fix(artwork): keep an eligible track's cover requestable when its album is absent

An embedded-eligible track with no resolved item_artwork row inherited the album's
ImageAbsent, so when the album resolved absent (e.g. CoverArtPriority without
'embedded') the track's coverArt was omitted permanently — the client never
requested it, so the lazy mediafile path never resolved it — even though the
serving path would extract and serve the track's own embedded art. Hydration now
never copies the album's absence onto an eligible-but-unresolved track.

persistence/artwork_hydration_test.go

@@ -233,6 +233,32 @@ var _ = Describe("Artwork hydration", func() {
 			Expect(byID["2002"].ImageAbsent).To(BeFalse())
 		})
 
+		It("keeps an eligible file optimistic when its own art is unresolved, even if the album is absent", func() {
+			// 1004 is eligible (has embedded cover) with no mf state row yet; its album (103) is absent.
+			setCover("1004", true)
+			DeferCleanup(func() { setCover("1004", false) })
+			putInfo("al", "103", "") // album known-absent
+
+			byID := getByID()
+
+			// The track's own embedded art is still unresolved, so it must NOT inherit the album's
+			// absence: coverArt stays requestable so serving can extract the embedded art.
+			Expect(byID["1004"].ImageAbsent).To(BeFalse())
+			Expect(byID["1004"].ImageHash).To(BeEmpty())
+			// A non-eligible sibling on the same absent album still inherits the absence.
+			Expect(byID["1003"].ImageAbsent).To(BeTrue())
+		})
+
+		It("uses the album hash for an eligible file whose own art is unresolved but album is found", func() {
+			setCover("1004", true)
+			DeferCleanup(func() { setCover("1004", false) })
+			putInfo("al", "103", "alh103found11111")
+
+			byID := getByID()
+			Expect(byID["1004"].ImageAbsent).To(BeFalse())
+			Expect(byID["1004"].ImageHash).To(Equal("alh103found11111"))
+		})
+
 		It("uses album info for an eligible file when EnableMediaFileCoverArt is off", func() {
 			conf.Server.EnableMediaFileCoverArt = false
 			setCover("1001", true)

persistence/mediafile_repository.go

@@ -241,11 +241,21 @@ func (r *mediaFileRepository) hydrateArtwork(mfs model.MediaFiles) {
 	mfInfos := hydrateItemImages(r.ctx, r.db, model.KindMediaFileArtwork.Prefix(), eligibleIDs)
 	for i := range mfs {
 		if mfs[i].HasCoverArt && conf.Server.EnableMediaFileCoverArt {
-			if info, ok := mfInfos[mfs[i].ID]; ok && !info.Absent() {
-				mfs[i].ImageHash = info.Hash
-				mfs[i].ImageAbsent = false
+			if info, ok := mfInfos[mfs[i].ID]; ok {
+				if !info.Absent() {
+					mfs[i].ImageHash = info.Hash
+					continue
+				}
+				// Own art resolved absent → serving delegates to the album, so mirror that.
+				applyItemImage(albumInfos, mfs[i].AlbumID, &mfs[i].ItemImage)
 				continue
 			}
+			// Eligible but unresolved: take a found album hash for caching, but never the
+			// album's absence — serving still extracts the track's own embedded art on request.
+			if albumInfo, ok := albumInfos[mfs[i].AlbumID]; ok && !albumInfo.Absent() {
+				mfs[i].ImageHash = albumInfo.Hash
+			}
+			continue
 		}
 		applyItemImage(albumInfos, mfs[i].AlbumID, &mfs[i].ItemImage)
 	}