feat: flush pending caret save on blur and panel hide

openspec/changes/sidepanel-ux-improvements/tasks.md

@@ -9,7 +9,7 @@
 
 - [x] 2.1 In `sidepanel/sidepanel.js`, pass current caret (`selectionStart`/`selectionEnd`) and `scrollTop` to `saveNote` in the existing autosave (`doSave`)
 - [x] 2.2 Track caret-only movement via `document` `selectionchange` (filtered to the editor) and editor `scroll`; debounce ~800ms into a caret-only save that calls `saveNote` without broadcasting; skip it while a content autosave is pending
-- [ ] 2.3 Flush any pending caret-only save on editor `blur` and on `visibilitychange` → hidden
+- [x] 2.3 Flush any pending caret-only save on editor `blur` and on `visibilitychange` → hidden
 
 ## 3. Focus and caret/scroll restore
 

sidepanel/sidepanel.js

@@ -118,6 +118,7 @@ function scheduleSave() {
 }
 
 async function doSave() {
+  saveTimer = null;
   if (!currentKey || currentTabId == null) return;
 
   try {
@@ -219,8 +220,22 @@ editor.addEventListener('blur', () => {
   if (deferredReload) {
     reloadFromDB();
   }
+  flushCaretSave();
 });
 
+document.addEventListener('visibilitychange', () => {
+  if (document.visibilityState === 'hidden') {
+    flushCaretSave();
+  }
+});
+
+function flushCaretSave() {
+  if (caretTimer) {
+    clearTimeout(caretTimer);
+    doCaretSave();
+  }
+}
+
 // ---------------------------------------------------------------------------
 // Caret-only persistence
 //