feat: add PageUp/PageDown support to SelectableList

internal/ui/selectable_list.go

@@ -95,6 +95,23 @@ func (sl *SelectableList) HandleListEvent(ev tcell.Event, rect Rect, itemCount i
 				sl.Selected++
 			}
 			return ListEventResult{Result: EventConsumed}
+		case tcell.KeyPgDn:
+			sl.Selected += rect.H
+			if sl.Selected >= itemCount {
+				sl.Selected = itemCount - 1
+			}
+			if sl.Selected < 0 {
+				sl.Selected = 0
+			}
+			sl.EnsureVisible(rect.H)
+			return ListEventResult{Result: EventConsumed}
+		case tcell.KeyPgUp:
+			sl.Selected -= rect.H
+			if sl.Selected < 0 {
+				sl.Selected = 0
+			}
+			sl.EnsureVisible(rect.H)
+			return ListEventResult{Result: EventConsumed}
 		case tcell.KeyEnter:
 			return ListEventResult{Result: EventConsumed, Action: ListActionActivate}
 		}

internal/ui/selectable_list_test.go

@@ -177,6 +177,119 @@ func TestSelectableListClampSelected(t *testing.T) {
 	}
 }
 
+func TestSelectableListPageDown(t *testing.T) {
+	sl := &SelectableList{Selected: 0, ScrollTop: 0}
+	r := Rect{X: 0, Y: 0, W: 20, H: 10}
+	items := 50
+
+	// PageDown moves by page size (rect.H = 10)
+	res := sl.HandleListEvent(tcell.NewEventKey(tcell.KeyPgDn, 0, 0), r, items)
+	if res.Result != EventConsumed {
+		t.Fatal("PageDown should be consumed")
+	}
+	if sl.Selected != 10 {
+		t.Fatalf("expected Selected 10, got %d", sl.Selected)
+	}
+
+	// PageDown again
+	sl.HandleListEvent(tcell.NewEventKey(tcell.KeyPgDn, 0, 0), r, items)
+	if sl.Selected != 20 {
+		t.Fatalf("expected Selected 20, got %d", sl.Selected)
+	}
+
+	// PageDown near end — clamps to last item
+	sl.Selected = 45
+	sl.HandleListEvent(tcell.NewEventKey(tcell.KeyPgDn, 0, 0), r, items)
+	if sl.Selected != 49 {
+		t.Fatalf("expected Selected 49 (clamped), got %d", sl.Selected)
+	}
+
+	// PageDown at last item — stays at last
+	sl.HandleListEvent(tcell.NewEventKey(tcell.KeyPgDn, 0, 0), r, items)
+	if sl.Selected != 49 {
+		t.Fatalf("expected Selected 49 (still), got %d", sl.Selected)
+	}
+}
+
+func TestSelectableListPageUp(t *testing.T) {
+	sl := &SelectableList{Selected: 30, ScrollTop: 25}
+	r := Rect{X: 0, Y: 0, W: 20, H: 10}
+	items := 50
+
+	// PageUp moves by page size (rect.H = 10)
+	res := sl.HandleListEvent(tcell.NewEventKey(tcell.KeyPgUp, 0, 0), r, items)
+	if res.Result != EventConsumed {
+		t.Fatal("PageUp should be consumed")
+	}
+	if sl.Selected != 20 {
+		t.Fatalf("expected Selected 20, got %d", sl.Selected)
+	}
+
+	// PageUp again
+	sl.HandleListEvent(tcell.NewEventKey(tcell.KeyPgUp, 0, 0), r, items)
+	if sl.Selected != 10 {
+		t.Fatalf("expected Selected 10, got %d", sl.Selected)
+	}
+
+	// PageUp near start — clamps to 0
+	sl.Selected = 5
+	sl.HandleListEvent(tcell.NewEventKey(tcell.KeyPgUp, 0, 0), r, items)
+	if sl.Selected != 0 {
+		t.Fatalf("expected Selected 0 (clamped), got %d", sl.Selected)
+	}
+
+	// PageUp at start — stays at 0
+	sl.HandleListEvent(tcell.NewEventKey(tcell.KeyPgUp, 0, 0), r, items)
+	if sl.Selected != 0 {
+		t.Fatalf("expected Selected 0 (still), got %d", sl.Selected)
+	}
+}
+
+func TestSelectableListPageDownScrollOffset(t *testing.T) {
+	sl := &SelectableList{Selected: 0, ScrollTop: 0}
+	r := Rect{X: 0, Y: 0, W: 20, H: 10}
+	items := 50
+
+	// PageDown should update ScrollTop to keep selection visible
+	sl.HandleListEvent(tcell.NewEventKey(tcell.KeyPgDn, 0, 0), r, items)
+	if sl.Selected != 10 {
+		t.Fatalf("expected Selected 10, got %d", sl.Selected)
+	}
+	// Selected=10 should be visible: ScrollTop should be at least 1
+	if sl.ScrollTop > sl.Selected || sl.Selected >= sl.ScrollTop+r.H {
+		t.Fatalf("Selected %d not visible with ScrollTop %d and H %d", sl.Selected, sl.ScrollTop, r.H)
+	}
+}
+
+func TestSelectableListPageUpScrollOffset(t *testing.T) {
+	sl := &SelectableList{Selected: 40, ScrollTop: 35}
+	r := Rect{X: 0, Y: 0, W: 20, H: 10}
+	items := 50
+
+	// PageUp should update ScrollTop to keep selection visible
+	sl.HandleListEvent(tcell.NewEventKey(tcell.KeyPgUp, 0, 0), r, items)
+	if sl.Selected != 30 {
+		t.Fatalf("expected Selected 30, got %d", sl.Selected)
+	}
+	if sl.ScrollTop > sl.Selected || sl.Selected >= sl.ScrollTop+r.H {
+		t.Fatalf("Selected %d not visible with ScrollTop %d and H %d", sl.Selected, sl.ScrollTop, r.H)
+	}
+}
+
+func TestSelectableListPageDownEmptyList(t *testing.T) {
+	sl := &SelectableList{Selected: 0}
+	r := Rect{X: 0, Y: 0, W: 20, H: 10}
+
+	// PageDown with 0 items should not panic, Selected stays 0
+	res := sl.HandleListEvent(tcell.NewEventKey(tcell.KeyPgDn, 0, 0), r, 0)
+	if res.Result != EventConsumed {
+		t.Fatal("PageDown should be consumed even for empty list")
+	}
+	if sl.Selected != 0 {
+		t.Fatalf("expected Selected 0 for empty list, got %d", sl.Selected)
+	}
+}
+
 func TestSelectableListUnhandledKey(t *testing.T) {
 	sl := &SelectableList{}
 	r := Rect{X: 0, Y: 0, W: 20, H: 10}