Series drill-down: season posters

The drill-down reads the series with includeSeasonImages=true (Sonarr
only sends season posters when asked, as TheTVDB links). A selected
season or episode shows its season's poster; without one, or when it
cannot be loaded, the series poster.

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

internal/ui/episodes.go

@@ -257,7 +257,32 @@ func (v *seriesView) renderDetail() {
 			sum = se
 		}
 	}
-	v.detail.Show(seriesRowDetail(v.series, r.ep, r.season, sum, v.seasonMonitored(r.season), time.Now().Format("2006-01-02")), v.cover)
+	v.detail.Show(seriesRowDetail(v.series, r.ep, r.season, sum, v.seasonMonitored(r.season), time.Now().Format("2006-01-02")), v.seasonCover(r.season))
+}
+
+// seasonCover is the poster of a season, for its row and its episodes: the
+// season's own poster where Sonarr has one (a TheTVDB link, fetched without
+// credentials), else, or when it cannot be loaded, the series poster.
+func (v *seriesView) seasonCover(season int) coverRef {
+	for _, se := range v.series.Seasons {
+		if se.SeasonNumber != season {
+			continue
+		}
+		for _, img := range se.Images {
+			if img.CoverType != "poster" || img.RemoteURL == "" {
+				continue
+			}
+			remote, series := img.RemoteURL, v.cover
+			return coverRef{key: "season|" + remote, fetch: func(ctx context.Context, large bool) ([]byte, error) {
+				data, err := arr.FetchURL(ctx, remote)
+				if err != nil && series.fetch != nil {
+					return series.fetch(ctx, large)
+				}
+				return data, err
+			}}
+		}
+	}
+	return v.cover
 }
 
 // seriesRowDetail is the detail text of the drill-down: the series, then the

internal/ui/library_test.go

@@ -1,6 +1,9 @@
 package ui
 
 import (
+	"context"
+	"net/http"
+	"net/http/httptest"
 	"slices"
 	"strings"
 	"testing"
@@ -308,3 +311,37 @@ func TestCutToWidth(t *testing.T) {
 		}
 	}
 }
+
+func TestSeasonPoster(t *testing.T) {
+	seasonSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/broken.jpg" {
+			http.NotFound(w, r)
+			return
+		}
+		w.Write([]byte("SEASON"))
+	}))
+	defer seasonSrv.Close()
+
+	series := coverRef{key: "series", fetch: func(context.Context, bool) ([]byte, error) { return []byte("SERIES"), nil }}
+	v := &seriesView{cover: series, series: sonarr.Series{Seasons: []sonarr.Season{
+		{SeasonNumber: 1, Images: []arr.Image{{CoverType: "poster", RemoteURL: seasonSrv.URL + "/s1.jpg"}}},
+		{SeasonNumber: 2},
+		{SeasonNumber: 3, Images: []arr.Image{{CoverType: "poster", RemoteURL: seasonSrv.URL + "/broken.jpg"}}},
+	}}}
+	fetch := func(season int) string {
+		data, err := v.seasonCover(season).fetch(t.Context(), false)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return string(data)
+	}
+	if got := fetch(1); got != "SEASON" || v.seasonCover(1).key == series.key {
+		t.Errorf("season 1: %q", got)
+	}
+	if v.seasonCover(2).key != series.key {
+		t.Error("a season without a poster shows the series poster")
+	}
+	if got := fetch(3); got != "SERIES" {
+		t.Errorf("a season poster that cannot be loaded falls back to the series poster: %q", got)
+	}
+}