diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0d684b9a0..bb7349a64 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -191,6 +191,8 @@
 - Added `ReadOnlyViolationError` to `ChangeSetCapture` to prevent write artifacts on
   read-only plans.
 - Added CLI fail-fast guards on `plan execute` and `plan apply` for read-only plans.
+- Added `DecisionService` with record/list/tree helpers and `SnapshotStore` for hash-based
+  deduplication of context snapshots during plan execution.
 - Expanded CONTRIBUTING.md with detailed guidance on the issue creation process, label system,
   ticket lifecycle, pull request requirements, and review/merge process.
 - Added commit scope, quality, and message format guidelines to CONTRIBUTING.md.