fix(fetch): map media:thumbnail so YouTube items get thumbnails

media:content-only mapping dropped media:thumbnail elements, but YouTube
(and podcast) feeds carry their only image there — media:content is the
video/audio itself. Map thumbnails as image/thumbnail media so the SPA's
existing image pick renders them.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HuVbgSbyfRBkd4XkEDHV4B

crates/newsfeed-fetch/src/lib.rs

@@ -93,11 +93,9 @@ fn entry_to_feed_entry(entry: feed_rs::model::Entry) -> FeedEntry {
     let tags = entry.categories.into_iter().map(|c| c.term).collect();
     let published_at = entry.published.or(entry.updated);
 
-    let media = entry
-        .media
-        .into_iter()
-        .flat_map(|m| m.content)
-        .filter_map(|c| {
+    let mut media = Vec::new();
+    for m in entry.media {
+        media.extend(m.content.into_iter().filter_map(|c| {
             c.url.map(|u| Media {
                 kind: c
                     .content_type
@@ -107,8 +105,16 @@ fn entry_to_feed_entry(entry: feed_rs::model::Entry) -> FeedEntry {
                 width: c.width,
                 height: c.height,
             })
-        })
-        .collect();
+        }));
+        // media:thumbnail is the only image YouTube (and many podcast) feeds carry —
+        // their media:content is the video/audio itself.
+        media.extend(m.thumbnails.into_iter().map(|t| Media {
+            kind: "image/thumbnail".to_string(),
+            url: t.image.uri,
+            width: t.image.width,
+            height: t.image.height,
+        }));
+    }
 
     FeedEntry {
         external_id,
@@ -363,6 +369,40 @@ mod tests {
         assert!(find_feed_link(html).is_none());
     }
 
+    #[test]
+    fn youtube_media_thumbnail_becomes_image_media() {
+        // Shape of a YouTube channel feed entry: the media:group's media:content is the
+        // video itself; the only image is the media:thumbnail.
+        let atom = r#"<?xml version="1.0" encoding="UTF-8"?>
+            <feed xmlns="http://www.w3.org/2005/Atom"
+                  xmlns:media="http://search.yahoo.com/mrss/">
+              <title>channel</title>
+              <entry>
+                <id>yt:video:abc123</id>
+                <title>a video</title>
+                <link rel="alternate" href="https://www.youtube.com/watch?v=abc123"/>
+                <media:group>
+                  <media:title>a video</media:title>
+                  <media:content url="https://www.youtube.com/v/abc123?version=3"
+                                 type="application/x-shockwave-flash" width="640" height="390"/>
+                  <media:thumbnail url="https://i2.ytimg.com/vi/abc123/hqdefault.jpg"
+                                   width="480" height="360"/>
+                </media:group>
+              </entry>
+            </feed>"#;
+        let feed = feed_rs::parser::parse(atom.as_bytes()).unwrap();
+        let entry = feed.entries.into_iter().next().unwrap();
+        let fe = entry_to_feed_entry(entry);
+        let thumb = fe
+            .media
+            .iter()
+            .find(|m| m.kind.starts_with("image"))
+            .expect("thumbnail mapped as image media");
+        assert_eq!(thumb.url, "https://i2.ytimg.com/vi/abc123/hqdefault.jpg");
+        assert_eq!(thumb.width, Some(480));
+        assert_eq!(thumb.height, Some(360));
+    }
+
     #[test]
     fn parses_opml_with_nested_folders() {
         let opml = r#"<?xml version="1.0"?>