Update to artist credit handling

src/routes/artists.rs

@@ -148,6 +148,7 @@ async fn get_cached_album_tracks(
     rg_id: &str,
     first_release_id: Option<&str>,
     ttl_seconds: i64,
+    extend_ttl: bool,
 ) -> Result<CachedAlbumTracks, ApiError> {
     let cache_key = format!("artist_rg_tracks:{rg_id}");
 
@@ -156,6 +157,10 @@ async fn get_cached_album_tracks(
         .map_err(|e| ApiError::Internal(e.to_string()))?
     {
         if let Ok(cached) = serde_json::from_str::<CachedAlbumTracks>(&json) {
+            // Extend TTL if artist is now watched (upgrades 7-day browse cache to permanent)
+            if extend_ttl {
+                let _ = queries::cache::set(state.db.conn(), &cache_key, "musicbrainz", &json, ttl_seconds).await;
+            }
             return Ok(cached);
         }
     }
@@ -353,13 +358,15 @@ async fn get_artist_full(
 
         // If artist has any watched items, cache permanently (10 years);
         // otherwise cache for 7 days (just browsing)
-        let cache_ttl = if artist_wanted.is_empty() { 7 * 86400 } else { 10 * 365 * 86400 };
+        let is_watched = !artist_wanted.is_empty();
+        let cache_ttl = if is_watched { 10 * 365 * 86400 } else { 7 * 86400 };
 
         let cached = match get_cached_album_tracks(
             &state,
             &rg.id,
             rg.first_release_id.as_deref(),
             cache_ttl,
+            is_watched,
         ).await {
             Ok(c) => c,
             Err(e) => {