The tab-swap useEffect in Editor.tsx watched [activeTabPath, tabs, editor].
When save updated tabs via setTabs, the effect re-ran and re-applied stale
cached blocks from the initial tab load, visually reverting the editor.
Subsequent edits would then save old content, effectively losing changes.
Fix: skip the block swap when activeTabPath hasn't changed (only tab content
was updated). Also refresh the cache with current editor blocks so a later
tab switch doesn't revert to stale content.
Added regression tests for the save → update round-trip (JS + Rust).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
e51bafd4b7