fix(artwork): address PR review feedback

- Add DevJpegCoverArt to logRemovedOptions so users with the old config
  key get a clear warning instead of a silent ignore.
- Include EnableWebPEncoding in the resized artwork cache key to prevent
  stale WebP responses after toggling the setting.
- Skip animated GIF to WebP conversion via ffmpeg when EnableWebPEncoding
  is false, so the setting is consistent across all image types.
- Fix data race in cache warmer by reading UICoverArtSize at construction
  time instead of per-image, avoiding concurrent access with config
  cleanup in tests.
- Clarify cache warmer docstring to accurately describe caching behavior.

conf/configuration.go

@@ -423,7 +423,7 @@ func Load(noConfigDump bool) {
 	logDeprecatedOptions("CoverJpegQuality", "CoverArtQuality")
 
 	// Removed options
-	logRemovedOptions("Spotify.ID", "Spotify.Secret")
+	logRemovedOptions("Spotify.ID", "Spotify.Secret", "DevJpegCoverArt")
 
 	// Call init hooks
 	for _, hook := range hooks {

core/artwork/cache_warmer.go

@@ -22,8 +22,8 @@ type CacheWarmer interface {
 }
 
 // NewCacheWarmer creates a new CacheWarmer instance. The CacheWarmer will pre-cache Artwork images in the background
-// to speed up the response time when the image is requested by the UI. The cache is pre-populated with the original
-// image size, as well as the size defined by the UICoverArtSize config option.
+// to speed up the response time when the image is requested by the UI. The cache is pre-populated with the size
+// defined by the UICoverArtSize config option (the original-size image is also cached as a side effect of resizing).
 func NewCacheWarmer(artwork Artwork, cache cache.FileCache) CacheWarmer {
 	// If image cache is disabled, return a NOOP implementation
 	if conf.Server.ImageCacheSize == "0" || !conf.Server.EnableArtworkPrecache {
@@ -37,10 +37,11 @@ func NewCacheWarmer(artwork Artwork, cache cache.FileCache) CacheWarmer {
 	}
 
 	a := &cacheWarmer{
-		artwork:    artwork,
-		cache:      cache,
-		buffer:     make(map[model.ArtworkID]struct{}),
-		wakeSignal: make(chan struct{}, 1),
+		artwork:      artwork,
+		cache:        cache,
+		buffer:       make(map[model.ArtworkID]struct{}),
+		wakeSignal:   make(chan struct{}, 1),
+		coverArtSize: conf.Server.UICoverArtSize,
 	}
 
 	// Create a context with a fake admin user, to be able to pre-cache Playlist CoverArts
@@ -50,11 +51,12 @@ func NewCacheWarmer(artwork Artwork, cache cache.FileCache) CacheWarmer {
 }
 
 type cacheWarmer struct {
-	artwork    Artwork
-	buffer     map[model.ArtworkID]struct{}
-	mutex      sync.Mutex
-	cache      cache.FileCache
-	wakeSignal chan struct{}
+	artwork      Artwork
+	buffer       map[model.ArtworkID]struct{}
+	mutex        sync.Mutex
+	cache        cache.FileCache
+	wakeSignal   chan struct{}
+	coverArtSize int
 }
 
 func (a *cacheWarmer) PreCache(artID model.ArtworkID) {
@@ -141,7 +143,7 @@ func (a *cacheWarmer) doCacheImage(ctx context.Context, id model.ArtworkID) erro
 	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
 	defer cancel()
 
-	size := conf.Server.UICoverArtSize
+	size := a.coverArtSize
 	r, _, err := a.artwork.Get(ctx, id, size, true)
 	if err != nil {
 		return fmt.Errorf("caching id='%s', size=%d: %w", id, size, err)

core/artwork/reader_resized.go

@@ -65,6 +65,9 @@ func (a *resizedArtworkReader) Key() string {
 	if a.square {
 		return baseKey + ".square"
 	}
+	if conf.Server.EnableWebPEncoding {
+		return fmt.Sprintf("%s.%d.webp", baseKey, conf.Server.CoverArtQuality)
+	}
 	return fmt.Sprintf("%s.%d", baseKey, conf.Server.CoverArtQuality)
 }
 
@@ -110,7 +113,7 @@ func (a *resizedArtworkReader) resizeImage(ctx context.Context, reader io.Reader
 
 	// Preserve animation for animated images
 	if isAnimatedGIF(data) {
-		if a.a.ffmpeg.IsAvailable() {
+		if conf.Server.EnableWebPEncoding && a.a.ffmpeg.IsAvailable() {
 			// Animated GIF: convert to animated WebP via ffmpeg (with optional resize)
 			r, err := a.a.ffmpeg.ConvertAnimatedImage(ctx, bytes.NewReader(data), a.size, conf.Server.CoverArtQuality)
 			if err == nil {