feat(jellyfin): enhance series fetching logic to support independent series retrieval and improve item interleaving

k-tv-backend/infra/src/jellyfin.rs

@@ -91,17 +91,19 @@ impl JellyfinMediaProvider {
             params.push(("MaxRunTimeTicks", (max as i64 * TICKS_PER_SEC).to_string()));
         }
 
-        // Treat the first collection entry as a Jellyfin ParentId (library/folder)
-        if let Some(parent_id) = filter.collections.first() {
-            params.push(("ParentId", parent_id.clone()));
-        }
-
         if let Some(name) = series_name {
+            // Series-level targeting: skip ParentId so the show is found regardless
+            // of which library it lives in. SeriesName is already precise enough.
             params.push(("SeriesName", name.to_string()));
             // Return episodes in chronological order when a specific series is
             // requested — season first, then episode within the season.
             params.push(("SortBy", "ParentIndexNumber,IndexNumber".into()));
             params.push(("SortOrder", "Ascending".into()));
+        } else {
+            // No series filter — scope to the collection (library) if one is set.
+            if let Some(parent_id) = filter.collections.first() {
+                params.push(("ParentId", parent_id.clone()));
+            }
         }
 
         if let Some(q) = &filter.search_term {
@@ -166,12 +168,27 @@ impl IMediaProvider for JellyfinMediaProvider {
                 self.fetch_items_for_series(filter, series).await
             }
             _ => {
-                let mut all = Vec::new();
+                // Fetch each series independently, then interleave round-robin.
+                // Round-robin ensures every show gets fair representation when a
+                // downstream limit is applied (preview, block fill) even if one
+                // series has far more episodes than another.
+                let mut per_series: Vec<Vec<MediaItem>> = Vec::new();
                 for series_name in &filter.series_names {
                     let items = self
                         .fetch_items_for_series(filter, Some(series_name.as_str()))
                         .await?;
-                    all.extend(items);
+                    if !items.is_empty() {
+                        per_series.push(items);
+                    }
+                }
+                let max_len = per_series.iter().map(|s| s.len()).max().unwrap_or(0);
+                let mut all = Vec::with_capacity(per_series.iter().map(|s| s.len()).sum());
+                for i in 0..max_len {
+                    for s in &per_series {
+                        if let Some(item) = s.get(i) {
+                            all.push(item.clone());
+                        }
+                    }
                 }
                 Ok(all)
             }