fix: improve word highlight cleanup in PDFViewer and update test

- Add cleanup function to prevent memory leaks in word highlighting
- Update test to allow blocks ending with ., !, or ? for better accuracy

package.json

@@ -1,6 +1,6 @@
 {
   "name": "openreader-webui",
-  "version": "v1.2.0",
+  "version": "v1.2.1",
   "private": true,
   "scripts": {
     "dev": "next dev --turbopack -p 3003",

src/components/PDFViewer.tsx

@@ -138,6 +138,8 @@ export function PDFViewer({ zoomLevel }: PDFViewerProps) {
 
   // Word-level highlight layered on top of the block highlight
   useEffect(() => {
+    clearWordHighlightTimeouts();
+
     if (!pdfHighlightEnabled || !pdfWordHighlightEnabled) {
       clearWordHighlights();
       return;
@@ -149,8 +151,7 @@ export function PDFViewer({ zoomLevel }: PDFViewerProps) {
     }
 
     const wordEntry =
-      currentSentenceAlignment &&
+      currentSentenceAlignment && currentWordIndex < currentSentenceAlignment.words.length
-      currentWordIndex < currentSentenceAlignment.words.length
         ? currentSentenceAlignment.words[currentWordIndex]
         : undefined;
     const wordText = wordEntry?.text || null;
@@ -160,8 +161,6 @@ export function PDFViewer({ zoomLevel }: PDFViewerProps) {
       return;
     }
 
-    clearWordHighlightTimeouts();
-
     const seq = ++wordHighlightSeqRef.current;
     const isLayoutChange = layoutKey !== lastWordLayoutKeyRef.current;
     lastWordLayoutKeyRef.current = layoutKey;
@@ -188,13 +187,18 @@ export function PDFViewer({ zoomLevel }: PDFViewerProps) {
       }
     };
 
+    const cleanup = () => {
+      clearWordHighlightTimeouts();
+    };
+
     if (isLayoutChange) {
       clearWordHighlights();
       scheduleWordTimeout(() => tryApplyWord(0), 250);
-      return;
+      return cleanup;
     }
 
     tryApplyWord(0);
+    return cleanup;
   }, [
     currentWordIndex,
     currentSentence,

tests/unit/nlp.spec.ts

@@ -104,7 +104,7 @@ test.describe('splitTextToTtsBlocks', () => {
     for (const block of result) {
       expect(block.length).toBeGreaterThan(0);
       expect(block.length).toBeLessThanOrEqual(450);
-      expect(block.endsWith('.')).toBe(true);
+      expect(block).toMatch(/[.!?]$/);
     }
   });