diff --git a/TODO.org b/TODO.org
index 39f9bf6b..f2888865 100644
--- a/TODO.org
+++ b/TODO.org
@@ -11,6 +11,11 @@ rejected without a record is an idea that gets re-proposed.
 
 * Language surface
 
+** NEXT Dyn unless annotated
+Decided 2026-09-25: in both syntaxes an unannotated value is dyn — [6 2 4 9] is a dyn
+vector, 1 a dyn integer — and a typed value needs an annotation. Rules and migration
+wait on a design pass.
+
 ** DONE Dynamic-first, and the dyn half of the language
 CLOSED: [2026-09-20]
 An unannotated parameter or return is =dyn=: a NaN-boxed value over a mark-sweep