diff --git a/CHANGELOG.md b/CHANGELOG.md
index 02c53bc9..e695d81e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,12 @@
 
 ## [Unreleased]
 
+## [v0.51.588] — 2026-06-22 — Release UU (preserve Thinking detail scroll across rebuilds)
+
+### Fixed
+
+- **An expanded Thinking/reasoning block no longer snaps back to the top while you're scrolling inside it.** When the live transcript re-rendered (a streaming rebuild or live-anchor refresh), an open Thinking or tool-detail block preserved only its open/closed state, not how far you'd scrolled inside it — so the inner scroll jumped back to the top mid-read. The render rebuild now captures and restores each open detail's inner `scrollTop` (clamped to the content height, backward-compatible with the prior open/closed snapshots), so your place in a long reasoning block survives the rebuild. Thanks @franksong2702. (#4711, fixes #4707)
+
 ## [v0.51.587] — 2026-06-22 — Release UT (running-first session ordering in sidebar)
 
 ### Fixed