fix(post-form): auto-convert YouTube links to thumbnail URLs

Add a countdown notice and shared hook to replace YouTube watch links
with img.youtube.com thumbnails in post and reply forms, with i18n copy.

public/translations/ar/default.json

@@ -400,5 +400,6 @@
   "timestamp": "الطابع الزمني",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "فيديو YouTube"
+  "youtube_video": "فيديو YouTube",
+  "youtube_thumbnail_link_conversion_notice": "تم اكتشاف رابط YouTube. جارٍ لصق الصورة المصغرة خلال {{count}}..."
 }

public/translations/bn/default.json

@@ -400,5 +400,6 @@
   "timestamp": "টাইমস্ট্যাম্প",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube ভিডিও"
+  "youtube_video": "YouTube ভিডিও",
+  "youtube_thumbnail_link_conversion_notice": "YouTube লিংক শনাক্ত হয়েছে। {{count}}-এর মধ্যে থাম্বনেইল ছবি পেস্ট করা হচ্ছে..."
 }

public/translations/cs/default.json

@@ -400,5 +400,6 @@
   "timestamp": "časové razítko",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "video YouTube"
+  "youtube_video": "video YouTube",
+  "youtube_thumbnail_link_conversion_notice": "Byl zjištěn odkaz na YouTube. Vkládám náhledový obrázek za {{count}}..."
 }

public/translations/da/default.json

@@ -400,5 +400,6 @@
   "timestamp": "tidsstempel",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube-video"
+  "youtube_video": "YouTube-video",
+  "youtube_thumbnail_link_conversion_notice": "YouTube-link registreret. Indsætter miniaturebillede om {{count}}..."
 }

public/translations/de/default.json

@@ -400,5 +400,6 @@
   "timestamp": "Zeitstempel",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube-Video"
+  "youtube_video": "YouTube-Video",
+  "youtube_thumbnail_link_conversion_notice": "YouTube-Link erkannt. Vorschaubild wird in {{count}} eingefügt..."
 }

public/translations/el/default.json

@@ -400,5 +400,6 @@
   "timestamp": "χρονοσήμανση",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "βίντεο YouTube"
+  "youtube_video": "βίντεο YouTube",
+  "youtube_thumbnail_link_conversion_notice": "Εντοπίστηκε σύνδεσμος YouTube. Επικόλληση μικρογραφίας σε {{count}}..."
 }

public/translations/en/default.json

@@ -419,5 +419,6 @@
   "timestamp": "timestamp",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube video"
+  "youtube_video": "YouTube video",
+  "youtube_thumbnail_link_conversion_notice": "YouTube link detected. Pasting thumbnail image in {{count}}..."
 }

public/translations/es/default.json

@@ -400,5 +400,6 @@
   "timestamp": "marca de tiempo",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "video de YouTube"
+  "youtube_video": "video de YouTube",
+  "youtube_thumbnail_link_conversion_notice": "Se detectó un enlace de YouTube. Pegando imagen en miniatura en {{count}}..."
 }

public/translations/fa/default.json

@@ -400,5 +400,6 @@
   "timestamp": "مهر زمان",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "ویدیوی YouTube"
+  "youtube_video": "ویدیوی YouTube",
+  "youtube_thumbnail_link_conversion_notice": "پیوند YouTube شناسایی شد. در حال چسباندن تصویر بندانگشتی در {{count}}..."
 }

public/translations/fi/default.json

@@ -400,5 +400,6 @@
   "timestamp": "aikaleimaustiedosto",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube-video"
+  "youtube_video": "YouTube-video",
+  "youtube_thumbnail_link_conversion_notice": "YouTube-linkki havaittu. Liitetään pikkukuva {{count}} kuluttua..."
 }

public/translations/fil/default.json

@@ -400,5 +400,6 @@
   "timestamp": "timestamp",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "video sa YouTube"
+  "youtube_video": "video sa YouTube",
+  "youtube_thumbnail_link_conversion_notice": "May nakita na link ng YouTube. Ipi-paste ang thumbnail image sa loob ng {{count}}..."
 }

public/translations/fr/default.json

@@ -400,5 +400,6 @@
   "timestamp": "horodatage",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "vidéo YouTube"
+  "youtube_video": "vidéo YouTube",
+  "youtube_thumbnail_link_conversion_notice": "Lien YouTube détecté. Collage de l'image miniature dans {{count}}..."
 }

public/translations/he/default.json

@@ -400,5 +400,6 @@
   "timestamp": "חותמת זמן",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "סרטון YouTube"
+  "youtube_video": "סרטון YouTube",
+  "youtube_thumbnail_link_conversion_notice": "זוהה קישור YouTube. מדביק תמונת ממוזערת בעוד {{count}}..."
 }

public/translations/hi/default.json

@@ -400,5 +400,6 @@
   "timestamp": "टाइमस्टैंप",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube वीडियो"
+  "youtube_video": "YouTube वीडियो",
+  "youtube_thumbnail_link_conversion_notice": "YouTube लिंक मिला। {{count}} में थंबनेल इमेज पेस्ट की जा रही है..."
 }

public/translations/hu/default.json

@@ -400,5 +400,6 @@
   "timestamp": "időbélyeg",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube-videó"
+  "youtube_video": "YouTube-videó",
+  "youtube_thumbnail_link_conversion_notice": "YouTube-link észlelve. Bélyegkép beillesztése {{count}} múlva..."
 }

public/translations/id/default.json

@@ -400,5 +400,6 @@
   "timestamp": "stempel waktu",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "video YouTube"
+  "youtube_video": "video YouTube",
+  "youtube_thumbnail_link_conversion_notice": "Tautan YouTube terdeteksi. Menempelkan gambar thumbnail dalam {{count}}..."
 }

public/translations/it/default.json

@@ -400,5 +400,6 @@
   "timestamp": "marca temporale",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "video YouTube"
+  "youtube_video": "video YouTube",
+  "youtube_thumbnail_link_conversion_notice": "Link YouTube rilevato. Incollando l'immagine di anteprima tra {{count}}..."
 }

public/translations/ja/default.json

@@ -400,5 +400,6 @@
   "timestamp": "タイムスタンプ",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube動画"
+  "youtube_video": "YouTube動画",
+  "youtube_thumbnail_link_conversion_notice": "YouTubeリンクを検出しました。{{count}}後にサムネイル画像を貼り付けます..."
 }

public/translations/ko/default.json

@@ -400,5 +400,6 @@
   "timestamp": "타임스탬프",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube 동영상"
+  "youtube_video": "YouTube 동영상",
+  "youtube_thumbnail_link_conversion_notice": "YouTube 링크가 감지되었습니다. {{count}} 후에 썸네일 이미지를 붙여넣는 중..."
 }

public/translations/mr/default.json

@@ -400,5 +400,6 @@
   "timestamp": "टाइमस्टॅम्प",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube व्हिडिओ"
+  "youtube_video": "YouTube व्हिडिओ",
+  "youtube_thumbnail_link_conversion_notice": "YouTube लिंक आढळली. {{count}} मध्ये थंबनेल प्रतिमा पेस्ट करत आहे..."
 }

public/translations/nl/default.json

@@ -400,5 +400,6 @@
   "timestamp": "tijdstempel",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube-video"
+  "youtube_video": "YouTube-video",
+  "youtube_thumbnail_link_conversion_notice": "YouTube-link gedetecteerd. Miniatuurafbeelding wordt over {{count}} geplakt..."
 }

public/translations/no/default.json

@@ -400,5 +400,6 @@
   "timestamp": "tidsstempel",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube-video"
+  "youtube_video": "YouTube-video",
+  "youtube_thumbnail_link_conversion_notice": "YouTube-lenke oppdaget. Limer inn miniatyrbilde om {{count}}..."
 }

public/translations/pl/default.json

@@ -400,5 +400,6 @@
   "timestamp": "znacznik czasu",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "wideo YouTube"
+  "youtube_video": "wideo YouTube",
+  "youtube_thumbnail_link_conversion_notice": "Wykryto link YouTube. Wklejam miniaturę za {{count}}..."
 }

public/translations/pt/default.json

@@ -400,5 +400,6 @@
   "timestamp": "marca de tempo",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "vídeo do YouTube"
+  "youtube_video": "vídeo do YouTube",
+  "youtube_thumbnail_link_conversion_notice": "Link do YouTube detectado. Colando imagem em miniatura em {{count}}..."
 }

public/translations/ro/default.json

@@ -400,5 +400,6 @@
   "timestamp": "marcă de timp",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "video YouTube"
+  "youtube_video": "video YouTube",
+  "youtube_thumbnail_link_conversion_notice": "Link YouTube detectat. Lipesc imaginea miniatură în {{count}}..."
 }

public/translations/ru/default.json

@@ -400,5 +400,6 @@
   "timestamp": "временная метка",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "видео YouTube"
+  "youtube_video": "видео YouTube",
+  "youtube_thumbnail_link_conversion_notice": "Обнаружена ссылка YouTube. Вставка миниатюры через {{count}}..."
 }

public/translations/sq/default.json

@@ -400,5 +400,6 @@
   "timestamp": "vulë kohe",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "video YouTube"
+  "youtube_video": "video YouTube",
+  "youtube_thumbnail_link_conversion_notice": "U zbulua lidhje YouTube. Po ngjis imazhin miniaturë pas {{count}}..."
 }

public/translations/sv/default.json

@@ -400,5 +400,6 @@
   "timestamp": "tidsstämpel",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube-video"
+  "youtube_video": "YouTube-video",
+  "youtube_thumbnail_link_conversion_notice": "YouTube-länk upptäckt. Klistrar in miniatyrbild om {{count}}..."
 }

public/translations/te/default.json

@@ -400,5 +400,6 @@
   "timestamp": "టైమ్‌స్టాంప్",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube వీడియో"
+  "youtube_video": "YouTube వీడియో",
+  "youtube_thumbnail_link_conversion_notice": "YouTube లింక్ గుర్తించబడింది. {{count}}లో థంబ్‌నెయిల్ చిత్రాన్ని పేస్ట్ చేస్తున్నాము..."
 }

public/translations/th/default.json

@@ -400,5 +400,6 @@
   "timestamp": "แสตมป์เวลา",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "วิดีโอ YouTube"
+  "youtube_video": "วิดีโอ YouTube",
+  "youtube_thumbnail_link_conversion_notice": "ตรวจพบลิงก์ YouTube กำลังวางรูปภาพขนาดย่อในอีก {{count}}..."
 }

public/translations/tr/default.json

@@ -400,5 +400,6 @@
   "timestamp": "zaman damgası",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube videosu"
+  "youtube_video": "YouTube videosu",
+  "youtube_thumbnail_link_conversion_notice": "YouTube bağlantısı algılandı. Küçük resim {{count}} içinde yapıştırılıyor..."
 }

public/translations/uk/default.json

@@ -400,5 +400,6 @@
   "timestamp": "часова мітка",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "відео YouTube"
+  "youtube_video": "відео YouTube",
+  "youtube_thumbnail_link_conversion_notice": "Виявлено посилання YouTube. Вставляю мініатюру через {{count}}..."
 }

public/translations/ur/default.json

@@ -400,5 +400,6 @@
   "timestamp": "ٹائم سٹیمپ",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube ویڈیو"
+  "youtube_video": "YouTube ویڈیو",
+  "youtube_thumbnail_link_conversion_notice": "YouTube لنک مل گیا۔ {{count}} میں تھمب نیل تصویر پیسٹ کی جا رہی ہے..."
 }

public/translations/vi/default.json

@@ -400,5 +400,6 @@
   "timestamp": "dấu thời gian",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "video YouTube"
+  "youtube_video": "video YouTube",
+  "youtube_thumbnail_link_conversion_notice": "Đã phát hiện liên kết YouTube. Đang dán ảnh thu nhỏ sau {{count}}..."
 }

public/translations/zh/default.json

@@ -400,5 +400,6 @@
   "timestamp": "时间戳",
   "tag": "tag",
   "post_form_flash_upload_prompt": "Recommended SWF host: <catbox>Catbox</catbox>. Upload a .swf, then paste the direct https://files.catbox.moe/...swf link in Link. Other hosts must provide a direct HTTPS .swf URL with CORS enabled.",
-  "youtube_video": "YouTube 视频"
+  "youtube_video": "YouTube 视频",
+  "youtube_thumbnail_link_conversion_notice": "检测到 YouTube 链接。将在 {{count}} 后粘贴缩略图..."
 }

src/components/post-form/__tests__/post-form.test.tsx

@@ -88,6 +88,7 @@ vi.mock('react-i18next', async () => {
     useTranslation: () => ({
       t: (key: string, options?: Record<string, unknown>) => {
         if (key === 'choose_one') return 'Choose one:';
+        if (typeof options?.count !== 'undefined') return `${key}:${options.count}`;
         return options?.domain ? `${key}:${options.domain}` : key;
       },
     }),
@@ -299,6 +300,16 @@ vi.mock('../../../lib/utils/media-utils', () => ({
     }
     return { type: 'link', url: link };
   },
+  getYouTubeThumbnailUrlFromLink: (link: string) => {
+    try {
+      const url = new URL(link);
+      if (!url.hostname.includes('youtube.com')) return undefined;
+      const videoId = url.searchParams.get('v');
+      return videoId ? `https://img.youtube.com/vi/${videoId}/0.jpg` : undefined;
+    } catch {
+      return undefined;
+    }
+  },
 }));
 
 vi.mock('../../../lib/media-hosting/show-upload-controls', () => ({
@@ -599,6 +610,63 @@ describe('PostForm', () => {
     expect(testState.setPublishPostOptionsMock).toHaveBeenCalledWith({ communityAddress: 'music-posting.eth' });
   });
 
+  it('converts YouTube links to thumbnail file links on media-only post forms', async () => {
+    const youtubeLink = 'https://www.youtube.com/watch?v=abc123';
+    const thumbnailLink = 'https://img.youtube.com/vi/abc123/0.jpg';
+
+    await renderPostForm('/all');
+    await clickByText(container, 'start_new_thread');
+
+    const table = container.querySelector('table') as HTMLTableElement;
+    const select = table.querySelector('select') as HTMLSelectElement;
+    const textarea = table.querySelector('textarea') as HTMLTextAreaElement;
+    const linkInput = table.querySelectorAll<HTMLInputElement>('input[type="text"]')[3];
+    const getConversionNotice = () =>
+      Array.from(container.querySelectorAll<HTMLDivElement>('div'))
+        .reverse()
+        .find((element) => element.textContent?.includes('youtube_thumbnail_link_conversion_notice'));
+
+    await dispatchChange(select, 'music-posting.eth');
+
+    vi.useFakeTimers();
+    try {
+      await dispatchInput(linkInput, youtubeLink);
+
+      expect(linkInput.value).toBe(youtubeLink);
+      expect(container.textContent).toContain('youtube_thumbnail_link_conversion_notice');
+      expect(container.textContent).toContain('3');
+      expect(table.textContent).not.toContain('youtube_thumbnail_link_conversion_notice');
+      expect(getConversionNotice()?.className).toContain('formError');
+
+      await act(async () => {
+        vi.advanceTimersByTime(1000);
+      });
+      expect(container.textContent).toContain('2');
+
+      await act(async () => {
+        vi.advanceTimersByTime(1000);
+      });
+      expect(container.textContent).toContain('1');
+
+      await act(async () => {
+        vi.advanceTimersByTime(1000);
+      });
+
+      expect(linkInput.value).toBe(thumbnailLink);
+      expect(textarea.value).toBe(youtubeLink);
+      expect(container.textContent).not.toContain('youtube_thumbnail_link_conversion_notice');
+    } finally {
+      vi.clearAllTimers();
+      vi.useRealTimers();
+    }
+
+    await clickByText(table, 'post');
+
+    expect(testState.publishPostMock).toHaveBeenCalledTimes(1);
+    expect(testState.publishedPostOptions?.link).toBe(thumbnailLink);
+    expect(testState.publishedPostOptions?.content).toBe(youtubeLink);
+  });
+
   it('shows Oekaki draw controls only on the /i/ board form', async () => {
     testState.directories.push({
       address: 'oekaki-posting.bso',

src/components/post-form/post-form.tsx

@@ -34,6 +34,7 @@ import useIsMobile from '../../hooks/use-is-mobile';
 import { useResolvedCommunityAddress } from '../../hooks/use-resolved-community-address';
 import useSafeAccountComment from '../../hooks/use-safe-account-comment';
 import useFetchGifFirstFrame from '../../hooks/use-fetch-gif-first-frame';
+import { useYouTubeThumbnailLinkConversion } from '../../hooks/use-youtube-thumbnail-link-conversion';
 import usePublishPost from '../../hooks/use-publish-post';
 import usePublishReply from '../../hooks/use-publish-reply';
 import { useFileUpload } from '../../hooks/use-file-upload';
@@ -144,10 +145,10 @@ interface PostFormFieldsProps {
   lengthError: string | null;
   handleContentChange: (e: React.ChangeEvent<HTMLTextAreaElement>) => void;
   handleContentValueChange: (content: string, options?: string) => void;
+  handleLinkChange: (link: string) => void;
   handleOptionsChange: (e: React.ChangeEvent<HTMLInputElement>) => void;
   setPublishPostOptions: (opts: Record<string, unknown>) => void;
   setPublishReplyOptions: (opts: Record<string, unknown>) => void;
-  setUrl: (url: string) => void;
   isUploading: boolean;
   uploadedFileName: string | null | undefined;
   showUploadControls: boolean;
@@ -195,10 +196,10 @@ const PostFormFields = ({
   lengthError,
   handleContentChange,
   handleContentValueChange,
+  handleLinkChange,
   handleOptionsChange,
   setPublishPostOptions,
   setPublishReplyOptions,
-  setUrl,
   isUploading,
   uploadedFileName,
   showUploadControls,
@@ -356,12 +357,7 @@ const PostFormFields = ({
           ref={urlRef}
           disabled={isUploading}
           onChange={(e) => {
-            setUrl(e.target.value);
+            handleLinkChange(e.target.value);
-            if (isInPostView) {
-              setPublishReplyOptions({ link: e.target.value });
-            } else {
-              setPublishPostOptions({ link: e.target.value });
-            }
           }}
         />
         <span className={styles.linkType}> {url && <LinkTypePreviewer link={url} />}</span>
@@ -602,6 +598,8 @@ const PostFormTable = ({ closeForm, postCid }: { closeForm: () => void; postCid:
   };
 
   const onPublishPost = () => {
+    const appliedYouTubeConversion = applyPendingConversion();
+
     const currentTitle = subjectRef.current?.value.trim() || '';
     const currentContent = textRef.current?.value || '';
     const currentUrl = urlRef.current?.value.trim() || '';
@@ -653,7 +651,7 @@ const PostFormTable = ({ closeForm, postCid }: { closeForm: () => void; postCid:
     };
 
     nonokoRedirectPathRef.current = hasNonokoOption(currentOptions) ? getBoardIndexPath() : null;
-    publishPost({ content: publishContent, ...publishOptions });
+    publishPost({ content: publishContent, ...(appliedYouTubeConversion ? { link: currentUrl } : {}), ...publishOptions });
   };
 
   // redirect to pending page when pending comment is created
@@ -725,6 +723,8 @@ const PostFormTable = ({ closeForm, postCid }: { closeForm: () => void; postCid:
   };
 
   const onPublishReply = () => {
+    const appliedYouTubeConversion = applyPendingConversion();
+
     const currentUrl = urlRef.current?.value.trim() || '';
     const currentOptions = optionsRef.current?.value || '';
     const currentOptionsError = getPostOptionsValidationError(currentOptions, postOptionsDirectoryCode);
@@ -764,7 +764,36 @@ const PostFormTable = ({ closeForm, postCid }: { closeForm: () => void; postCid:
     const flagPublishOptions = getCommentFlagPublishOptionsForDirectory(directoryEntry, flagRef.current?.value);
 
     nonokoRedirectPathRef.current = hasNonokoOption(currentOptions) ? getBoardIndexPath() : null;
-    publishReply({ content: publishContent, ...flagPublishOptions });
+    publishReply({ content: publishContent, ...(appliedYouTubeConversion ? { link: currentUrl } : {}), ...flagPublishOptions });
+  };
+
+  const setLinkValue = (nextUrl: string) => {
+    setUrl(nextUrl);
+    if (isInPostView) {
+      setPublishReplyOptions({ link: nextUrl });
+    } else {
+      setPublishPostOptions({ link: nextUrl });
+    }
+  };
+
+  const {
+    applyPendingConversion,
+    cancelPendingConversion,
+    noticeCountdown: youtubeThumbnailConversionCountdown,
+    queueLinkConversion,
+  } = useYouTubeThumbnailLinkConversion({
+    enabled: requirePostLinkIsMedia,
+    onContentChange: handleContentValueChange,
+    onLinkChange: setLinkValue,
+    textRef,
+    urlRef,
+  });
+
+  const handleLinkChange = (nextUrl: string) => {
+    setLinkValue(nextUrl);
+    if (queueLinkConversion(nextUrl)) {
+      setFormError(null);
+    }
   };
 
   useEffect(() => {
@@ -782,33 +811,22 @@ const PostFormTable = ({ closeForm, postCid }: { closeForm: () => void; postCid:
   const { isUploading, uploadedFileName, handleUpload, uploadFile } = useFileUpload({
     onUploadComplete: (uploadedUrl: string) => {
       if (uploadedUrl) {
-        setUrl(uploadedUrl);
+        cancelPendingConversion();
+        setLinkValue(uploadedUrl);
         if (urlRef.current) {
           urlRef.current.value = uploadedUrl;
         }
-        if (isInPostView) {
-          setPublishReplyOptions({ link: uploadedUrl });
-        } else {
-          setPublishPostOptions({ link: uploadedUrl });
-        }
       }
     },
   });
-  const handleOekakiClearUploadedUrl = useCallback(
+  const handleOekakiClearUploadedUrl = (uploadedUrl: string) => {
-    (uploadedUrl: string) => {
+    if ((urlRef.current?.value || url) !== uploadedUrl) return;
-      if ((urlRef.current?.value || url) !== uploadedUrl) return;
+    cancelPendingConversion();
-      setUrl('');
+    setLinkValue('');
-      if (urlRef.current) {
+    if (urlRef.current) {
-        urlRef.current.value = '';
+      urlRef.current.value = '';
-      }
+    }
-      if (isInPostView) {
+  };
-        setPublishReplyOptions({ link: '' });
-      } else {
-        setPublishPostOptions({ link: '' });
-      }
-    },
-    [isInPostView, setPublishPostOptions, setPublishReplyOptions, url],
-  );
   const uploadMode = useMediaHostingStore((state) => state.uploadMode);
   const showUploadControls = getShowUploadControls(uploadMode, isWebRuntime());
 
@@ -846,10 +864,10 @@ const PostFormTable = ({ closeForm, postCid }: { closeForm: () => void; postCid:
             lengthError={lengthError}
             handleContentChange={handleContentChange}
             handleContentValueChange={handleContentValueChange}
+            handleLinkChange={handleLinkChange}
             handleOptionsChange={handleOptionsChange}
             setPublishPostOptions={setPublishPostOptions}
             setPublishReplyOptions={setPublishReplyOptions}
-            setUrl={setUrl}
             isUploading={isUploading}
             uploadedFileName={uploadedFileName}
             showUploadControls={showUploadControls}
@@ -881,7 +899,11 @@ const PostFormTable = ({ closeForm, postCid }: { closeForm: () => void; postCid:
         </tbody>
       </table>
       {moderationPostingWarning ? <div className={`${styles.error} ${styles.formError}`}>{moderationPostingWarning}</div> : null}
-      {formError ? (
+      {youtubeThumbnailConversionCountdown !== null ? (
+        <div className={`${styles.error} ${styles.formError}`} aria-live='polite'>
+          {t('youtube_thumbnail_link_conversion_notice', { count: youtubeThumbnailConversionCountdown })}
+        </div>
+      ) : formError ? (
         <div className={`${styles.error} ${styles.formError}`}>
           {isPostOptionsValidationError(formError) ? <PostOptionsErrorMessage error={formError} directories={directories} /> : formError}
         </div>

src/components/reply-modal/__tests__/reply-modal.test.tsx

@@ -621,6 +621,44 @@ describe('ReplyModal', () => {
     expect(testState.publishReplyMock).toHaveBeenCalledTimes(1);
   });
 
+  it('moves YouTube links into reply content and publishes the thumbnail link on media-only boards', async () => {
+    const youtubeLink = 'https://youtu.be/reply123';
+    const thumbnailLink = 'https://img.youtube.com/vi/reply123/0.jpg';
+    testState.openEmpty = true;
+    testState.selectedText = 'reply body';
+    testState.directoryByAddress['music-posting.eth'] = {
+      address: 'music-posting.eth',
+      features: { requirePostLinkIsMedia: true },
+      title: '/mu/ - Music',
+    };
+
+    await renderReplyModal('/mu/thread/post-1');
+
+    const textarea = container.querySelector<HTMLTextAreaElement>('textarea') as HTMLTextAreaElement;
+    const linkInput = container.querySelectorAll<HTMLInputElement>('input[type="text"]')[2];
+    const linkContainer = linkInput.parentElement as HTMLElement;
+    const getConversionNotice = () =>
+      Array.from(container.querySelectorAll<HTMLDivElement>('div'))
+        .reverse()
+        .find((element) => element.textContent?.includes('youtube_thumbnail_link_conversion_notice'));
+
+    await dispatchInput(linkInput, youtubeLink);
+
+    expect(linkInput.value).toBe(youtubeLink);
+    expect(container.textContent).toContain('youtube_thumbnail_link_conversion_notice:{"count":3}');
+    expect(linkContainer.textContent).not.toContain('youtube_thumbnail_link_conversion_notice');
+    expect(getConversionNotice()?.className).toContain('error');
+
+    await clickButtonByText('post');
+
+    expect(linkInput.value).toBe(thumbnailLink);
+    expect(textarea.value).toBe(`${youtubeLink}\nreply body`);
+    expect(testState.publishReplyMock).toHaveBeenCalledWith({
+      content: `${youtubeLink}\nreply body`,
+      link: thumbnailLink,
+    });
+  });
+
   it('validates unsupported options and stores fortune output in reply content', async () => {
     const randomSpy = vi.spyOn(Math, 'random').mockReturnValue(0.25);
     testState.openEmpty = true;

src/components/reply-modal/reply-modal.tsx

@@ -28,6 +28,7 @@ import { findDirectoryByAddress, useDirectories } from '../../hooks/use-director
 import usePublishReply from '../../hooks/use-publish-reply';
 import useIsMobile from '../../hooks/use-is-mobile';
 import { useFileUpload } from '../../hooks/use-file-upload';
+import { useYouTubeThumbnailLinkConversion } from '../../hooks/use-youtube-thumbnail-link-conversion';
 import { useCommunityField } from '../../hooks/use-stable-community';
 import { OEKAKI_WEB_WARNING_TEXT } from '../../lib/oekaki/oekaki-copy';
 import BbcodeEditorToolbar, { BbcodePreview } from '../bbcode-editor-toolbar/bbcode-editor-toolbar';
@@ -140,6 +141,8 @@ const ReplyModal = ({ closeModal, showReplyModal, parentCid, parentNumber, threa
   );
 
   const onPublishReply = () => {
+    const appliedYouTubeConversion = applyPendingConversion();
+
     const currentContent = textRef.current?.value || '';
     const currentUrl = urlRef.current?.value.trim() || '';
     const currentOptions = optionsRef.current?.value || '';
@@ -180,7 +183,7 @@ const ReplyModal = ({ closeModal, showReplyModal, parentCid, parentNumber, threa
 
     setError(null);
     nonokoRedirectPathRef.current = hasNonokoOption(currentOptions) ? `/${postOptionsDirectoryCode || params.boardIdentifier || communityAddress}` : null;
-    publishReply({ content: publishContent, ...flagPublishOptions });
+    publishReply({ content: publishContent, ...(appliedYouTubeConversion ? { link: currentUrl } : {}), ...flagPublishOptions });
   };
 
   useEffect(() => {
@@ -391,6 +394,39 @@ const ReplyModal = ({ closeModal, showReplyModal, parentCid, parentNumber, threa
     setIsBbcodePreviewing(true);
   };
 
+  const setLinkValue = (nextUrl: string) => {
+    setUrl(nextUrl);
+    setPublishReplyOptions({ link: nextUrl });
+  };
+
+  const handleConvertedContentChange = (content: string) => {
+    const nextSelection = content.length;
+    if (textRef.current) {
+      textRef.current.setSelectionRange(nextSelection, nextSelection);
+    }
+    handleContentValueChange(content, nextSelection, nextSelection);
+  };
+
+  const {
+    applyPendingConversion,
+    cancelPendingConversion,
+    noticeCountdown: youtubeThumbnailConversionCountdown,
+    queueLinkConversion,
+  } = useYouTubeThumbnailLinkConversion({
+    enabled: requirePostLinkIsMedia,
+    onContentChange: handleConvertedContentChange,
+    onLinkChange: setLinkValue,
+    textRef,
+    urlRef,
+  });
+
+  const handleLinkChange = (nextUrl: string) => {
+    setLinkValue(nextUrl);
+    if (queueLinkConversion(nextUrl)) {
+      setError(null);
+    }
+  };
+
   useEffect(() => {
     const canInsertQuote = showReplyModal && quoteInsertRequestId !== 0 && !!textRef.current;
 
@@ -438,25 +474,27 @@ const ReplyModal = ({ closeModal, showReplyModal, parentCid, parentNumber, threa
   const { isUploading, uploadedFileName, handleUpload, uploadFile } = useFileUpload({
     onUploadComplete: (uploadedUrl: string) => {
       if (uploadedUrl) {
-        setUrl(uploadedUrl);
+        cancelPendingConversion();
+        setLinkValue(uploadedUrl);
         if (urlRef.current) {
           urlRef.current.value = uploadedUrl;
         }
-        setPublishReplyOptions({ link: uploadedUrl });
       }
     },
   });
   const handleOekakiClearUploadedUrl = (uploadedUrl: string) => {
     if ((urlRef.current?.value || url) !== uploadedUrl) return;
-    setUrl('');
+    cancelPendingConversion();
+    setLinkValue('');
     if (urlRef.current) {
       urlRef.current.value = '';
     }
-    setPublishReplyOptions({ link: '' });
   };
   const uploadMode = useMediaHostingStore((state) => state.uploadMode);
   const showUploadControls = getShowUploadControls(uploadMode, isWebRuntime());
   const displayedFileName = getPublishURLFilename(url) || uploadedFileName;
+  const youtubeThumbnailConversionNotice =
+    youtubeThumbnailConversionCountdown !== null ? t('youtube_thumbnail_link_conversion_notice', { count: youtubeThumbnailConversionCountdown }) : null;
 
   const hasInitializedDisplayName = useRef(false);
   useEffect(() => {
@@ -555,8 +593,7 @@ const ReplyModal = ({ closeModal, showReplyModal, parentCid, parentNumber, threa
             placeholder={requirePostLinkIsMedia ? FILE_LINK_PLACEHOLDER : capitalize(t('link'))}
             disabled={isUploading}
             onChange={(e) => {
-              setUrl(e.target.value);
+              handleLinkChange(e.target.value);
-              setPublishReplyOptions({ link: e.target.value });
             }}
           />
         </div>
@@ -613,7 +650,11 @@ const ReplyModal = ({ closeModal, showReplyModal, parentCid, parentNumber, threa
           </button>
         </div>
         {moderationPostingWarning ? <div className={styles.error}>{moderationPostingWarning}</div> : null}
-        {lengthError ? (
+        {youtubeThumbnailConversionNotice ? (
+          <div className={styles.error} aria-live='polite'>
+            {youtubeThumbnailConversionNotice}
+          </div>
+        ) : lengthError ? (
           <div className={styles.error}>{lengthError}</div>
         ) : error ? (
           <div className={styles.error}>{isPostOptionsValidationError(error) ? <PostOptionsErrorMessage error={error} directories={directories} /> : error}</div>

src/hooks/use-youtube-thumbnail-link-conversion.ts

@@ -0,0 +1,159 @@
+import { useCallback, useEffect, useRef, useState } from 'react';
+import { getYouTubeThumbnailUrlFromLink } from '../lib/utils/media-utils';
+
+const YOUTUBE_THUMBNAIL_LINK_CONVERSION_DELAY_SECONDS = 3;
+const YOUTUBE_THUMBNAIL_LINK_CONVERSION_INTERVAL_MS = 1000;
+
+type ElementRef<T extends HTMLElement> = {
+  readonly current: T | null;
+};
+
+interface PendingYouTubeThumbnailLinkConversion {
+  thumbnailLink: string;
+  youtubeLink: string;
+}
+
+interface UseYouTubeThumbnailLinkConversionOptions {
+  enabled: boolean;
+  onContentChange: (content: string) => void;
+  onLinkChange: (link: string) => void;
+  textRef: ElementRef<HTMLTextAreaElement>;
+  urlRef: ElementRef<HTMLInputElement>;
+}
+
+const getContentWithYouTubeLinkAtTop = (content: string, youtubeLink: string): string => {
+  if (!content) return youtubeLink;
+  if (content === youtubeLink || content.startsWith(`${youtubeLink}\n`) || content.startsWith(`${youtubeLink}\r\n`)) return content;
+  return `${youtubeLink}\n${content}`;
+};
+
+const getPendingConversion = (link: string): PendingYouTubeThumbnailLinkConversion | null => {
+  const youtubeLink = link.trim();
+  const thumbnailLink = getYouTubeThumbnailUrlFromLink(youtubeLink);
+
+  if (!youtubeLink || !thumbnailLink || youtubeLink === thumbnailLink) {
+    return null;
+  }
+
+  return { thumbnailLink, youtubeLink };
+};
+
+export const useYouTubeThumbnailLinkConversion = ({ enabled, onContentChange, onLinkChange, textRef, urlRef }: UseYouTubeThumbnailLinkConversionOptions) => {
+  const [noticeCountdown, setNoticeCountdown] = useState<number | null>(null);
+  const pendingConversionRef = useRef<PendingYouTubeThumbnailLinkConversion | null>(null);
+  const timeoutRef = useRef<number | null>(null);
+
+  const clearCountdownTimer = useCallback(() => {
+    if (timeoutRef.current !== null) {
+      window.clearTimeout(timeoutRef.current);
+      timeoutRef.current = null;
+    }
+  }, []);
+
+  const cancelPendingConversion = useCallback(() => {
+    clearCountdownTimer();
+    pendingConversionRef.current = null;
+    setNoticeCountdown(null);
+  }, [clearCountdownTimer]);
+
+  const applyPendingConversion = useCallback(() => {
+    if (!enabled) {
+      cancelPendingConversion();
+      return false;
+    }
+
+    const currentLink = urlRef.current?.value.trim() || '';
+    const pendingConversion = pendingConversionRef.current ?? getPendingConversion(currentLink);
+    if (!pendingConversion || currentLink !== pendingConversion.youtubeLink) {
+      cancelPendingConversion();
+      return false;
+    }
+
+    clearCountdownTimer();
+    pendingConversionRef.current = null;
+    setNoticeCountdown(null);
+
+    const currentContent = textRef.current?.value || '';
+    const nextContent = getContentWithYouTubeLinkAtTop(currentContent, pendingConversion.youtubeLink);
+
+    if (textRef.current) {
+      textRef.current.value = nextContent;
+    }
+    if (urlRef.current) {
+      urlRef.current.value = pendingConversion.thumbnailLink;
+    }
+
+    onContentChange(nextContent);
+    onLinkChange(pendingConversion.thumbnailLink);
+    return true;
+  }, [cancelPendingConversion, clearCountdownTimer, enabled, onContentChange, onLinkChange, textRef, urlRef]);
+
+  const scheduleConversionCountdown = useCallback(
+    (remainingSeconds: number) => {
+      clearCountdownTimer();
+
+      const tick = (seconds: number) => {
+        if (!pendingConversionRef.current) {
+          setNoticeCountdown(null);
+          return;
+        }
+
+        if (seconds <= 0) {
+          applyPendingConversion();
+          return;
+        }
+
+        setNoticeCountdown(seconds);
+        timeoutRef.current = window.setTimeout(() => tick(seconds - 1), YOUTUBE_THUMBNAIL_LINK_CONVERSION_INTERVAL_MS);
+      };
+
+      tick(remainingSeconds);
+    },
+    [applyPendingConversion, clearCountdownTimer],
+  );
+
+  const queueLinkConversion = useCallback(
+    (link: string) => {
+      if (!enabled) {
+        cancelPendingConversion();
+        return false;
+      }
+
+      const pendingConversion = getPendingConversion(link);
+      if (!pendingConversion) {
+        cancelPendingConversion();
+        return false;
+      }
+
+      if (pendingConversionRef.current?.youtubeLink === pendingConversion.youtubeLink) {
+        return true;
+      }
+
+      pendingConversionRef.current = pendingConversion;
+      scheduleConversionCountdown(YOUTUBE_THUMBNAIL_LINK_CONVERSION_DELAY_SECONDS);
+      return true;
+    },
+    [cancelPendingConversion, enabled, scheduleConversionCountdown],
+  );
+
+  useEffect(() => {
+    if (!enabled) {
+      cancelPendingConversion();
+    }
+  }, [cancelPendingConversion, enabled]);
+
+  useEffect(
+    () => () => {
+      clearCountdownTimer();
+      pendingConversionRef.current = null;
+    },
+    [clearCountdownTimer],
+  );
+
+  return {
+    applyPendingConversion,
+    cancelPendingConversion,
+    noticeCountdown,
+    queueLinkConversion,
+  };
+};

src/lib/utils/__tests__/media-utils.test.ts

@@ -46,6 +46,7 @@ import {
   getMediaDimensions,
   getPostMediaTypeLabel,
   getYouTubeEmbedPostMediaFileLink,
+  getYouTubeThumbnailUrlFromLink,
 } from '../media-utils';
 
 const clearMemoizedCache = (fn: unknown) => {
@@ -125,6 +126,8 @@ describe('media-utils', () => {
     expect(getYouTubeEmbedPostMediaFileLink(mediaInfo)).toBe('https://img.youtube.com/vi/abc123/0.jpg');
     expect(getPostMediaTypeLabel(mediaInfo, 'iframe', (key) => key)).toBe('youtube_video');
     expect(getYouTubeEmbedPostMediaFileLink({ type: 'iframe', url: 'https://streamable.com/clip123' })).toBeUndefined();
+    expect(getYouTubeThumbnailUrlFromLink('https://youtu.be/short123')).toBe('https://img.youtube.com/vi/short123/0.jpg');
+    expect(getYouTubeThumbnailUrlFromLink('https://example.com/watch?v=not-youtube')).toBeUndefined();
   });
 
   it('recognizes which media types expose thumbnails', () => {

src/lib/utils/media-utils.ts

@@ -1,5 +1,5 @@
 import localForageLru from '@bitsocial/bitsocial-react-hooks/dist/lib/localforage-lru/index.js';
-import { canEmbed, getYouTubeVideoId } from '../../components/embed/embed-utils';
+import { canEmbed, getYouTubeVideoId, youtubeHosts } from '../../components/embed/embed-utils';
 import memoize from 'memoizee';
 import { isPrivateNetworkHostname, isValidURL, parseHttpUrl } from './url-utils';
 import { Capacitor, CapacitorHttp } from '@capacitor/core';
@@ -65,6 +65,22 @@ export const getPostMediaTypeLabel = (commentMediaInfo: CommentMediaInfo | undef
   return getDisplayMediaInfoType(resolvedType, t);
 };
 
+const isYouTubeLikeUrl = (url: URL): boolean => youtubeHosts.has(url.host) || url.host.startsWith('yt.');
+
+export const getYouTubeThumbnailUrl = (url: URL): string | undefined => {
+  if (!isYouTubeLikeUrl(url)) {
+    return undefined;
+  }
+
+  const videoId = getYouTubeVideoId(url);
+  return videoId ? `https://img.youtube.com/vi/${videoId}/0.jpg` : undefined;
+};
+
+export const getYouTubeThumbnailUrlFromLink = (link: string): string | undefined => {
+  const parsedUrl = parseHttpUrl(link.trim());
+  return parsedUrl ? getYouTubeThumbnailUrl(parsedUrl) : undefined;
+};
+
 export const getHasThumbnail = memoize(
   (commentMediaInfo: CommentMediaInfo | undefined, link: string | undefined): boolean => {
     if (!link || !commentMediaInfo) return false;
@@ -81,10 +97,9 @@ export const getHasThumbnail = memoize(
 );
 
 const getPatternThumbnailUrl = (url: URL): string | undefined => {
-  const videoId = getYouTubeVideoId(url);
+  const youtubeThumbnailUrl = getYouTubeThumbnailUrl(url);
-  if (videoId) {
+  if (youtubeThumbnailUrl) return youtubeThumbnailUrl;
-    return `https://img.youtube.com/vi/${videoId}/0.jpg`;
+
-  }
   if (url.host.includes('streamable.com')) {
     const videoId = url.pathname.split('/')[1];
     return `https://cdn-cf-east.streamable.com/image/${videoId}.jpg`;