Support Reddit gallery posts

src/reddit/api.ts

@@ -63,6 +63,20 @@ export interface RedditPost {
       resolutions: Array<{ url: string; width: number; height: number }>;
     }>;
   };
+  is_gallery?: boolean;
+  gallery_data?: {
+    items: Array<{ media_id: string; id?: number }>;
+  };
+  media_metadata?: Record<string, {
+    status?: string;
+    m?: string;
+    s?: {
+      u?: string;
+      gif?: string;
+      x?: number;
+      y?: number;
+    };
+  }>;
   created_utc: number;
   over_18: boolean;
   spoiler: boolean;
@@ -252,6 +266,8 @@ export class RedditApiClient {
   }
 
   private hasImage(post: RedditPost): boolean {
+    if (this.getGalleryImageUrl(post)) return true;
+
     // Check post_hint
     if (post.post_hint === 'image') return true;
 
@@ -272,6 +288,9 @@ export class RedditApiClient {
   }
 
   getImageUrl(post: RedditPost): string | null {
+    const galleryImageUrl = this.getGalleryImageUrl(post);
+    if (galleryImageUrl) return galleryImageUrl;
+
     // Prefer high-quality preview images (already processed by Reddit)
     if (post.preview?.images?.[0]?.source?.url) {
       // Reddit encodes URLs in preview, need to decode HTML entities
@@ -312,6 +331,24 @@ export class RedditApiClient {
     return null;
   }
 
+  /** Return the first valid gallery image in Reddit's declared display order. */
+  private getGalleryImageUrl(post: RedditPost): string | null {
+    if (!post.is_gallery || !post.media_metadata) return null;
+
+    const orderedMediaIds = post.gallery_data?.items.map((item) => item.media_id)
+      ?? Object.keys(post.media_metadata);
+    for (const mediaId of orderedMediaIds) {
+      const media = post.media_metadata[mediaId];
+      if (!media || (media.status && media.status !== 'valid')) continue;
+      if (media.m && !media.m.startsWith('image/')) continue;
+
+      const sourceUrl = media.s?.u ?? media.s?.gif;
+      if (sourceUrl) return this.decodeRedditUrl(sourceUrl);
+    }
+
+    return null;
+  }
+
   private decodeRedditUrl(url: string): string {
     return url.replace(/&amp;/g, '&');
   }