diff --git a/messages_essentials.go b/messages_essentials.go
index ad95e04..7955b6e 100644
--- a/messages_essentials.go
+++ b/messages_essentials.go
@@ -26,6 +26,8 @@ func init() {
 		"signature_pad.empty": {"Sign here", "请在此签名"},
 		"signature_pad.clear": {"Clear", "清除"},
 
+		"undo_toast.undo": {"Undo", "撤销"},
+
 		"qr_code.label":    {"QR code", "二维码"},
 		"qr_code.too_long": {"Text too long for a QR code", "文字过长，无法生成二维码"},
 	})
diff --git a/testdata/snapshots/darwin/undo_toast-dark.png b/testdata/snapshots/darwin/undo_toast-dark.png
new file mode 100644
index 0000000..61e51a2
Binary files /dev/null and b/testdata/snapshots/darwin/undo_toast-dark.png differ
diff --git a/testdata/snapshots/darwin/undo_toast-light.png b/testdata/snapshots/darwin/undo_toast-light.png
new file mode 100644
index 0000000..26b855e
Binary files /dev/null and b/testdata/snapshots/darwin/undo_toast-light.png differ
diff --git a/undo_toast.go b/undo_toast.go
new file mode 100644
index 0000000..bbbe138
--- /dev/null
+++ b/undo_toast.go
@@ -0,0 +1,136 @@
+package mujica
+
+import (
+	"cmp"
+	"fmt"
+	"log/slog"
+	"math"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/icons"
+	"mujicaui/theme"
+)
+
+// UndoToastOptions configure an UndoToast.
+type UndoToastOptions struct {
+	// OnUndo is required; it runs when the user undoes.
+	OnUndo func()
+	// Duration is the countdown; zero is ToastDuration.
+	Duration time.Duration
+	// Action labels the button; empty uses "Undo".
+	Action string
+}
+
+// UndoToastResult reports how an UndoToast ended this frame, if it did.
+type UndoToastResult struct {
+	Element *ui.Element
+	Undone  bool
+	// Expired: the countdown ran out, or the user closed it; the action stands.
+	Expired bool
+}
+
+// undoToastClock counts the time shown, stopped while hovered or focused.
+type undoToastClock struct {
+	message string
+	spent   time.Duration
+	runFrom time.Time
+}
+
+// UndoToast shows message at the bottom of the window with a countdown while *open; it never takes the focus.
+func UndoToast(c *ui.Context, open *bool, message string, opts UndoToastOptions) UndoToastResult {
+	if open == nil || message == "" || opts.OnUndo == nil {
+		panic("mujica: UndoToast needs open, a message and OnUndo")
+	}
+	if opts.Duration < 0 {
+		panic("mujica: negative UndoToast Duration")
+	}
+	clock := ui.Local(c.Root(), "undo_toast", func() *undoToastClock { return &undoToastClock{} })
+	s := *clock
+	var res UndoToastResult
+	if !*open {
+		*s = undoToastClock{}
+		return res
+	}
+	now := c.Now()
+	life := cmp.Or(opts.Duration, ToastDuration)
+	if s.message != message {
+		*s = undoToastClock{message: message, runFrom: now}
+		c.Announce(message)
+	}
+	spent := s.spent
+	if !s.runFrom.IsZero() {
+		spent += now.Sub(s.runFrom)
+	}
+	if spent >= life {
+		*open, res.Expired = false, true
+		*s = undoToastClock{}
+		slog.Debug("mujica: undo_toast expired")
+		return res
+	}
+	k := Tokens(c)
+	u := Density(c).Unit()
+	ww, _ := c.Size()
+	left := life - spent
+	ui.Overlay(c, func() {
+		dock := ui.Row(c).Absolute().Left(0).Right(0).Bottom(u * 4).Justify(ui.Center).PassThrough()
+		dock.Children(func() {
+			card := ui.Column(c).Width(min(420, ww-8*u)).Radius(theme.PopupRadius).Background(k.Surface).
+				Border(theme.BorderWidth, k.ControlBorder).Role(ui.RoleStatus).Label(message).Clip()
+			card.Shadow(0, 4, 12, 0, ui.RGBA(0, 0, 0, 0.14))
+			card.Transition(ui.ElementTransition{Duration: theme.PopupDuration, Enter: &ui.Motion{Y: 8}, Exit: &ui.Motion{}})
+			res.Element = card
+			card.Children(func() {
+				ui.Row(c).AlignItems(ui.Center).Gap(u*3).Padding(u*2, u*2, u*2, u*4).Children(func() {
+					ui.Text(c, message).TextColor(k.Text).Grow(1).Shrink(1)
+					secs := int(math.Ceil(left.Seconds()))
+					label := fmt.Sprintf("%s (%d)", cmp.Or(opts.Action, msg(c, "undo_toast.undo")), secs)
+					if Button(c, label, ButtonOptions{Variant: Ghost, Icon: icons.Must("refresh-cw")}).Clicked() {
+						res.Undone = true
+					}
+					if iconAction(c, icons.Must("x"), msg(c, "toast.close")).Clicked() {
+						res.Expired = true
+					}
+				})
+				still := c.Preferences().ReduceMotion
+				ui.Box(c).FillWidth().Height(2).Role(ui.RoleNone).Draw(func(p *ui.Painter, r ui.Rect) {
+					if still {
+						return
+					}
+					rest := left
+					if !s.runFrom.IsZero() {
+						rest = life - s.spent - p.Now().Sub(s.runFrom)
+						p.AnimationFrame()
+					}
+					p.Fill(ui.Rect{X: r.X, Y: r.Y, W: r.W * max(0, float32(rest)/float32(life)), H: r.H}, k.AccentText, 0)
+				})
+			})
+			if card.Shortcut(0, ui.KeyEscape) {
+				res.Expired = true
+			}
+			// Hover or focus holds the countdown.
+			switch held := card.Hovered() || card.FocusWithin(); {
+			case held && !s.runFrom.IsZero():
+				s.spent, s.runFrom = spent, time.Time{}
+			case !held && s.runFrom.IsZero():
+				s.runFrom = now
+			}
+		})
+	})
+	switch {
+	case res.Undone:
+		*open, res.Expired = false, false
+		*s = undoToastClock{}
+		slog.Debug("mujica: undo_toast undo")
+		opts.OnUndo()
+	case res.Expired:
+		*open = false
+		*s = undoToastClock{}
+		slog.Debug("mujica: undo_toast closed")
+	case !s.runFrom.IsZero():
+		// Wake for the next whole second of the count, and for the end.
+		c.After(min(left, left-left.Truncate(time.Second)+time.Millisecond))
+	}
+	return res
+}
diff --git a/undo_toast_test.go b/undo_toast_test.go
new file mode 100644
index 0000000..4c687d7
--- /dev/null
+++ b/undo_toast_test.go
@@ -0,0 +1,91 @@
+package mujica
+
+import (
+	"slices"
+	"testing"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+)
+
+func undoTester(open *bool, life time.Duration, undos *int, last *UndoToastResult) *ui.Tester {
+	return ui.NewTester(func(c *ui.Context) {
+		Use(c, Settings{})
+		if Button(c, "Delete", ButtonOptions{}).Clicked() {
+			*open = true
+		}
+		if r := UndoToast(c, open, "File deleted", UndoToastOptions{Duration: life, OnUndo: func() { *undos++ }}); r.Undone || r.Expired {
+			*last = r
+		}
+	}, 600, 400)
+}
+
+func TestUndoToastUndoAndFocus(t *testing.T) {
+	open, undos := false, 0
+	var last UndoToastResult
+	tt := undoTester(&open, 0, &undos, &last)
+	tt.Key(0, ui.KeyTab)
+	tt.Key(0, ui.KeyEnter)
+	if !tt.HasText("File deleted") || !tt.HasText("Undo (5)") || !tt.Focused("Delete") {
+		t.Fatalf("shown %q, focus kept %v", tt.Texts(), tt.Focused("Delete"))
+	}
+	if !slices.Contains(tt.Announcements(), "File deleted") {
+		t.Fatal("not announced")
+	}
+	if err := tt.Click("Undo (5)"); err != nil {
+		t.Fatal(err)
+	}
+	if undos != 1 || open || !last.Undone || tt.HasText("File deleted") {
+		t.Fatalf("undo: %d %v %+v", undos, open, last)
+	}
+}
+
+func TestUndoToastCountdownPauseAndClose(t *testing.T) {
+	open, undos := false, 0
+	var last UndoToastResult
+	tt := undoTester(&open, 60*time.Millisecond, &undos, &last)
+	_ = tt.Click("Delete")
+	r, _ := tt.Find("File deleted")
+	tt.Move(r.X+r.W/2, r.Y+r.H/2)
+	time.Sleep(90 * time.Millisecond)
+	tt.Frame()
+	if !open {
+		t.Fatal("hovered countdown ran out")
+	}
+	tt.Move(5, 5)
+	time.Sleep(90 * time.Millisecond)
+	tt.Frame()
+	if open || !last.Expired || undos != 0 {
+		t.Fatalf("expiry: %v %+v %d", open, last, undos)
+	}
+	last = UndoToastResult{}
+	_ = tt.Click("Delete")
+	_ = tt.Click("Dismiss notification")
+	if open || !last.Expired || undos != 0 {
+		t.Fatalf("close: %v %+v", open, last)
+	}
+}
+
+func TestUndoToastRejects(t *testing.T) {
+	open := true
+	for name, f := range map[string]func(c *ui.Context){
+		"no undo":  func(c *ui.Context) { UndoToast(c, &open, "x", UndoToastOptions{}) },
+		"negative": func(c *ui.Context) { UndoToast(c, &open, "x", UndoToastOptions{OnUndo: func() {}, Duration: -1}) },
+	} {
+		func() {
+			defer func() {
+				if recover() == nil {
+					t.Errorf("%s: no panic", name)
+				}
+			}()
+			ui.NewTester(func(c *ui.Context) { Use(c, Settings{}); f(c) }, 300, 200)
+		}()
+	}
+}
+
+func TestUndoToastSnapshot(t *testing.T) {
+	open := true
+	snapshot(t, "undo_toast", 520, 160, func(c *ui.Context) {
+		UndoToast(c, &open, "3 messages archived", UndoToastOptions{OnUndo: func() {}, Duration: time.Hour})
+	})
+}