add changelog entry

Author: Trivo25

CHANGELOG.md

@@ -18,6 +18,11 @@ This project adheres to
 
 ## [Unreleased](https://github.com/o1-labs/o1js/compare/3453d1e53...HEAD)
 
+### Internal
+
+- Change cache harness to only allow writes when `dump` mode is active.
+  https://github.com/o1-labs/o1js/pull/2599
+
 ## [2.10.0](https://github.com/o1-labs/o1js/compare/114acff...3453d1e53) - 2025-09-27
 
 ### Internal