feat(api): add GET /api/library/albums handler

Implements the paged alpha-sorted album list endpoint used by the M6a
wrapping-grid SPA page. Mirrors handleListArtists alpha branch using
ListAlbumsAlphaWithArtist + CountAlbums; 2/2 integration tests pass.

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

internal/api/library_albums.go

@@ -0,0 +1,41 @@
+package api
+
+import (
+	"net/http"
+
+	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
+)
+
+// handleListLibraryAlbums implements GET /api/library/albums. Mirrors
+// /api/artists?sort=alpha but for albums. The new wrapping-grid page on
+// the SPA infinite-scrolls against this endpoint via TanStack
+// createInfiniteQuery.
+func (h *handlers) handleListLibraryAlbums(w http.ResponseWriter, r *http.Request) {
+	limit, offset, err := parsePaging(r.URL.Query())
+	if err != nil {
+		writeErr(w, http.StatusBadRequest, "bad_request", err.Error())
+		return
+	}
+	q := dbq.New(h.pool)
+	rows, err := q.ListAlbumsAlphaWithArtist(r.Context(), dbq.ListAlbumsAlphaWithArtistParams{
+		Limit: int32(limit), Offset: int32(offset),
+	})
+	if err != nil {
+		h.logger.Error("api: list library albums", "err", err)
+		writeErr(w, http.StatusInternalServerError, "server_error", "lookup failed")
+		return
+	}
+	total, err := q.CountAlbums(r.Context())
+	if err != nil {
+		h.logger.Error("api: count albums", "err", err)
+		writeErr(w, http.StatusInternalServerError, "server_error", "count failed")
+		return
+	}
+	items := make([]AlbumRef, 0, len(rows))
+	for _, row := range rows {
+		items = append(items, albumRefFrom(row.Album, row.ArtistName, 0, 0))
+	}
+	writeJSON(w, http.StatusOK, Page[AlbumRef]{
+		Items: items, Total: int(total), Limit: limit, Offset: offset,
+	})
+}

internal/api/library_albums_test.go

@@ -0,0 +1,95 @@
+package api
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/go-chi/chi/v5"
+
+	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
+)
+
+func newLibraryAlbumsRouter(h *handlers) chi.Router {
+	r := chi.NewRouter()
+	r.Get("/api/library/albums", h.handleListLibraryAlbums)
+	return r
+}
+
+func doListLibraryAlbums(h *handlers, user dbq.User, query string) *httptest.ResponseRecorder {
+	url := "/api/library/albums"
+	if query != "" {
+		url += "?" + query
+	}
+	req := httptest.NewRequest(http.MethodGet, url, nil)
+	req = withUser(req, user)
+	w := httptest.NewRecorder()
+	newLibraryAlbumsRouter(h).ServeHTTP(w, req)
+	return w
+}
+
+func TestLibraryAlbums_AlphaSorted(t *testing.T) {
+	h, pool := testHandlers(t)
+	user := seedUser(t, pool, "alice", "pw", false)
+	q := dbq.New(pool)
+	artist, _ := q.UpsertArtist(context.Background(), dbq.UpsertArtistParams{
+		Name: "ArtistA", SortName: "ArtistA",
+	})
+	_, _ = q.UpsertAlbum(context.Background(), dbq.UpsertAlbumParams{
+		Title: "Zoo", SortTitle: "Zoo", ArtistID: artist.ID,
+	})
+	_, _ = q.UpsertAlbum(context.Background(), dbq.UpsertAlbumParams{
+		Title: "Apple", SortTitle: "Apple", ArtistID: artist.ID,
+	})
+	_, _ = q.UpsertAlbum(context.Background(), dbq.UpsertAlbumParams{
+		Title: "Mango", SortTitle: "Mango", ArtistID: artist.ID,
+	})
+
+	w := doListLibraryAlbums(h, user, "limit=10")
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d, body = %s", w.Code, w.Body.String())
+	}
+	var got Page[AlbumRef]
+	if err := json.Unmarshal(w.Body.Bytes(), &got); err != nil {
+		t.Fatalf("decode: %v", err)
+	}
+	if got.Total != 3 {
+		t.Errorf("total = %d, want 3", got.Total)
+	}
+	titles := []string{got.Items[0].Title, got.Items[1].Title, got.Items[2].Title}
+	if titles[0] != "Apple" || titles[1] != "Mango" || titles[2] != "Zoo" {
+		t.Errorf("titles = %v, want [Apple Mango Zoo]", titles)
+	}
+	if got.Items[0].SortTitle != "Apple" {
+		t.Errorf("sort_title = %q, want Apple", got.Items[0].SortTitle)
+	}
+}
+
+func TestLibraryAlbums_Paging(t *testing.T) {
+	h, pool := testHandlers(t)
+	user := seedUser(t, pool, "alice", "pw", false)
+	q := dbq.New(pool)
+	artist, _ := q.UpsertArtist(context.Background(), dbq.UpsertArtistParams{
+		Name: "ArtistA", SortName: "ArtistA",
+	})
+	for _, title := range []string{"A", "B", "C", "D"} {
+		_, _ = q.UpsertAlbum(context.Background(), dbq.UpsertAlbumParams{
+			Title: title, SortTitle: title, ArtistID: artist.ID,
+		})
+	}
+
+	w := doListLibraryAlbums(h, user, "limit=2&offset=2")
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d", w.Code)
+	}
+	var got Page[AlbumRef]
+	_ = json.Unmarshal(w.Body.Bytes(), &got)
+	if got.Total != 4 || got.Limit != 2 || got.Offset != 2 {
+		t.Errorf("envelope = %+v, want total=4 limit=2 offset=2", got)
+	}
+	if len(got.Items) != 2 || got.Items[0].Title != "C" || got.Items[1].Title != "D" {
+		t.Errorf("items = %v, want [C D]", got.Items)
+	}
+}