App v0.2.26 and gateway 0.1.20

Client: seek controls, Bazarr subtitle download and cast panel in the
player; MDBList ratings strip; episode and schedule detail pages; series
pace estimate; what's new panel; install-permission onboarding step;
synced per-profile preferences; Emby outage banner.

Gateway: rebuilt admin console (one fragment per page), preference
history and restore, merged Continue Watching, Emby health probe,
subtitle selection and Bazarr download, structured request logging with
per-request identity, and embedded build version.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

server/internal/recommend/related_test.go

@@ -0,0 +1,152 @@
+package recommend
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"io"
+	"log/slog"
+	"testing"
+
+	"github.com/ponzischeme89/memby/server/internal/emby"
+)
+
+func relatedSubject() Item {
+	decoded := Decode([]json.RawMessage{
+		json.RawMessage(`{"Id":"subject","Name":"The Subject","Type":"Movie","Genres":["Thriller"]}`),
+	})
+	return decoded[0]
+}
+
+func relatedEngine(source Source) *Engine {
+	engine := NewEngine(source, slog.New(slog.NewTextHandler(io.Discard, nil)))
+	engine.MinRowItems = 2
+	return engine
+}
+
+func relatedCatalogue(prefix string, count int) []json.RawMessage {
+	out := make([]json.RawMessage, 0, count)
+	for i := 0; i < count; i++ {
+		id := prefix + string(rune('a'+i))
+		out = append(out, json.RawMessage(
+			`{"Id":"`+id+`","Name":"`+id+`","Type":"Movie","Genres":["Thriller"]}`,
+		))
+	}
+	return out
+}
+
+func relatedIDs(items []Item) []string {
+	out := make([]string, 0, len(items))
+	for _, item := range items {
+		out = append(out, item.ID)
+	}
+	return out
+}
+
+// The taste profile costs the same Emby fan-out the home rows pay for, and it is the
+// half of this answer a detail page can do without. Losing it must cost the reasons, not
+// the carousel — before this the whole request 502'd and the page said it had failed.
+func TestRelatedSurvivesAProfileThatCannotBeBuilt(t *testing.T) {
+	source := &fakeSource{
+		itemsErr: errors.New("emby is unwell"),
+		similar:  map[string][]json.RawMessage{"subject": relatedCatalogue("similar-", 4)},
+	}
+
+	reasons, related, err := relatedEngine(source).RelatedTo(
+		context.Background(), emby.Credentials{UserID: "u1"}, relatedSubject(), 12,
+	)
+	if err != nil {
+		t.Fatalf("expected a degraded answer, got error: %v", err)
+	}
+	if len(related) != 4 {
+		t.Fatalf("expected Emby's similar list, got %v", relatedIDs(related))
+	}
+	for _, reason := range reasons {
+		if reason == "" {
+			t.Fatal("a reason must never be blank")
+		}
+	}
+}
+
+// A viewer who navigated on is not a fault, and continuing to fan out on their behalf
+// spends Emby requests nobody is waiting for.
+func TestRelatedReportsAnAbandonedRequest(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	source := &fakeSource{itemsErr: context.Canceled}
+	_, _, err := relatedEngine(source).RelatedTo(
+		ctx, emby.Credentials{UserID: "u1"}, relatedSubject(), 12,
+	)
+	if !errors.Is(err, context.Canceled) {
+		t.Fatalf("expected the cancellation to be reported, got %v", err)
+	}
+}
+
+// Emby erroring and Emby honestly knowing nothing similar look identical on a TV, so both
+// fall through to the household's own catalogue in the same genres.
+func TestRelatedFallsBackToTheImportedCatalogue(t *testing.T) {
+	for name, source := range map[string]*fakeSource{
+		"similar lookup failed": {similarErr: errors.New("emby is unwell")},
+		"nothing similar known": {similar: map[string][]json.RawMessage{}},
+	} {
+		t.Run(name, func(t *testing.T) {
+			engine := relatedEngine(source)
+			engine.Library = &fakeForYouLibrary{items: relatedCatalogue("library-", 3)}
+
+			_, related, err := engine.RelatedTo(
+				context.Background(), emby.Credentials{UserID: "u1"}, relatedSubject(), 12,
+			)
+			if err != nil {
+				t.Fatalf("the fallback must not fail: %v", err)
+			}
+			if len(related) != 3 {
+				t.Fatalf("expected the genre pool, got %v", relatedIDs(related))
+			}
+		})
+	}
+}
+
+// The catalogue always contains the title the page is about, and Emby's own similarity
+// list occasionally does.
+func TestRelatedNeverIncludesItsOwnSubject(t *testing.T) {
+	subject := json.RawMessage(
+		`{"Id":"subject","Name":"The Subject","Type":"Movie","Genres":["Thriller"]}`,
+	)
+	source := &fakeSource{similar: map[string][]json.RawMessage{
+		"subject": append([]json.RawMessage{subject}, relatedCatalogue("similar-", 3)...),
+	}}
+	engine := relatedEngine(source)
+	engine.Library = &fakeForYouLibrary{items: []json.RawMessage{subject}}
+
+	_, related, err := engine.RelatedTo(
+		context.Background(), emby.Credentials{UserID: "u1"}, relatedSubject(), 12,
+	)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	for _, item := range related {
+		if item.ID == "subject" {
+			t.Fatalf("the page's own title was returned to it: %v", relatedIDs(related))
+		}
+	}
+}
+
+// With no imported catalogue there is nothing to fall back to, and an empty carousel is
+// still an answer the page can open with.
+func TestRelatedWithoutALibraryStillAnswers(t *testing.T) {
+	source := &fakeSource{similarErr: errors.New("emby is unwell")}
+
+	reasons, related, err := relatedEngine(source).RelatedTo(
+		context.Background(), emby.Credentials{UserID: "u1"}, relatedSubject(), 12,
+	)
+	if err != nil {
+		t.Fatalf("expected an empty answer, got error: %v", err)
+	}
+	if len(related) != 0 {
+		t.Fatalf("expected nothing, got %v", relatedIDs(related))
+	}
+	if len(reasons) == 0 {
+		t.Fatal("catalogue facts should still explain the title")
+	}
+}