diff --git a/CHANGELOG.md b/CHANGELOG.md
index f97226fe..d5e0ee32 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,37 @@ stable release.
 
 ## [Unreleased]
 
+## [1.21.0rc3] — 2026-07-06
+
+### Added
+- **Isolate objects and traces.** New actions to focus on a subset while
+  proofreading. "Hide Other Objects" hides every non-selected object across the
+  whole series so the isolation persists as you change sections (locked objects
+  are hidden too, since a lock guards edits and quantification, not visibility);
+  "Show all objects" restores them; and "Hide all objects" hides everything so
+  objects can be revealed a few at a time. All are undoable series-wide. "Invert
+  selection" flips the object-list selection, and a matching field action flips
+  the trace selection on the current section. Object actions live in the object
+  list's new Selection menu, its right-click menu, and the field Object submenu;
+  the trace actions live in the field Traces menu. Menu-only for now. (#51)
+- **Colorblind-safe colors for imported auto-segmentations.** Traces imported
+  from automatic segmentation are colored from a curated, grayscale-visible,
+  colorblind-distinguishable palette, deterministically mapped from each label
+  id. The live label overlay uses the same mapping, so the preview matches the
+  imported traces, and the color seed is exposed as an option. (#50)
+
+### Fixed
+- **3D scene now tracks 2D edits.** An already-open 3D scene updates when the
+  underlying 2D traces change, instead of showing a stale mesh until the object
+  is removed and re-added. (#49)
+- **Copy to sections hardening.** Copying to a large or partial section range, or
+  with non-decimal input, no longer hangs, and invert/empty-set edge cases are
+  guarded, so copies land correctly regardless of input. (#46)
+- **Correlation-alignment propagation respects locks and undo.** Propagating an
+  alignment by correlation across a range now skips alignment-locked sections and
+  records a single undo state, and composes the corrAlign transform in the
+  correct order. (#47)
+
 ## [1.21.0rc2] — 2026-07-05
 
 ### Added
diff --git a/WHATS_NEW.md b/WHATS_NEW.md
index 1ebc5a61..034270b9 100644
--- a/WHATS_NEW.md
+++ b/WHATS_NEW.md
@@ -4,6 +4,14 @@ Short, plain-language highlights shown in PyReconstruct's "What's new" dialog
 after you install or update. For the complete, detailed list of changes, see the
 full release notes on GitHub (linked from the dialog).
 
+## [1.21.0rc3] — 2026-07-06
+
+- **Isolate the objects you're working on.** "Hide Other Objects" hides everything except your selection across the whole series, so your object stays isolated as you page through sections. "Show all objects" brings them back, and "Hide all objects" clears the view so you can reveal objects a few at a time. Look in the object list's new Selection menu or the right-click menu.
+- **Invert a selection in one step.** Flip which objects are selected in the object list, or which traces are selected on the current section, so you can pick a few and instantly switch to all the rest.
+- **Clearer colors for imported traces.** Traces brought in from automatic segmentation now get distinct, easy-to-tell-apart colors that also work well for colorblind viewers and stand out against the grayscale image. The colors you see while importing match the final result, and you can shuffle them if you'd like a different set.
+- **The 3D scene keeps up with your edits.** Changes to your 2D traces now show up right away in an open 3D view, instead of it showing an old shape until you remove and add the object back.
+- **Smoother copying and alignment.** Copying traces to many sections at once no longer freezes on unusual input, and propagating an alignment by correlation now leaves locked sections untouched and can be undone in a single step.
+
 ## [1.21.0rc2] — 2026-07-05
 
 - **Copy traces to multiple sections at once.** Select traces, right-click, choose "Copy to sections," and place them at the same spot across a range of sections in one step.