docs(release): stamp v0.51.551 — manual /compress preserves visible transcript (#4594/#3133)

CHANGELOG.md

@@ -3,6 +3,12 @@
 
 ## [Unreleased]
 
+## [v0.51.551] — 2026-06-21 — Release TJ (manual /compress keeps the visible conversation)
+
+### Fixed
+
+- **Manually compressing a session no longer makes earlier messages disappear from the conversation window (#3133).** The manual `/compress` action was overwriting the visible transcript with the reduced model-facing context (and clearing settled tool history), so messages vanished on screen and after reload even though only the model's context should shrink. It now preserves the visible transcript and tool history and prunes only the model-facing context payload — matching how automatic compression already behaves. Thanks @franksong2702.
+
 ## [v0.51.550] — 2026-06-21 — Release TI (Transparent Stream keeps its activity after a turn settles or reloads)
 
 ### Fixed