Stage 7 (wip): tests + UI CI

- Vitest units: board replay, placement machine, premium parity, i18n key parity, FlatBuffers codec round-trips (19 tests)
- Playwright smoke (mock transport): guest -> lobby -> board -> place tile -> preview
- ui-test.yaml workflow: check/unit/build + bundle-size budget (67.5KB gzip < 100KB) + chromium e2e
- gateway transcode tests for games.list (seat display_name), pass, hint
- backend integration test for game.ListForAccount

backend/internal/inttest/game_test.go

@@ -86,6 +86,63 @@ func readStats(t *testing.T, id uuid.UUID) (wins, losses, draws, maxGame, maxWor
 	return wins, losses, draws, maxGame, maxWord, true
 }
 
+// TestListForAccount checks the lobby "my games" query: it returns exactly the
+// games the account is seated in (each with its seats), and nothing for an outsider.
+func TestListForAccount(t *testing.T) {
+	ctx := context.Background()
+	svc := newGameService()
+	me, opp := provisionAccount(t), provisionAccount(t)
+
+	g1, err := svc.Create(ctx, game.CreateParams{
+		Variant: engine.VariantEnglish, Seats: []uuid.UUID{me, opp}, TurnTimeout: 24 * time.Hour, Seed: 1,
+	})
+	if err != nil {
+		t.Fatalf("create g1: %v", err)
+	}
+	g2, err := svc.Create(ctx, game.CreateParams{
+		Variant: engine.VariantEnglish, Seats: []uuid.UUID{opp, me}, TurnTimeout: 24 * time.Hour, Seed: 2,
+	})
+	if err != nil {
+		t.Fatalf("create g2: %v", err)
+	}
+
+	games, err := svc.ListForAccount(ctx, me)
+	if err != nil {
+		t.Fatalf("list: %v", err)
+	}
+	if len(games) != 2 {
+		t.Fatalf("got %d games, want 2", len(games))
+	}
+	seen := map[uuid.UUID]bool{}
+	for _, g := range games {
+		seen[g.ID] = true
+		if len(g.Seats) != 2 {
+			t.Errorf("game %s has %d seats, want 2", g.ID, len(g.Seats))
+		}
+		seated := false
+		for _, s := range g.Seats {
+			if s.AccountID == me {
+				seated = true
+			}
+		}
+		if !seated {
+			t.Errorf("account not found among seats of returned game %s", g.ID)
+		}
+	}
+	if !seen[g1.ID] || !seen[g2.ID] {
+		t.Errorf("returned games %v missing g1=%s or g2=%s", seen, g1.ID, g2.ID)
+	}
+
+	other := provisionAccount(t)
+	og, err := svc.ListForAccount(ctx, other)
+	if err != nil {
+		t.Fatalf("list other: %v", err)
+	}
+	if len(og) != 0 {
+		t.Errorf("outsider sees %d games, want 0", len(og))
+	}
+}
+
 // TestGameLifecycleAndStats drives a greedy two-player game to its natural end
 // through the service and checks the finish state and statistics.
 func TestGameLifecycleAndStats(t *testing.T) {