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 7d935351..dda442e5 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
@@ -218,3 +218,8 @@ names the principle that settles it, and is cited as "design 47 G A-n".
 - **A-56** (ADR 0573 §2, §4; principle 5, everything ships the same way) The locks check treats every `@novox/mesh-*`
   package as it treats the SDK's, since the builder builds a module against the latest published version of each mesh
   package as it does for Go; the order between the contracts' publish and gitea's build is the delivery plan's.
+- **A-57** (§466, §52, §334, §349, §371; principle 7) BL1 is the whole `package-published` emission, built after BL5's
+  watched-branch half: the builder says it per artifact when it hears the registry seat's `published`, carrying
+  `resolved` and `toolchain` from the step's result (`dependencies`, §673), `branch` the watched branch of the catalog
+  revision whose entry the build came from, and `source` that revision, both kept on the build's reservation from the
+  candidate it built.