Trakt lists: keep the Radarr/Sonarr lookups of their titles on disk

Library membership is asked every time via movie?tmdbId= / series?tvdbId=;
only the lookups of titles not in the library are stored (3 days).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/ui/lookups_test.go

@@ -0,0 +1,63 @@
+package ui
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"sync/atomic"
+	"testing"
+
+	"git.stinnesbeck.com/nils/arr-tui/internal/radarr"
+	"git.stinnesbeck.com/nils/arr-tui/internal/trakt"
+)
+
+func TestListLookupsKeptOnDisk(t *testing.T) {
+	var lookups, libraryAsks atomic.Int32
+	inLibrary := false
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/api/v3/movie":
+			libraryAsks.Add(1)
+			if inLibrary && r.URL.Query().Get("tmdbId") == "949" {
+				w.Write([]byte(`[{"id":7,"title":"Heat","year":1995,"tmdbId":949}]`))
+				return
+			}
+			w.Write([]byte(`[{"id":3,"title":"Other","tmdbId":1}]`)) // ignores the filter
+		case "/api/v3/movie/lookup":
+			lookups.Add(1)
+			w.Write([]byte(`[{"title":"Heat","year":1995,"tmdbId":949,"overview":"Cops and robbers."}]`))
+		}
+	}))
+	defer srv.Close()
+	disk := &diskCache{dir: t.TempDir()}
+	entry := trakt.Entry{Title: "Heat", IDs: trakt.IDs{TMDB: 949}}
+	resolve := func() result {
+		t.Helper()
+		store := newLookupStore(disk) // a new run
+		b := radarrBackend{radarr.NewClient(srv.URL, "k"), store}
+		r, err := b.resolve(context.Background(), entry)
+		if err != nil || r == nil {
+			t.Fatalf("resolve: %v %v", r, err)
+		}
+		if err := store.save(); err != nil {
+			t.Fatal(err)
+		}
+		return r
+	}
+
+	if r := resolve(); r.inLibrary() || lookups.Load() != 1 {
+		t.Fatalf("first run: in library %v, %d lookups", r.inLibrary(), lookups.Load())
+	}
+	r := resolve()
+	if lookups.Load() != 1 || r.details().plot != "Cops and robbers." {
+		t.Errorf("second run: %d lookups, plot %q", lookups.Load(), r.details().plot)
+	}
+	// Added meanwhile (elsewhere): the library answer wins over the stored lookup.
+	inLibrary = true
+	if r := resolve(); !r.inLibrary() || lookups.Load() != 1 {
+		t.Errorf("after adding: in library %v, %d lookups", r.inLibrary(), lookups.Load())
+	}
+	if libraryAsks.Load() != 3 {
+		t.Errorf("library asked %d times", libraryAsks.Load())
+	}
+}