diff --git a/blink_highlight_test.go b/blink_highlight_test.go
new file mode 100644
index 0000000..ebc9e59
--- /dev/null
+++ b/blink_highlight_test.go
@@ -0,0 +1,71 @@
+package mujica
+
+import (
+	"bytes"
+	"testing"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+)
+
+func TestBlinkHighlightFlashesOnceWithDirection(t *testing.T) {
+	value := 10.0
+	tt, n := motionFrames(func(c *ui.Context) {
+		BlinkHighlight(c, value, BlinkHighlightOptions{Duration: 200 * time.Millisecond})
+	}, 200, 60)
+	if motionBusy(tt, n) {
+		t.Fatal("first value flashed")
+	}
+	if _, ok := tt.Find("10.00"); !ok {
+		t.Fatal("value not named")
+	}
+	value = 12
+	tt.Frame()
+	a := encode(t, tt.Image())
+	if _, ok := tt.Find("12.00, up"); !ok {
+		t.Fatalf("direction not named: %q", tt.Texts())
+	}
+	time.Sleep(250 * time.Millisecond)
+	tt.Frame()
+	if bytes.Equal(a, encode(t, tt.Image())) || motionBusy(tt, n) {
+		t.Fatal("flash did not fade and stop")
+	}
+	value = 9
+	tt.Frame()
+	if _, ok := tt.Find("9.00, down"); !ok {
+		t.Fatalf("down not named: %q", tt.Texts())
+	}
+	tt.SetPreferences(ui.Preferences{ReduceMotion: true, TextScale: 1})
+	value = 11
+	tt.Frame()
+	if motionBusy(tt, n) {
+		t.Fatal("flash under reduced motion")
+	}
+	if _, ok := tt.Find("11.00, up"); !ok {
+		t.Fatal("static mark missing under reduced motion")
+	}
+}
+
+func TestBlinkHighlightInvalid(t *testing.T) {
+	defer func() {
+		if recover() == nil {
+			t.Fatal("no panic")
+		}
+	}()
+	ui.Render(func(c *ui.Context) {
+		Use(c, Settings{})
+		BlinkHighlight(c, 1, BlinkHighlightOptions{Duration: -1})
+	}, 100, 50, 1)
+}
+
+func TestBlinkHighlightSnapshot(t *testing.T) {
+	snapshotAfter(t, "blink_highlight", 300, 100, func(c *ui.Context) {
+		v := ui.Local(c.Root(), "v", func() float64 { return 101.5 })
+		w := ui.Local(c.Root(), "w", func() float64 { return 88.25 })
+		ui.Column(c).Padding(16).Gap(8).AlignItems(ui.Start).Children(func() {
+			BlinkHighlight(c, *v, BlinkHighlightOptions{})
+			BlinkHighlight(c, *w, BlinkHighlightOptions{})
+		})
+		*v, *w = 103.75, 86.5
+	}, func(tt *ui.Tester) { tt.Frame() })
+}
diff --git a/cost_breakdown.go b/cost_breakdown.go
index b86296c..7b88a78 100644
--- a/cost_breakdown.go
+++ b/cost_breakdown.go
@@ -91,8 +91,8 @@ func CostBreakdown(c *ui.Context, s *CostBreakdownState, items []CostItem, opts
 	cols := []DataColumn[costRow]{
 		{ID: "name", Title: groupTitle, Sortable: true, Compare: func(a, b costRow) int { return cmp.Compare(a.name, b.name) }, Text: func(r costRow) string { return r.name }},
 		{ID: "calls", Title: msg(c, "cost_breakdown.calls"), Width: 80, Align: ui.End, Sortable: true, Compare: func(a, b costRow) int { return cmp.Compare(a.calls, b.calls) }, Text: func(r costRow) string { return count(r.calls) }},
-		{ID: "input", Title: msg(c, "cost_breakdown.input"), Width: 110, Align: ui.End, Sortable: true, Compare: func(a, b costRow) int { return cmp.Compare(a.input, b.input) }, Text: func(r costRow) string { return count(r.input) }},
-		{ID: "output", Title: msg(c, "cost_breakdown.output"), Width: 110, Align: ui.End, Sortable: true, Compare: func(a, b costRow) int { return cmp.Compare(a.output, b.output) }, Text: func(r costRow) string { return count(r.output) }},
+		{ID: "input", Title: msg(c, "cost_breakdown.input"), Width: 120, Align: ui.End, Sortable: true, Compare: func(a, b costRow) int { return cmp.Compare(a.input, b.input) }, Text: func(r costRow) string { return count(r.input) }},
+		{ID: "output", Title: msg(c, "cost_breakdown.output"), Width: 130, Align: ui.End, Sortable: true, Compare: func(a, b costRow) int { return cmp.Compare(a.output, b.output) }, Text: func(r costRow) string { return count(r.output) }},
 		{ID: "cost", Title: msg(c, "cost_breakdown.cost"), Width: 160, Sortable: true, Compare: func(a, b costRow) int { return cmp.Compare(a.cost, b.cost) },
 			Text: func(r costRow) string { return money(r.cost) },
 			Cell: func(r costRow) {
diff --git a/cost_breakdown_test.go b/cost_breakdown_test.go
new file mode 100644
index 0000000..0445900
--- /dev/null
+++ b/cost_breakdown_test.go
@@ -0,0 +1,95 @@
+package mujica
+
+import (
+	"testing"
+
+	"github.com/egoist/mygo/ui"
+)
+
+func costSample() []CostItem {
+	return []CostItem{
+		{Model: "opus", Tool: "search", Step: "plan", InputTokens: 1000, OutputTokens: 200, Cost: 0.30},
+		{Model: "haiku", Tool: "search", Step: "gather", InputTokens: 4000, OutputTokens: 500, Cost: 0.05},
+		{Model: "opus", Tool: "write", Step: "write", InputTokens: 2000, OutputTokens: 3000, Cost: 1.15},
+	}
+}
+
+func TestCostSum(t *testing.T) {
+	rows, total := costSum(costSample(), CostByModel, "?")
+	if len(rows) != 2 || rows[0].name != "opus" || rows[0].calls != 2 || rows[0].input != 3000 || total.calls != 3 {
+		t.Fatalf("rows %+v total %+v", rows, total)
+	}
+	if d := total.cost - 1.5; d > 1e-9 || d < -1e-9 {
+		t.Fatalf("total cost %v", total.cost)
+	}
+	rows, _ = costSum([]CostItem{{Cost: 1}}, CostByTool, "(none)")
+	if rows[0].name != "(none)" {
+		t.Fatalf("unnamed group %q", rows[0].name)
+	}
+}
+
+func TestCostBreakdownGroupsAndTotal(t *testing.T) {
+	var s CostBreakdownState
+	by := CostByModel
+	items := costSample()
+	tt := ui.NewTester(func(c *ui.Context) {
+		Use(c, Settings{})
+		ui.Column(c).Height(400).Children(func() {
+			CostBreakdown(c, &s, items, CostBreakdownOptions{GroupBy: by}).Element.Grow(1)
+		})
+	}, 800, 420)
+	for _, want := range []string{"opus", "haiku", "$1.45", "$0.05", "97%", "Total", "$1.50", "7000 in · 3700 out"} {
+		if !tt.HasText(want) {
+			t.Errorf("missing %q in %q", want, tt.Texts())
+		}
+	}
+	if _, ok := tt.Find("Total $1.50 over 3 calls"); !ok {
+		t.Error("total not named")
+	}
+	rows := &s.rows[0]
+	tt.Frame()
+	if &s.rows[0] != rows {
+		t.Fatal("sums recomputed without a change")
+	}
+	by = CostByStep
+	tt.Frame()
+	if !tt.HasText("gather") || tt.HasText("haiku") {
+		t.Fatalf("group by step: %q", tt.Texts())
+	}
+	if err := tt.Click("Cost"); err != nil {
+		t.Fatal(err)
+	}
+	if s.Table.Sort.Column != "cost" {
+		t.Fatalf("sort %+v", s.Table.Sort)
+	}
+}
+
+func TestCostBreakdownInvalid(t *testing.T) {
+	for _, tc := range []struct {
+		items []CostItem
+		opts  CostBreakdownOptions
+	}{{[]CostItem{{Cost: -1}}, CostBreakdownOptions{}}, {nil, CostBreakdownOptions{GroupBy: 7}}, {nil, CostBreakdownOptions{Decimals: -1}}} {
+		func() {
+			defer func() {
+				if recover() == nil {
+					t.Errorf("%+v did not panic", tc)
+				}
+			}()
+			ui.Render(func(c *ui.Context) {
+				Use(c, Settings{})
+				var s CostBreakdownState
+				CostBreakdown(c, &s, tc.items, tc.opts)
+			}, 300, 200, 1)
+		}()
+	}
+}
+
+func TestCostBreakdownSnapshot(t *testing.T) {
+	items := costSample()
+	snapshot(t, "cost_breakdown", 760, 300, func(c *ui.Context) {
+		s := ui.Local(c.Root(), "s", func() *CostBreakdownState { return &CostBreakdownState{} })
+		ui.Column(c).Padding(16).Height(300).Children(func() {
+			CostBreakdown(c, *s, items, CostBreakdownOptions{}).Element.Grow(1)
+		})
+	})
+}
diff --git a/count_up_test.go b/count_up_test.go
new file mode 100644
index 0000000..a5e2bc9
--- /dev/null
+++ b/count_up_test.go
@@ -0,0 +1,85 @@
+package mujica
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+)
+
+func TestCountUpCountsAndSettles(t *testing.T) {
+	value := 100.0
+	tt, n := motionFrames(func(c *ui.Context) {
+		CountUp(c, value, CountUpOptions{Duration: 300 * time.Millisecond})
+	}, 200, 60)
+	if !tt.HasText("100") || motionBusy(tt, n) {
+		t.Fatalf("first value shown at once: %q", tt.Texts())
+	}
+	value = 200
+	tt.Frame()
+	time.Sleep(100 * time.Millisecond)
+	tt.Frame()
+	mid := ""
+	for _, s := range tt.Texts() {
+		if s != "200" {
+			mid = s
+		}
+	}
+	if mid == "" || mid == "100" {
+		t.Fatalf("no value between: %q", tt.Texts())
+	}
+	time.Sleep(300 * time.Millisecond)
+	tt.Frame()
+	if motionCount(tt, "200") != 2 || motionBusy(tt, n) {
+		t.Fatalf("did not settle: %q", tt.Texts())
+	}
+	tt.SetPreferences(ui.Preferences{ReduceMotion: true, TextScale: 1})
+	value = 5
+	tt.Frame()
+	if motionCount(tt, "5") != 2 {
+		t.Fatalf("reduced motion did not jump: %q", tt.Texts())
+	}
+}
+
+func TestCountUpFormatAndInvalid(t *testing.T) {
+	tt := ui.NewTester(func(c *ui.Context) {
+		Use(c, Settings{})
+		CountUp(c, 12.345, CountUpOptions{Decimals: 1})
+		CountUp(c, 3, CountUpOptions{Format: func(v float64) string { return fmt.Sprintf("%.0f items", v) }})
+	}, 300, 80)
+	if !tt.HasText("12.3") || !tt.HasText("3 items") {
+		t.Fatalf("format: %q", tt.Texts())
+	}
+	for _, o := range []CountUpOptions{{Duration: -1}, {Decimals: -1}} {
+		func() {
+			defer func() {
+				if recover() == nil {
+					t.Errorf("%+v did not panic", o)
+				}
+			}()
+			ui.Render(func(c *ui.Context) { Use(c, Settings{}); CountUp(c, 1, o) }, 100, 50, 1)
+		}()
+	}
+	defer func() {
+		if r := recover(); r == nil || !strings.Contains(fmt.Sprint(r), "finite") {
+			t.Fatal("NaN did not panic")
+		}
+	}()
+	ui.Render(func(c *ui.Context) { Use(c, Settings{}); CountUp(c, nanValue(), CountUpOptions{}) }, 100, 50, 1)
+}
+
+func nanValue() float64 {
+	zero := 0.0
+	return zero / zero
+}
+
+func TestCountUpSnapshot(t *testing.T) {
+	snapshot(t, "count_up", 300, 100, func(c *ui.Context) {
+		ui.Column(c).Padding(16).Gap(8).Children(func() {
+			CountUp(c, 12840, CountUpOptions{}).FontSize(FontSize(c, 28)).Font("Georgia, serif")
+			CountUp(c, 0.875, CountUpOptions{Format: func(v float64) string { return fmt.Sprintf("%.1f%%", v*100) }})
+		})
+	})
+}
diff --git a/eval_result_table_test.go b/eval_result_table_test.go
new file mode 100644
index 0000000..80051fd
--- /dev/null
+++ b/eval_result_table_test.go
@@ -0,0 +1,74 @@
+package mujica
+
+import (
+	"testing"
+
+	"github.com/egoist/mygo/ui"
+)
+
+func evalSample() []EvalCase {
+	return []EvalCase{
+		{ID: "c1", Name: "Greets by title", Score: 0.98, Passed: true},
+		{ID: "c2", Name: "Refuses forgery", Score: 0.41},
+		{ID: "c3", Name: "Summarizes letter", Score: 0.87, Passed: true},
+	}
+}
+
+func TestEvalResultTableSummaryAndDiff(t *testing.T) {
+	var s DataTableState[string]
+	diff := ""
+	tt := ui.NewTester(func(c *ui.Context) {
+		Use(c, Settings{})
+		ui.Column(c).Height(400).Children(func() {
+			r := EvalResultTable(c, &s, evalSample(), EvalResultTableOptions{})
+			r.Table.Element.Grow(1)
+			if id, ok := r.Diff(); ok {
+				diff = id
+			}
+		})
+	}, 700, 420)
+	for _, want := range []string{"2 of 3 passed", "0.41", "Fail", "Pass"} {
+		if !tt.HasText(want) {
+			t.Errorf("missing %q: %q", want, tt.Texts())
+		}
+	}
+	if err := tt.Click("View differences for Refuses forgery"); err != nil {
+		t.Fatal(err)
+	}
+	if diff != "c2" {
+		t.Fatalf("diff %q", diff)
+	}
+	if err := tt.Click("Score"); err != nil {
+		t.Fatal(err)
+	}
+	if s.Sort.Column != "score" {
+		t.Fatalf("sort %+v", s.Sort)
+	}
+}
+
+func TestEvalResultTableInvalid(t *testing.T) {
+	for _, cases := range [][]EvalCase{{{Name: "x"}}, {{ID: "a", Score: nanValue()}}} {
+		func() {
+			defer func() {
+				if recover() == nil {
+					t.Errorf("%+v did not panic", cases)
+				}
+			}()
+			ui.Render(func(c *ui.Context) {
+				Use(c, Settings{})
+				var s DataTableState[string]
+				EvalResultTable(c, &s, cases, EvalResultTableOptions{})
+			}, 300, 200, 1)
+		}()
+	}
+}
+
+func TestEvalResultTableSnapshot(t *testing.T) {
+	cases := evalSample()
+	snapshot(t, "eval_result_table", 640, 300, func(c *ui.Context) {
+		s := ui.Local(c.Root(), "s", func() *DataTableState[string] { return &DataTableState[string]{} })
+		ui.Column(c).Padding(16).Height(300).Children(func() {
+			EvalResultTable(c, *s, cases, EvalResultTableOptions{}).Table.Element.Grow(1)
+		})
+	})
+}
diff --git a/interrupt_button_test.go b/interrupt_button_test.go
new file mode 100644
index 0000000..d7cd259
--- /dev/null
+++ b/interrupt_button_test.go
@@ -0,0 +1,76 @@
+package mujica
+
+import (
+	"testing"
+
+	"github.com/egoist/mygo/ui"
+)
+
+func TestInterruptButtonDirectAndConfirmed(t *testing.T) {
+	running, interrupting, confirm := true, false, false
+	stops := 0
+	tt := ui.NewTester(func(c *ui.Context) {
+		Use(c, Settings{})
+		ui.Column(c).Padding(20).Children(func() {
+			if InterruptButton(c, running, InterruptButtonOptions{Confirm: confirm, Interrupting: interrupting}).Changed() {
+				stops++
+			}
+		})
+	}, 400, 300)
+	if err := tt.Click("Stop"); err != nil {
+		t.Fatal(err)
+	}
+	if stops != 1 {
+		t.Fatalf("direct stop %d", stops)
+	}
+	confirm = true
+	tt.Frame()
+	_ = tt.Click("Stop")
+	if stops != 1 || !tt.HasText("Stop the agent?") {
+		t.Fatalf("confirm not asked: %q", tt.Texts())
+	}
+	_ = tt.Click("Keep running")
+	if stops != 1 || tt.HasText("Stop the agent?") {
+		t.Fatal("cancel interrupted")
+	}
+	_ = tt.Click("Stop")
+	tt.Key(0, ui.KeyTab) // Danger focuses Cancel first; Tab reaches Stop
+	tt.Key(0, ui.KeyEnter)
+	if stops != 2 {
+		t.Fatalf("confirmed stop %d: %q", stops, tt.Texts())
+	}
+	interrupting = true
+	tt.Frame()
+	_ = tt.Click("Stopping")
+	if stops != 2 || !tt.HasText("Stopping") {
+		t.Fatalf("interrupting: stops %d %q", stops, tt.Texts())
+	}
+	interrupting, running = false, false
+	tt.Frame()
+	_ = tt.Click("Stop")
+	if stops != 2 {
+		t.Fatal("idle button interrupted")
+	}
+}
+
+func TestInterruptButtonInvalid(t *testing.T) {
+	defer func() {
+		if recover() == nil {
+			t.Fatal("no panic")
+		}
+	}()
+	ui.Render(func(c *ui.Context) {
+		Use(c, Settings{})
+		InterruptButton(c, false, InterruptButtonOptions{Interrupting: true})
+	}, 100, 50, 1)
+}
+
+func TestInterruptButtonSnapshot(t *testing.T) {
+	snapshot(t, "interrupt_button", 460, 90, func(c *ui.Context) {
+		ui.Row(c).Padding(20).Gap(12).Children(func() {
+			InterruptButton(c, true, InterruptButtonOptions{})
+			InterruptButton(c, true, InterruptButtonOptions{Interrupting: true})
+			InterruptButton(c, false, InterruptButtonOptions{Label: "Cancel run"})
+		})
+	})
+}
diff --git a/messages_motion.go b/messages_motion.go
index cc4cc5a..8597473 100644
--- a/messages_motion.go
+++ b/messages_motion.go
@@ -45,6 +45,7 @@ func init() {
 		"tool_registry_panel.empty":     {"No tools", "没有工具"},
 		"tool_registry_panel.choose":    {"Choose a tool to see its parameters", "选择工具查看参数"},
 		"tool_registry_panel.no_params": {"No parameters", "无参数"},
+		"tool_registry_panel.enable":    {"Enable %s", "启用 %s"},
 		"tool_registry_panel.required":  {"required", "必填"},
 
 		"typewriter.skip": {"Skip", "跳过"},
diff --git a/shimmer.go b/shimmer.go
index b4df863..174a960 100644
--- a/shimmer.go
+++ b/shimmer.go
@@ -45,23 +45,26 @@ func Shimmer(c *ui.Context, loading bool, opts ShimmerOptions, content func()) *
 		fill = k.Border
 	}
 	still := c.Preferences().ReduceMotion
-	e := ui.Box(c).Key(still).Height(h).Role(ui.RoleProgress).Label(label)
+	e := ui.Column(c).Height(h).AlignItems(ui.Stretch).Role(ui.RoleProgress).Label(label)
 	if opts.Width > 0 {
 		e.Width(opts.Width)
 	} else {
 		e.FillWidth()
 	}
-	e.Draw(func(p *ui.Painter, r ui.Rect) {
-		p.Fill(r, fill, theme.CardRadius)
-		if still {
-			return
-		}
-		p.AnimationFrame()
-		t := float32(p.Now().UnixMilli()%1600) / 1600
-		band := max(r.W*0.25, 24)
-		x := internal.Snap(p, r.X-band+(r.W+band)*t)
-		p.Clip(r, theme.CardRadius, func() {
-			p.Fill(ui.Rect{X: x, Y: r.Y, W: band, H: r.H}, k.Surface.Alpha(0.55), 0)
+	// Keyed by motion so a flip repaints.
+	e.Children(func() {
+		ui.Box(c).Key(still).Grow(1).Role(ui.RoleNone).Draw(func(p *ui.Painter, r ui.Rect) {
+			p.Fill(r, fill, theme.CardRadius)
+			if still {
+				return
+			}
+			p.AnimationFrame()
+			t := float32(p.Now().UnixMilli()%1600) / 1600
+			band := max(r.W*0.25, 24)
+			x := internal.Snap(p, r.X-band+(r.W+band)*t)
+			p.Clip(r, theme.CardRadius, func() {
+				p.Fill(ui.Rect{X: x, Y: r.Y, W: band, H: r.H}, k.Surface.Alpha(0.55), 0)
+			})
 		})
 	})
 	return e
diff --git a/shimmer_test.go b/shimmer_test.go
new file mode 100644
index 0000000..7479e93
--- /dev/null
+++ b/shimmer_test.go
@@ -0,0 +1,101 @@
+package mujica
+
+import (
+	"bytes"
+	"testing"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+)
+
+func TestShimmerOnlyWhileLoading(t *testing.T) {
+	loading := true
+	tt, n := motionFrames(func(c *ui.Context) {
+		Shimmer(c, loading, ShimmerOptions{Height: 40, Label: "Loading report"}, func() { ui.Text(c, "Report ready") })
+	}, 300, 100)
+	if _, ok := tt.Find("Loading report"); !ok || tt.HasText("Report ready") {
+		t.Fatalf("loading: %q", tt.Texts())
+	}
+	a := encode(t, tt.Image())
+	time.Sleep(150 * time.Millisecond)
+	tt.Frame()
+	if bytes.Equal(a, encode(t, tt.Image())) || !motionBusy(tt, n) {
+		t.Fatal("shimmer does not sweep")
+	}
+	tt.SetPreferences(ui.Preferences{ReduceMotion: true, TextScale: 1})
+	if motionBusy(tt, n) {
+		t.Fatal("shimmer repaints under reduced motion")
+	}
+	tt.SetPreferences(ui.Preferences{TextScale: 1})
+	loading = false
+	tt.Frame()
+	if !tt.HasText("Report ready") || motionBusy(tt, n) {
+		t.Fatalf("loaded: %q", tt.Texts())
+	}
+}
+
+func TestShimmerInvalid(t *testing.T) {
+	defer func() {
+		if recover() == nil {
+			t.Fatal("no panic")
+		}
+	}()
+	ui.Render(func(c *ui.Context) {
+		Use(c, Settings{})
+		Shimmer(c, true, ShimmerOptions{Width: -1}, nil)
+	}, 100, 50, 1)
+}
+
+func TestShimmerSnapshot(t *testing.T) {
+	snapshot(t, "shimmer", 400, 140, func(c *ui.Context) {
+		ui.Column(c).Padding(16).Gap(12).Children(func() {
+			Shimmer(c, true, ShimmerOptions{}, nil)
+			Shimmer(c, true, ShimmerOptions{Width: 160, Height: 24}, nil)
+			Shimmer(c, false, ShimmerOptions{}, func() { ui.Text(c, "Loaded content") })
+		})
+	})
+}
+
+func TestShimmerTextSweepsAndStops(t *testing.T) {
+	active := true
+	tt, n := motionFrames(func(c *ui.Context) {
+		ShimmerText(c, "Thinking", ShimmerTextOptions{Active: active})
+	}, 200, 60)
+	if _, ok := tt.Find("Thinking"); !ok {
+		t.Fatal("text not named")
+	}
+	a := encode(t, tt.Image())
+	time.Sleep(200 * time.Millisecond)
+	tt.Frame()
+	if bytes.Equal(a, encode(t, tt.Image())) || !motionBusy(tt, n) {
+		t.Fatal("no sweep")
+	}
+	active = false
+	tt.Frame()
+	if motionBusy(tt, n) || !tt.HasText("Thinking") {
+		t.Fatal("inactive text still sweeps")
+	}
+	active = true
+	tt.SetPreferences(ui.Preferences{ReduceMotion: true, TextScale: 1})
+	if motionBusy(tt, n) {
+		t.Fatal("sweeps under reduced motion")
+	}
+	defer func() {
+		if recover() == nil {
+			t.Fatal("empty text did not panic")
+		}
+	}()
+	ui.Render(func(c *ui.Context) {
+		Use(c, Settings{})
+		ShimmerText(c, "", ShimmerTextOptions{})
+	}, 100, 50, 1)
+}
+
+func TestShimmerTextSnapshot(t *testing.T) {
+	snapshot(t, "shimmer_text", 300, 80, func(c *ui.Context) {
+		ui.Column(c).Padding(16).Gap(8).Children(func() {
+			ShimmerText(c, "Thinking…", ShimmerTextOptions{Active: true})
+			ShimmerText(c, "思考中…", ShimmerTextOptions{})
+		})
+	})
+}
diff --git a/testdata/snapshots/darwin/blink_highlight-dark.png b/testdata/snapshots/darwin/blink_highlight-dark.png
new file mode 100644
index 0000000..c2c3624
Binary files /dev/null and b/testdata/snapshots/darwin/blink_highlight-dark.png differ
diff --git a/testdata/snapshots/darwin/blink_highlight-light.png b/testdata/snapshots/darwin/blink_highlight-light.png
new file mode 100644
index 0000000..8b68578
Binary files /dev/null and b/testdata/snapshots/darwin/blink_highlight-light.png differ
diff --git a/testdata/snapshots/darwin/cost_breakdown-dark.png b/testdata/snapshots/darwin/cost_breakdown-dark.png
new file mode 100644
index 0000000..7cbd2e4
Binary files /dev/null and b/testdata/snapshots/darwin/cost_breakdown-dark.png differ
diff --git a/testdata/snapshots/darwin/cost_breakdown-light.png b/testdata/snapshots/darwin/cost_breakdown-light.png
new file mode 100644
index 0000000..2313ff7
Binary files /dev/null and b/testdata/snapshots/darwin/cost_breakdown-light.png differ
diff --git a/testdata/snapshots/darwin/count_up-dark.png b/testdata/snapshots/darwin/count_up-dark.png
new file mode 100644
index 0000000..aecbad5
Binary files /dev/null and b/testdata/snapshots/darwin/count_up-dark.png differ
diff --git a/testdata/snapshots/darwin/count_up-light.png b/testdata/snapshots/darwin/count_up-light.png
new file mode 100644
index 0000000..f04253c
Binary files /dev/null and b/testdata/snapshots/darwin/count_up-light.png differ
diff --git a/testdata/snapshots/darwin/eval_result_table-dark.png b/testdata/snapshots/darwin/eval_result_table-dark.png
new file mode 100644
index 0000000..6a3fdf0
Binary files /dev/null and b/testdata/snapshots/darwin/eval_result_table-dark.png differ
diff --git a/testdata/snapshots/darwin/eval_result_table-light.png b/testdata/snapshots/darwin/eval_result_table-light.png
new file mode 100644
index 0000000..96502fd
Binary files /dev/null and b/testdata/snapshots/darwin/eval_result_table-light.png differ
diff --git a/testdata/snapshots/darwin/interrupt_button-dark.png b/testdata/snapshots/darwin/interrupt_button-dark.png
new file mode 100644
index 0000000..6a1ddf4
Binary files /dev/null and b/testdata/snapshots/darwin/interrupt_button-dark.png differ
diff --git a/testdata/snapshots/darwin/interrupt_button-light.png b/testdata/snapshots/darwin/interrupt_button-light.png
new file mode 100644
index 0000000..a4f5601
Binary files /dev/null and b/testdata/snapshots/darwin/interrupt_button-light.png differ
diff --git a/testdata/snapshots/darwin/layout_transition-dark.png b/testdata/snapshots/darwin/layout_transition-dark.png
new file mode 100644
index 0000000..c38afe9
Binary files /dev/null and b/testdata/snapshots/darwin/layout_transition-dark.png differ
diff --git a/testdata/snapshots/darwin/layout_transition-light.png b/testdata/snapshots/darwin/layout_transition-light.png
new file mode 100644
index 0000000..b0f6b3e
Binary files /dev/null and b/testdata/snapshots/darwin/layout_transition-light.png differ
diff --git a/testdata/snapshots/darwin/presence-dark.png b/testdata/snapshots/darwin/presence-dark.png
new file mode 100644
index 0000000..dd58ee3
Binary files /dev/null and b/testdata/snapshots/darwin/presence-dark.png differ
diff --git a/testdata/snapshots/darwin/presence-light.png b/testdata/snapshots/darwin/presence-light.png
new file mode 100644
index 0000000..0f1422d
Binary files /dev/null and b/testdata/snapshots/darwin/presence-light.png differ
diff --git a/testdata/snapshots/darwin/reorder_transition-dark.png b/testdata/snapshots/darwin/reorder_transition-dark.png
new file mode 100644
index 0000000..888af78
Binary files /dev/null and b/testdata/snapshots/darwin/reorder_transition-dark.png differ
diff --git a/testdata/snapshots/darwin/reorder_transition-light.png b/testdata/snapshots/darwin/reorder_transition-light.png
new file mode 100644
index 0000000..466fc25
Binary files /dev/null and b/testdata/snapshots/darwin/reorder_transition-light.png differ
diff --git a/testdata/snapshots/darwin/shimmer-dark.png b/testdata/snapshots/darwin/shimmer-dark.png
new file mode 100644
index 0000000..524c841
Binary files /dev/null and b/testdata/snapshots/darwin/shimmer-dark.png differ
diff --git a/testdata/snapshots/darwin/shimmer-light.png b/testdata/snapshots/darwin/shimmer-light.png
new file mode 100644
index 0000000..ce924ab
Binary files /dev/null and b/testdata/snapshots/darwin/shimmer-light.png differ
diff --git a/testdata/snapshots/darwin/shimmer_text-dark.png b/testdata/snapshots/darwin/shimmer_text-dark.png
new file mode 100644
index 0000000..82d6c55
Binary files /dev/null and b/testdata/snapshots/darwin/shimmer_text-dark.png differ
diff --git a/testdata/snapshots/darwin/shimmer_text-light.png b/testdata/snapshots/darwin/shimmer_text-light.png
new file mode 100644
index 0000000..06cd472
Binary files /dev/null and b/testdata/snapshots/darwin/shimmer_text-light.png differ
diff --git a/testdata/snapshots/darwin/stagger-dark.png b/testdata/snapshots/darwin/stagger-dark.png
new file mode 100644
index 0000000..3867f81
Binary files /dev/null and b/testdata/snapshots/darwin/stagger-dark.png differ
diff --git a/testdata/snapshots/darwin/stagger-light.png b/testdata/snapshots/darwin/stagger-light.png
new file mode 100644
index 0000000..ccb86b9
Binary files /dev/null and b/testdata/snapshots/darwin/stagger-light.png differ
diff --git a/testdata/snapshots/darwin/token_usage_chart-dark.png b/testdata/snapshots/darwin/token_usage_chart-dark.png
new file mode 100644
index 0000000..71af2ee
Binary files /dev/null and b/testdata/snapshots/darwin/token_usage_chart-dark.png differ
diff --git a/testdata/snapshots/darwin/token_usage_chart-light.png b/testdata/snapshots/darwin/token_usage_chart-light.png
new file mode 100644
index 0000000..812efcb
Binary files /dev/null and b/testdata/snapshots/darwin/token_usage_chart-light.png differ
diff --git a/testdata/snapshots/darwin/tool_registry_panel-dark.png b/testdata/snapshots/darwin/tool_registry_panel-dark.png
new file mode 100644
index 0000000..0dc412f
Binary files /dev/null and b/testdata/snapshots/darwin/tool_registry_panel-dark.png differ
diff --git a/testdata/snapshots/darwin/tool_registry_panel-light.png b/testdata/snapshots/darwin/tool_registry_panel-light.png
new file mode 100644
index 0000000..8ed4916
Binary files /dev/null and b/testdata/snapshots/darwin/tool_registry_panel-light.png differ
diff --git a/testdata/snapshots/darwin/trace_viewer-dark.png b/testdata/snapshots/darwin/trace_viewer-dark.png
new file mode 100644
index 0000000..2846673
Binary files /dev/null and b/testdata/snapshots/darwin/trace_viewer-dark.png differ
diff --git a/testdata/snapshots/darwin/trace_viewer-light.png b/testdata/snapshots/darwin/trace_viewer-light.png
new file mode 100644
index 0000000..a1f5863
Binary files /dev/null and b/testdata/snapshots/darwin/trace_viewer-light.png differ
diff --git a/testdata/snapshots/darwin/typewriter-dark.png b/testdata/snapshots/darwin/typewriter-dark.png
new file mode 100644
index 0000000..4573c7f
Binary files /dev/null and b/testdata/snapshots/darwin/typewriter-dark.png differ
diff --git a/testdata/snapshots/darwin/typewriter-light.png b/testdata/snapshots/darwin/typewriter-light.png
new file mode 100644
index 0000000..ee60d53
Binary files /dev/null and b/testdata/snapshots/darwin/typewriter-light.png differ
diff --git a/token_usage_chart_test.go b/token_usage_chart_test.go
new file mode 100644
index 0000000..4e6d21a
--- /dev/null
+++ b/token_usage_chart_test.go
@@ -0,0 +1,64 @@
+package mujica
+
+import (
+	"testing"
+
+	"github.com/egoist/mygo/ui"
+)
+
+func tokenUsageSample() []TokenUsage {
+	return []TokenUsage{{Label: "Plan", Input: 1200, Output: 300}, {Label: "Search", Input: 4800, Output: 650}, {Label: "Write", Input: 2100, Output: 2900}}
+}
+
+func TestTokenUsageChartBarsKeyboard(t *testing.T) {
+	usage := tokenUsageSample()
+	h := &chartHarness{build: func(c *ui.Context) ChartResult { return TokenUsageChart(c, usage, TokenUsageChartOptions{}) }}
+	tt := ui.NewTester(h.view, 520, 420)
+	tabTo(t, tt, "Token usage")
+	want := []string{"Plan · Input 1200", "Plan · Output 300", "Search · Input 4800"}
+	for i, w := range want {
+		tt.Key(0, ui.KeyRight)
+		if got := chartReadout(tt); got != w {
+			t.Fatalf("mark %d readout %q, want %q", i, got, w)
+		}
+	}
+	if !tt.HasText("Input") || !tt.HasText("Output") {
+		t.Fatal("legend missing")
+	}
+}
+
+func TestTokenUsageChartLineEmptyInvalid(t *testing.T) {
+	usage := tokenUsageSample()
+	h := &chartHarness{build: func(c *ui.Context) ChartResult {
+		return TokenUsageChart(c, usage, TokenUsageChartOptions{Line: true, Frame: ChartFrame{Label: "Tokens per step"}})
+	}}
+	tt := ui.NewTester(h.view, 520, 420)
+	tabTo(t, tt, "Tokens per step")
+	tt.Key(0, ui.KeyRight)
+	if h.res.Point < 0 {
+		t.Fatal("line chart has no keyboard path")
+	}
+	usage = nil
+	tt.Frame()
+	if !tt.HasText("No data") {
+		t.Fatalf("empty: %q", tt.Texts())
+	}
+	defer func() {
+		if recover() == nil {
+			t.Fatal("negative tokens did not panic")
+		}
+	}()
+	ui.Render(func(c *ui.Context) {
+		Use(c, Settings{})
+		TokenUsageChart(c, []TokenUsage{{Label: "x", Input: -1}}, TokenUsageChartOptions{})
+	}, 300, 200, 1)
+}
+
+func TestTokenUsageChartSnapshot(t *testing.T) {
+	usage := tokenUsageSample()
+	snapshot(t, "token_usage_chart", 520, 360, func(c *ui.Context) {
+		ui.Column(c).Padding(16).Children(func() {
+			TokenUsageChart(c, usage, TokenUsageChartOptions{})
+		})
+	})
+}
diff --git a/tool_registry_panel.go b/tool_registry_panel.go
index 93867ac..cafa661 100644
--- a/tool_registry_panel.go
+++ b/tool_registry_panel.go
@@ -1,6 +1,7 @@
 package mujica
 
 import (
+	"fmt"
 	"log/slog"
 
 	"github.com/egoist/mygo/ui"
@@ -66,7 +67,7 @@ func ToolRegistryPanel(c *ui.Context, s *ListState[string], tools []AgentTool, o
 					ui.Text(c, t.Description).FontSize(FontSize(c, theme.CaptionSize)).TextColor(k.TextMuted).SingleLine()
 				})
 				on := t.Enabled
-				Switch(c, &on, "", SwitchOptions{Description: t.Name}).Label(t.Name)
+				Switch(c, &on, "", SwitchOptions{}).Label(fmt.Sprintf(msg(c, "tool_registry_panel.enable"), t.Name))
 				if on != t.Enabled && !row.IsDisabled() {
 					res.toggled, res.on = t.Name, on
 					slog.Debug("mujica: tool registry toggle", "tool", t.Name, "on", on)
diff --git a/tool_registry_panel_test.go b/tool_registry_panel_test.go
new file mode 100644
index 0000000..8e93561
--- /dev/null
+++ b/tool_registry_panel_test.go
@@ -0,0 +1,89 @@
+package mujica
+
+import (
+	"testing"
+
+	"github.com/egoist/mygo/ui"
+)
+
+func toolSample() []AgentTool {
+	return []AgentTool{
+		{Name: "web_search", Description: "Search the web", Enabled: true, Params: []ToolParam{
+			{Name: "query", Type: "string", Required: true, Description: "What to look for"},
+			{Name: "limit", Type: "integer"},
+		}},
+		{Name: "read_file", Description: "Read a local file"},
+	}
+}
+
+func TestToolRegistryPanelToggleAndPreview(t *testing.T) {
+	var s ListState[string]
+	tools := toolSample()
+	disabled := false
+	var toggled []string
+	tt := ui.NewTester(func(c *ui.Context) {
+		Use(c, Settings{})
+		ui.Column(c).Height(400).Children(func() {
+			r := ToolRegistryPanel(c, &s, tools, ToolRegistryPanelOptions{Disabled: disabled})
+			r.Element.Grow(1)
+			if name, on, ok := r.Toggled(); ok {
+				toggled = append(toggled, name)
+				for i := range tools {
+					if tools[i].Name == name {
+						tools[i].Enabled = on
+					}
+				}
+			}
+		})
+	}, 800, 420)
+	if !tt.HasText("Choose a tool to see its parameters") {
+		t.Fatalf("empty preview: %q", tt.Texts())
+	}
+	if err := tt.Click("Search the web"); err != nil {
+		t.Fatal(err)
+	}
+	if !tt.HasText("query") || !tt.HasText("required") || !tt.HasText("integer") {
+		t.Fatalf("schema: %q", tt.Texts())
+	}
+	if err := tt.Click("read_file"); err != nil {
+		t.Fatal(err)
+	}
+	if !tt.HasText("No parameters") {
+		t.Fatalf("no params: %q", tt.Texts())
+	}
+	if err := tt.Click("Enable read_file"); err != nil {
+		t.Fatal(err)
+	}
+	if len(toggled) != 1 || toggled[0] != "read_file" || !tools[1].Enabled {
+		t.Fatalf("toggle %q enabled %v", toggled, tools[1].Enabled)
+	}
+	disabled = true
+	tt.Frame()
+	_ = tt.Click("Enable read_file")
+	if len(toggled) != 1 {
+		t.Fatal("disabled panel toggled")
+	}
+}
+
+func TestToolRegistryPanelInvalid(t *testing.T) {
+	defer func() {
+		if recover() == nil {
+			t.Fatal("no panic")
+		}
+	}()
+	ui.Render(func(c *ui.Context) {
+		Use(c, Settings{})
+		var s ListState[string]
+		ToolRegistryPanel(c, &s, []AgentTool{{Name: "a"}, {Name: "a"}}, ToolRegistryPanelOptions{})
+	}, 300, 200, 1)
+}
+
+func TestToolRegistryPanelSnapshot(t *testing.T) {
+	tools := toolSample()
+	snapshotAfter(t, "tool_registry_panel", 760, 300, func(c *ui.Context) {
+		s := ui.Local(c.Root(), "s", func() *ListState[string] { return &ListState[string]{} })
+		ui.Column(c).Padding(16).Height(300).Children(func() {
+			ToolRegistryPanel(c, *s, tools, ToolRegistryPanelOptions{}).Element.Grow(1)
+		})
+	}, func(tt *ui.Tester) { _ = tt.Click("Search the web") })
+}
diff --git a/trace_viewer.go b/trace_viewer.go
index b562cd1..7304c72 100644
--- a/trace_viewer.go
+++ b/trace_viewer.go
@@ -8,6 +8,7 @@ import (
 
 	"github.com/egoist/mygo/ui"
 
+	"mujicaui/icons"
 	"mujicaui/internal"
 	"mujicaui/theme"
 )
@@ -70,6 +71,9 @@ func TraceViewer(c *ui.Context, s *TraceViewerState, spans []TraceSpan, opts Tra
 		{ID: "name", Title: msg(c, "trace_viewer.span"), Compare: func(a, b string) int { return cmp.Compare(span(a).Name, span(b).Name) },
 			Cell: func(id string) {
 				sp := span(id)
+				if sp.Failed {
+					ui.Icon(c, icons.Must("circle-x")).Size(14, 14).TextColor(k.Danger).Shrink(0).Margin(0, u, 0, 0)
+				}
 				t := ui.Text(c, sp.Name).SingleLine()
 				if sp.Failed {
 					t.TextColor(k.Danger).Label(sp.Name + ", " + msg(c, "trace_viewer.failed"))
@@ -95,7 +99,14 @@ func TraceViewer(c *ui.Context, s *TraceViewerState, spans []TraceSpan, opts Tra
 					}
 					x0 := r.X + r.W*float32(float64(sp.Start)/float64(ix.end))
 					w := max(2, r.W*float32(float64(sp.End-sp.Start)/float64(ix.end)))
-					p.Fill(ui.Rect{X: internal.Snap(p, x0), Y: r.Y, W: internal.Snap(p, w), H: r.H}, col, 2)
+					bar := ui.Rect{X: internal.Snap(p, x0), Y: r.Y, W: internal.Snap(p, w), H: r.H}
+					if sp.Failed {
+						// Failed spans are hollow, not told apart by color alone.
+						p.Fill(bar, k.Surface, 2)
+						p.Stroke(bar, col, 2, 1.5)
+						return
+					}
+					p.Fill(bar, col, 2)
 				})
 			}},
 	}
diff --git a/trace_viewer_test.go b/trace_viewer_test.go
new file mode 100644
index 0000000..f6b3de1
--- /dev/null
+++ b/trace_viewer_test.go
@@ -0,0 +1,85 @@
+package mujica
+
+import (
+	"testing"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+)
+
+func traceSample() []TraceSpan {
+	ms := time.Millisecond
+	return []TraceSpan{
+		{ID: "root", Name: "agent.run", Start: 0, End: 900 * ms, Attrs: []TraceAttr{{"model", "opus"}}},
+		{ID: "plan", Parent: "root", Name: "llm.plan", Start: 10 * ms, End: 210 * ms, Attrs: []TraceAttr{{"tokens", "1200"}}},
+		{ID: "search", Parent: "root", Name: "tool.search", Start: 220 * ms, End: 520 * ms, Failed: true},
+		{ID: "fetch", Parent: "search", Name: "http.get", Start: 230 * ms, End: 500 * ms},
+		{ID: "write", Parent: "root", Name: "llm.write", Start: 530 * ms, End: 880 * ms},
+	}
+}
+
+func TestTraceBuild(t *testing.T) {
+	ix := traceBuild(traceSample())
+	if len(ix.roots) != 1 || ix.roots[0] != "root" || len(ix.kids["root"]) != 3 || ix.end != 900*time.Millisecond {
+		t.Fatalf("index %+v", ix)
+	}
+	for name, spans := range map[string][]TraceSpan{
+		"dup":   {{ID: "a"}, {ID: "a"}},
+		"time":  {{ID: "a", Start: 2, End: 1}},
+		"cycle": {{ID: "a", Parent: "b"}, {ID: "b", Parent: "a"}},
+	} {
+		func() {
+			defer func() {
+				if recover() == nil {
+					t.Errorf("%s did not panic", name)
+				}
+			}()
+			traceBuild(spans)
+		}()
+	}
+}
+
+func TestTraceViewerSelectShowsAttributes(t *testing.T) {
+	var s TraceViewerState
+	spans := traceSample()
+	tt := ui.NewTester(func(c *ui.Context) {
+		Use(c, Settings{})
+		ui.Column(c).Height(600).Children(func() {
+			TraceViewer(c, &s, spans, TraceViewerOptions{}).Element.Grow(1)
+		})
+	}, 900, 620)
+	if !tt.HasText("llm.plan") || !tt.HasText("200.0 ms") {
+		t.Fatalf("tree: %q", tt.Texts())
+	}
+	if _, ok := tt.Find("tool.search, failed"); !ok {
+		t.Fatal("failed span not named")
+	}
+	if tt.HasText("http.get") {
+		t.Fatal("nested span shown before opening its parent")
+	}
+	if err := tt.Click("llm.plan"); err != nil {
+		t.Fatal(err)
+	}
+	if id, _ := s.Tree.Selected(); id != "plan" || !tt.HasText("tokens") || !tt.HasText("1200") {
+		t.Fatalf("attributes: %q", tt.Texts())
+	}
+	tt.Key(0, ui.KeyDown)
+	tt.Key(0, ui.KeyRight)
+	if id, _ := s.Tree.Selected(); id != "search" || !tt.HasText("http.get") {
+		t.Fatalf("keyboard open: %q", tt.Texts())
+	}
+}
+
+func TestTraceViewerSnapshot(t *testing.T) {
+	spans := traceSample()
+	snapshot(t, "trace_viewer", 820, 420, func(c *ui.Context) {
+		s := ui.Local(c.Root(), "s", func() *TraceViewerState {
+			st := &TraceViewerState{}
+			st.Tree.SetOpen("search", true)
+			return st
+		})
+		ui.Column(c).Padding(16).Height(420).Children(func() {
+			TraceViewer(c, *s, spans, TraceViewerOptions{}).Element.Grow(1)
+		})
+	})
+}
diff --git a/transitions_test.go b/transitions_test.go
new file mode 100644
index 0000000..e42cfa3
--- /dev/null
+++ b/transitions_test.go
@@ -0,0 +1,210 @@
+package mujica
+
+import (
+	"testing"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+)
+
+func TestPresenceEntersExitsAndRemoves(t *testing.T) {
+	for _, kind := range []PresenceKind{PresenceFade, PresenceSlide, PresenceCollapse} {
+		show := false
+		tt, n := motionFrames(func(c *ui.Context) {
+			ui.Column(c).Children(func() {
+				Presence(c, show, PresenceOptions{Kind: kind}, func() { ui.Text(c, "Notice") })
+				ui.Text(c, "Below")
+			})
+		}, 300, 120)
+		if tt.HasText("Notice") {
+			t.Fatal("hidden content built")
+		}
+		show = true
+		before := *n
+		tt.Frame()
+		if !tt.HasText("Notice") || *n-before < 3 {
+			t.Fatalf("kind %d: no entry motion (%d frames)", kind, *n-before)
+		}
+		time.Sleep(250 * time.Millisecond)
+		tt.Frame()
+		show = false
+		before = *n
+		tt.Frame()
+		if *n-before < 3 {
+			t.Fatalf("kind %d: no exit motion", kind)
+		}
+		time.Sleep(250 * time.Millisecond)
+		tt.Frame()
+		if tt.HasText("Notice") || motionBusy(tt, n) {
+			t.Fatalf("kind %d: not removed after exit", kind)
+		}
+	}
+}
+
+func TestPresenceReducedMotionAndInvalid(t *testing.T) {
+	show := false
+	tt, n := motionFrames(func(c *ui.Context) {
+		ui.Column(c).Children(func() { Presence(c, show, PresenceOptions{Kind: PresenceSlide}, func() { ui.Text(c, "Notice") }) })
+	}, 300, 120)
+	tt.SetPreferences(ui.Preferences{ReduceMotion: true, TextScale: 1})
+	show = true
+	if motionBusy(tt, n) || !tt.HasText("Notice") {
+		t.Fatal("reduced motion animated")
+	}
+	defer func() {
+		if recover() == nil {
+			t.Fatal("unknown kind did not panic")
+		}
+	}()
+	ui.Render(func(c *ui.Context) { Use(c, Settings{}); Presence(c, true, PresenceOptions{Kind: 9}, nil) }, 100, 50, 1)
+}
+
+func TestStaggerRevealsInTurnOnce(t *testing.T) {
+	count := 5
+	tt, n := motionFrames(func(c *ui.Context) {
+		ui.Column(c).Children(func() {
+			Stagger(c, count, StaggerOptions{Interval: 50 * time.Millisecond}, func(i int) { ui.Textf(c, "Row %d", i) })
+		})
+	}, 300, 240)
+	if !tt.HasText("Row 0") || tt.HasText("Row 4") {
+		t.Fatalf("first frame: %q", tt.Texts())
+	}
+	time.Sleep(120 * time.Millisecond)
+	tt.Frame()
+	if !tt.HasText("Row 2") || tt.HasText("Row 4") {
+		t.Fatalf("after 120 ms: %q", tt.Texts())
+	}
+	time.Sleep(300 * time.Millisecond)
+	tt.Frame()
+	time.Sleep(250 * time.Millisecond)
+	tt.Frame()
+	if !tt.HasText("Row 4") || motionBusy(tt, n) {
+		t.Fatalf("did not finish and settle: %q", tt.Texts())
+	}
+	count = 6
+	tt.Frame()
+	if !tt.HasText("Row 5") {
+		t.Fatal("item added after the sequence waited")
+	}
+}
+
+func TestStaggerReducedMotionAndInvalid(t *testing.T) {
+	tt := ui.NewTester(func(c *ui.Context) {
+		Use(c, Settings{})
+		if c.Preferences().ReduceMotion {
+			Stagger(c, 3, StaggerOptions{}, func(i int) { ui.Textf(c, "Row %d", i) })
+		}
+	}, 300, 200)
+	tt.SetPreferences(ui.Preferences{ReduceMotion: true, TextScale: 1})
+	if !tt.HasText("Row 2") {
+		t.Fatalf("reduced motion staggered: %q", tt.Texts())
+	}
+	defer func() {
+		if recover() == nil {
+			t.Fatal("negative n did not panic")
+		}
+	}()
+	ui.Render(func(c *ui.Context) { Use(c, Settings{}); Stagger(c, -1, StaggerOptions{}, nil) }, 100, 50, 1)
+}
+
+func TestReorderTransitionSlides(t *testing.T) {
+	keys := []string{"a", "b", "c"}
+	tt, n := motionFrames(func(c *ui.Context) {
+		ReorderTransition(c, keys, ReorderTransitionOptions{Gap: 4}, func(k string) {
+			ui.Text(c, "Item "+k).Padding(8)
+		})
+	}, 300, 200)
+	ra, _ := tt.Find("Item a")
+	keys = []string{"c", "b", "a"}
+	before := *n
+	tt.Frame()
+	if *n-before < 3 {
+		t.Fatal("reorder did not animate")
+	}
+	mid, _ := tt.Find("Item a")
+	time.Sleep(260 * time.Millisecond)
+	tt.Frame()
+	end, _ := tt.Find("Item a")
+	if !(mid.Y > ra.Y && mid.Y < end.Y) || motionBusy(tt, n) {
+		t.Fatalf("a moved %v → %v → %v", ra.Y, mid.Y, end.Y)
+	}
+	defer func() {
+		if recover() == nil {
+			t.Fatal("duplicate key did not panic")
+		}
+	}()
+	ui.Render(func(c *ui.Context) {
+		Use(c, Settings{})
+		ReorderTransition(c, []int{1, 1}, ReorderTransitionOptions{}, func(int) {})
+	}, 100, 50, 1)
+}
+
+func TestLayoutTransitionResizes(t *testing.T) {
+	wide := false
+	var w float32
+	tt, n := motionFrames(func(c *ui.Context) {
+		ui.Column(c).AlignItems(ui.Start).Children(func() {
+			box := LayoutTransition(c, LayoutTransitionOptions{Clip: true}, func() {
+				width := float32(100)
+				if wide {
+					width = 300
+				}
+				ui.Box(c).Size(width, 40)
+			})
+			w = box.Bounds().W
+		})
+	}, 400, 120)
+	wide = true
+	before := *n
+	tt.Frame()
+	if *n-before < 3 {
+		t.Fatal("resize did not animate")
+	}
+	time.Sleep(260 * time.Millisecond)
+	tt.Frame()
+	if motionBusy(tt, n) || w != 300 {
+		t.Fatalf("settled width %v", w)
+	}
+	defer func() {
+		if recover() == nil {
+			t.Fatal("negative duration did not panic")
+		}
+	}()
+	ui.Render(func(c *ui.Context) { Use(c, Settings{}); LayoutTransition(c, LayoutTransitionOptions{Duration: -1}, nil) }, 100, 50, 1)
+}
+
+func TestPresenceSnapshot(t *testing.T) {
+	snapshot(t, "presence", 300, 100, func(c *ui.Context) {
+		ui.Column(c).Padding(16).Children(func() {
+			Presence(c, true, PresenceOptions{}, func() { ui.Text(c, "The doors open.") })
+		})
+	})
+}
+
+func TestStaggerSnapshot(t *testing.T) {
+	snapshot(t, "stagger", 300, 140, func(c *ui.Context) {
+		ui.Column(c).Padding(16).Children(func() {
+			Stagger(c, 3, StaggerOptions{}, func(i int) { ui.Textf(c, "Guest %d arrives", i+1) })
+		})
+	})
+}
+
+func TestReorderTransitionSnapshot(t *testing.T) {
+	snapshot(t, "reorder_transition", 300, 140, func(c *ui.Context) {
+		ui.Column(c).Padding(16).Children(func() {
+			ReorderTransition(c, []string{"Sakiko", "Uika", "Mutsumi"}, ReorderTransitionOptions{Gap: 4}, func(k string) {
+				ui.Text(c, k).Padding(4, 8).Background(Tokens(c).Surface).Radius(4)
+			})
+		})
+	})
+}
+
+func TestLayoutTransitionSnapshot(t *testing.T) {
+	snapshot(t, "layout_transition", 300, 100, func(c *ui.Context) {
+		ui.Column(c).Padding(16).AlignItems(ui.Start).Children(func() {
+			LayoutTransition(c, LayoutTransitionOptions{}, func() {
+				ui.Text(c, "A panel that grows").Padding(12).Background(Tokens(c).Surface).Radius(4)
+			})
+		})
+	})
+}
diff --git a/typewriter.go b/typewriter.go
index 4d23dcb..b1bc810 100644
--- a/typewriter.go
+++ b/typewriter.go
@@ -42,7 +42,7 @@ func Typewriter(c *ui.Context, text string, opts TypewriterOptions) TypewriterRe
 	if speed < 0 {
 		panic("mujica: Typewriter Speed is negative")
 	}
-	col := ui.Column(c).AlignItems(ui.Start).Gap(Density(c).Unit() * 2)
+	col := ui.Column(c).AlignItems(ui.Start).Gap(Density(c).Unit() * 2).Role(ui.RoleGroup).Label(text)
 	res := TypewriterResult{Element: col}
 	st := ui.Local(col, "typing", func() *typewriterState { return &typewriterState{last: c.Now()} })
 	s := *st
@@ -51,8 +51,9 @@ func Typewriter(c *ui.Context, text string, opts TypewriterOptions) TypewriterRe
 		s.shown, s.skipped, s.done = 0, false, false
 		slog.Debug("mujica: typewriter restart")
 	}
-	if len(runes) > len(s.text) {
-		s.done = false
+	if len(runes) > len(s.text) && s.done {
+		// New text continues from where it stood, at the typing speed.
+		s.done, s.skipped, s.last = false, false, c.Now()
 	}
 	s.text = runes
 	now := c.Now()
@@ -71,7 +72,7 @@ func Typewriter(c *ui.Context, text string, opts TypewriterOptions) TypewriterRe
 		s.last = now
 	}
 	col.Children(func() {
-		ui.Text(c, string(runes[:s.shown])).Label(text)
+		ui.Text(c, string(runes[:s.shown]))
 		if opts.Skippable && s.shown < len(runes) {
 			if Button(c, msg(c, "typewriter.skip"), ButtonOptions{Variant: Ghost}).Clicked() {
 				s.skipped, s.shown = true, len(runes)
diff --git a/typewriter_test.go b/typewriter_test.go
new file mode 100644
index 0000000..23f2103
--- /dev/null
+++ b/typewriter_test.go
@@ -0,0 +1,80 @@
+package mujica
+
+import (
+	"testing"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+)
+
+func TestTypewriterRevealsFinishesAndSkips(t *testing.T) {
+	text := "The court assembles at dusk."
+	finished := 0
+	tt, n := motionFrames(func(c *ui.Context) {
+		if Typewriter(c, text, TypewriterOptions{Speed: 100, Skippable: true}).Finished() {
+			finished++
+		}
+	}, 400, 120)
+	if tt.HasText(text) && motionCount(tt, text) == 2 {
+		t.Fatal("whole text shown at once")
+	}
+	time.Sleep(120 * time.Millisecond)
+	tt.Frame()
+	shown := 0
+	for _, s := range tt.Texts() {
+		if s != text && s != "Skip" && len(s) > shown {
+			shown = len(s)
+		}
+	}
+	if shown < 5 || shown >= len(text) {
+		t.Fatalf("partial reveal %d of %d: %q", shown, len(text), tt.Texts())
+	}
+	if err := tt.Click("Skip"); err != nil {
+		t.Fatal(err)
+	}
+	if motionCount(tt, text) != 2 || finished != 1 || tt.HasText("Skip") || motionBusy(tt, n) {
+		t.Fatalf("skip: finished %d texts %q", finished, tt.Texts())
+	}
+	text += " The music begins."
+	tt.Frame()
+	if motionCount(tt, "The court assembles at dusk.") != 1 {
+		t.Fatalf("appended text restarted: %q", tt.Texts())
+	}
+	time.Sleep(300 * time.Millisecond)
+	tt.Frame()
+	if motionCount(tt, text) != 2 || finished != 2 {
+		t.Fatalf("append: finished %d %q", finished, tt.Texts())
+	}
+}
+
+func TestTypewriterReducedMotionAndInvalid(t *testing.T) {
+	finished := false
+	tt := ui.NewTester(func(c *ui.Context) {
+		Use(c, Settings{})
+		finished = Typewriter(c, "All at once", TypewriterOptions{}).Finished() || finished
+	}, 300, 80)
+	tt.SetPreferences(ui.Preferences{ReduceMotion: true, TextScale: 1})
+	_ = tt
+	tt2 := ui.NewTester(func(c *ui.Context) {
+		Use(c, Settings{})
+		finished = Typewriter(c, "Shown now", TypewriterOptions{}).Finished() || finished
+	}, 300, 80)
+	tt2.SetPreferences(ui.Preferences{ReduceMotion: true, TextScale: 1})
+	if motionCount(tt2, "Shown now") != 2 || !finished {
+		t.Fatalf("reduced motion: %q", tt2.Texts())
+	}
+	defer func() {
+		if recover() == nil {
+			t.Fatal("negative speed did not panic")
+		}
+	}()
+	ui.Render(func(c *ui.Context) { Use(c, Settings{}); Typewriter(c, "x", TypewriterOptions{Speed: -1}) }, 100, 50, 1)
+}
+
+func TestTypewriterSnapshot(t *testing.T) {
+	snapshot(t, "typewriter", 420, 100, func(c *ui.Context) {
+		ui.Column(c).Padding(16).Children(func() {
+			Typewriter(c, "The court assembles at dusk; the music begins.", TypewriterOptions{Skippable: true})
+		})
+	})
+}