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 16dd3db1..5c4183d7 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
@@ -396,3 +396,8 @@ names the principle that settles it, and is cited as "design 47 G A-n".
 - **A-100** (§379, A-96; principle 7) As built in mesh-delivery a5e1a5e5 and 5a352482: `build.ended` is said for a done
   build only; its `branch` is empty for the trunk; its old-section stream keeps 7 days with no keep-last setting (an
   old `streams` entry has none), which A-96's "kept last per subject" gives up.
+- **A-101** (§532, §521, A-74, A-89; principles 1, 3 and 7, shared code in mesh-sdk) mesh-sdk's `stdio.TopicMatches`
+  understands the bus's own `>`, so an adopted follower's `<seat>.<event>.>` hears every event, not the first view only.
+  The operator-channel asker (the seat holder found on the seat list, the ask published, the router's record read for
+  the warrant, `decided` heard) is one mesh-sdk helper that the builder, the teller, the indexer and the runner use; no
+  module keeps its own copy. A step's own bound is a key with its own time to live too (A-77), not a timer.