refactor: use stdlib slices/maps and utils helpers in artwork code

Mechanical cleanups, no behavior change:

- 15 copies of the same id-extraction loop collapse to slice.Map (5 repo
  mocks, the scanner's track sweep, 4 wantIDs assertions) and slice.ToMap
  (6 index-by-id loops in the hydration specs).
- disc.go built a map[string]bool purely to dedup folder ids and then
  walked it back into a slice; slice.Unique says that directly.
- folders_artist.go's image filter is slice.Filter over model.IsImageFile.
- mock_artwork_repo deleted from a map while ranging it; maps.DeleteFunc
  states the intent.
- sort.Slice -> slices.SortFunc + cmp.Or; math.Min/Max -> builtin min/max;
  make+copy -> bytes.Clone; strings.Split -> SplitSeq on a per-request
  path; three-clause pixel loops -> for range.
- Reuse utils.BaseName where a stem was recomputed by hand. Not at
  playlist_cover.go:27: that path is a full OS path and utils.BaseName
  uses path.Base, which does not split backslashes.
- Drop a dead nil-guard in agents.go: getAgent returns a bare nil
  interface, and a type assertion on nil already yields ok == false.

cmp.Or was rejected for the gate fallback (func types are not comparable,
does not compile) and for ItemArtwork.AttemptedAt (cmp.Or compares
time.Time with ==, which includes loc; IsZero does not).

core/agents/agents.go

@@ -141,11 +141,7 @@ type AlbumImageAgent struct {
 func (a *Agents) ArtistImageAgents() []ArtistImageAgent {
 	var result []ArtistImageAgent
 	for _, ea := range a.getEnabledAgentNames() {
-		ag := a.getAgent(ea)
-		if ag == nil {
-			continue
-		}
-		if retriever, ok := ag.(ArtistImageRetriever); ok {
+		if retriever, ok := a.getAgent(ea).(ArtistImageRetriever); ok {
 			result = append(result, ArtistImageAgent{Name: ea.name, Retriever: retriever})
 		}
 	}
@@ -157,11 +153,7 @@ func (a *Agents) ArtistImageAgents() []ArtistImageAgent {
 func (a *Agents) AlbumImageAgents() []AlbumImageAgent {
 	var result []AlbumImageAgent
 	for _, ea := range a.getEnabledAgentNames() {
-		ag := a.getAgent(ea)
-		if ag == nil {
-			continue
-		}
-		if retriever, ok := ag.(AlbumImageRetriever); ok {
+		if retriever, ok := a.getAgent(ea).(AlbumImageRetriever); ok {
 			result = append(result, AlbumImageAgent{Name: ea.name, Retriever: retriever})
 		}
 	}

core/artwork/blurhash/blurhash.go

@@ -57,13 +57,13 @@ func Encode(img image.Image, xComp, yComp int) (string, error) {
 
 	lin := srgbToLinearTable()
 	factors := make([][3]float64, xComp*yComp)
-	for y := 0; y < h; y++ {
+	for y := range h {
 		row := rgba.Pix[y*rgba.Stride:]
-		for x := 0; x < w; x++ {
+		for x := range w {
 			p := x * 4
 			lr, lg, lb := lin[row[p]], lin[row[p+1]], lin[row[p+2]]
-			for j := 0; j < yComp; j++ {
-				for i := 0; i < xComp; i++ {
+			for j := range yComp {
+				for i := range xComp {
 					basis := cosX[i][x] * cosY[j][y]
 					f := &factors[j*xComp+i]
 					f[0] += basis * lr
@@ -94,7 +94,7 @@ func Encode(img image.Image, xComp, yComp int) (string, error) {
 		for _, f := range ac {
 			actualMax = max(actualMax, math.Abs(f[0]), math.Abs(f[1]), math.Abs(f[2]))
 		}
-		quantMax := int(math.Max(0, math.Min(82, math.Floor(actualMax*166-0.5))))
+		quantMax := int(max(0, min(82, math.Floor(actualMax*166-0.5))))
 		maxVal = float64(quantMax+1) / 166
 		sb.WriteString(Encode83(quantMax, 1))
 	} else {
@@ -141,7 +141,7 @@ func downscale(img image.Image) image.Image {
 }
 
 func quantAC(v, maxVal float64) int {
-	return int(math.Max(0, math.Min(18, math.Floor(signPow(v/maxVal, 0.5)*9+9.5))))
+	return int(max(0, min(18, math.Floor(signPow(v/maxVal, 0.5)*9+9.5))))
 }
 
 func signPow(v, exp float64) float64 {
@@ -157,7 +157,7 @@ func srgbToLinear(v int) float64 {
 }
 
 func linearToSRGB(v float64) int {
-	v = math.Min(math.Max(0, v), 1)
+	v = min(max(0, v), 1)
 	if v <= 0.0031308 {
 		return int(v*12.92*255 + 0.5)
 	}

core/artwork/blurhash/blurhash_test.go

@@ -22,8 +22,8 @@ func decode83(s string) int {
 
 func solidImage(w, h int, c color.NRGBA) image.Image {
 	img := image.NewNRGBA(image.Rect(0, 0, w, h))
-	for y := 0; y < h; y++ {
-		for x := 0; x < w; x++ {
+	for y := range h {
+		for x := range w {
 			img.SetNRGBA(x, y, c)
 		}
 	}
@@ -32,8 +32,8 @@ func solidImage(w, h int, c color.NRGBA) image.Image {
 
 func gradientImage(w, h int) image.Image {
 	img := image.NewNRGBA(image.Rect(0, 0, w, h))
-	for y := 0; y < h; y++ {
-		for x := 0; x < w; x++ {
+	for y := range h {
+		for x := range w {
 			img.SetNRGBA(x, y, color.NRGBA{R: uint8(255 * x / w), G: uint8(255 * y / h), B: 128, A: 255})
 		}
 	}

core/artwork/disc.go

@@ -15,6 +15,7 @@ import (
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/utils"
+	"github.com/navidrome/navidrome/utils/slice"
 )
 
 // discArtworkReader resolves disc-level artwork from a library's folder images
@@ -76,21 +77,17 @@ func newDiscArtworkReader(ctx context.Context, ds model.DataStore, artID model.A
 
 	// Build disc folder set and find first track. mf.Path is already library-relative.
 	var firstTrackRel string
-	allFolderIDs := make(map[string]bool)
 	for _, mf := range mfs {
-		allFolderIDs[mf.FolderID] = true
-		if firstTrackRel == "" {
+		if mf.Path != "" {
 			firstTrackRel = filepath.ToSlash(mf.Path)
+			break
 		}
 	}
+	folderIDs := slice.Unique(slice.Map(mfs, func(mf model.MediaFile) string { return mf.FolderID }))
 
 	// Resolve folder IDs to library-relative paths
 	discFoldersRel := make(map[string]bool)
-	if len(allFolderIDs) > 0 {
-		folderIDs := make([]string, 0, len(allFolderIDs))
-		for id := range allFolderIDs {
-			folderIDs = append(folderIDs, id)
-		}
+	if len(folderIDs) > 0 {
 		folders, err := ds.Folder(ctx).GetAll(model.QueryOptions{
 			Filters: squirrel.Eq{"folder.id": folderIDs},
 		})
@@ -144,8 +141,7 @@ func (d *discArtworkReader) fromDiscArtPriority(ctx context.Context, ffmpeg ffmp
 func (d *discArtworkReader) fromDiscSubtitle(ctx context.Context, subtitle string) sourceFunc {
 	return func() (io.ReadCloser, string, error) {
 		for _, file := range d.imgFiles {
-			name := path.Base(file)
-			stem := strings.TrimSuffix(name, path.Ext(name))
+			stem := utils.BaseName(file)
 			if !strings.EqualFold(stem, subtitle) {
 				continue
 			}

core/artwork/e2e/playlist_test.go

@@ -10,6 +10,7 @@ import (
 	"github.com/navidrome/navidrome/consts"
 	"github.com/navidrome/navidrome/core/artwork"
 	"github.com/navidrome/navidrome/model"
+	"github.com/navidrome/navidrome/utils/slice"
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
 )
@@ -182,10 +183,7 @@ var _ = Describe("Playlist artwork resolution", func() {
 			mfs, err := rds.MediaFile(rctx).GetAll(model.QueryOptions{})
 			Expect(err).ToNot(HaveOccurred())
 			Expect(mfs).To(HaveLen(4))
-			ids := make([]string, 0, len(mfs))
-			for _, mf := range mfs {
-				ids = append(ids, mf.ID)
-			}
+			ids := slice.Map(mfs, func(mf model.MediaFile) string { return mf.ID })
 
 			pl := model.Playlist{ID: "pl-8", Name: "Four", OwnerID: "admin-1"}
 			pl.AddMediaFilesByID(ids)

core/artwork/e2e/resolution_harness_test.go

@@ -9,6 +9,7 @@ import (
 	"image/color"
 	"image/png"
 	"io"
+	"maps"
 	"os"
 	"path/filepath"
 	"strings"
@@ -295,9 +296,7 @@ func pngBytes(label string) []byte {
 func trackFile(num int, title string, extra ...map[string]any) *fstest.MapFile {
 	tags := storagetest.Track(num, title)
 	for _, e := range extra {
-		for k, v := range e {
-			tags[k] = v
-		}
+		maps.Copy(tags, e)
 	}
 	return storagetest.MP3(tags)
 }

core/artwork/folders_artist.go

@@ -17,6 +17,8 @@ import (
 	"github.com/navidrome/navidrome/core"
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
+	"github.com/navidrome/navidrome/utils"
+	"github.com/navidrome/navidrome/utils/slice"
 	"github.com/navidrome/navidrome/utils/str"
 )
 
@@ -72,13 +74,7 @@ func findImageInFolder(ctx context.Context, libFS fs.FS, relFolder, absFolder, p
 		return nil, "", err
 	}
 
-	var imagePaths []string
-	for _, m := range matches {
-		if !model.IsImageFile(m) {
-			continue
-		}
-		imagePaths = append(imagePaths, m)
-	}
+	imagePaths := slice.Filter(matches, model.IsImageFile)
 
 	// Prefer base filenames over numeric-suffixed ones (artist.jpg before artist.1.jpg)
 	slices.SortFunc(imagePaths, compareImageFiles)
@@ -157,7 +153,7 @@ func findImageInArtistFolder(folder, mbzArtistID, artistName string) string {
 				continue
 			}
 			name := entry.Name()
-			base := strings.TrimSuffix(name, filepath.Ext(name))
+			base := utils.BaseName(name)
 			if strings.EqualFold(base, candidate) && model.IsImageFile(name) {
 				return filepath.Join(folder, name)
 			}

core/artwork/housekeeping.go

@@ -13,6 +13,7 @@ import (
 	"github.com/navidrome/navidrome/core/auth"
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
+	"github.com/navidrome/navidrome/utils/slice"
 )
 
 const staleAbsentAge = 24 * time.Hour
@@ -85,12 +86,11 @@ func enqueueBackfillKind(ctx context.Context, ds model.DataStore, kind model.Kin
 	if len(ids) == 0 {
 		return nil
 	}
-	items := make([]model.ArtworkQueueItem, len(ids))
-	for i, id := range ids {
-		items[i] = model.ArtworkQueueItem{
+	items := slice.Map(ids, func(id string) model.ArtworkQueueItem {
+		return model.ArtworkQueueItem{
 			ItemKind: kind.Prefix(), ItemID: id, ImageType: model.ImageTypePrimary, Priority: model.ArtworkPriorityBackfill,
 		}
-	}
+	})
 	return ds.ArtworkQueue(ctx).Enqueue(items...)
 }
 

core/artwork/playlist_cover.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
+	"github.com/navidrome/navidrome/utils"
 	xdraw "golang.org/x/image/draw"
 )
 
@@ -33,7 +34,7 @@ func findPlaylistSidecarPath(ctx context.Context, plsPath string) string {
 	}
 	for _, entry := range entries {
 		name := entry.Name()
-		nameBase := strings.TrimSuffix(name, filepath.Ext(name))
+		nameBase := utils.BaseName(name)
 		if !entry.IsDir() && strings.EqualFold(nameBase, base) && model.IsImageFile(name) {
 			return filepath.Join(dir, name)
 		}

core/artwork/resize.go

@@ -129,8 +129,7 @@ func resizeStaticImage(data []byte, size int, square bool) (io.Reader, int, erro
 		return nil, originalSize, err
 	}
 	// Copy bytes before returning buffer to pool (pool may reuse the buffer)
-	encoded := make([]byte, buf.Len())
-	copy(encoded, buf.Bytes())
+	encoded := bytes.Clone(buf.Bytes())
 	bufPool.Put(buf)
 	return bytes.NewReader(encoded), originalSize, nil
 }

core/artwork/worker.go

@@ -2,6 +2,7 @@ package artwork
 
 import (
 	"bytes"
+	"cmp"
 	"context"
 	"io"
 	"math"
@@ -253,9 +254,7 @@ func (w *Worker) broadcastRefresh(ctx context.Context, found []model.ArtworkQueu
 }
 
 func (w *Worker) process(ctx context.Context, item model.ArtworkQueueItem) (outcome, *acquired) {
-	if item.ImageType == "" {
-		item.ImageType = model.ImageTypePrimary
-	}
+	item.ImageType = cmp.Or(item.ImageType, model.ImageTypePrimary)
 	out, got := w.proc.acquire(ctx, item)
 
 	queue := w.proc.ds.ArtworkQueue(ctx)
@@ -333,7 +332,7 @@ func (w *Worker) precache(ctx context.Context, got *acquired) {
 
 // backoffFor returns min(5s×4^n, giveUpAfter) scaled by (1+jitter), with jitter in [-0.4, 0.4].
 func backoffFor(attempts int, jitter float64) time.Duration {
-	d := math.Min(float64(backoffBase)*math.Pow(4, float64(attempts)), float64(giveUpAfter))
+	d := min(float64(backoffBase)*math.Pow(4, float64(attempts)), float64(giveUpAfter))
 	return time.Duration(d * (1 + jitter))
 }
 

core/artwork/worker_test.go

@@ -7,6 +7,7 @@ import (
 	"io"
 	"net/http"
 	"os"
+	"slices"
 	"sync"
 	"time"
 
@@ -43,7 +44,7 @@ func (c *recordingCache) Get(ctx context.Context, arg cache.Item) (*cache.Cached
 func (c *recordingCache) getKeys() []string {
 	c.mu.Lock()
 	defer c.mu.Unlock()
-	return append([]string(nil), c.keys...)
+	return slices.Clone(c.keys)
 }
 
 // Simulates a concurrent Enqueue between DequeueBatch and the worker's delete, so
@@ -88,7 +89,7 @@ func (f *fakeEventBroker) SendBroadcastMessage(_ context.Context, event events.E
 func (f *fakeEventBroker) getEvents() []events.Event {
 	f.mu.Lock()
 	defer f.mu.Unlock()
-	return f.events
+	return slices.Clone(f.events)
 }
 
 var _ events.Broker = (*fakeEventBroker)(nil)

model/mediafile.go

@@ -144,9 +144,7 @@ func (mf MediaFile) CoverArtID() ArtworkID {
 // otherwise it returns the album artwork ID.
 func (mf MediaFile) DiscCoverArtID() ArtworkID {
 	if mf.DiscNumber > 0 {
-		id := NewArtworkID(KindDiscArtwork, DiscArtworkID(mf.AlbumID, mf.DiscNumber), nil)
-		id.Hash = mf.ImageHash
-		return id
+		return ArtworkID{Kind: KindDiscArtwork, ID: DiscArtworkID(mf.AlbumID, mf.DiscNumber), Hash: mf.ImageHash}
 	}
 	return mf.AlbumCoverArtID()
 }

persistence/album_repository_test.go

@@ -13,6 +13,7 @@ import (
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/model/id"
 	"github.com/navidrome/navidrome/model/request"
+	"github.com/navidrome/navidrome/utils/slice"
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
 )
@@ -89,13 +90,9 @@ var _ = Describe("AlbumRepository", func() {
 			want, err := albumRepo.GetAll()
 			Expect(err).ToNot(HaveOccurred())
 			Expect(want).ToNot(BeEmpty())
-			wantIDs := make([]string, 0, len(want))
-			for _, a := range want {
-				wantIDs = append(wantIDs, a.ID)
-			}
 			ids, err := albumRepo.GetAllIDs()
 			Expect(err).ToNot(HaveOccurred())
-			Expect(ids).To(ConsistOf(wantIDs))
+			Expect(ids).To(ConsistOf(slice.Map(want, func(a model.Album) string { return a.ID })))
 		})
 	})
 

persistence/artist_repository_test.go

@@ -15,6 +15,7 @@ import (
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/model/request"
 	"github.com/navidrome/navidrome/utils"
+	"github.com/navidrome/navidrome/utils/slice"
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
 )
@@ -289,13 +290,9 @@ var _ = Describe("ArtistRepository", func() {
 				want, err := repo.GetAll()
 				Expect(err).ToNot(HaveOccurred())
 				Expect(want).ToNot(BeEmpty())
-				wantIDs := make([]string, 0, len(want))
-				for _, a := range want {
-					wantIDs = append(wantIDs, a.ID)
-				}
 				ids, err := repo.GetAllIDs()
 				Expect(err).ToNot(HaveOccurred())
-				Expect(ids).To(ConsistOf(wantIDs))
+				Expect(ids).To(ConsistOf(slice.Map(want, func(a model.Artist) string { return a.ID })))
 			})
 		})
 

persistence/artwork_hydration_test.go

@@ -66,12 +66,9 @@ var _ = Describe("Artwork hydration", func() {
 			putInfo("al", albumAbbeyRoad.ID, "")
 			// albumRadioactivity: no row -> unresolved
 
-			byID := map[string]model.Album{}
 			all, err := repo.GetAll()
 			Expect(err).ToNot(HaveOccurred())
-			for _, a := range all {
-				byID[a.ID] = a
-			}
+			byID := slice.ToMap(all, func(a model.Album) (string, model.Album) { return a.ID, a })
 
 			Expect(byID[albumSgtPeppers.ID].ImageHash).To(Equal("althash11111111"))
 			Expect(byID[albumSgtPeppers.ID].ImageAbsent).To(BeFalse())
@@ -118,12 +115,9 @@ var _ = Describe("Artwork hydration", func() {
 			putInfo("ar", artistKraftwerk.ID, "")
 			// artistCJK: no row -> unresolved
 
-			byID := map[string]model.Artist{}
 			all, err := repo.GetAll()
 			Expect(err).ToNot(HaveOccurred())
-			for _, a := range all {
-				byID[a.ID] = a
-			}
+			byID := slice.ToMap(all, func(a model.Artist) (string, model.Artist) { return a.ID, a })
 
 			Expect(byID[artistBeatles.ID].ImageHash).To(Equal("arhash444444444"))
 			Expect(byID[artistBeatles.ID].ImageAbsent).To(BeFalse())
@@ -157,12 +151,9 @@ var _ = Describe("Artwork hydration", func() {
 			putInfo("pl", plsBest.ID, "plhash777777777")
 			putInfo("pl", plsCool.ID, "")
 
-			byID := map[string]model.Playlist{}
 			all, err := repo.GetAll()
 			Expect(err).ToNot(HaveOccurred())
-			for _, p := range all {
-				byID[p.ID] = p
-			}
+			byID := slice.ToMap(all, func(p model.Playlist) (string, model.Playlist) { return p.ID, p })
 
 			Expect(byID[plsBest.ID].ImageHash).To(Equal("plhash777777777"))
 			Expect(byID[plsBest.ID].ImageAbsent).To(BeFalse())
@@ -185,10 +176,7 @@ var _ = Describe("Artwork hydration", func() {
 			Expect(err).ToNot(HaveOccurred())
 			tracks := pls.Tracks
 			Expect(tracks).ToNot(BeEmpty())
-			byID := map[string]model.PlaylistTrack{}
-			for _, t := range tracks {
-				byID[t.MediaFile.ID] = t
-			}
+			byID := slice.ToMap(tracks, func(t model.PlaylistTrack) (string, model.PlaylistTrack) { return t.MediaFile.ID, t })
 			Expect(byID).To(HaveKey(songDayInALife.ID))
 			Expect(byID[songDayInALife.ID].AlbumImage.ImageHash).To(Equal("pltrackhash1234"))
 			Expect(byID[songDayInALife.ID].BlurHash).To(Equal("LPLBLURhash"))
@@ -216,12 +204,9 @@ var _ = Describe("Artwork hydration", func() {
 			putInfo("ra", radioWithHomePage.ID, "rahash999999999")
 			putInfo("ra", radioWithoutHomePage.ID, "")
 
-			byID := map[string]model.Radio{}
 			all, err := repo.GetAll()
 			Expect(err).ToNot(HaveOccurred())
-			for _, rd := range all {
-				byID[rd.ID] = rd
-			}
+			byID := slice.ToMap(all, func(rd model.Radio) (string, model.Radio) { return rd.ID, rd })
 
 			Expect(byID[radioWithHomePage.ID].ImageHash).To(Equal("rahash999999999"))
 			Expect(byID[radioWithHomePage.ID].ImageAbsent).To(BeFalse())
@@ -247,13 +232,9 @@ var _ = Describe("Artwork hydration", func() {
 		}
 
 		getByID := func() map[string]model.MediaFile {
-			byID := map[string]model.MediaFile{}
 			all, err := repo.GetAll()
 			Expect(err).ToNot(HaveOccurred())
-			for _, mf := range all {
-				byID[mf.ID] = mf
-			}
-			return byID
+			return slice.ToMap(all, func(mf model.MediaFile) (string, model.MediaFile) { return mf.ID, mf })
 		}
 
 		BeforeEach(func() {

persistence/artwork_queue_repository.go

@@ -1,6 +1,7 @@
 package persistence
 
 import (
+	"cmp"
 	"context"
 	"fmt"
 	"slices"
@@ -43,10 +44,7 @@ func (r *artworkQueueRepository) enqueue(conflict string, items []model.ArtworkQ
 	for chunk := range slices.Chunk(items, enqueueChunkSize) {
 		ins := Insert(r.tableName).Columns("item_kind", "item_id", "image_type", "priority", "attempts", "retry_at", "enqueued_at")
 		for _, it := range chunk {
-			if it.ImageType == "" {
-				it.ImageType = model.ImageTypePrimary
-			}
-			ins = ins.Values(it.ItemKind, it.ItemID, it.ImageType, it.Priority, 0, now, now)
+			ins = ins.Values(it.ItemKind, it.ItemID, cmp.Or(it.ImageType, model.ImageTypePrimary), it.Priority, 0, now, now)
 		}
 		ins = ins.Suffix(conflict)
 		if _, err := r.executeSQL(ins); err != nil {

persistence/artwork_queue_repository_test.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/Masterminds/squirrel"
 	"github.com/navidrome/navidrome/model"
+	"github.com/navidrome/navidrome/utils/slice"
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
 	"github.com/pocketbase/dbx"
@@ -193,10 +194,7 @@ var _ = Describe("ArtworkQueueRepository", func() {
 		Expect(purged).To(Equal(int64(5)))
 
 		got, _ := repo.DequeueBatch(100)
-		ids := make([]string, 0, len(got))
-		for _, it := range got {
-			ids = append(ids, it.ItemID)
-		}
+		ids := slice.Map(got, func(it model.ArtworkQueueItem) string { return it.ItemID })
 		Expect(ids).To(ConsistOf(albumSgtPeppers.ID, artistKraftwerk.ID, plsBest.ID, radioWithHomePage.ID, songDayInALife.ID))
 	})
 

persistence/artwork_repository.go

@@ -1,6 +1,7 @@
 package persistence
 
 import (
+	"cmp"
 	"context"
 	"slices"
 	"time"
@@ -155,9 +156,7 @@ func (r *artworkRepository) GetItemArtwork(kind model.Kind, id, imageType string
 }
 
 func (r *artworkRepository) PutItemArtwork(ia *model.ItemArtwork) error {
-	if ia.ImageType == "" {
-		ia.ImageType = model.ImageTypePrimary
-	}
+	ia.ImageType = cmp.Or(ia.ImageType, model.ImageTypePrimary)
 	ia.UpdatedAt = time.Now()
 	// PutItemArtwork records the outcome of an attempt, so an unset attempted_at is now.
 	if ia.AttemptedAt.IsZero() {

persistence/playlist_repository_test.go

@@ -8,6 +8,7 @@ import (
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/model/request"
+	"github.com/navidrome/navidrome/utils/slice"
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
 	"github.com/pocketbase/dbx"
@@ -42,13 +43,9 @@ var _ = Describe("PlaylistRepository", func() {
 			want, err := repo.GetAll()
 			Expect(err).ToNot(HaveOccurred())
 			Expect(want).ToNot(BeEmpty())
-			wantIDs := make([]string, 0, len(want))
-			for _, p := range want {
-				wantIDs = append(wantIDs, p.ID)
-			}
 			ids, err := repo.GetAllIDs()
 			Expect(err).ToNot(HaveOccurred())
-			Expect(ids).To(ConsistOf(wantIDs))
+			Expect(ids).To(ConsistOf(slice.Map(want, func(p model.Playlist) string { return p.ID })))
 		})
 	})
 

persistence/radio_repository_test.go

@@ -7,6 +7,7 @@ import (
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/model/request"
+	"github.com/navidrome/navidrome/utils/slice"
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
 )
@@ -83,13 +84,9 @@ var _ = Describe("RadioRepository", func() {
 				want, err := repo.GetAll()
 				Expect(err).To(BeNil())
 				Expect(want).ToNot(BeEmpty())
-				wantIDs := make([]string, 0, len(want))
-				for _, r := range want {
-					wantIDs = append(wantIDs, r.ID)
-				}
 				ids, err := repo.GetAllIDs()
 				Expect(err).To(BeNil())
-				Expect(ids).To(ConsistOf(wantIDs))
+				Expect(ids).To(ConsistOf(slice.Map(want, func(r model.Radio) string { return r.ID })))
 			})
 		})
 

scanner/phase_1_folders.go

@@ -401,10 +401,7 @@ func (p *phaseFolders) persistChanges(entry *folderEntry) (*folderEntry, error)
 
 		// A re-imported track returns to unresolved so new embedded art is picked up lazily.
 		if len(entry.tracks) > 0 {
-			trackIDs := make([]string, len(entry.tracks))
-			for i := range entry.tracks {
-				trackIDs[i] = entry.tracks[i].ID
-			}
+			trackIDs := slice.Map(entry.tracks, func(t model.MediaFile) string { return t.ID })
 			if err := tx.Artwork(p.ctx).DeleteForItems(model.KindMediaFileArtwork, trackIDs); err != nil {
 				log.Warn(p.ctx, "Scanner: could not invalidate media_file artwork", "folder", entry.path, err)
 			}

server/imghttp/headers.go

@@ -56,7 +56,7 @@ func ifNoneMatch(header, hash string) bool {
 	if header == "*" {
 		return true
 	}
-	for _, tag := range strings.Split(header, ",") {
+	for tag := range strings.SplitSeq(header, ",") {
 		tag = strings.TrimSpace(tag)
 		tag = strings.TrimPrefix(tag, "W/")
 		if strings.Trim(tag, `"`) == hash {

server/nativeapi/artwork.go

@@ -2,6 +2,7 @@ package nativeapi
 
 import (
 	"net/http"
+	"slices"
 
 	"github.com/go-chi/chi/v5"
 	"github.com/navidrome/navidrome/core/artwork"
@@ -9,12 +10,12 @@ import (
 	"github.com/navidrome/navidrome/model"
 )
 
-var refreshableArtworkKinds = map[model.Kind]bool{
-	model.KindAlbumArtwork:     true,
-	model.KindArtistArtwork:    true,
-	model.KindPlaylistArtwork:  true,
-	model.KindRadioArtwork:     true,
-	model.KindMediaFileArtwork: true,
+var refreshableArtworkKinds = []model.Kind{
+	model.KindAlbumArtwork,
+	model.KindArtistArtwork,
+	model.KindPlaylistArtwork,
+	model.KindRadioArtwork,
+	model.KindMediaFileArtwork,
 }
 
 func (api *Router) addArtworkRoute(r chi.Router) {
@@ -27,7 +28,7 @@ func (api *Router) refreshArtwork() http.HandlerFunc {
 		ctx := r.Context()
 		kind, _ := model.ParseKind(chi.URLParam(r, "kind"))
 		id := chi.URLParam(r, "id")
-		if !refreshableArtworkKinds[kind] {
+		if !slices.Contains(refreshableArtworkKinds, kind) {
 			http.Error(w, "invalid artwork kind", http.StatusBadRequest)
 			return
 		}

tests/mock_album_repo.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/model/id"
+	"github.com/navidrome/navidrome/utils/slice"
 )
 
 func CreateMockAlbumRepo() *MockAlbumRepo {
@@ -86,11 +87,7 @@ func (m *MockAlbumRepo) GetAllIDs(qo ...model.QueryOptions) ([]string, error) {
 	if err != nil {
 		return nil, err
 	}
-	ids := make([]string, len(all))
-	for i, a := range all {
-		ids[i] = a.ID
-	}
-	return ids, nil
+	return slice.Map(all, func(a model.Album) string { return a.ID }), nil
 }
 
 func (m *MockAlbumRepo) GetCursor(qo ...model.QueryOptions) (model.AlbumCursor, error) {

tests/mock_artist_repo.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/model/id"
+	"github.com/navidrome/navidrome/utils/slice"
 )
 
 func CreateMockArtistRepo() *MockArtistRepo {
@@ -118,11 +119,7 @@ func (m *MockArtistRepo) GetAllIDs(options ...model.QueryOptions) ([]string, err
 	if err != nil {
 		return nil, err
 	}
-	ids := make([]string, len(all))
-	for i, a := range all {
-		ids[i] = a.ID
-	}
-	return ids, nil
+	return slice.Map(all, func(a model.Artist) string { return a.ID }), nil
 }
 
 func (m *MockArtistRepo) GetCursor(options ...model.QueryOptions) (model.ArtistCursor, error) {

tests/mock_artwork_queue_repo.go

@@ -1,8 +1,8 @@
 package tests
 
 import (
+	"cmp"
 	"slices"
-	"sort"
 	"sync"
 	"time"
 
@@ -67,11 +67,8 @@ func (m *MockArtworkQueueRepo) DequeueBatch(n int, kinds ...string) ([]model.Art
 			res = append(res, it)
 		}
 	}
-	sort.Slice(res, func(i, j int) bool {
-		if res[i].Priority != res[j].Priority {
-			return res[i].Priority > res[j].Priority
-		}
-		return res[i].EnqueuedAt.Before(res[j].EnqueuedAt)
+	slices.SortFunc(res, func(a, b model.ArtworkQueueItem) int {
+		return cmp.Or(cmp.Compare(b.Priority, a.Priority), a.EnqueuedAt.Compare(b.EnqueuedAt))
 	})
 	if len(res) > n {
 		res = res[:n]

tests/mock_artwork_repo.go

@@ -1,10 +1,12 @@
 package tests
 
 import (
+	"maps"
 	"sync"
 	"time"
 
 	"github.com/navidrome/navidrome/model"
+	"github.com/navidrome/navidrome/utils/slice"
 )
 
 type MockArtworkRepo struct {
@@ -167,11 +169,9 @@ func (m *MockArtworkRepo) DeleteForItem(kind model.Kind, id string) error {
 	if m.Err != nil {
 		return m.Err
 	}
-	for k, ia := range m.ItemData {
-		if ia.ItemKind == kind.Prefix() && ia.ItemID == id {
-			delete(m.ItemData, k)
-		}
-	}
+	maps.DeleteFunc(m.ItemData, func(_ string, ia model.ItemArtwork) bool {
+		return ia.ItemKind == kind.Prefix() && ia.ItemID == id
+	})
 	return nil
 }
 
@@ -181,15 +181,11 @@ func (m *MockArtworkRepo) DeleteForItems(kind model.Kind, ids []string) error {
 	if m.Err != nil {
 		return m.Err
 	}
-	idSet := make(map[string]bool, len(ids))
-	for _, id := range ids {
-		idSet[id] = true
-	}
-	for k, ia := range m.ItemData {
-		if ia.ItemKind == kind.Prefix() && idSet[ia.ItemID] {
-			delete(m.ItemData, k)
-		}
-	}
+	idSet := slice.ToSet(ids)
+	maps.DeleteFunc(m.ItemData, func(_ string, ia model.ItemArtwork) bool {
+		_, ok := idSet[ia.ItemID]
+		return ok && ia.ItemKind == kind.Prefix()
+	})
 	return nil
 }
 

tests/mock_mediafile_repo.go

@@ -132,11 +132,7 @@ func (m *MockMediaFileRepo) GetAllIDs(qo ...model.QueryOptions) ([]string, error
 	if err != nil {
 		return nil, err
 	}
-	ids := make([]string, len(all))
-	for i, mf := range all {
-		ids[i] = mf.ID
-	}
-	return ids, nil
+	return slice.Map(all, func(mf model.MediaFile) string { return mf.ID }), nil
 }
 
 func (m *MockMediaFileRepo) Put(mf *model.MediaFile) error {

tests/mock_playlist_repo.go

@@ -7,6 +7,7 @@ import (
 	"github.com/deluan/rest"
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/model/id"
+	"github.com/navidrome/navidrome/utils/slice"
 )
 
 func CreateMockPlaylistRepo() *MockPlaylistRepo {
@@ -57,11 +58,7 @@ func (m *MockPlaylistRepo) GetAllIDs(options ...model.QueryOptions) ([]string, e
 	if err != nil {
 		return nil, err
 	}
-	ids := make([]string, len(all))
-	for i, p := range all {
-		ids[i] = p.ID
-	}
-	return ids, nil
+	return slice.Map(all, func(p model.Playlist) string { return p.ID }), nil
 }
 
 func (m *MockPlaylistRepo) GetCursor(options ...model.QueryOptions) (model.PlaylistCursor, error) {

tests/mock_radio_repository.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/model/id"
+	"github.com/navidrome/navidrome/utils/slice"
 )
 
 type MockedRadioRepo struct {
@@ -78,11 +79,7 @@ func (m *MockedRadioRepo) GetAllIDs(qo ...model.QueryOptions) ([]string, error)
 	if err != nil {
 		return nil, err
 	}
-	ids := make([]string, len(all))
-	for i, r := range all {
-		ids[i] = r.ID
-	}
-	return ids, nil
+	return slice.Map(all, func(r model.Radio) string { return r.ID }), nil
 }
 
 func (m *MockedRadioRepo) Put(radio *model.Radio, _ ...string) error {