Support Reddit gallery posts

tests/reddit-api.test.ts

@@ -69,6 +69,51 @@ describe('RedditApiClient', () => {
       expect(url).toBe('http://i.redd.it/image.jpg');
     });
 
+    it('extracts the first valid image from a Reddit gallery in display order', () => {
+      const post = validPostFactory({
+        url: 'https://www.reddit.com/gallery/t3_gallery',
+        is_gallery: true,
+        gallery_data: {
+          items: [
+            { media_id: 'second-in-metadata' },
+            { media_id: 'first-in-metadata' },
+          ],
+        },
+        media_metadata: {
+          'first-in-metadata': {
+            status: 'valid',
+            m: 'image/jpg',
+            s: { u: 'https://i.redd.it/first.jpg' },
+          },
+          'second-in-metadata': {
+            status: 'valid',
+            m: 'image/jpg',
+            s: { u: 'https://preview.redd.it/second.jpg?width=1080&format=pjpg' },
+          },
+        },
+      });
+
+      expect(client.getImageUrl(post)).toBe(
+        'https://preview.redd.it/second.jpg?width=1080&format=pjpg',
+      );
+    });
+
+    it('ignores invalid and non-image gallery media', () => {
+      const post = validPostFactory({
+        url: 'https://www.reddit.com/gallery/t3_gallery',
+        is_gallery: true,
+        gallery_data: {
+          items: [{ media_id: 'invalid' }, { media_id: 'video' }],
+        },
+        media_metadata: {
+          invalid: { status: 'failed', m: 'image/jpg', s: { u: 'https://i.redd.it/invalid.jpg' } },
+          video: { status: 'valid', m: 'video/mp4', s: { u: 'https://v.redd.it/video.mp4' } },
+        },
+      });
+
+      expect(client.getImageUrl(post)).toBeNull();
+    });
+
     it('accepts posts with i.redd.it URLs', () => {
       const post = validPostFactory({ url: 'https://i.redd.it/abc123.jpg' });
       const url = client.getImageUrl(post);
@@ -615,6 +660,42 @@ describe('RedditApiClient', () => {
       expect(result[0].title).toBe('Image post 1');
     });
 
+    it('keeps Reddit gallery posts whose images are stored in media metadata', async () => {
+      const galleryPost: RedditPost = {
+        id: 't3_gallery',
+        name: 't3_gallery',
+        subreddit: 'test',
+        author: 'gallery-user',
+        title: 'Gallery post',
+        url: 'https://www.reddit.com/gallery/t3_gallery',
+        permalink: '/r/test/comments/t3_gallery/gallery_post',
+        thumbnail: 'nsfw',
+        is_self: false,
+        is_gallery: true,
+        gallery_data: { items: [{ media_id: 'media-1' }] },
+        media_metadata: {
+          'media-1': {
+            status: 'valid',
+            m: 'image/jpg',
+            s: { u: 'https://preview.redd.it/gallery-image.jpg' },
+          },
+        },
+        created_utc: 1000000,
+        over_18: true,
+        spoiler: false,
+      };
+      const mockAxios = {
+        get: vi.fn().mockResolvedValue({
+          data: { data: { children: [{ data: galleryPost }] } },
+        }),
+      };
+      vi.mocked(axios.create).mockReturnValue(mockAxios as unknown as AxiosInstance);
+      const client2 = new RedditApiClient(getTestConfig(), logger);
+
+      await expect(client2.getNewPosts('test')).resolves.toEqual([galleryPost]);
+      expect(client2.getImageUrl(galleryPost)).toBe('https://preview.redd.it/gallery-image.jpg');
+    });
+
     it('filters out deleted authors', async () => {
       const mockResponse = {
         data: { data: { children: [