fix(reader): stop a quick-deleted highlight from being re-drawn (#4773) (#4779)

The per-relocate re-apply effect reads a memoized annotation index. A
highlight deleted in place after the index was built still sits in its
bucket, and selectLocationAnnotations trusted the build-time deletedAt
filter, so the effect re-drew the just-deleted overlay and left it
orphaned on the page until the book was reopened.

Re-check deletedAt at the read site: in selectLocationAnnotations and in
the sibling globals re-apply loop in Annotator.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/readest-app/src/__tests__/utils/annotation-index.test.ts

@@ -54,6 +54,22 @@ describe('buildAnnotationIndex / selectLocationAnnotations', () => {
     expect(globals).toEqual([]);
   });
 
+  it('skips an annotation deleted in place after the index was built (stale index)', () => {
+    // #4773: the re-apply effect holds a memoized index. A quick delete stamps
+    // `deletedAt` on the SAME object that is still sitting in the bucket (the
+    // memo has not recomputed yet). If the read trusts the build-time filter,
+    // the just-deleted highlight gets re-drawn and its overlay is orphaned —
+    // visible on the page until the book is reopened. The read must re-check.
+    const highlight = note({ style: 'highlight', color: 'yellow', note: 'hi' });
+    const index = buildAnnotationIndex([highlight]);
+    // The user deletes the highlight: `deletedAt` is stamped in place on the
+    // booknote object that the stale index still references.
+    highlight.deletedAt = 123;
+    const { annotations, notes } = selectLocationAnnotations(index, location);
+    expect(annotations).toEqual([]);
+    expect(notes).toEqual([]);
+  });
+
   it('classifies a styled annotation into annotations only', () => {
     const highlight = note({ style: 'highlight', color: 'yellow' });
     const index = buildAnnotationIndex([highlight]);

apps/readest-app/src/app/reader/components/annotator/Annotator.tsx

@@ -985,6 +985,10 @@ const Annotator: React.FC<{ bookKey: string; contentInsets: Insets }> = ({
       // covered by `onCreateOverlay`. Using the pre-built `globals`
       // array avoids re-walking booknotes per page turn.
       for (const annotation of annotationIndex.globals) {
+        // Same stale-index guard as selectLocationAnnotations: a global deleted
+        // in place after the memoized index was built must not be re-fanned out
+        // across sections, which would orphan its overlays (#4773).
+        if (annotation.deletedAt) continue;
         if (view) expandAllRenderedSections(view, annotation);
       }
     } catch (e) {

apps/readest-app/src/app/reader/utils/annotationIndex.ts

@@ -70,6 +70,10 @@ export function selectLocationAnnotations(
   const candidates = index.bySection.get(sectionKey) ?? [];
   const matchesLocation = createCfiLocationMatcher(location);
   for (const item of candidates) {
+    // Re-check `deletedAt` at read time: the index is memoized, so a highlight
+    // deleted in place after the index was built still sits in this bucket. Re-
+    // drawing it here would orphan its overlay (visible until reopen) — #4773.
+    if (item.deletedAt) continue;
     if (!matchesLocation(item.cfi)) continue;
     if (item.style) annotations.push(item);
     if (item.note && item.note.trim().length > 0) notes.push(item);