diff --git a/apps/readest-app/src/__tests__/utils/txt.test.ts b/apps/readest-app/src/__tests__/utils/txt.test.ts
index 970a2fb9..b16232ad 100644
--- a/apps/readest-app/src/__tests__/utils/txt.test.ts
+++ b/apps/readest-app/src/__tests__/utils/txt.test.ts
@@ -115,6 +115,22 @@ describe('createChapterRegexps — Chinese (zh) regex matching', () => {
     );
   });
 
+  describe('番外 (bonus) prefix variants', () => {
+    it.each([
+      '番外',
+      '番外 第1章 旗开得胜',
+      '番外 第一章 灰猫',
+      '番外 第二章 再战',
+      '番外 灰猫',
+      '番外篇 灰猫',
+      '外传',
+      '外传 一',
+    ])('should match "%s"', (heading) => {
+      const regex = getFirstRegex('zh');
+      expect(regex.test(`\n${heading}\n`)).toBe(true);
+    });
+  });
+
   describe('should not match', () => {
     it('should not match chapter heading embedded mid-line', () => {
       const regex = getFirstRegex('zh');
@@ -333,6 +349,28 @@ describe('extractChaptersFromSegment — Chinese (zh)', () => {
     expect(chapters.length).toBeGreaterThanOrEqual(2);
     expect(chapters[0]!.content).toContain('前文');
   });
+
+  it('should extract 番外 chapters mixed with regular chapters (issue #4016)', () => {
+    const text = [
+      '第57章 s级冰系掌控',
+      '第57章正文',
+      '第58章 觉醒天赋',
+      '第58章正文',
+      '番外 第1章 旗开得胜',
+      '番外1正文',
+      '番外 第2章 再战',
+      '番外2正文',
+      '番外 灰猫',
+      '番外3正文',
+    ].join('\n');
+    const chapters = extractChapters(text, 'zh');
+    const titles = chapters.map((c) => c.title);
+    expect(titles.some((t) => t.includes('第57章'))).toBe(true);
+    expect(titles.some((t) => t.includes('第58章'))).toBe(true);
+    expect(titles.some((t) => t.includes('番外 第1章'))).toBe(true);
+    expect(titles.some((t) => t.includes('番外 第2章'))).toBe(true);
+    expect(titles.some((t) => t.includes('番外 灰猫'))).toBe(true);
+  });
 });
 
 // ---------------------------------------------------------------------------
diff --git a/apps/readest-app/src/utils/txt.ts b/apps/readest-app/src/utils/txt.ts
index 4da26816..cc22b50f 100644
--- a/apps/readest-app/src/utils/txt.ts
+++ b/apps/readest-app/src/utils/txt.ts
@@ -635,7 +635,7 @@ export class TxtToEpubConverter {
             '(' +
             [
               String.raw`第[ 　零〇一二三四五六七八九十0-9][ 　零〇一二三四五六七八九十百千万0-9]*(?:[章卷节回讲篇封本册部话])(?:[：:、 　\(\)0-9]*[^\n-]{0,36})(?!\S)`,
-              String.raw`(?:楔子|前言|简介|引言|序言|序章|总论|概论|后记)(?:[：: 　][^\n-]{0,36})?(?!\S)`,
+              String.raw`(?:楔子|前言|简介|引言|序言|序章|总论|概论|后记|番外篇|番外|外传)(?:[：: 　][^\n-]{0,36})?(?!\S)`,
               String.raw`chapter[\s.]*[0-9]+(?:[：:. 　]+[^\n-]{0,50})?(?!\S)`,
             ].join('|') +
             ')',