fix(artwork): clamp requested square size to original dimensions for cover art, to avoid upscaling

Signed-off-by: Deluan <deluan@navidrome.org>

core/artwork/artwork_internal_test.go

@@ -302,6 +302,33 @@ var _ = Describe("Artwork", func() {
 				Entry("landscape jpg image", "jpg", true, 200),
 			)
 		})
+		When("Requested size is larger than original", func() {
+			It("clamps size to original dimensions", func() {
+				conf.Server.CoverArtPriority = "front.png"
+				// front.png is 16x16, requesting 99999 should return at original size
+				r, _, err := aw.Get(context.Background(), alMultipleCovers.CoverArtID(), 99999, false)
+				Expect(err).ToNot(HaveOccurred())
+
+				img, _, err := image.Decode(r)
+				Expect(err).ToNot(HaveOccurred())
+				// Should be clamped to original size (16), not 99999
+				Expect(img.Bounds().Size().X).To(Equal(16))
+				Expect(img.Bounds().Size().Y).To(Equal(16))
+			})
+
+			It("clamps square size to original dimensions", func() {
+				conf.Server.CoverArtPriority = "front.png"
+				// front.png is 16x16, requesting 99999 with square should return 16x16 square
+				r, _, err := aw.Get(context.Background(), alMultipleCovers.CoverArtID(), 99999, true)
+				Expect(err).ToNot(HaveOccurred())
+
+				img, _, err := image.Decode(r)
+				Expect(err).ToNot(HaveOccurred())
+				// Should be clamped to original size (16), not 99999
+				Expect(img.Bounds().Size().X).To(Equal(16))
+				Expect(img.Bounds().Size().Y).To(Equal(16))
+			})
+		})
 	})
 })
 

core/artwork/reader_resized.go

@@ -87,6 +87,11 @@ func resizeImage(reader io.Reader, size int, square bool) (io.Reader, int, error
 	bounds := original.Bounds()
 	originalSize := max(bounds.Max.X, bounds.Max.Y)
 
+	// Clamp size to original dimensions - upscaling wastes resources and adds no information
+	if size > originalSize {
+		size = originalSize
+	}
+
 	if originalSize <= size && !square {
 		return nil, originalSize, nil
 	}