README.md

@@ -88,6 +88,15 @@ For album artwork to display in Discord, Discord needs to be able to access the
 
 **How it works**: Album art is automatically uploaded to uguu.se (temporary, anonymous hosting service) so Discord can access it. Files are deleted after 3 hours.
 
+### Backup: Cover Art Archive
+**Use this if**: You have your music tagged with MusicBrainz
+
+**Setup**:
+1. In plugin settings: **Enable** "Use artwork from Cover Art Archive"
+2. No other configuration needed
+
+**How it works**: Cover art is linked directly from MusicBrainz via Release ID using the [Cover Art Archive API](https://musicbrainz.org/doc/Cover_Art_Archive/API). Will fall back to other methods if no artwork is found.
+
 ### Troubleshooting Album Art
 - **No album art showing**: Check Navidrome logs for errors
 - **Using public instance**: Verify ND_BASEURL is correct and Navidrome was restarted
@@ -115,6 +124,10 @@ Access the plugin configuration in Navidrome: **Settings > Plugins > Discord Ric
   - **Album**: Shows the currently playing track's album name
   - **Artist**: Shows the currently playing track's artist name
 
+#### Use artwork from Cover Art Archive
+- **When to enable**: Your Navidrome instance is NOT publicly accessible from the internet, or you don't feel comfortable with directly linking
+- **What it does**: Attempts to find and link album artwork with MusicBrainz before using other methods
+
 #### Upload to uguu.se
 - **When to enable**: Your Navidrome instance is NOT publicly accessible from the internet
 - **What it does**: Automatically uploads album artwork to uguu.se (temporary hosting) so Discord can display it

coverart.go

@@ -4,30 +4,16 @@ import (
 	"encoding/json"
 	"fmt"
 	"strings"
+	"time"
 
 	"github.com/navidrome/navidrome/plugins/pdk/go/host"
 	"github.com/navidrome/navidrome/plugins/pdk/go/pdk"
+	"github.com/navidrome/navidrome/plugins/pdk/go/scrobbler"
 )
 
-// Configuration key for uguu.se image hosting
-const uguuEnabledKey = "uguuenabled"
-
-// uguu.se API response
-type uguuResponse struct {
-	Success bool `json:"success"`
-	Files   []struct {
-		URL string `json:"url"`
-	} `json:"files"`
-}
-
-// getImageURL retrieves the track artwork URL, optionally uploading to uguu.se.
-func getImageURL(username, trackID string) string {
-	uguuEnabled, _ := pdk.GetConfig(uguuEnabledKey)
-	if uguuEnabled == "true" {
-		return getImageViaUguu(username, trackID)
-	}
-	return getImageDirect(trackID)
-}
+// ============================================================================
+// Direct
+// ============================================================================
 
 // getImageDirect returns the artwork URL directly from Navidrome (current behavior).
 func getImageDirect(trackID string) string {
@@ -44,13 +30,25 @@ func getImageDirect(trackID string) string {
 	return artworkURL
 }
 
+// ============================================================================
+// uguu.se
+// ============================================================================
+
+// uguu.se API response
+type uguuResponse struct {
+	Success bool `json:"success"`
+	Files   []struct {
+		URL string `json:"url"`
+	} `json:"files"`
+}
+
 // getImageViaUguu fetches artwork and uploads it to uguu.se.
 func getImageViaUguu(username, trackID string) string {
 	// Check cache first
 	cacheKey := fmt.Sprintf("uguu.artwork.%s", trackID)
 	cachedURL, exists, err := host.CacheGetString(cacheKey)
 	if err == nil && exists {
-		pdk.Log(pdk.LogDebug, fmt.Sprintf("Cache hit for uguu artwork: %s", trackID))
+		pdk.Log(pdk.LogDebug, fmt.Sprintf("Cache hit for uguu.se artwork: %s", trackID))
 		return cachedURL
 	}
 
@@ -108,3 +106,99 @@ func uploadToUguu(imageData []byte, contentType string) (string, error) {
 
 	return result.Files[0].URL, nil
 }
+
+// ============================================================================
+// Cover Art Archive
+// ============================================================================
+
+const CAA_TIMEOUT = 5 * time.Second
+
+// caaResponse only includes relevant parameters; see API for full response
+// https://musicbrainz.org/doc/Cover_Art_Archive/API
+type caaResponse struct {
+	Images []struct {
+		Front              bool   `json:"front"`
+		Back               bool   `json:"back"`
+		ImageURL           string `json:"image"`
+		ThumbnailImageURLs struct {
+			Size250  string `json:"250"`
+			Size500  string `json:"500"`
+			Size1200 string `json:"1200"`
+		} `json:"thumbnails"`
+	} `json:"images"`
+}
+
+func getThumbnailForMBZAlbumID(mbzAlbumID string) (string, error) {
+	req := pdk.NewHTTPRequest(pdk.MethodGet, fmt.Sprintf("https://coverartarchive.org/release/%s", mbzAlbumID))
+
+	respChan := make(chan pdk.HTTPResponse, 1)
+	go func() { respChan <- req.Send() }()
+
+	var result caaResponse
+
+	select {
+	case resp := <-respChan:
+		if status := resp.Status(); status == 404 {
+			pdk.Log(pdk.LogDebug, fmt.Sprintf("No cover art for MusicBrainz Album ID: %s", mbzAlbumID))
+			return "", nil
+		} else if status >= 400 {
+			return "", fmt.Errorf("HTTP %d", resp.Status())
+		}
+
+		if err := json.Unmarshal(resp.Body(), &result); err != nil {
+			return "", fmt.Errorf("failed to parse: %w", err)
+		}
+	case <-time.After(CAA_TIMEOUT):
+		return "", fmt.Errorf("Timed out")
+	}
+
+	for _, image := range result.Images {
+		if image.Front {
+			return image.ThumbnailImageURLs.Size250, nil
+		}
+	}
+
+	pdk.Log(pdk.LogDebug, fmt.Sprintf("No front cover art for MusicBrainz Album ID: %s (%d images)", mbzAlbumID, len(result.Images)))
+	return "", nil
+}
+
+func getImageViaCAA(mbzAlbumID string) string {
+	cacheKey := fmt.Sprintf("caa.artwork.%s", mbzAlbumID)
+	cachedURL, exists, err := host.CacheGetString(cacheKey)
+	if err == nil && exists {
+		pdk.Log(pdk.LogDebug, fmt.Sprintf("Cache hit for Cover Art Archive artwork: %s", mbzAlbumID))
+		return cachedURL
+	}
+
+	url, err := getThumbnailForMBZAlbumID(mbzAlbumID)
+	if err != nil {
+		pdk.Log(pdk.LogWarn, fmt.Sprintf("Cover Art Archive request failed for %s: %v", mbzAlbumID, err))
+		return ""
+	}
+
+	_ = host.CacheSetString(cacheKey, url, 86400)
+	return url
+}
+
+// ============================================================================
+// Image URL Resolution
+// ============================================================================
+
+const uguuEnabledKey = "uguuenabled"
+const caaEnabledKey = "caaenabled"
+
+func getImageURL(username string, track scrobbler.TrackInfo) string {
+	caaEnabled, _ := pdk.GetConfig(caaEnabledKey)
+	if caaEnabled == "true" && track.MBZAlbumID != "" {
+		if url := getImageViaCAA(track.MBZAlbumID); url != "" {
+			return url
+		}
+	}
+
+	uguuEnabled, _ := pdk.GetConfig(uguuEnabledKey)
+	if uguuEnabled == "true" {
+		return getImageViaUguu(username, track.ID)
+	}
+
+	return getImageDirect(track.ID)
+}

coverart_test.go

@@ -2,9 +2,11 @@ package main
 
 import (
 	"errors"
+	"time"
 
 	"github.com/navidrome/navidrome/plugins/pdk/go/host"
 	"github.com/navidrome/navidrome/plugins/pdk/go/pdk"
+	"github.com/navidrome/navidrome/plugins/pdk/go/scrobbler"
 	"github.com/stretchr/testify/mock"
 
 	. "github.com/onsi/ginkgo/v2"
@@ -23,29 +25,30 @@ var _ = Describe("getImageURL", func() {
 		pdk.PDKMock.On("Log", mock.Anything, mock.Anything).Maybe()
 	})
 
-	Describe("uguu disabled (default)", func() {
+	Describe("direct", func() {
 		BeforeEach(func() {
 			pdk.PDKMock.On("GetConfig", uguuEnabledKey).Return("", false)
+			pdk.PDKMock.On("GetConfig", caaEnabledKey).Return("", false)
 		})
 
 		It("returns artwork URL directly", func() {
 			host.ArtworkMock.On("GetTrackUrl", "track1", int32(300)).Return("https://example.com/art.jpg", nil)
 
-			url := getImageURL("testuser", "track1")
+			url := getImageURL("testuser", scrobbler.TrackInfo{ID: "track1"})
 			Expect(url).To(Equal("https://example.com/art.jpg"))
 		})
 
 		It("returns empty for localhost URL", func() {
 			host.ArtworkMock.On("GetTrackUrl", "track1", int32(300)).Return("http://localhost:4533/art.jpg", nil)
 
-			url := getImageURL("testuser", "track1")
+			url := getImageURL("testuser", scrobbler.TrackInfo{ID: "track1"})
 			Expect(url).To(BeEmpty())
 		})
 
 		It("returns empty when artwork fetch fails", func() {
 			host.ArtworkMock.On("GetTrackUrl", "track1", int32(300)).Return("", errors.New("not found"))
 
-			url := getImageURL("testuser", "track1")
+			url := getImageURL("testuser", scrobbler.TrackInfo{ID: "track1"})
 			Expect(url).To(BeEmpty())
 		})
 	})
@@ -53,12 +56,13 @@ var _ = Describe("getImageURL", func() {
 	Describe("uguu enabled", func() {
 		BeforeEach(func() {
 			pdk.PDKMock.On("GetConfig", uguuEnabledKey).Return("true", true)
+			pdk.PDKMock.On("GetConfig", caaEnabledKey).Return("", false)
 		})
 
 		It("returns cached URL when available", func() {
 			host.CacheMock.On("GetString", "uguu.artwork.track1").Return("https://a.uguu.se/cached.jpg", true, nil)
 
-			url := getImageURL("testuser", "track1")
+			url := getImageURL("testuser", scrobbler.TrackInfo{ID: "track1"})
 			Expect(url).To(Equal("https://a.uguu.se/cached.jpg"))
 		})
 
@@ -79,7 +83,7 @@ var _ = Describe("getImageURL", func() {
 			// Mock cache set
 			host.CacheMock.On("SetString", "uguu.artwork.track1", "https://a.uguu.se/uploaded.jpg", int64(9000)).Return(nil)
 
-			url := getImageURL("testuser", "track1")
+			url := getImageURL("testuser", scrobbler.TrackInfo{ID: "track1"})
 			Expect(url).To(Equal("https://a.uguu.se/uploaded.jpg"))
 			host.CacheMock.AssertCalled(GinkgoT(), "SetString", "uguu.artwork.track1", "https://a.uguu.se/uploaded.jpg", int64(9000))
 		})
@@ -89,7 +93,7 @@ var _ = Describe("getImageURL", func() {
 			host.SubsonicAPIMock.On("CallRaw", "/getCoverArt?u=testuser&id=track1&size=300").
 				Return("", []byte(nil), errors.New("fetch failed"))
 
-			url := getImageURL("testuser", "track1")
+			url := getImageURL("testuser", scrobbler.TrackInfo{ID: "track1"})
 			Expect(url).To(BeEmpty())
 		})
 
@@ -102,8 +106,79 @@ var _ = Describe("getImageURL", func() {
 			pdk.PDKMock.On("NewHTTPRequest", pdk.MethodPost, "https://uguu.se/upload").Return(uguuReq)
 			pdk.PDKMock.On("Send", uguuReq).Return(pdk.NewStubHTTPResponse(500, nil, []byte(`{"success":false}`)))
 
-			url := getImageURL("testuser", "track1")
+			url := getImageURL("testuser", scrobbler.TrackInfo{ID: "track1"})
 			Expect(url).To(BeEmpty())
 		})
 	})
+
+	Describe("caa enabled", func() {
+		BeforeEach(func() {
+			pdk.PDKMock.On("GetConfig", uguuEnabledKey).Return("", false)
+			pdk.PDKMock.On("GetConfig", caaEnabledKey).Return("true", true)
+		})
+
+		It("returns cached URL when available", func() {
+			host.CacheMock.On("GetString", "caa.artwork.test").Return("https://coverartarchive.org/release/test/0-250.jpg", true, nil)
+
+			url := getImageURL("testuser", scrobbler.TrackInfo{MBZAlbumID: "test"})
+			Expect(url).To(Equal("https://coverartarchive.org/release/test/0-250.jpg"))
+		})
+
+		It("fetches 250px thumbnail and caches the result", func() {
+			host.CacheMock.On("GetString", "caa.artwork.test").Return("", false, nil)
+
+			// Mock coverartarchive.org HTTP get
+			caaReq := &pdk.HTTPRequest{}
+			pdk.PDKMock.On("NewHTTPRequest", pdk.MethodGet, "https://coverartarchive.org/release/test").Return(caaReq)
+			pdk.PDKMock.On("Send", caaReq).Return(pdk.NewStubHTTPResponse(200, nil,
+				[]byte(`{"images":[{"front":true,"thumbnails":{"250":"https://coverartarchive.org/release/test/0-250.jpg"}}]}`)))
+
+			// Mock cache set
+			host.CacheMock.On("SetString", "caa.artwork.test", "https://coverartarchive.org/release/test/0-250.jpg", int64(86400)).Return(nil)
+
+			url := getImageURL("testuser", scrobbler.TrackInfo{MBZAlbumID: "test"})
+			Expect(url).To(Equal("https://coverartarchive.org/release/test/0-250.jpg"))
+			host.CacheMock.AssertCalled(GinkgoT(), "SetString", "caa.artwork.test", "https://coverartarchive.org/release/test/0-250.jpg", int64(86400))
+		})
+
+		It("returns artwork directly when no MBZAlbumID is provided", func() {
+			host.CacheMock.On("GetString", "caa.artwork.test").Return("", false, nil)
+			host.ArtworkMock.On("GetTrackUrl", "track1", int32(300)).Return("https://example.com/art.jpg", nil)
+
+			url := getImageURL("testuser", scrobbler.TrackInfo{ID: "track1"})
+			Expect(url).To(Equal("https://example.com/art.jpg"))
+		})
+
+		It("returns artwork directly when no suitable artwork is found", func() {
+			host.CacheMock.On("GetString", "caa.artwork.test").Return("", false, nil)
+			host.ArtworkMock.On("GetTrackUrl", "track1", int32(300)).Return("https://example.com/art.jpg", nil)
+
+			// Mock coverartarchive.org HTTP get
+			caaReq := &pdk.HTTPRequest{}
+			pdk.PDKMock.On("NewHTTPRequest", pdk.MethodGet, "https://coverartarchive.org/release/test").Return(caaReq)
+			pdk.PDKMock.On("Send", caaReq).Return(pdk.NewStubHTTPResponse(200, nil,
+				[]byte(`{"images":[{"front":false,"thumbnails":{"250":"https://coverartarchive.org/release/test/0-250.jpg"}}]}`)))
+
+			// Mock cache set
+			host.CacheMock.On("SetString", "caa.artwork.test", "", int64(86400)).Return(nil)
+
+			url := getImageURL("testuser", scrobbler.TrackInfo{ID: "track1", MBZAlbumID: "test"})
+			Expect(url).To(Equal("https://example.com/art.jpg"))
+			host.CacheMock.AssertCalled(GinkgoT(), "SetString", "caa.artwork.test", "", int64(86400))
+		})
+
+		It("returns artwork directly after 5 second timeout", func() {
+			host.CacheMock.On("GetString", "caa.artwork.test").Return("", false, nil)
+			host.ArtworkMock.On("GetTrackUrl", "track1", int32(300)).Return("https://example.com/art.jpg", nil)
+
+			// Mock coverartarchive.org HTTP get
+			caaReq := &pdk.HTTPRequest{}
+			pdk.PDKMock.On("NewHTTPRequest", pdk.MethodGet, "https://coverartarchive.org/release/test").Return(caaReq)
+			pdk.PDKMock.On("Send", caaReq).WaitUntil(time.After(7 * time.Second)).Return(pdk.NewStubHTTPResponse(200, nil,
+				[]byte(`{"images":[{"front":false,"thumbnails":{"250":"https://coverartarchive.org/release/test/0-250.jpg"}}]}`)))
+
+			url := getImageURL("testuser", scrobbler.TrackInfo{ID: "track1", MBZAlbumID: "test"})
+			Expect(url).To(Equal("https://example.com/art.jpg"))
+		})
+	})
 })

main.go

@@ -169,7 +169,7 @@ func (p *discordPlugin) NowPlaying(input scrobbler.NowPlayingRequest) error {
 			End:   endTime,
 		},
 		Assets: activityAssets{
-			LargeImage: getImageURL(input.Username, input.Track.ID),
+			LargeImage: getImageURL(input.Username, input.Track),
 			LargeText:  input.Track.Album,
 		},
 	}); err != nil {

main_test.go

@@ -120,6 +120,7 @@ var _ = Describe("discordPlugin", func() {
 			pdk.PDKMock.On("GetConfig", clientIDKey).Return("test-client-id", true)
 			pdk.PDKMock.On("GetConfig", usersKey).Return(`[{"username":"testuser","token":"test-token"}]`, true)
 			pdk.PDKMock.On("GetConfig", uguuEnabledKey).Return("", false)
+			pdk.PDKMock.On("GetConfig", caaEnabledKey).Return("", false)
 			pdk.PDKMock.On("GetConfig", activityNameKey).Return("", false)
 
 			// Connect mocks (isConnected check via heartbeat)
@@ -177,6 +178,7 @@ var _ = Describe("discordPlugin", func() {
 				pdk.PDKMock.On("GetConfig", clientIDKey).Return("test-client-id", true)
 				pdk.PDKMock.On("GetConfig", usersKey).Return(`[{"username":"testuser","token":"test-token"}]`, true)
 				pdk.PDKMock.On("GetConfig", uguuEnabledKey).Return("", false)
+				pdk.PDKMock.On("GetConfig", caaEnabledKey).Return("", false)
 				pdk.PDKMock.On("GetConfig", activityNameKey).Return(configValue, configExists)
 
 				// Connect mocks

manifest.json

@@ -13,7 +13,8 @@
       "reason": "To communicate with Discord API for gateway discovery and image uploads",
       "requiredHosts": [
         "discord.com",
-        "uguu.se"
+        "uguu.se",
+        "coverartarchive.org"
       ]
     },
     "websocket": {
@@ -64,6 +65,11 @@
           "title": "Upload artwork to uguu.se (enable if Navidrome is not publicly accessible)",
           "default": false
         },
+        "caaenabled": {
+          "type": "boolean",
+          "title": "Use artwork from Cover Art Archive when available",
+          "default": false
+        },
         "users": {
           "type": "array",
           "title": "User Tokens",
@@ -111,6 +117,10 @@
             "format": "radio"
           }
         },
+        {
+          "type": "Control",
+          "scope": "#/properties/caaenabled"
+        },
         {
           "type": "Control",
           "scope": "#/properties/uguuenabled"