feat(jellyfin): add opt-in LAN auto-discovery (#6169)

* feat(jellyfin): compute the address advertised by auto-discovery

* fix(jellyfin): use TLSEnabled and path.Join for the auto-discovery address

* feat(jellyfin): answer LAN auto-discovery broadcasts

* test(jellyfin): e2e check that auto-discovery matches the public server identity

* feat(jellyfin): add opt-in AutoDiscovery option and start the listener

* fix(jellyfin): close the auto-discovery socket on read errors and quiet reply failures

* refactor(jellyfin): build the auto-discovery address with publicurl and log bind failures in place

discoveryAddress now hands only the discovery-specific part (the requester-facing host) to publicurl.AbsoluteURL, so the BaseURL, scheme and BasePath rules live in one place. ServeDiscovery logs its own bind failure and returns nothing, so the caller cannot route the error into the server errgroup. Tests use a DescribeTable and no longer wait on a fixed timeout to prove a packet was ignored.

* refactor(jellyfin): run auto-discovery as its own service in the main errgroup

Discovery is now a small type that needs only a DataStore, started by startJellyfinDiscovery like the other background services, so the errgroup waits for it on shutdown and startServer is back to a one-line mount. The server id resolution moved to resolveServerID with a package-level lock: the Router and Discovery are separate objects, and a per-Router lock would let them persist two different ids on first boot.

* refactor(jellyfin): build Discovery through wire and drop the serverName forwarder

startJellyfinDiscovery now follows its siblings: negative guard with a DISABLED debug log, and the service comes from a CreateJellyfinDiscovery wire injector instead of an inline constructor. The Router.serverName method only forwarded to the package function, so its four call sites call the function directly.

* fix(jellyfin): skip auto-discovery for unix socket servers without a BaseURL host

With Address set to a unix socket nothing listens on Port, so the route-facing IP plus Port pointed clients at a dead URL. Discovery now logs a warning and does not start in that mode unless BaseURL names the proxy host, which AbsoluteURL already advertises as-is.

* docs(jellyfin): note which address auto-discovery advertises on restricted binds

Also stop using a hostname Address in the fallback spec: a hostname like localhost binds a single interface, so it is not an example of the route-facing fallback being right. An empty Address is.

cmd/root.go

@@ -86,6 +86,7 @@ func runNavidrome(ctx context.Context) {
 	g.Go(startSignaller(ctx))
 	g.Go(startScheduler(ctx))
 	g.Go(startPlaybackServer(ctx))
+	g.Go(startJellyfinDiscovery(ctx))
 	g.Go(schedulePeriodicBackup(ctx))
 	g.Go(startInsightsCollector(ctx))
 	g.Go(scheduleDBAnalyzer(ctx))
@@ -343,6 +344,18 @@ func startInsightsCollector(ctx context.Context) func() error {
 	}
 }
 
+// startJellyfinDiscovery never returns an error: a discovery failure must not stop the server.
+func startJellyfinDiscovery(ctx context.Context) func() error {
+	return func() error {
+		if !conf.Server.Jellyfin.Enabled || !conf.Server.Jellyfin.AutoDiscovery {
+			log.Debug("Jellyfin auto-discovery is DISABLED")
+			return nil
+		}
+		CreateJellyfinDiscovery().Serve(ctx)
+		return nil
+	}
+}
+
 // startPlaybackServer starts the Navidrome playback server, if configured.
 // It is responsible for the Jukebox functionality
 func startPlaybackServer(ctx context.Context) func() error {

cmd/wire_gen.go

@@ -168,6 +168,13 @@ func CreateListenBrainzRouter() *listenbrainz.Router {
 	return router
 }
 
+func CreateJellyfinDiscovery() *jellyfin.Discovery {
+	sqlDB := db.Db()
+	dataStore := persistence.New(sqlDB)
+	discovery := jellyfin.NewDiscovery(dataStore)
+	return discovery
+}
+
 func CreateInsights() metrics.Insights {
 	sqlDB := db.Db()
 	dataStore := persistence.New(sqlDB)
@@ -249,7 +256,7 @@ func getPluginManager() *plugins.Manager {
 
 // wire_injectors.go:
 
-var allProviders = wire.NewSet(core.Set, artwork.Set, server.New, subsonic.New, jellyfin.New, nativeapi.New, public.New, persistence.New, lastfm.NewRouter, listenbrainz.NewRouter, events.GetBroker, scanner.GetInstance, scanner.GetWatcher, metrics.GetPrometheusInstance, db.Db, plugins.GetManager, sonic.New, wire.Bind(new(agents.PluginLoader), new(*plugins.Manager)), wire.Bind(new(scrobbler.PluginLoader), new(*plugins.Manager)), wire.Bind(new(lyrics.PluginLoader), new(*plugins.Manager)), wire.Bind(new(sonic.PluginLoader), new(*plugins.Manager)), wire.Bind(new(sonic.Engine), new(*sonic.Sonic)), wire.Bind(new(nativeapi.PluginManager), new(*plugins.Manager)), wire.Bind(new(core.PluginUnloader), new(*plugins.Manager)), wire.Bind(new(plugins.PluginMetricsRecorder), new(metrics.Metrics)), wire.Bind(new(core.Watcher), new(scanner.Watcher)), wire.Bind(new(playlists.ImageUploadService), new(artwork.Uploader)))
+var allProviders = wire.NewSet(core.Set, artwork.Set, server.New, subsonic.New, jellyfin.New, jellyfin.NewDiscovery, nativeapi.New, public.New, persistence.New, lastfm.NewRouter, listenbrainz.NewRouter, events.GetBroker, scanner.GetInstance, scanner.GetWatcher, metrics.GetPrometheusInstance, db.Db, plugins.GetManager, sonic.New, wire.Bind(new(agents.PluginLoader), new(*plugins.Manager)), wire.Bind(new(scrobbler.PluginLoader), new(*plugins.Manager)), wire.Bind(new(lyrics.PluginLoader), new(*plugins.Manager)), wire.Bind(new(sonic.PluginLoader), new(*plugins.Manager)), wire.Bind(new(sonic.Engine), new(*sonic.Sonic)), wire.Bind(new(nativeapi.PluginManager), new(*plugins.Manager)), wire.Bind(new(core.PluginUnloader), new(*plugins.Manager)), wire.Bind(new(plugins.PluginMetricsRecorder), new(metrics.Metrics)), wire.Bind(new(core.Watcher), new(scanner.Watcher)), wire.Bind(new(playlists.ImageUploadService), new(artwork.Uploader)))
 
 func GetPluginManager(ctx context.Context) *plugins.Manager {
 	manager := getPluginManager()

cmd/wire_injectors.go

@@ -36,6 +36,7 @@ var allProviders = wire.NewSet(
 	server.New,
 	subsonic.New,
 	jellyfin.New,
+	jellyfin.NewDiscovery,
 	nativeapi.New,
 	public.New,
 	persistence.New,
@@ -108,6 +109,12 @@ func CreateListenBrainzRouter() *listenbrainz.Router {
 	))
 }
 
+func CreateJellyfinDiscovery() *jellyfin.Discovery {
+	panic(wire.Build(
+		allProviders,
+	))
+}
+
 func CreateInsights() metrics.Insights {
 	panic(wire.Build(
 		allProviders,

conf/configuration.go

@@ -235,6 +235,7 @@ type jellyfinOptions struct {
 	// ExposedPublicUsers is a comma-separated list of usernames to advertise on the unauthenticated
 	// GET /Users/Public, so Jellyfin clients can show a login user-picker. Empty exposes no users.
 	ExposedPublicUsers string
+	AutoDiscovery      bool
 	// MaxConcurrentStreams bounds how many collection responses can stream at once. Each holds a DB
 	// cursor — and its pooled connection — for the whole client-paced response, so without a bound
 	// enough slow clients would take the entire pool and stall the scanner, scrobbles and the UI.
@@ -1087,6 +1088,7 @@ func setViperDefaults() {
 	viper.SetDefault("listenbrainz.trackalgorithm", consts.DefaultListenBrainzTrackAlgorithm)
 	viper.SetDefault("jellyfin.enabled", false)
 	viper.SetDefault("jellyfin.servername", "")
+	viper.SetDefault("jellyfin.autodiscovery", false)
 	viper.SetDefault("enablescrobblehistory", true)
 	viper.SetDefault("httpheaders.frameoptions", "DENY")
 	viper.SetDefault("backup.path", "")

server/jellyfin/README.md

@@ -22,6 +22,8 @@ Enabled = true
 ServerName = "My Music Server"
 # Optional: usernames to show in the client login user-picker (default: none). See "Public user list".
 ExposedPublicUsers = "alice, bob"
+# Optional: answer LAN auto-discovery broadcasts on UDP 7359 (default: false). See "Auto discovery".
+AutoDiscovery = true
 # Optional: max collection responses streaming at once (default: half the DB connection pool,
 # min 2). Each streaming response holds a DB connection for its whole duration; excess requests
 # queue rather than fail.
@@ -34,6 +36,7 @@ or via environment variables:
 ND_JELLYFIN_ENABLED=true
 ND_JELLYFIN_SERVERNAME="My Music Server"
 ND_JELLYFIN_EXPOSEDPUBLICUSERS="alice,bob"
+ND_JELLYFIN_AUTODISCOVERY=true
 ```
 
 Once enabled, the API is mounted at:
@@ -46,6 +49,25 @@ All the paths below are relative to that base URL (e.g. `System/Info/Public` mea
 `http://localhost:4533/jellyfin/System/Info/Public`). Routes are matched **case-insensitively**,
 since real Jellyfin clients (and `jellyfin-apiclient-python`) send mixed-case paths.
 
+## Auto discovery
+
+With `AutoDiscovery = true`, Navidrome answers the Jellyfin LAN discovery broadcast
+(`who is JellyfinServer?` on UDP port 7359), so clients list the server without a typed URL.
+It is off by default because a real Jellyfin server on the same host owns that port. If the port
+is taken, Navidrome logs a warning and keeps running without discovery.
+
+The advertised address is `BaseURL` when it includes a host. Otherwise it is the bind `Address`
+when that is a specific IP, or else the local IP that faces the requesting client, plus `Port`. With a
+unix socket `Address` there is no port to advertise, so discovery only starts when `BaseURL` has a host.
+
+Discovery answers on all IPv4 interfaces, but the advertised address follows `BaseURL`, `Address` and
+`Port`. If `Address` is a loopback or a single interface IP and `BaseURL` has no host, clients on other
+networks get an address they cannot reach. Set `BaseURL` to the address clients should use.
+
+Docker: publish the port (`-p 7359:7359/udp`). In bridge mode the server only sees its container
+IP, so also set `ND_BASEURL` to the LAN address (for example `http://192.168.1.10:4533`), or use
+host networking. Keep UDP 7359 on the LAN: never forward it from the internet.
+
 ## Authentication
 
 Jellyfin clients authenticate with `POST /Users/AuthenticateByName` using the user's Navidrome

server/jellyfin/api.go

@@ -3,7 +3,6 @@ package jellyfin
 import (
 	"encoding/json"
 	"net/http"
-	"sync"
 	"time"
 
 	"github.com/go-chi/chi/v5"
@@ -41,7 +40,6 @@ type Router struct {
 	broker           events.Broker
 	lyricsCache      cache.SimpleCache[string, model.LyricList]
 	similarFlight    singleflight.Group
-	serverIDMu       sync.Mutex
 	serverIDVal      string
 }
 

server/jellyfin/auth.go

@@ -45,7 +45,7 @@ func (api *Router) authenticateByName(w http.ResponseWriter, r *http.Request) {
 	a := parseMediaBrowserAuth(r)
 	serverID := api.serverID(ctx)
 	api.ok(w, r, dto.AuthenticationResult{
-		User:        userToDto(usr, api.serverName(), serverID),
+		User:        userToDto(usr, serverName(), serverID),
 		SessionInfo: dto.NewSessionInfo(usr, a.Client, a.DeviceId, a.Device, a.Version, serverID),
 		AccessToken: token,
 		ServerId:    serverID,

server/jellyfin/discovery.go

@@ -0,0 +1,110 @@
+package jellyfin
+
+import (
+	"context"
+	"encoding/json"
+	"net"
+	"strconv"
+	"strings"
+
+	"github.com/navidrome/navidrome/conf"
+	"github.com/navidrome/navidrome/consts"
+	"github.com/navidrome/navidrome/core/publicurl"
+	"github.com/navidrome/navidrome/log"
+	"github.com/navidrome/navidrome/model"
+	"github.com/navidrome/navidrome/model/request"
+	"github.com/navidrome/navidrome/utils/gg"
+)
+
+// Jellyfin clients broadcast this query text to this UDP port.
+const (
+	discoveryPort  = 7359
+	discoveryQuery = "who is jellyfinserver?"
+)
+
+type discoveryInfo struct {
+	Address         string  `json:"Address"`
+	Id              string  `json:"Id"`
+	Name            string  `json:"Name"`
+	EndpointAddress *string `json:"EndpointAddress"`
+}
+
+// Discovery answers LAN auto-discovery broadcasts with the same identity the Router reports.
+type Discovery struct {
+	ds          model.DataStore
+	serverIDVal string
+}
+
+func NewDiscovery(ds model.DataStore) *Discovery {
+	return &Discovery{ds: ds}
+}
+
+func (d *Discovery) serverID(ctx context.Context) string {
+	return resolveServerID(ctx, d.ds, &d.serverIDVal)
+}
+
+// Serve runs until ctx is done. A failed bind is only logged: discovery is best-effort.
+func (d *Discovery) Serve(ctx context.Context) {
+	if !hasAdvertisableAddress() {
+		log.Warn(ctx, "Jellyfin API: auto-discovery is off, a unix socket server needs a BaseURL with a host to advertise")
+		return
+	}
+	// udp4 only: a dual-stack bind can share the port with another server and never get a packet.
+	conn, err := net.ListenPacket("udp4", net.JoinHostPort("0.0.0.0", strconv.Itoa(discoveryPort)))
+	if err != nil {
+		log.Warn(ctx, "Jellyfin API: auto-discovery is off, the UDP port is unavailable. Is another Jellyfin server running?", "port", discoveryPort, err)
+		return
+	}
+	log.Info(ctx, "Jellyfin API: listening for auto-discovery broadcasts", "port", discoveryPort)
+	d.ServeOn(ctx, conn)
+}
+
+// ServeOn answers discovery queries on conn until ctx is done, then closes conn.
+func (d *Discovery) ServeOn(ctx context.Context, conn net.PacketConn) {
+	defer conn.Close()
+	stop := context.AfterFunc(ctx, func() { _ = conn.Close() })
+	defer stop()
+	buf := make([]byte, 1024)
+	for {
+		n, remote, err := conn.ReadFrom(buf)
+		if err != nil {
+			if ctx.Err() == nil {
+				log.Error(ctx, "Jellyfin API: auto-discovery listener stopped", err)
+			}
+			return
+		}
+		if !strings.Contains(strings.ToLower(string(buf[:n])), discoveryQuery) {
+			continue
+		}
+		info := discoveryInfo{Address: discoveryAddress(ctx, remote), Id: d.serverID(ctx), Name: serverName()}
+		res, _ := json.Marshal(info)
+		log.Debug(ctx, "Jellyfin API: answering auto-discovery request", "from", remote.String(), "address", info.Address)
+		if _, err := conn.WriteTo(res, remote); err != nil {
+			log.Debug(ctx, "Jellyfin API: could not answer auto-discovery request", "to", remote.String(), err)
+		}
+	}
+}
+
+// Behind a unix socket nothing listens on Port, so only a BaseURL host gives clients an address.
+func hasAdvertisableAddress() bool {
+	return conf.Server.BaseHost != "" || !strings.HasPrefix(conf.Server.Address, "unix:")
+}
+
+func discoveryAddress(ctx context.Context, remote net.Addr) string {
+	scheme := gg.If(conf.Server.TLSEnabled(), "https", "http")
+	host := net.JoinHostPort(localIPFor(remote), strconv.Itoa(conf.Server.Port))
+	return publicurl.AbsoluteURL(request.WithServerAddress(ctx, scheme, host), consts.URLPathJellyfinAPI, nil)
+}
+
+// On a multi-homed host, only the interface that routes to the requester is reachable by it.
+func localIPFor(remote net.Addr) string {
+	if ip := parseIP(conf.Server.Address); ip.IsValid() && !ip.IsUnspecified() {
+		return ip.String()
+	}
+	c, err := net.Dial("udp", remote.String())
+	if err != nil {
+		return conf.Server.Address
+	}
+	defer c.Close()
+	return c.LocalAddr().(*net.UDPAddr).IP.String()
+}

server/jellyfin/discovery_test.go

@@ -0,0 +1,175 @@
+package jellyfin
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"net"
+	"os"
+	"time"
+
+	"github.com/navidrome/navidrome/conf"
+	"github.com/navidrome/navidrome/conf/configtest"
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+type failingConn struct {
+	net.PacketConn
+	closed bool
+}
+
+func (c *failingConn) ReadFrom([]byte) (int, net.Addr, error) {
+	return 0, nil, errors.New("read failed")
+}
+
+func (c *failingConn) Close() error {
+	c.closed = true
+	return nil
+}
+
+var _ = Describe("Discovery", func() {
+	var d *Discovery
+
+	BeforeEach(func() {
+		DeferCleanup(configtest.SetupConfig())
+		conf.Server.Jellyfin.ServerName = "Test Server"
+		conf.Server.Address = "0.0.0.0"
+		conf.Server.Port = 4533
+		conf.Server.BaseHost = ""
+		conf.Server.BaseScheme = ""
+		conf.Server.BasePath = ""
+		conf.Server.TLSCert = ""
+		conf.Server.TLSKey = ""
+		d = &Discovery{}
+	})
+
+	DescribeTable("discoveryAddress",
+		func(setup func(), expected string) {
+			setup()
+			remote := &net.UDPAddr{IP: net.ParseIP("127.0.0.1"), Port: 50000}
+			Expect(discoveryAddress(context.Background(), remote)).To(Equal(expected))
+		},
+		Entry("uses the BaseURL host and scheme when set", func() {
+			conf.Server.BaseScheme = "https"
+			conf.Server.BaseHost = "music.example.com"
+			conf.Server.BasePath = "/nd"
+		}, "https://music.example.com/nd/jellyfin"),
+		Entry("uses a specific bind Address with the Port", func() {
+			conf.Server.Address = "192.168.1.10"
+		}, "http://192.168.1.10:4533/jellyfin"),
+		Entry("falls back to the interface facing the requester when Address is unspecified", func() {},
+			"http://127.0.0.1:4533/jellyfin"),
+		Entry("falls back to the interface facing the requester when Address is empty", func() {
+			conf.Server.Address = ""
+		}, "http://127.0.0.1:4533/jellyfin"),
+		Entry("advertises https when TLS is configured", func() {
+			conf.Server.TLSCert = "/path/cert.pem"
+			conf.Server.TLSKey = "/path/key.pem"
+		}, "https://127.0.0.1:4533/jellyfin"),
+		Entry("advertises http when only the TLS cert is configured", func() {
+			conf.Server.TLSCert = "/path/cert.pem"
+		}, "http://127.0.0.1:4533/jellyfin"),
+		Entry("keeps a path-only BaseURL as the path prefix", func() {
+			conf.Server.BasePath = "/music"
+		}, "http://127.0.0.1:4533/music/jellyfin"),
+		Entry("does not double the slash when BasePath has a trailing slash", func() {
+			conf.Server.BasePath = "/music/"
+		}, "http://127.0.0.1:4533/music/jellyfin"),
+	)
+
+	DescribeTable("hasAdvertisableAddress",
+		func(address, baseHost string, expected bool) {
+			conf.Server.Address = address
+			conf.Server.BaseHost = baseHost
+			Expect(hasAdvertisableAddress()).To(Equal(expected))
+		},
+		Entry("TCP listener", "0.0.0.0", "", true),
+		Entry("unix socket without a BaseURL host", "unix:/tmp/navidrome.sock", "", false),
+		Entry("unix socket behind a proxy named by BaseURL", "unix:/tmp/navidrome.sock", "music.example.com", true),
+	)
+
+	It("closes the connection when the read loop fails", func() {
+		fake := &failingConn{}
+		d.ServeOn(context.Background(), fake)
+		Expect(fake.closed).To(BeTrue())
+	})
+
+	Describe("ServeOn", func() {
+		var (
+			server net.PacketConn
+			client net.PacketConn
+			cancel context.CancelFunc
+			done   chan struct{}
+		)
+
+		BeforeEach(func() {
+			var err error
+			server, err = net.ListenPacket("udp4", "127.0.0.1:0")
+			Expect(err).ToNot(HaveOccurred())
+			client, err = net.ListenPacket("udp4", "127.0.0.1:0")
+			Expect(err).ToNot(HaveOccurred())
+			DeferCleanup(client.Close)
+
+			var ctx context.Context
+			ctx, cancel = context.WithCancel(context.Background())
+			done = make(chan struct{})
+			go func() {
+				defer close(done)
+				d.ServeOn(ctx, server)
+			}()
+			DeferCleanup(func() {
+				cancel()
+				Eventually(done).Should(BeClosed())
+			})
+		})
+
+		send := func(msg string) {
+			_, err := client.WriteTo([]byte(msg), server.LocalAddr())
+			Expect(err).ToNot(HaveOccurred())
+		}
+		receive := func() ([]byte, error) {
+			Expect(client.SetReadDeadline(time.Now().Add(time.Second))).To(Succeed())
+			buf := make([]byte, 1024)
+			n, _, err := client.ReadFrom(buf)
+			return buf[:n], err
+		}
+
+		It("answers the discovery query with the server identity", func() {
+			send("who is JellyfinServer?")
+			res, err := receive()
+			Expect(err).ToNot(HaveOccurred())
+
+			var info discoveryInfo
+			Expect(json.Unmarshal(res, &info)).To(Succeed())
+			Expect(info.Address).To(Equal("http://127.0.0.1:4533/jellyfin"))
+			Expect(info.Id).To(Equal(d.serverID(context.Background())))
+			Expect(info.Name).To(Equal("Test Server"))
+			Expect(string(res)).To(ContainSubstring(`"EndpointAddress":null`))
+		})
+
+		It("matches the query case-insensitively", func() {
+			send("WHO IS JELLYFINSERVER?")
+			_, err := receive()
+			Expect(err).ToNot(HaveOccurred())
+		})
+
+		// The loop is serial, so a reply to the first packet would arrive before the second's.
+		It("ignores unrelated packets", func() {
+			send("who is PlexServer?")
+			send("who is JellyfinServer?")
+			_, err := receive()
+			Expect(err).ToNot(HaveOccurred())
+			Expect(client.SetReadDeadline(time.Now().Add(50 * time.Millisecond))).To(Succeed())
+			_, _, err = client.ReadFrom(make([]byte, 1024))
+			Expect(errors.Is(err, os.ErrDeadlineExceeded)).To(BeTrue())
+		})
+
+		It("stops and closes the socket when the context is cancelled", func() {
+			cancel()
+			Eventually(done).Should(BeClosed())
+			_, _, err := server.ReadFrom(make([]byte, 1))
+			Expect(err).To(HaveOccurred())
+		})
+	})
+})

server/jellyfin/e2e/discovery_test.go

@@ -0,0 +1,50 @@
+package e2e
+
+import (
+	"context"
+	"encoding/json"
+	"net"
+	"time"
+
+	"github.com/navidrome/navidrome/server/jellyfin"
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Auto discovery", func() {
+	BeforeEach(func() { setupTestDB() })
+
+	It("advertises the same Id and Name as /System/Info/Public", func() {
+		server, err := net.ListenPacket("udp4", "127.0.0.1:0")
+		Expect(err).ToNot(HaveOccurred())
+		client, err := net.ListenPacket("udp4", "127.0.0.1:0")
+		Expect(err).ToNot(HaveOccurred())
+		DeferCleanup(client.Close)
+
+		ctx, cancel := context.WithCancel(context.Background())
+		done := make(chan struct{})
+		go func() {
+			defer close(done)
+			jellyfin.NewDiscovery(ds).ServeOn(ctx, server)
+		}()
+		DeferCleanup(func() {
+			cancel()
+			Eventually(done).Should(BeClosed())
+		})
+
+		_, err = client.WriteTo([]byte("who is JellyfinServer?"), server.LocalAddr())
+		Expect(err).ToNot(HaveOccurred())
+		Expect(client.SetReadDeadline(time.Now().Add(time.Second))).To(Succeed())
+		buf := make([]byte, 1024)
+		n, _, err := client.ReadFrom(buf)
+		Expect(err).ToNot(HaveOccurred())
+		var reply map[string]any
+		Expect(json.Unmarshal(buf[:n], &reply)).To(Succeed())
+
+		var pub map[string]any
+		parseInto(rawReq("GET", "/System/Info/Public", ""), &pub)
+		Expect(reply["Id"]).To(Equal(pub["Id"]))
+		Expect(reply["Name"]).To(Equal(pub["ServerName"]))
+		Expect(reply["Address"]).To(HaveSuffix("/jellyfin"))
+	})
+})

server/jellyfin/system.go

@@ -10,6 +10,7 @@ import (
 	"net/netip"
 	"path"
 	"strings"
+	"sync"
 
 	"github.com/google/uuid"
 	"github.com/navidrome/navidrome/conf"
@@ -24,35 +25,37 @@ import (
 // it (Streamyfin and the Android apps refuse < 10.10), and some parsers need exactly three parts.
 const jellyfinVersion = "12.1.0"
 
-func (api *Router) serverName() string {
+func serverName() string {
 	if conf.Server.Jellyfin.ServerName != "" {
 		return conf.Server.Jellyfin.ServerName
 	}
 	return fmt.Sprintf("Navidrome %s", consts.Version)
 }
 
-// serverID returns a stable Id that survives restarts, get-or-created in the Property table.
-// Jellyfin clients cache ServerId across sessions, so a per-process value would break
-// re-authentication. api.ds is nil only in unit tests; New() always sets it.
-//
-// The mutex serializes first-boot resolution so concurrent requests can't persist different
-// UUIDs. Only a successful read or persisted id is cached; a transient failure yields a
-// temporary id and retries on the next request rather than pinning a value.
 func (api *Router) serverID(ctx context.Context) string {
-	api.serverIDMu.Lock()
-	defer api.serverIDMu.Unlock()
-	if api.serverIDVal != "" {
-		return api.serverIDVal
+	return resolveServerID(ctx, api.ds, &api.serverIDVal)
+}
+
+// Package-level: the Router and Discovery are separate objects and must not persist different ids.
+var serverIDMu sync.Mutex
+
+// Clients cache ServerId across sessions, so it is persisted. Only a successful read or write is
+// cached: a transient failure yields a temporary id and retries on the next call.
+func resolveServerID(ctx context.Context, ds model.DataStore, cached *string) string {
+	serverIDMu.Lock()
+	defer serverIDMu.Unlock()
+	if *cached != "" {
+		return *cached
 	}
-	if api.ds == nil {
-		api.serverIDVal = newServerID()
-		return api.serverIDVal
+	if ds == nil {
+		*cached = newServerID()
+		return *cached
 	}
-	id, err := api.ds.Property(ctx).Get(consts.JellyfinServerIDKey)
+	id, err := ds.Property(ctx).Get(consts.JellyfinServerIDKey)
 	switch {
 	case errors.Is(err, model.ErrNotFound):
 		id = newServerID()
-		if err := api.ds.Property(ctx).Put(consts.JellyfinServerIDKey, id); err != nil {
+		if err := ds.Property(ctx).Put(consts.JellyfinServerIDKey, id); err != nil {
 			log.Error(ctx, "Jellyfin API: could not persist server id", err)
 			return id
 		}
@@ -61,8 +64,8 @@ func (api *Router) serverID(ctx context.Context) string {
 		return newServerID()
 	}
 	// Ids persisted before this change are dashed; normalize on read rather than rewriting the DB.
-	api.serverIDVal = strings.ReplaceAll(id, "-", "")
-	return api.serverIDVal
+	*cached = strings.ReplaceAll(id, "-", "")
+	return *cached
 }
 
 // newServerID returns a UUID in Jellyfin's no-dash GUID form (Guid.ToString("N")).
@@ -74,7 +77,7 @@ func newServerID() string {
 func (api *Router) publicInfo(r *http.Request) dto.PublicSystemInfo {
 	return dto.PublicSystemInfo{
 		LocalAddress:           localAddress(r),
-		ServerName:             api.serverName(),
+		ServerName:             serverName(),
 		Version:                jellyfinVersion,
 		ProductName:            "Jellyfin Server",
 		Id:                     api.serverID(r.Context()),
@@ -106,7 +109,7 @@ func (api *Router) getSystemInfo(w http.ResponseWriter, r *http.Request) {
 func (api *Router) ping(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 	w.WriteHeader(http.StatusOK)
-	_, _ = w.Write([]byte(api.serverName()))
+	_, _ = w.Write([]byte(serverName()))
 }
 
 // getEndpointInfo answers /System/Endpoint, which Finamp's connection test uses to pick between a

server/jellyfin/system_test.go

@@ -7,6 +7,7 @@ import (
 	"net"
 	"net/http"
 	"net/http/httptest"
+	"sync"
 
 	"github.com/navidrome/navidrome/conf"
 	"github.com/navidrome/navidrome/conf/configtest"
@@ -173,6 +174,17 @@ var _ = Describe("System", func() {
 			Expect(second.serverID(ctx)).To(Equal(id))
 		})
 
+		It("resolves one id when a Router and a Discovery race on first boot", func() {
+			r, d := &Router{ds: ds}, NewDiscovery(ds)
+			ids := make([]string, 2)
+			var wg sync.WaitGroup
+			wg.Go(func() { ids[0] = r.serverID(ctx) })
+			wg.Go(func() { ids[1] = d.serverID(ctx) })
+			wg.Wait()
+			Expect(ids[0]).ToNot(BeEmpty())
+			Expect(ids[1]).To(Equal(ids[0]))
+		})
+
 		It("memoizes the id across repeated calls on the same Router", func() {
 			r := &Router{ds: ds}
 			id := r.serverID(ctx)

server/jellyfin/users.go

@@ -34,7 +34,7 @@ func (api *Router) getUserViews(w http.ResponseWriter, r *http.Request) {
 func (api *Router) getCurrentUser(w http.ResponseWriter, r *http.Request) {
 	ctx := r.Context()
 	u, _ := request.UserFrom(ctx)
-	api.ok(w, r, userToDto(&u, api.serverName(), api.serverID(ctx)))
+	api.ok(w, r, userToDto(&u, serverName(), api.serverID(ctx)))
 }
 
 // getPublicUsers advertises the users named in Jellyfin.ExposedPublicUsers for a client login