6 @@ names the principle that settles it, and is cited as "design 47 G A-n".
   (`mesh-pipeline-runner`, `mesh-catalog`, `mesh-wants`, `mesh-builds`, `mesh-delivery-checker`), not a nickname, so
   steprun checks it against the callers the build seat's definition lists, read from the seat list; no table of its
   own and no name map. A body's kind is the word the seat definition gives; a queue keeps its own name.
+- **A-164** (§468, §76, §495, A-115; principles 4 and 7) The runner's process writes each durable consumer's oldest
+  unacknowledged age into a state of the runner's own when it changes; the bundle's `runner_health` reads that state,
+  its own module's, and asks no seat verb of itself; tools stay the bundle's (A-115).