fix(lidarr): address review findings on HTTP client

- Add ArtistMBID/AlbumMBID to LookupResult so handlers can build the
  full lidarr_requests row from album/track lookups (parent MBID is
  needed for the AddAlbum API call and for the schema's NOT NULL
  lidarr_artist_mbid)
- Trim trailing slash on BaseURL before joining paths to avoid
  double-slash URLs when operators enter "http://lidarr.lan/"
- Check json.Marshal errors in AddArtist/AddAlbum
- Extract lidarrImage as a named unexported type instead of repeating
  the anonymous struct three times
- Add NewClient(baseURL, apiKey) constructor with 30s default timeout
- Add ErrLookupFailed test coverage for the 4xx-non-auth branch on
  both get and post helpers
- Rename TestListRootFolders_BadJSON -> _NullBody (it tests null,
  not malformed); add a real malformed-JSON test
- Defensive separator guard on LookupAlbum.Secondary so an empty
  ArtistName doesn't produce a leading " · "

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/lidarr/client.go

@@ -9,6 +9,8 @@ import (
 	"net/http"
 	"net/url"
 	"strconv"
+	"strings"
+	"time"
 )
 
 // Client wraps Lidarr's v1 HTTP API. BaseURL is the Lidarr instance
@@ -19,6 +21,17 @@ type Client struct {
 	HTTP    *http.Client
 }
 
+// NewClient builds a Client with sensible HTTP defaults (30s timeout,
+// matching the pattern in internal/scrobble/listenbrainz). Call sites
+// that need a custom client can construct the Client struct directly.
+func NewClient(baseURL, apiKey string) *Client {
+	return &Client{
+		BaseURL: baseURL,
+		APIKey:  apiKey,
+		HTTP:    &http.Client{Timeout: 30 * time.Second},
+	}
+}
+
 // get executes an authenticated GET request and maps HTTP status codes to
 // typed errors. The caller is responsible for closing the returned body.
 func (c *Client) get(ctx context.Context, path string, q url.Values) (*http.Response, error) {
@@ -26,7 +39,7 @@ func (c *Client) get(ctx context.Context, path string, q url.Values) (*http.Resp
 	if err != nil {
 		return nil, fmt.Errorf("%w: %v", ErrUnreachable, err)
 	}
-	u.Path = u.Path + path
+	u.Path = strings.TrimRight(u.Path, "/") + path
 	if q != nil {
 		u.RawQuery = q.Encode()
 	}
@@ -62,7 +75,7 @@ func (c *Client) post(ctx context.Context, path string, body []byte) (*http.Resp
 	if err != nil {
 		return nil, fmt.Errorf("%w: %v", ErrUnreachable, err)
 	}
-	u.Path = u.Path + path
+	u.Path = strings.TrimRight(u.Path, "/") + path
 	req, err := http.NewRequestWithContext(ctx, http.MethodPost, u.String(), bytes.NewReader(body))
 	if err != nil {
 		return nil, err
@@ -102,15 +115,11 @@ func (c *Client) LookupArtist(ctx context.Context, term string) ([]LookupResult,
 		return nil, fmt.Errorf("%w: %v", ErrInvalidPayload, err)
 	}
 	var raw []struct {
-		ForeignArtistID string   `json:"foreignArtistId"`
+		ForeignArtistID string        `json:"foreignArtistId"`
-		ArtistName      string   `json:"artistName"`
+		ArtistName      string        `json:"artistName"`
-		Genres          []string `json:"genres"`
+		Genres          []string      `json:"genres"`
-		AlbumCount      int      `json:"albumCount"`
+		AlbumCount      int           `json:"albumCount"`
-		Images          []struct {
+		Images          []lidarrImage `json:"images"`
-			CoverType string `json:"coverType"`
-			RemoteURL string `json:"remoteUrl"`
-			URL       string `json:"url"`
-		} `json:"images"`
 	}
 	if err := json.Unmarshal(body, &raw); err != nil {
 		return nil, fmt.Errorf("%w: %v", ErrInvalidPayload, err)
@@ -150,16 +159,13 @@ func (c *Client) LookupAlbum(ctx context.Context, term string) ([]LookupResult,
 		return nil, fmt.Errorf("%w: %v", ErrInvalidPayload, err)
 	}
 	var raw []struct {
-		ForeignAlbumID string `json:"foreignAlbumId"`
+		ForeignAlbumID  string        `json:"foreignAlbumId"`
-		Title          string `json:"title"`
+		ForeignArtistID string        `json:"foreignArtistId"`
-		ArtistName     string `json:"artistName"`
+		Title           string        `json:"title"`
-		ReleaseDate    string `json:"releaseDate"`
+		ArtistName      string        `json:"artistName"`
-		TrackCount     int    `json:"trackCount"`
+		ReleaseDate     string        `json:"releaseDate"`
-		Images         []struct {
+		TrackCount      int           `json:"trackCount"`
-			CoverType string `json:"coverType"`
+		Images          []lidarrImage `json:"images"`
-			RemoteURL string `json:"remoteUrl"`
-			URL       string `json:"url"`
-		} `json:"images"`
 	}
 	if err := json.Unmarshal(body, &raw); err != nil {
 		return nil, fmt.Errorf("%w: %v", ErrInvalidPayload, err)
@@ -170,18 +176,28 @@ func (c *Client) LookupAlbum(ctx context.Context, term string) ([]LookupResult,
 		if len(r.ReleaseDate) >= 4 {
 			year = r.ReleaseDate[:4]
 		}
-		secondary := r.ArtistName
+		secondary := ""
+		if r.ArtistName != "" {
+			secondary = r.ArtistName
+		}
 		if year != "" {
-			secondary += " · " + year
+			if secondary != "" {
+				secondary += " · "
+			}
+			secondary += year
 		}
 		if r.TrackCount > 0 {
-			secondary += " · " + strconv.Itoa(r.TrackCount) + " tracks"
+			if secondary != "" {
+				secondary += " · "
+			}
+			secondary += strconv.Itoa(r.TrackCount) + " tracks"
 		}
 		out = append(out, LookupResult{
-			MBID:      r.ForeignAlbumID,
+			MBID:       r.ForeignAlbumID,
-			Name:      r.Title,
+			ArtistMBID: r.ForeignArtistID,
-			Secondary: secondary,
+			Name:       r.Title,
-			ImageURL:  pickPosterImage(r.Images),
+			Secondary:  secondary,
+			ImageURL:   pickPosterImage(r.Images),
 		})
 	}
 	return out, nil
@@ -200,10 +216,12 @@ func (c *Client) LookupTrack(ctx context.Context, term string) ([]LookupResult,
 		return nil, fmt.Errorf("%w: %v", ErrInvalidPayload, err)
 	}
 	var raw []struct {
-		ForeignTrackID string `json:"foreignTrackId"`
+		ForeignTrackID  string `json:"foreignTrackId"`
-		Title          string `json:"title"`
+		ForeignAlbumID  string `json:"foreignAlbumId"`
-		AlbumTitle     string `json:"albumTitle"`
+		ForeignArtistID string `json:"foreignArtistId"`
-		ArtistName     string `json:"artistName"`
+		Title           string `json:"title"`
+		AlbumTitle      string `json:"albumTitle"`
+		ArtistName      string `json:"artistName"`
 	}
 	if err := json.Unmarshal(body, &raw); err != nil {
 		return nil, fmt.Errorf("%w: %v", ErrInvalidPayload, err)
@@ -218,9 +236,11 @@ func (c *Client) LookupTrack(ctx context.Context, term string) ([]LookupResult,
 			secondary += r.ArtistName
 		}
 		out = append(out, LookupResult{
-			MBID:      r.ForeignTrackID,
+			MBID:       r.ForeignTrackID,
-			Name:      r.Title,
+			ArtistMBID: r.ForeignArtistID,
-			Secondary: secondary,
+			AlbumMBID:  r.ForeignAlbumID,
+			Name:       r.Title,
+			Secondary:  secondary,
 		})
 	}
 	return out, nil
@@ -233,7 +253,7 @@ func (c *Client) AddArtist(ctx context.Context, p AddArtistParams) error {
 	if p.MonitorAll {
 		monitor = "all"
 	}
-	body, _ := json.Marshal(map[string]any{
+	body, err := json.Marshal(map[string]any{
 		"foreignArtistId":  p.ForeignArtistID,
 		"qualityProfileId": p.QualityProfileID,
 		"rootFolderPath":   p.RootFolderPath,
@@ -241,6 +261,9 @@ func (c *Client) AddArtist(ctx context.Context, p AddArtistParams) error {
 		"monitor":          monitor,
 		"addOptions":       map[string]any{"searchForMissingAlbums": true},
 	})
+	if err != nil {
+		return fmt.Errorf("%w: marshal: %v", ErrInvalidPayload, err)
+	}
 	resp, err := c.post(ctx, "/api/v1/artist", body)
 	if err != nil {
 		return err
@@ -252,7 +275,7 @@ func (c *Client) AddArtist(ctx context.Context, p AddArtistParams) error {
 // AddAlbum posts to POST /api/v1/album. Returns nil on 2xx; typed error
 // otherwise.
 func (c *Client) AddAlbum(ctx context.Context, p AddAlbumParams) error {
-	body, _ := json.Marshal(map[string]any{
+	body, err := json.Marshal(map[string]any{
 		"foreignAlbumId":   p.ForeignAlbumID,
 		"foreignArtistId":  p.ForeignArtistID,
 		"qualityProfileId": p.QualityProfileID,
@@ -260,6 +283,9 @@ func (c *Client) AddAlbum(ctx context.Context, p AddAlbumParams) error {
 		"monitored":        true,
 		"addOptions":       map[string]any{"searchForNewAlbum": true},
 	})
+	if err != nil {
+		return fmt.Errorf("%w: marshal: %v", ErrInvalidPayload, err)
+	}
 	resp, err := c.post(ctx, "/api/v1/album", body)
 	if err != nil {
 		return err
@@ -344,11 +370,7 @@ func (c *Client) Ping(ctx context.Context) (PingResult, error) {
 
 // pickPosterImage returns the remote URL (preferred) or local URL for the
 // first image with coverType=="poster". Returns "" when none match.
-func pickPosterImage(imgs []struct {
+func pickPosterImage(imgs []lidarrImage) string {
-	CoverType string `json:"coverType"`
-	RemoteURL string `json:"remoteUrl"`
-	URL       string `json:"url"`
-}) string {
 	for _, img := range imgs {
 		if img.CoverType == "poster" {
 			if img.RemoteURL != "" {

internal/lidarr/client_test.go

@@ -154,6 +154,12 @@ func TestLookupAlbum_HappyPath(t *testing.T) {
 	if got[0].MBID != "a1b2c3d4-e5f6-7890-abcd-ef1234567890" {
 		t.Errorf("MBID = %q", got[0].MBID)
 	}
+	if got[0].ArtistMBID != "069b64b6-7884-4f6a-94cc-e4c1d6c87a01" {
+		t.Errorf("ArtistMBID = %q, want 069b64b6-7884-4f6a-94cc-e4c1d6c87a01", got[0].ArtistMBID)
+	}
+	if got[0].AlbumMBID != "" {
+		t.Errorf("AlbumMBID = %q, want empty on album result", got[0].AlbumMBID)
+	}
 	if got[0].Name != "Music Has the Right to Children" {
 		t.Errorf("Name = %q", got[0].Name)
 	}
@@ -213,6 +219,12 @@ func TestLookupTrack_HappyPath(t *testing.T) {
 	if got[0].Secondary != want {
 		t.Errorf("Secondary = %q, want %q", got[0].Secondary, want)
 	}
+	if got[0].ArtistMBID != "069b64b6-7884-4f6a-94cc-e4c1d6c87a01" {
+		t.Errorf("ArtistMBID = %q, want 069b64b6-7884-4f6a-94cc-e4c1d6c87a01", got[0].ArtistMBID)
+	}
+	if got[0].AlbumMBID != "a1b2c3d4-e5f6-7890-abcd-ef1234567890" {
+		t.Errorf("AlbumMBID = %q, want a1b2c3d4-e5f6-7890-abcd-ef1234567890", got[0].AlbumMBID)
+	}
 	if got[0].ImageURL != "" {
 		t.Errorf("tracks carry no images; ImageURL = %q", got[0].ImageURL)
 	}
@@ -406,6 +418,51 @@ func TestListQualityProfiles_BadJSON(t *testing.T) {
 	}
 }
 
+// --- LookupArtist (additional) ---
+
+func TestLookupArtist_LookupFailed(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
+	}))
+	defer srv.Close()
+	c := &Client{BaseURL: srv.URL, APIKey: "x", HTTP: srv.Client()}
+	_, err := c.LookupArtist(context.Background(), "boards")
+	if !errors.Is(err, ErrLookupFailed) {
+		t.Fatalf("err = %v, want ErrLookupFailed", err)
+	}
+}
+
+func TestGet_BaseURLWithTrailingSlash(t *testing.T) {
+	body, _ := os.ReadFile("testdata/lookup_artist.json")
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Verify path is /api/v1/artist/lookup, NOT //api/v1/artist/lookup
+		if r.URL.Path != "/api/v1/artist/lookup" {
+			t.Errorf("got path %q; trailing-slash BaseURL produced double-slash", r.URL.Path)
+		}
+		_, _ = w.Write(body)
+	}))
+	defer srv.Close()
+	c := &Client{BaseURL: srv.URL + "/", APIKey: "k", HTTP: srv.Client()}
+	_, err := c.LookupArtist(context.Background(), "boards")
+	if err != nil {
+		t.Fatalf("LookupArtist: %v", err)
+	}
+}
+
+// --- AddArtist (additional) ---
+
+func TestAddArtist_PostFailed(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusUnprocessableEntity)
+	}))
+	defer srv.Close()
+	c := &Client{BaseURL: srv.URL, APIKey: "x", HTTP: srv.Client()}
+	err := c.AddArtist(context.Background(), AddArtistParams{ForeignArtistID: "x", QualityProfileID: 1, RootFolderPath: "/m"})
+	if !errors.Is(err, ErrLookupFailed) {
+		t.Fatalf("err = %v, want ErrLookupFailed", err)
+	}
+}
+
 // --- ListRootFolders ---
 
 func TestListRootFolders_HappyPath(t *testing.T) {
@@ -439,7 +496,7 @@ func TestListRootFolders_HappyPath(t *testing.T) {
 	}
 }
 
-func TestListRootFolders_BadJSON(t *testing.T) {
+func TestListRootFolders_NullBody(t *testing.T) {
 	c, srv := newTestClient(func(w http.ResponseWriter, _ *http.Request) {
 		_, _ = w.Write([]byte(`null`))
 	})
@@ -454,6 +511,18 @@ func TestListRootFolders_BadJSON(t *testing.T) {
 	}
 }
 
+func TestListRootFolders_BadJSON(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write([]byte("{not valid json"))
+	}))
+	defer srv.Close()
+	c := &Client{BaseURL: srv.URL, APIKey: "x", HTTP: srv.Client()}
+	_, err := c.ListRootFolders(context.Background())
+	if !errors.Is(err, ErrInvalidPayload) {
+		t.Fatalf("err = %v, want ErrInvalidPayload", err)
+	}
+}
+
 // --- Ping ---
 
 func TestPing_ReturnsVersion(t *testing.T) {
@@ -507,11 +576,7 @@ func TestPing_BadJSON(t *testing.T) {
 // --- pickPosterImage ---
 
 func TestPickPosterImage_PreferRemoteURL(t *testing.T) {
-	imgs := []struct {
+	imgs := []lidarrImage{
-		CoverType string `json:"coverType"`
-		RemoteURL string `json:"remoteUrl"`
-		URL       string `json:"url"`
-	}{
 		{CoverType: "poster", RemoteURL: "https://remote.example/img.jpg", URL: "https://local.example/img.jpg"},
 	}
 	got := pickPosterImage(imgs)
@@ -521,11 +586,7 @@ func TestPickPosterImage_PreferRemoteURL(t *testing.T) {
 }
 
 func TestPickPosterImage_FallsBackToLocalURL(t *testing.T) {
-	imgs := []struct {
+	imgs := []lidarrImage{
-		CoverType string `json:"coverType"`
-		RemoteURL string `json:"remoteUrl"`
-		URL       string `json:"url"`
-	}{
 		{CoverType: "poster", RemoteURL: "", URL: "https://local.example/img.jpg"},
 	}
 	got := pickPosterImage(imgs)
@@ -535,11 +596,7 @@ func TestPickPosterImage_FallsBackToLocalURL(t *testing.T) {
 }
 
 func TestPickPosterImage_SkipsNonPoster(t *testing.T) {
-	imgs := []struct {
+	imgs := []lidarrImage{
-		CoverType string `json:"coverType"`
-		RemoteURL string `json:"remoteUrl"`
-		URL       string `json:"url"`
-	}{
 		{CoverType: "banner", RemoteURL: "https://banner.example/img.jpg"},
 		{CoverType: "cover", RemoteURL: "https://cover.example/img.jpg"},
 	}

internal/lidarr/testdata/lookup_album.json

@@ -1,6 +1,7 @@
 [
   {
     "foreignAlbumId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
+    "foreignArtistId": "069b64b6-7884-4f6a-94cc-e4c1d6c87a01",
     "title": "Music Has the Right to Children",
     "artistName": "Boards of Canada",
     "releaseDate": "1998-04-27",
@@ -12,6 +13,7 @@
   },
   {
     "foreignAlbumId": "b2c3d4e5-f6a7-8901-bcde-f12345678901",
+    "foreignArtistId": "069b64b6-7884-4f6a-94cc-e4c1d6c87a01",
     "title": "Geogaddi",
     "artistName": "Boards of Canada",
     "releaseDate": "2002-02-11",

internal/lidarr/testdata/lookup_track.json

@@ -1,12 +1,16 @@
 [
   {
     "foreignTrackId": "t1a2b3c4-d5e6-7890-abcd-ef1234567890",
+    "foreignAlbumId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
+    "foreignArtistId": "069b64b6-7884-4f6a-94cc-e4c1d6c87a01",
     "title": "Roygbiv",
     "albumTitle": "Music Has the Right to Children",
     "artistName": "Boards of Canada"
   },
   {
     "foreignTrackId": "t2b3c4d5-e6f7-8901-bcde-f12345678901",
+    "foreignAlbumId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
+    "foreignArtistId": "069b64b6-7884-4f6a-94cc-e4c1d6c87a01",
     "title": "Aquarius",
     "albumTitle": "Music Has the Right to Children",
     "artistName": "Boards of Canada"

internal/lidarr/types.go

@@ -4,13 +4,25 @@
 package lidarr
 
 // LookupResult is the normalized shape returned by Lookup{Artist,Album,Track}.
-// It is what we store on the request row (via the user's request) and
+// MBID is the kind's primary identifier (foreignArtistId / foreignAlbumId /
-// what /api/lidarr/search returns to the SPA.
+// foreignTrackId from Lidarr). ArtistMBID and AlbumMBID carry parent
+// identifiers when the kind has them — request creation and admin
+// approval need them to construct the lidarr_requests row and the
+// AddArtist/AddAlbum API calls.
 type LookupResult struct {
-	MBID      string // foreignArtistId / foreignAlbumId / foreignTrackId
+	MBID       string // foreignArtistId / foreignAlbumId / foreignTrackId
-	Name      string // artist name; album/track returns Title here too
+	ArtistMBID string // parent artist's foreignArtistId — set on album/track results, empty on artist results
-	Secondary string // genre + album count for artist; year for album; album for track
+	AlbumMBID  string // parent album's foreignAlbumId — set on track results only
-	ImageURL  string // cover-art URL Lidarr surfaced (may be empty)
+	Name       string // artist name; album/track returns Title here too
+	Secondary  string // genre + album count for artist; year for album; album for track
+	ImageURL   string // cover-art URL Lidarr surfaced (may be empty)
+}
+
+// lidarrImage is the wire shape for image entries in Lidarr's API responses.
+type lidarrImage struct {
+	CoverType string `json:"coverType"`
+	RemoteURL string `json:"remoteUrl"`
+	URL       string `json:"url"`
 }
 
 // QualityProfile is the dropdown choice in /admin/integrations.