fix(annotation): preserve line breaks in selected text across <br> elements, closes #3981 (#3986)

In multi-line PDF selections, pdf.js renders each text run as its own <span>
and inserts <br role="presentation"> at line endings. getTextFromRange only
walked text nodes, so <br>s were dropped and adjacent line-final/line-initial
words glued together (e.g. "lastfirst") in highlights, notes, and AI inputs.

Walk elements alongside text nodes and emit "\n" for <br>, mirroring how
Selection.toString() handles line breaks.

apps/readest-app/src/__tests__/utils/sel.test.ts

@@ -340,6 +340,43 @@ describe('sel utilities', () => {
 
       document.body.removeChild(container);
     });
+
+    it('should insert a newline for <br> between adjacent text spans (PDF line wrap)', async () => {
+      const { getTextFromRange } = await import('@/utils/sel');
+      // Mirrors how pdf.js renders the text layer: each text run is its
+      // own <span>, and line endings are <br role="presentation">.
+      const container = document.createElement('div');
+      container.className = 'textLayer';
+      container.innerHTML =
+        '<span role="presentation">last word of line 1</span>' +
+        '<br role="presentation">' +
+        '<span role="presentation">first word of line 2</span>';
+      document.body.appendChild(container);
+
+      const range = document.createRange();
+      range.selectNodeContents(container);
+
+      const text = getTextFromRange(range);
+      // Without separating the spans the text becomes
+      // "last word of line 1first word of line 2" — words are glued.
+      expect(text).toBe('last word of line 1\nfirst word of line 2');
+
+      document.body.removeChild(container);
+    });
+
+    it('should insert a newline for explicit <br> in HTML content', async () => {
+      const { getTextFromRange } = await import('@/utils/sel');
+      const container = document.createElement('div');
+      container.innerHTML = 'first<br>second<br>third';
+      document.body.appendChild(container);
+
+      const range = document.createRange();
+      range.selectNodeContents(container);
+
+      expect(getTextFromRange(range)).toBe('first\nsecond\nthird');
+
+      document.body.removeChild(container);
+    });
   });
 
   describe('snapRangeToWords', () => {

apps/readest-app/src/utils/sel.ts

@@ -271,21 +271,33 @@ export const snapRangeToWords = (range: Range): void => {
 export const getTextFromRange = (range: Range, rejectTags: string[] = []): string => {
   const clonedRange = range.cloneRange();
   const fragment = clonedRange.cloneContents();
-  const walker = document.createTreeWalker(fragment, NodeFilter.SHOW_TEXT, {
-    acceptNode: (node) => {
-      const parent = node.parentElement;
-      if (rejectTags.includes(parent?.tagName.toLowerCase() || '')) {
-        return NodeFilter.FILTER_REJECT;
-      }
-      return NodeFilter.FILTER_ACCEPT;
+  const walker = document.createTreeWalker(
+    fragment,
+    NodeFilter.SHOW_TEXT | NodeFilter.SHOW_ELEMENT,
+    {
+      acceptNode: (node) => {
+        const parent = node.parentElement;
+        if (rejectTags.includes(parent?.tagName.toLowerCase() || '')) {
+          return NodeFilter.FILTER_REJECT;
+        }
+        return NodeFilter.FILTER_ACCEPT;
+      },
     },
-  });
+  );
 
+  // pdf.js inserts <br role="presentation"> between text spans at line endings
+  // (see TextLayer#appendText in pdfjs). Without this, multi-line PDF
+  // selections collapse adjacent line-final and line-initial words into a
+  // single token (e.g. "lastfirst"). Treat <br> as a newline, matching how
+  // Selection.toString() handles line breaks in the browser.
   let text = '';
-  let node: Text | null;
-
-  while ((node = walker.nextNode() as Text | null)) {
-    text += node.nodeValue ?? '';
+  let node: Node | null;
+  while ((node = walker.nextNode())) {
+    if (node.nodeType === Node.TEXT_NODE) {
+      text += (node as Text).nodeValue ?? '';
+    } else if ((node as Element).tagName === 'BR') {
+      text += '\n';
+    }
   }
 
   return text;