diff --git a/TODO.org b/TODO.org
index 542a1ca8..eaf8fc9e 100644
--- a/TODO.org
+++ b/TODO.org
@@ -1120,7 +1120,8 @@ The module links and runs. What is not proved is a collection running while a li
 instance of a dyn-holding struct sits in a frame of a body that module delivered.
 For the next sweep rather than for a lane.
 
-** TODO A sliced string loses the trailing NUL
+** NEXT A sliced string loses the trailing NUL
+Decided 2026-09-25: both backends emit a NUL after every string literal, and a declare-c wrapper passes a literal argument to C without the copy it makes for any other string. A string is still pointer and length; no slice is promised a NUL. Rules out a NUL guarantee on every string.
 The x86 backend emits a NUL after every string constant and the LLVM one does not,
 so a =declare-c= wrapper leaning on the courtesy is already backend-dependent as
 well as slice-dependent. The contract is pointer and length, and nothing promised