diff --git a/bars_loader.go b/bars_loader.go
new file mode 100644
index 0000000..fbdab80
--- /dev/null
+++ b/bars_loader.go
@@ -0,0 +1,23 @@
+package mujica
+
+import (
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/internal"
+)
+
+// BarsLoader shows four bars rising and falling in turn.
+func BarsLoader(c *ui.Context, opts LoaderOptions) *ui.Element {
+	return loaderMark(c, opts, 1.25, 1000, func(p *ui.Painter, r ui.Rect, t float64, col ui.Color, still bool) {
+		w := r.W / 7
+		for i := range 4 {
+			h := float32(0.6)
+			if !still {
+				h = 0.3 + 0.7*loaderWave(t-float64(i)/8)
+			}
+			bh := internal.Snap(p, r.H*h)
+			x := r.X + float32(i)*w*2
+			p.Fill(ui.Rect{X: x, Y: internal.Snap(p, r.Y+(r.H-bh)/2), W: w, H: bh}, col, 1)
+		}
+	})
+}
diff --git a/blink_highlight.go b/blink_highlight.go
new file mode 100644
index 0000000..31b351b
--- /dev/null
+++ b/blink_highlight.go
@@ -0,0 +1,81 @@
+package mujica
+
+import (
+	"log/slog"
+	"math"
+	"strconv"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/icons"
+	"mujicaui/theme"
+)
+
+// BlinkHighlightOptions configure a BlinkHighlight.
+type BlinkHighlightOptions struct {
+	// Format writes the value; nil uses two decimals.
+	Format func(v float64) string
+	// Duration of the fade; zero means 800 ms.
+	Duration time.Duration
+}
+
+type blinkState struct {
+	value float64
+	dir   int
+	at    time.Time
+	set   bool
+}
+
+// BlinkHighlight shows value and tints it once when it changes, up in Success, down in Danger.
+// An arrow marks the last direction, and stays as the only mark under reduced motion.
+func BlinkHighlight(c *ui.Context, value float64, opts BlinkHighlightOptions) *ui.Element {
+	if math.IsNaN(value) || math.IsInf(value, 0) || opts.Duration < 0 {
+		panic("mujica: BlinkHighlight needs a finite value and a non-negative Duration")
+	}
+	d := opts.Duration
+	if d == 0 {
+		d = 800 * time.Millisecond
+	}
+	format := opts.Format
+	if format == nil {
+		format = func(v float64) string { return strconv.FormatFloat(v, 'f', 2, 64) }
+	}
+	k := Tokens(c)
+	u := Density(c).Unit()
+	row := ui.Row(c).AlignItems(ui.Center).Gap(u).Padding(0, u*1.5).Radius(theme.ControlRadius).Shrink(0)
+	st := ui.Local(row, "blink", func() blinkState { return blinkState{} })
+	now := c.Now()
+	if st.set && value != st.value {
+		st.dir = 1
+		if value < st.value {
+			st.dir = -1
+		}
+		st.at = now
+		slog.Debug("mujica: blink highlight", "from", st.value, "to", value)
+	}
+	st.value, st.set = value, true
+	col := k.Success
+	icon, word := "arrow-up", "blink_highlight.up"
+	if st.dir < 0 {
+		col, icon, word = k.Danger, "arrow-down", "blink_highlight.down"
+	}
+	name := format(value)
+	if st.dir != 0 {
+		name += ", " + msg(c, word)
+	}
+	row.Label(name)
+	if dur := Motion(c, d); st.dir != 0 && dur > 0 {
+		if p := float32(now.Sub(st.at)) / float32(dur); p < 1 {
+			row.Background(col.Alpha(0.22 * (1 - p)))
+			c.AnimationFrame()
+		}
+	}
+	row.Children(func() {
+		ui.Text(c, format(value)).FontFeatures("tnum").SingleLine()
+		if st.dir != 0 {
+			ui.Icon(c, icons.Must(icon)).Size(12, 12).TextColor(col)
+		}
+	})
+	return row
+}
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
new file mode 100644
index 0000000..7b88a78
--- /dev/null
+++ b/cost_breakdown.go
@@ -0,0 +1,152 @@
+package mujica
+
+import (
+	"cmp"
+	"fmt"
+	"log/slog"
+	"math"
+	"strconv"
+
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/theme"
+)
+
+// CostItem is the usage and cost of one call.
+type CostItem struct {
+	Model, Tool, Step string
+	InputTokens       int
+	OutputTokens      int
+	Cost              float64
+}
+
+// CostGroup chooses what a CostBreakdown sums by.
+type CostGroup int
+
+const (
+	CostByModel CostGroup = iota
+	CostByTool
+	CostByStep
+)
+
+// CostBreakdownOptions configure a CostBreakdown.
+type CostBreakdownOptions struct {
+	GroupBy CostGroup
+	// Currency precedes amounts; empty means "$".
+	Currency string
+	// Decimals of amounts; zero means 2.
+	Decimals int
+}
+
+// CostBreakdownState holds the table's sort and selection and the sums.
+type CostBreakdownState struct {
+	Table DataTableState[string]
+	rows  []costRow
+	total costRow
+	src   *CostItem
+	n     int
+	group CostGroup
+	built bool
+}
+
+type costRow struct {
+	name          string
+	calls         int
+	input, output int
+	cost          float64
+}
+
+// CostBreakdown sums costs by model, tool or step in a sortable table with a total; give it a height.
+func CostBreakdown(c *ui.Context, s *CostBreakdownState, items []CostItem, opts CostBreakdownOptions) DataTableView {
+	if opts.GroupBy < CostByModel || opts.GroupBy > CostByStep || opts.Decimals < 0 {
+		panic("mujica: CostBreakdown needs a known GroupBy and non-negative Decimals")
+	}
+	cur, dec := opts.Currency, opts.Decimals
+	if cur == "" {
+		cur = "$"
+	}
+	if dec == 0 {
+		dec = 2
+	}
+	var first *CostItem
+	if len(items) > 0 {
+		first = &items[0]
+	}
+	if !s.built || s.src != first || s.n != len(items) || s.group != opts.GroupBy {
+		s.rows, s.total = costSum(items, opts.GroupBy, msg(c, "cost_breakdown.unnamed"))
+		s.src, s.n, s.group, s.built = first, len(items), opts.GroupBy, true
+		slog.Debug("mujica: cost breakdown sum", "items", len(items), "groups", len(s.rows))
+	}
+	money := func(v float64) string { return cur + strconv.FormatFloat(v, 'f', dec, 64) }
+	count := func(n int) string { return strconv.Itoa(n) }
+	share := func(r costRow) float64 {
+		if s.total.cost == 0 {
+			return 0
+		}
+		return r.cost / s.total.cost
+	}
+	k := Tokens(c)
+	u := Density(c).Unit()
+	groupTitle := msg(c, []string{"cost_breakdown.model", "cost_breakdown.tool", "cost_breakdown.step"}[opts.GroupBy])
+	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: 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) {
+				ui.Row(c).Grow(1).Gap(u * 2).AlignItems(ui.Center).Children(func() {
+					f := share(r)
+					ui.Box(c).Height(6).Grow(1).Radius(1).Background(k.Border).Role(ui.RoleNone).Draw(func(p *ui.Painter, b ui.Rect) {
+						p.Fill(ui.Rect{X: b.X, Y: b.Y, W: b.W * float32(f), H: b.H}, k.AccentText, 1)
+					})
+					ui.Text(c, money(r.cost)).FontFeatures("tnum").Shrink(0)
+					ui.Text(c, fmt.Sprintf("%.0f%%", 100*f)).FontFeatures("tnum").TextColor(k.TextMuted).FontSize(FontSize(c, theme.CaptionSize)).Width(36).TextAlign(ui.End).Shrink(0)
+				})
+			}},
+	}
+	var v DataTableView
+	col := ui.Column(c).AlignItems(ui.Stretch).Gap(u * 2)
+	col.Children(func() {
+		v = DataTable(c, &s.Table, s.rows, DataTableOptions[costRow, string]{Columns: cols, Key: func(r costRow) string { return r.name }, Empty: msg(c, "cost_breakdown.empty")})
+		v.Element.Grow(1)
+		ui.Row(c).AlignItems(ui.Center).Gap(u*4).Padding(u*2, u*3).Background(k.Background).Radius(theme.ControlRadius).Role(ui.RoleStatus).
+			Label(fmt.Sprintf(msg(c, "cost_breakdown.total_name"), money(s.total.cost), s.total.calls)).Children(func() {
+			ui.Text(c, msg(c, "cost_breakdown.total")).Font(theme.SerifFont).FontWeight(600).Grow(1)
+			ui.Text(c, fmt.Sprintf(msg(c, "cost_breakdown.tokens"), s.total.input, s.total.output)).FontFeatures("tnum").TextColor(k.TextMuted)
+			ui.Text(c, money(s.total.cost)).FontWeight(700).FontFeatures("tnum")
+		})
+	})
+	v.Element = col
+	return v
+}
+
+// costSum totals items per group, in order of first appearance.
+func costSum(items []CostItem, by CostGroup, unnamed string) ([]costRow, costRow) {
+	var rows []costRow
+	at := map[string]int{}
+	var total costRow
+	for _, it := range items {
+		if it.InputTokens < 0 || it.OutputTokens < 0 || it.Cost < 0 || math.IsNaN(it.Cost) || math.IsInf(it.Cost, 0) {
+			panic("mujica: CostItem needs non-negative, finite counts and cost")
+		}
+		name := []string{it.Model, it.Tool, it.Step}[by]
+		if name == "" {
+			name = unnamed
+		}
+		i, ok := at[name]
+		if !ok {
+			i = len(rows)
+			at[name] = i
+			rows = append(rows, costRow{name: name})
+		}
+		for _, r := range []*costRow{&rows[i], &total} {
+			r.calls++
+			r.input += it.InputTokens
+			r.output += it.OutputTokens
+			r.cost += it.Cost
+		}
+	}
+	return rows, total
+}
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.go b/count_up.go
new file mode 100644
index 0000000..71b75be
--- /dev/null
+++ b/count_up.go
@@ -0,0 +1,65 @@
+package mujica
+
+import (
+	"log/slog"
+	"math"
+	"strconv"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+)
+
+// CountUpOptions configure a CountUp.
+type CountUpOptions struct {
+	// Duration of a change; zero means 600 ms.
+	Duration time.Duration
+	// Decimals shown; Format overrides it.
+	Decimals int
+	// Format writes the shown value; nil uses Decimals.
+	Format func(v float64) string
+}
+
+type countUpState struct {
+	from, to float64
+	start    time.Time
+	set      bool
+}
+
+// CountUp counts from the last value to value; reduced motion shows it at once.
+func CountUp(c *ui.Context, value float64, opts CountUpOptions) *ui.Element {
+	if math.IsNaN(value) || math.IsInf(value, 0) {
+		panic("mujica: CountUp value must be finite")
+	}
+	if opts.Duration < 0 || opts.Decimals < 0 {
+		panic("mujica: CountUp Duration and Decimals must not be negative")
+	}
+	d := opts.Duration
+	if d == 0 {
+		d = 600 * time.Millisecond
+	}
+	format := opts.Format
+	if format == nil {
+		format = func(v float64) string { return strconv.FormatFloat(v, 'f', opts.Decimals, 64) }
+	}
+	dur := Motion(c, d)
+	now := c.Now()
+	row := ui.Row(c).Shrink(0).Label(format(value))
+	st := ui.Local(row, "count", func() countUpState { return countUpState{from: value, to: value} })
+	at := func() float64 {
+		if dur == 0 {
+			return st.to
+		}
+		p := min(1, float64(now.Sub(st.start))/float64(dur))
+		return st.from + (st.to-st.from)*float64(ui.EaseOut(float32(p)))
+	}
+	if value != st.to {
+		from := at()
+		slog.Debug("mujica: count up", "from", from, "to", value)
+		st.from, st.to, st.start = from, value, now
+	}
+	shown := at()
+	if shown != st.to {
+		c.AnimationFrame()
+	}
+	return row.Children(func() { ui.Text(c, format(shown)).FontFeatures("tnum").SingleLine() })
+}
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/dots_loader.go b/dots_loader.go
new file mode 100644
index 0000000..b1cbb8a
--- /dev/null
+++ b/dots_loader.go
@@ -0,0 +1,80 @@
+package mujica
+
+import (
+	"math"
+
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/theme"
+)
+
+// LoaderOptions configure the loaders: DotsLoader, BarsLoader, PulseLoader, OrbitLoader and WaveLoader.
+type LoaderOptions struct {
+	// Size is the mark's height in DIPs; zero means 16.
+	Size float32
+	// Label is read out, and shown with ShowLabel; empty means "Loading".
+	Label     string
+	ShowLabel bool
+	// Color paints the mark; zero uses AccentText.
+	Color ui.Color
+}
+
+// loaderDraw paints a loader at phase t in [0, 1); t is 0 and still is set under reduced motion.
+type loaderDraw func(p *ui.Painter, r ui.Rect, t float64, col ui.Color, still bool)
+
+// loaderMark builds a loader of aspect w:1 that repaints only while painted and moving.
+func loaderMark(c *ui.Context, opts LoaderOptions, aspect float32, period int64, draw loaderDraw) *ui.Element {
+	if !(opts.Size >= 0) || math.IsInf(float64(opts.Size), 1) {
+		panic("mujica: loader Size must be finite and not negative")
+	}
+	k := Tokens(c)
+	size := opts.Size
+	if size == 0 {
+		size = 16
+	}
+	label := opts.Label
+	if label == "" {
+		label = msg(c, "loading")
+	}
+	col := opts.Color
+	if col.A == 0 {
+		col = k.AccentText
+	}
+	still := c.Preferences().ReduceMotion
+	row := ui.Row(c).Gap(Density(c).Unit() * 2).AlignItems(ui.Center).Shrink(0).Role(ui.RoleProgress).Label(label)
+	row.Children(func() {
+		ui.Box(c).Key(still).Size(size*aspect, size).Shrink(0).Role(ui.RoleNone).Draw(func(p *ui.Painter, r ui.Rect) {
+			t := 0.0
+			if !still {
+				t = float64(p.Now().UnixMilli()%period) / float64(period)
+				p.AnimationFrame()
+			}
+			draw(p, r, t, col, still)
+		})
+		// Reduced motion shows the words, as the mark stands still.
+		if opts.ShowLabel || still {
+			ui.Text(c, label).TextColor(k.TextMuted).FontSize(FontSize(c, theme.CaptionSize)).SingleLine()
+		}
+	})
+	return row
+}
+
+// loaderWave is a smooth 0..1 rise and fall over phase t.
+func loaderWave(t float64) float32 { return float32(0.5 - 0.5*math.Cos(2*math.Pi*t)) }
+
+// DotsLoader shows three dots lighting up in turn.
+func DotsLoader(c *ui.Context, opts LoaderOptions) *ui.Element {
+	return loaderMark(c, opts, 2.5, 1200, func(p *ui.Painter, r ui.Rect, t float64, col ui.Color, still bool) {
+		d := r.H * 0.36
+		for i := range 3 {
+			a := float32(1)
+			if !still {
+				a = 0.3 + 0.7*loaderWave(t-float64(i)/6)
+			}
+			var dot ui.Path
+			cx := r.X + r.W*(float32(i)+0.5)/3
+			dot.Circle(cx, r.Y+r.H/2, d/2)
+			p.FillPath(&dot, col.Alpha(a))
+		}
+	})
+}
diff --git a/eval_result_table.go b/eval_result_table.go
new file mode 100644
index 0000000..915e0c7
--- /dev/null
+++ b/eval_result_table.go
@@ -0,0 +1,115 @@
+package mujica
+
+import (
+	"cmp"
+	"fmt"
+	"log/slog"
+	"math"
+	"strconv"
+
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/icons"
+)
+
+// EvalCase is one evaluation case and its outcome.
+type EvalCase struct {
+	ID     string
+	Name   string
+	Score  float64
+	Passed bool
+}
+
+// EvalResultTableOptions configure an EvalResultTable.
+type EvalResultTableOptions struct {
+	// Decimals of scores; zero means 2.
+	Decimals int
+	Status   DataStatus
+	Error    string
+}
+
+// EvalResultTableResult is a built EvalResultTable and its events.
+type EvalResultTableResult struct {
+	Table DataTableView
+	diff  string
+}
+
+// Diff returns the case whose differences the user asked to see this frame.
+func (r EvalResultTableResult) Diff() (string, bool) { return r.diff, r.diff != "" }
+
+// EvalResultTable lists eval cases with score and pass or fail, sortable, with a pass summary; give it a height.
+func EvalResultTable(c *ui.Context, s *DataTableState[string], cases []EvalCase, opts EvalResultTableOptions) EvalResultTableResult {
+	if opts.Decimals < 0 {
+		panic("mujica: EvalResultTable Decimals is negative")
+	}
+	dec := opts.Decimals
+	if dec == 0 {
+		dec = 2
+	}
+	passed := 0
+	for _, ec := range cases {
+		if ec.ID == "" || math.IsNaN(ec.Score) || math.IsInf(ec.Score, 0) {
+			panic("mujica: EvalCase needs an ID and a finite Score")
+		}
+		if ec.Passed {
+			passed++
+		}
+	}
+	k := Tokens(c)
+	u := Density(c).Unit()
+	var res EvalResultTableResult
+	verdict := func(ec EvalCase) string {
+		if ec.Passed {
+			return msg(c, "eval_result_table.pass")
+		}
+		return msg(c, "eval_result_table.fail")
+	}
+	cols := []DataColumn[EvalCase]{
+		{ID: "name", Title: msg(c, "eval_result_table.case"), Sortable: true, Compare: func(a, b EvalCase) int { return cmp.Compare(a.Name, b.Name) }, Text: func(e EvalCase) string { return e.Name }},
+		{ID: "score", Title: msg(c, "eval_result_table.score"), Width: 90, Align: ui.End, Sortable: true, Compare: func(a, b EvalCase) int { return cmp.Compare(a.Score, b.Score) },
+			Text: func(e EvalCase) string { return strconv.FormatFloat(e.Score, 'f', dec, 64) }},
+		{ID: "result", Title: msg(c, "eval_result_table.result"), Width: 110, Sortable: true,
+			Compare: func(a, b EvalCase) int { return cmp.Compare(evalRank(a), evalRank(b)) }, Text: verdict,
+			Cell: func(e EvalCase) {
+				icon, col := "circle-check", k.Success
+				if !e.Passed {
+					icon, col = "circle-x", k.Danger
+				}
+				ui.Row(c).Gap(u).AlignItems(ui.Center).TextColor(col).Children(func() {
+					ui.Icon(c, icons.Must(icon)).Size(14, 14)
+					ui.Text(c, verdict(e)).FontWeight(600)
+				})
+			}},
+		{ID: "diff", Title: "", Width: 48, Text: func(EvalCase) string { return "" },
+			Cell: func(e EvalCase) {
+				b := iconAction(c, icons.Must("arrow-left-right"), fmt.Sprintf(msg(c, "eval_result_table.diff"), e.Name)).Tooltip(msg(c, "eval_result_table.view"))
+				if b.Clicked() && !b.IsDisabled() {
+					res.diff = e.ID
+					slog.Debug("mujica: eval result diff", "case", e.ID)
+				}
+			}},
+	}
+	col := ui.Column(c).AlignItems(ui.Stretch).Gap(u * 2)
+	col.Children(func() {
+		if len(cases) > 0 {
+			ui.Row(c).Gap(u * 3).AlignItems(ui.Center).Role(ui.RoleStatus).Children(func() {
+				ui.Text(c, fmt.Sprintf(msg(c, "eval_result_table.summary"), passed, len(cases))).FontWeight(600)
+				ui.Box(c).Height(6).Width(160).Radius(1).Background(k.Danger.Mix(k.Surface, 0.6)).Role(ui.RoleNone).Draw(func(p *ui.Painter, r ui.Rect) {
+					p.Fill(ui.Rect{X: r.X, Y: r.Y, W: r.W * float32(passed) / float32(len(cases)), H: r.H}, k.Success, 1)
+				})
+			})
+		}
+		res.Table = DataTable(c, s, cases, DataTableOptions[EvalCase, string]{Columns: cols, Key: func(e EvalCase) string { return e.ID },
+			Empty: msg(c, "eval_result_table.empty"), Status: opts.Status, Error: opts.Error})
+		res.Table.Element.Grow(1)
+	})
+	res.Table.Element = col
+	return res
+}
+
+func evalRank(e EvalCase) int {
+	if e.Passed {
+		return 1
+	}
+	return 0
+}
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.go b/interrupt_button.go
new file mode 100644
index 0000000..fea58a9
--- /dev/null
+++ b/interrupt_button.go
@@ -0,0 +1,61 @@
+package mujica
+
+import (
+	"log/slog"
+
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/icons"
+)
+
+// InterruptButtonOptions configure an InterruptButton.
+type InterruptButtonOptions struct {
+	// Confirm asks before interrupting.
+	Confirm bool
+	// Interrupting shows the stop in progress until the run ends.
+	Interrupting bool
+	// Label replaces the built-in "Stop".
+	Label string
+}
+
+// InterruptButton stops a running agent; Changed reports the interrupt, confirmed when asked.
+func InterruptButton(c *ui.Context, running bool, opts InterruptButtonOptions) ChoiceResult {
+	if opts.Interrupting && !running {
+		panic("mujica: InterruptButton cannot be Interrupting while not running")
+	}
+	label := opts.Label
+	if label == "" {
+		label = msg(c, "interrupt_button.stop")
+	}
+	shown := label
+	if opts.Interrupting {
+		shown = msg(c, "interrupt_button.stopping")
+	}
+	live := running && !opts.Interrupting
+	var res ChoiceResult
+	wrap := ui.Row(c).Shrink(0)
+	res.Element = wrap
+	wrap.Children(func() {
+		b := Button(c, shown, ButtonOptions{Variant: Danger, Icon: icons.Must("circle-x"), Loading: opts.Interrupting, Disabled: !running})
+		open := ui.Local(wrap, "confirm", func() bool { return false })
+		if !live || b.IsDisabled() {
+			*open = false
+		}
+		clicked := b.Clicked() && live
+		switch {
+		case clicked && opts.Confirm:
+			*open = true
+		case clicked:
+			res.changed = true
+		}
+		r := Popconfirm(c, b, open, PopconfirmOptions{Title: msg(c, "interrupt_button.confirm"),
+			Description: msg(c, "interrupt_button.detail"), ConfirmLabel: label, CancelLabel: msg(c, "interrupt_button.keep"), Danger: true})
+		if r.Confirmed && live {
+			res.changed = true
+		}
+	})
+	if res.changed {
+		slog.Debug("mujica: interrupt button interrupt")
+	}
+	return res
+}
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/layout_transition.go b/layout_transition.go
new file mode 100644
index 0000000..3567d07
--- /dev/null
+++ b/layout_transition.go
@@ -0,0 +1,41 @@
+package mujica
+
+import (
+	"time"
+
+	"github.com/egoist/mygo/ui"
+)
+
+// LayoutTransitionOptions configure a LayoutTransition.
+type LayoutTransitionOptions struct {
+	// Duration of a change; zero means 200 ms.
+	Duration time.Duration
+	// Row lays the content in a row instead of a column.
+	Row bool
+	// Clip hides content outside the box while it resizes.
+	Clip bool
+}
+
+// LayoutTransition holds content whose size and place animate from where they were (FLIP).
+// Siblings that the change moves need a LayoutTransition of their own to move in step.
+func LayoutTransition(c *ui.Context, opts LayoutTransitionOptions, content func()) *ui.Element {
+	if opts.Duration < 0 {
+		panic("mujica: LayoutTransition Duration is negative")
+	}
+	d := opts.Duration
+	if d == 0 {
+		d = 200 * time.Millisecond
+	}
+	box := ui.Column(c).AlignItems(ui.Stretch)
+	if opts.Row {
+		box.Row()
+	}
+	if opts.Clip {
+		box.Clip()
+	}
+	box.Transition(ui.ElementTransition{Duration: d, Position: true, Size: true})
+	if content != nil {
+		box.Children(content)
+	}
+	return box
+}
diff --git a/loaders_test.go b/loaders_test.go
new file mode 100644
index 0000000..0761011
--- /dev/null
+++ b/loaders_test.go
@@ -0,0 +1,115 @@
+package mujica
+
+import (
+	"bytes"
+	"testing"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+)
+
+// motionFrames builds view and returns its tester and a counter of built frames.
+func motionFrames(view func(c *ui.Context), w, h int) (*ui.Tester, *int) {
+	n := new(int)
+	tt := ui.NewTester(func(c *ui.Context) {
+		*n++
+		Use(c, Settings{})
+		view(c)
+	}, w, h)
+	return tt, n
+}
+
+// motionBusy reports whether one more frame keeps asking for frames.
+func motionBusy(tt *ui.Tester, n *int) bool {
+	before := *n
+	tt.Frame()
+	return *n-before > 2
+}
+
+// motionCount counts texts and names equal to s.
+func motionCount(tt *ui.Tester, s string) int {
+	n := 0
+	for _, x := range tt.Texts() {
+		if x == s {
+			n++
+		}
+	}
+	return n
+}
+
+var loaderCases = map[string]func(c *ui.Context, o LoaderOptions) *ui.Element{
+	"dots": DotsLoader, "bars": BarsLoader, "pulse": PulseLoader, "orbit": OrbitLoader, "wave": WaveLoader,
+}
+
+func TestLoadersMoveStopAndLabel(t *testing.T) {
+	for name, loader := range loaderCases {
+		t.Run(name, func(t *testing.T) {
+			show := true
+			tt, n := motionFrames(func(c *ui.Context) {
+				if show {
+					loader(c, LoaderOptions{Size: 32, Label: "Thinking"})
+				}
+			}, 200, 80)
+			if _, ok := tt.Find("Thinking"); !ok {
+				t.Fatal("loader not named")
+			}
+			if motionCount(tt, "Thinking") != 1 {
+				t.Fatal("label shown without ShowLabel")
+			}
+			a := encode(t, tt.Image())
+			time.Sleep(120 * time.Millisecond)
+			tt.Frame()
+			if bytes.Equal(a, encode(t, tt.Image())) || !motionBusy(tt, n) {
+				t.Fatal("loader does not move")
+			}
+			tt.SetPreferences(ui.Preferences{ReduceMotion: true, TextScale: 1})
+			if motionBusy(tt, n) || motionCount(tt, "Thinking") != 2 {
+				t.Fatalf("reduced motion: still repainting or no static label: %q", tt.Texts())
+			}
+			a = encode(t, tt.Image())
+			time.Sleep(120 * time.Millisecond)
+			tt.Frame()
+			if !bytes.Equal(a, encode(t, tt.Image())) {
+				t.Fatal("loader moved under reduced motion")
+			}
+			tt.SetPreferences(ui.Preferences{TextScale: 1})
+			show = false
+			tt.Frame()
+			if motionBusy(tt, n) {
+				t.Fatal("hidden loader keeps repainting")
+			}
+		})
+	}
+}
+
+func TestLoadersInvalidSize(t *testing.T) {
+	for name, loader := range loaderCases {
+		func() {
+			defer func() {
+				if recover() == nil {
+					t.Errorf("%s: negative size did not panic", name)
+				}
+			}()
+			ui.Render(func(c *ui.Context) {
+				Use(c, Settings{})
+				loader(c, LoaderOptions{Size: -1})
+			}, 100, 50, 1)
+		}()
+	}
+}
+
+func loaderSnapshot(t *testing.T, name string, loader func(c *ui.Context, o LoaderOptions) *ui.Element) {
+	snapshot(t, name, 480, 90, func(c *ui.Context) {
+		ui.Row(c).Padding(20).Gap(24).AlignItems(ui.Center).Children(func() {
+			loader(c, LoaderOptions{})
+			loader(c, LoaderOptions{Size: 28, Label: "Thinking", ShowLabel: true})
+			loader(c, LoaderOptions{Size: 20, Color: Tokens(c).Info})
+		})
+	})
+}
+
+func TestDotsLoaderSnapshot(t *testing.T)  { loaderSnapshot(t, "dots_loader", DotsLoader) }
+func TestBarsLoaderSnapshot(t *testing.T)  { loaderSnapshot(t, "bars_loader", BarsLoader) }
+func TestPulseLoaderSnapshot(t *testing.T) { loaderSnapshot(t, "pulse_loader", PulseLoader) }
+func TestOrbitLoaderSnapshot(t *testing.T) { loaderSnapshot(t, "orbit_loader", OrbitLoader) }
+func TestWaveLoaderSnapshot(t *testing.T)  { loaderSnapshot(t, "wave_loader", WaveLoader) }
diff --git a/messages_motion.go b/messages_motion.go
new file mode 100644
index 0000000..8597473
--- /dev/null
+++ b/messages_motion.go
@@ -0,0 +1,56 @@
+package mujica
+
+func init() {
+	addMessages(map[string][2]string{
+		"interrupt_button.stop":     {"Stop", "停止"},
+		"interrupt_button.stopping": {"Stopping", "正在停止"},
+		"interrupt_button.confirm":  {"Stop the agent?", "停止智能体？"},
+		"interrupt_button.detail":   {"Work in progress will be lost.", "进行中的工作将会丢失。"},
+		"interrupt_button.keep":     {"Keep running", "继续运行"},
+
+		"token_usage_chart.label":  {"Token usage", "Token 用量"},
+		"token_usage_chart.input":  {"Input", "输入"},
+		"token_usage_chart.output": {"Output", "输出"},
+
+		"cost_breakdown.model":      {"Model", "模型"},
+		"cost_breakdown.tool":       {"Tool", "工具"},
+		"cost_breakdown.step":       {"Step", "步骤"},
+		"cost_breakdown.calls":      {"Calls", "调用"},
+		"cost_breakdown.input":      {"Input tokens", "输入 token"},
+		"cost_breakdown.output":     {"Output tokens", "输出 token"},
+		"cost_breakdown.cost":       {"Cost", "费用"},
+		"cost_breakdown.empty":      {"No costs yet", "暂无费用"},
+		"cost_breakdown.unnamed":    {"(unnamed)", "（未命名）"},
+		"cost_breakdown.total":      {"Total", "合计"},
+		"cost_breakdown.total_name": {"Total %s over %d calls", "合计 %s，共 %d 次调用"},
+		"cost_breakdown.tokens":     {"%d in · %d out", "输入 %d · 输出 %d"},
+
+		"trace_viewer.span":     {"Span", "跨度"},
+		"trace_viewer.duration": {"Duration", "耗时"},
+		"trace_viewer.timeline": {"Timeline", "时间轴"},
+		"trace_viewer.start":    {"Start", "开始"},
+		"trace_viewer.failed":   {"failed", "失败"},
+		"trace_viewer.empty":    {"No spans", "没有跨度"},
+
+		"eval_result_table.case":    {"Case", "用例"},
+		"eval_result_table.score":   {"Score", "得分"},
+		"eval_result_table.result":  {"Result", "结果"},
+		"eval_result_table.pass":    {"Pass", "通过"},
+		"eval_result_table.fail":    {"Fail", "失败"},
+		"eval_result_table.diff":    {"View differences for %s", "查看 %s 的差异"},
+		"eval_result_table.view":    {"View differences", "查看差异"},
+		"eval_result_table.summary": {"%d of %d passed", "通过 %d / %d"},
+		"eval_result_table.empty":   {"No eval cases", "没有评测用例"},
+
+		"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"},
+
+		"blink_highlight.up":   {"up", "上升"},
+		"blink_highlight.down": {"down", "下降"},
+	})
+}
diff --git a/orbit_loader.go b/orbit_loader.go
new file mode 100644
index 0000000..6a32103
--- /dev/null
+++ b/orbit_loader.go
@@ -0,0 +1,26 @@
+package mujica
+
+import (
+	"math"
+
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/internal"
+)
+
+// OrbitLoader moves a diamond around a ring of small diamonds, in Spinner's language.
+func OrbitLoader(c *ui.Context, opts LoaderOptions) *ui.Element {
+	return loaderMark(c, opts, 1, 1600, func(p *ui.Painter, r ui.Rect, t float64, col ui.Color, still bool) {
+		cx, cy, rad := r.X+r.W/2, r.Y+r.H/2, r.W*0.36
+		at := func(turn float64) (float32, float32) {
+			a := 2*math.Pi*turn - math.Pi/2
+			return internal.Snap(p, cx+rad*float32(math.Cos(a))), internal.Snap(p, cy+rad*float32(math.Sin(a)))
+		}
+		for i := range 8 {
+			x, y := at(float64(i) / 8)
+			p.FillPath(internal.Diamond(x, y, r.W*0.12), col.Alpha(0.3))
+		}
+		x, y := at(t)
+		p.FillPath(internal.Diamond(x, y, internal.Snap(p, r.W*0.28)), col)
+	})
+}
diff --git a/presence.go b/presence.go
new file mode 100644
index 0000000..2eacd5a
--- /dev/null
+++ b/presence.go
@@ -0,0 +1,71 @@
+package mujica
+
+import (
+	"log/slog"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/theme"
+)
+
+// PresenceKind is how content comes and goes.
+type PresenceKind int
+
+const (
+	// PresenceFade fades in and out.
+	PresenceFade PresenceKind = iota
+	// PresenceSlide fades while moving up into place and down out.
+	PresenceSlide
+	// PresenceCollapse grows open and shrinks shut along the parent's direction.
+	PresenceCollapse
+)
+
+// PresenceOptions configure a Presence.
+type PresenceOptions struct {
+	Kind PresenceKind
+	// Duration is PopupDuration when zero.
+	Duration time.Duration
+}
+
+// presenceMotion is where content of kind comes from and goes to.
+func presenceMotion(kind PresenceKind) *ui.Motion {
+	switch kind {
+	case PresenceFade:
+		return &ui.Motion{}
+	case PresenceSlide:
+		return &ui.Motion{Y: 8}
+	case PresenceCollapse:
+		return &ui.Motion{Collapse: true, Opacity: 1}
+	}
+	panic("mujica: unknown PresenceKind")
+}
+
+type presenceState struct{ shown bool }
+
+// Presence builds content while show is true; it enters and exits with motion, removed once the exit ends.
+func Presence(c *ui.Context, show bool, opts PresenceOptions, content func()) *ui.Element {
+	m := presenceMotion(opts.Kind)
+	if opts.Duration < 0 {
+		panic("mujica: Presence Duration is negative")
+	}
+	d := opts.Duration
+	if d == 0 {
+		d = theme.PopupDuration
+	}
+	holder := ui.Column(c).AlignItems(ui.Stretch).Shrink(0)
+	st := ui.Local(holder, "presence", func() presenceState { return presenceState{shown: show} })
+	if st.shown != show {
+		st.shown = show
+		slog.Debug("mujica: presence", "show", show)
+	}
+	holder.Children(func() {
+		if !show {
+			return
+		}
+		box := ui.Column(c).AlignItems(ui.Stretch).Key("presence")
+		box.Transition(ui.ElementTransition{Duration: d, Enter: m, Exit: m})
+		box.Children(content)
+	})
+	return holder
+}
diff --git a/pulse_loader.go b/pulse_loader.go
new file mode 100644
index 0000000..a500bcf
--- /dev/null
+++ b/pulse_loader.go
@@ -0,0 +1,21 @@
+package mujica
+
+import (
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/internal"
+)
+
+// PulseLoader shows one dot breathing between 60% and full size; never a halo.
+func PulseLoader(c *ui.Context, opts LoaderOptions) *ui.Element {
+	return loaderMark(c, opts, 1, 1600, func(p *ui.Painter, r ui.Rect, t float64, col ui.Color, still bool) {
+		s, a := float32(1), float32(1)
+		if !still {
+			w := loaderWave(t)
+			s, a = 0.6+0.4*w, 0.55+0.45*w
+		}
+		var dot ui.Path
+		dot.Circle(r.X+r.W/2, r.Y+r.H/2, internal.Snap(p, r.H*0.4*s))
+		p.FillPath(&dot, col.Alpha(a))
+	})
+}
diff --git a/reorder_transition.go b/reorder_transition.go
new file mode 100644
index 0000000..9b27221
--- /dev/null
+++ b/reorder_transition.go
@@ -0,0 +1,43 @@
+package mujica
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+)
+
+// ReorderTransitionOptions configure a ReorderTransition.
+type ReorderTransitionOptions struct {
+	// Duration of a move; zero means 200 ms.
+	Duration time.Duration
+	// Gap between items in DIPs.
+	Gap float32
+}
+
+// ReorderTransition lays out keyed items in a column; when their order changes they slide to their new places.
+// Items added fade in and items removed fade out.
+func ReorderTransition[K comparable](c *ui.Context, keys []K, opts ReorderTransitionOptions, item func(key K)) *ui.Element {
+	if opts.Duration < 0 || opts.Gap < 0 {
+		panic("mujica: ReorderTransition Duration and Gap must not be negative")
+	}
+	d := opts.Duration
+	if d == 0 {
+		d = 200 * time.Millisecond
+	}
+	seen := make(map[K]bool, len(keys))
+	for _, k := range keys {
+		if seen[k] {
+			panic(fmt.Sprintf("mujica: ReorderTransition duplicate key %v", k))
+		}
+		seen[k] = true
+	}
+	move := ui.ElementTransition{Duration: d, Position: true, Enter: &ui.Motion{}, Exit: &ui.Motion{}}
+	col := ui.Column(c).AlignItems(ui.Stretch).Gap(opts.Gap)
+	col.Children(func() {
+		for _, k := range keys {
+			ui.Column(c).Key(k).AlignItems(ui.Stretch).Transition(move).Children(func() { item(k) })
+		}
+	})
+	return col
+}
diff --git a/shimmer.go b/shimmer.go
new file mode 100644
index 0000000..174a960
--- /dev/null
+++ b/shimmer.go
@@ -0,0 +1,71 @@
+package mujica
+
+import (
+	"math"
+
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/internal"
+	"mujicaui/theme"
+)
+
+// ShimmerOptions configure a Shimmer placeholder.
+type ShimmerOptions struct {
+	// Width fills the parent when zero.
+	Width float32
+	// Height is ControlHeight when zero.
+	Height float32
+	// Label is read out while loading; empty means "Loading".
+	Label string
+}
+
+// Shimmer shows a sweeping placeholder while loading, then builds content instead.
+func Shimmer(c *ui.Context, loading bool, opts ShimmerOptions, content func()) *ui.Element {
+	if !(opts.Width >= 0) || !(opts.Height >= 0) || math.IsInf(float64(opts.Width+opts.Height), 1) {
+		panic("mujica: Shimmer size must be finite and not negative")
+	}
+	if !loading {
+		box := ui.Column(c).AlignItems(ui.Stretch)
+		if content != nil {
+			box.Children(content)
+		}
+		return box
+	}
+	k := Tokens(c)
+	h := opts.Height
+	if h == 0 {
+		h = Density(c).ControlHeight()
+	}
+	label := opts.Label
+	if label == "" {
+		label = msg(c, "loading")
+	}
+	fill := k.SurfaceHover
+	if k.Dark {
+		fill = k.Border
+	}
+	still := c.Preferences().ReduceMotion
+	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()
+	}
+	// 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/shimmer_text.go b/shimmer_text.go
new file mode 100644
index 0000000..1b7b9bd
--- /dev/null
+++ b/shimmer_text.go
@@ -0,0 +1,43 @@
+package mujica
+
+import (
+	"github.com/egoist/mygo/ui"
+)
+
+// ShimmerTextOptions configure a ShimmerText.
+type ShimmerTextOptions struct {
+	// Active sweeps the light; false shows plain muted text.
+	Active bool
+}
+
+// ShimmerText shows a status such as "Thinking" with light sweeping across its letters.
+func ShimmerText(c *ui.Context, text string, opts ShimmerTextOptions) *ui.Element {
+	if text == "" {
+		panic("mujica: ShimmerText needs text")
+	}
+	k := Tokens(c)
+	still := c.Preferences().ReduceMotion
+	if !opts.Active || still {
+		e := ui.Text(c, text).TextColor(k.TextMuted)
+		if opts.Active {
+			e.Role(ui.RoleStatus)
+		}
+		return e
+	}
+	runes := []rune(text)
+	size := c.Theme().FontSize
+	// The text keeps its layout and name; the sweep is painted over it.
+	e := ui.Text(c, text).TextColor(ui.Transparent).Role(ui.RoleStatus).SingleLine()
+	e.DrawOver(func(p *ui.Painter, r ui.Rect) {
+		p.AnimationFrame()
+		t := float32(p.Now().UnixMilli()%1800) / 1800
+		at := t*float32(len(runes)+6) - 3
+		spans := make([]ui.Span, len(runes))
+		for i, ch := range runes {
+			d := max(0, 1-abs32(float32(i)-at)/3)
+			spans[i] = ui.Span{Text: string(ch), Size: size, Color: k.TextMuted.Mix(k.Text, d)}
+		}
+		p.RichText(r.X, r.Y, 0, spans...)
+	})
+	return e
+}
diff --git a/stagger.go b/stagger.go
new file mode 100644
index 0000000..1b39ab1
--- /dev/null
+++ b/stagger.go
@@ -0,0 +1,71 @@
+package mujica
+
+import (
+	"log/slog"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/theme"
+)
+
+// StaggerOptions configure a Stagger.
+type StaggerOptions struct {
+	// Interval between items; zero means 60 ms.
+	Interval time.Duration
+	// Duration of each item's entry; zero means PopupDuration.
+	Duration time.Duration
+	// Horizontal lays items in a row.
+	Horizontal bool
+}
+
+type staggerState struct {
+	born  time.Time
+	shown int
+	done  bool
+}
+
+// Stagger builds n items, each entering after the one before, once when it first appears.
+// Items added after the sequence ends appear with their own entry.
+func Stagger(c *ui.Context, n int, opts StaggerOptions, item func(i int)) *ui.Element {
+	if n < 0 || opts.Interval < 0 || opts.Duration < 0 {
+		panic("mujica: Stagger needs non-negative n, Interval and Duration")
+	}
+	every, d := opts.Interval, opts.Duration
+	if every == 0 {
+		every = 60 * time.Millisecond
+	}
+	if d == 0 {
+		d = theme.PopupDuration
+	}
+	box := ui.Column(c).AlignItems(ui.Stretch)
+	if opts.Horizontal {
+		box.Row().AlignItems(ui.Start)
+	}
+	st := ui.Local(box, "stagger", func() *staggerState { return &staggerState{born: c.Now()} })
+	s := *st
+	upto := n
+	if !s.done && !c.Preferences().ReduceMotion {
+		upto = min(n, 1+int(c.Now().Sub(s.born)/every))
+		if upto < n {
+			c.After(s.born.Add(time.Duration(upto) * every).Sub(c.Now()))
+		} else {
+			s.done = true
+			slog.Debug("mujica: stagger done", "items", n)
+		}
+	}
+	if c.Preferences().ReduceMotion {
+		s.done = true
+	}
+	enter := &ui.Motion{Y: 8}
+	if opts.Horizontal {
+		enter = &ui.Motion{X: 8}
+	}
+	box.Children(func() {
+		for i := range upto {
+			ui.Column(c).Key(i).AlignItems(ui.Stretch).
+				Transition(ui.ElementTransition{Duration: d, Enter: enter}).Children(func() { item(i) })
+		}
+	})
+	return box
+}
diff --git a/testdata/snapshots/darwin/bars_loader-dark.png b/testdata/snapshots/darwin/bars_loader-dark.png
new file mode 100644
index 0000000..96707b3
Binary files /dev/null and b/testdata/snapshots/darwin/bars_loader-dark.png differ
diff --git a/testdata/snapshots/darwin/bars_loader-light.png b/testdata/snapshots/darwin/bars_loader-light.png
new file mode 100644
index 0000000..dbe7c19
Binary files /dev/null and b/testdata/snapshots/darwin/bars_loader-light.png differ
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/dots_loader-dark.png b/testdata/snapshots/darwin/dots_loader-dark.png
new file mode 100644
index 0000000..bb32f30
Binary files /dev/null and b/testdata/snapshots/darwin/dots_loader-dark.png differ
diff --git a/testdata/snapshots/darwin/dots_loader-light.png b/testdata/snapshots/darwin/dots_loader-light.png
new file mode 100644
index 0000000..c2c3c13
Binary files /dev/null and b/testdata/snapshots/darwin/dots_loader-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/orbit_loader-dark.png b/testdata/snapshots/darwin/orbit_loader-dark.png
new file mode 100644
index 0000000..f80e876
Binary files /dev/null and b/testdata/snapshots/darwin/orbit_loader-dark.png differ
diff --git a/testdata/snapshots/darwin/orbit_loader-light.png b/testdata/snapshots/darwin/orbit_loader-light.png
new file mode 100644
index 0000000..fdf0dce
Binary files /dev/null and b/testdata/snapshots/darwin/orbit_loader-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/pulse_loader-dark.png b/testdata/snapshots/darwin/pulse_loader-dark.png
new file mode 100644
index 0000000..715cc24
Binary files /dev/null and b/testdata/snapshots/darwin/pulse_loader-dark.png differ
diff --git a/testdata/snapshots/darwin/pulse_loader-light.png b/testdata/snapshots/darwin/pulse_loader-light.png
new file mode 100644
index 0000000..c971922
Binary files /dev/null and b/testdata/snapshots/darwin/pulse_loader-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/testdata/snapshots/darwin/wave_loader-dark.png b/testdata/snapshots/darwin/wave_loader-dark.png
new file mode 100644
index 0000000..6010e38
Binary files /dev/null and b/testdata/snapshots/darwin/wave_loader-dark.png differ
diff --git a/testdata/snapshots/darwin/wave_loader-light.png b/testdata/snapshots/darwin/wave_loader-light.png
new file mode 100644
index 0000000..143110b
Binary files /dev/null and b/testdata/snapshots/darwin/wave_loader-light.png differ
diff --git a/token_usage_chart.go b/token_usage_chart.go
new file mode 100644
index 0000000..11e139e
--- /dev/null
+++ b/token_usage_chart.go
@@ -0,0 +1,65 @@
+package mujica
+
+import (
+	"strconv"
+
+	"github.com/egoist/mygo/ui"
+)
+
+// TokenUsage is the tokens one session or step used.
+type TokenUsage struct {
+	Label         string
+	Input, Output int
+}
+
+// TokenUsageChartOptions configure a TokenUsageChart.
+type TokenUsageChartOptions struct {
+	// Frame names, sizes and states the chart; an empty Label uses the built-in name.
+	Frame ChartFrame
+	// Line draws input and output as lines instead of stacked bars.
+	Line bool
+}
+
+type tokenUsageSeries struct {
+	src    *TokenUsage
+	n      int
+	labels []string
+	series []ChartSeries
+}
+
+// TokenUsageChart shows input and output tokens per session or step, as stacked bars or lines.
+func TokenUsageChart(c *ui.Context, usage []TokenUsage, opts TokenUsageChartOptions) ChartResult {
+	if opts.Frame.Label == "" {
+		opts.Frame.Label = msg(c, "token_usage_chart.label")
+	}
+	holder := ui.Column(c).AlignItems(ui.Stretch)
+	cache := ui.Local(holder, "series", func() *tokenUsageSeries { return &tokenUsageSeries{} })
+	s := *cache
+	var first *TokenUsage
+	if len(usage) > 0 {
+		first = &usage[0]
+	}
+	if s.series == nil || s.src != first || s.n != len(usage) {
+		in, out := make([]float64, len(usage)), make([]float64, len(usage))
+		s.labels = make([]string, len(usage))
+		for i, u := range usage {
+			if u.Input < 0 || u.Output < 0 {
+				panic("mujica: TokenUsage counts must not be negative")
+			}
+			in[i], out[i], s.labels[i] = float64(u.Input), float64(u.Output), u.Label
+		}
+		s.series = []ChartSeries{{Name: msg(c, "token_usage_chart.input"), Values: in}, {Name: msg(c, "token_usage_chart.output"), Values: out}}
+		s.src, s.n = first, len(usage)
+	}
+	format := func(v float64) string { return strconv.FormatFloat(v, 'f', 0, 64) }
+	var res ChartResult
+	holder.Children(func() {
+		if opts.Line {
+			res = LineChart(c, s.series, LineChartOptions{Frame: opts.Frame, Format: format})
+			return
+		}
+		res = BarChart(c, s.labels, s.series, BarChartOptions{Frame: opts.Frame, Stacked: true, Format: format})
+	})
+	res.Element = holder
+	return res
+}
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
new file mode 100644
index 0000000..cafa661
--- /dev/null
+++ b/tool_registry_panel.go
@@ -0,0 +1,125 @@
+package mujica
+
+import (
+	"fmt"
+	"log/slog"
+
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/theme"
+)
+
+// ToolParam is a parameter in a tool's input schema.
+type ToolParam struct {
+	Name        string
+	Type        string
+	Required    bool
+	Description string
+}
+
+// AgentTool is a tool an agent may call; the caller keeps Enabled.
+type AgentTool struct {
+	Name        string
+	Description string
+	Enabled     bool
+	Params      []ToolParam
+}
+
+// ToolRegistryPanelOptions configure a ToolRegistryPanel.
+type ToolRegistryPanelOptions struct {
+	Disabled bool
+}
+
+// ToolRegistryResult is a built ToolRegistryPanel and its events.
+type ToolRegistryResult struct {
+	Element *ui.Element
+	toggled string
+	on      bool
+}
+
+// Toggled returns the tool switched this frame and its new state.
+func (r ToolRegistryResult) Toggled() (name string, on, ok bool) {
+	return r.toggled, r.on, r.toggled != ""
+}
+
+// ToolRegistryPanel lists tools with on/off switches and previews the chosen tool's parameters.
+func ToolRegistryPanel(c *ui.Context, s *ListState[string], tools []AgentTool, opts ToolRegistryPanelOptions) ToolRegistryResult {
+	seen := map[string]bool{}
+	for _, t := range tools {
+		if t.Name == "" || seen[t.Name] {
+			panic("mujica: AgentTool needs a unique Name")
+		}
+		seen[t.Name] = true
+	}
+	k := Tokens(c)
+	u := Density(c).Unit()
+	row := ui.Row(c).AlignItems(ui.Stretch).Gap(u * 3).Disabled(opts.Disabled)
+	res := ToolRegistryResult{Element: row}
+	row.Children(func() {
+		ui.Column(c).Width(300).Shrink(0).AlignItems(ui.Stretch).Children(func() {
+			List(c, s, len(tools), ListOptions[string]{
+				Key: func(i int) string { return tools[i].Name }, Label: func(i int) string { return tools[i].Name },
+				Empty: msg(c, "tool_registry_panel.empty"),
+			}, func(i int) {
+				t := tools[i]
+				ui.Column(c).Grow(1).MinWidth(0).Children(func() {
+					ui.Text(c, t.Name).Font(theme.MonoFont).FontWeight(600).SingleLine()
+					ui.Text(c, t.Description).FontSize(FontSize(c, theme.CaptionSize)).TextColor(k.TextMuted).SingleLine()
+				})
+				on := t.Enabled
+				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)
+				}
+			}).Element.Grow(1)
+		})
+		ui.Column(c).Grow(1).MinWidth(0).Gap(u*2).Padding(u*3, u*4).Background(k.Surface).Border(theme.BorderWidth, k.Border).
+			Radius(theme.CardRadius).Children(func() {
+			name, ok := s.Selected()
+			var tool *AgentTool
+			for i := range tools {
+				if ok && tools[i].Name == name {
+					tool = &tools[i]
+				}
+			}
+			if tool == nil {
+				ui.Text(c, msg(c, "tool_registry_panel.choose")).TextColor(k.TextMuted)
+				return
+			}
+			toolSchema(c, *tool)
+		})
+	})
+	return res
+}
+
+// toolSchema previews a tool's parameters as a typed list.
+func toolSchema(c *ui.Context, t AgentTool) {
+	k := Tokens(c)
+	u := Density(c).Unit()
+	small := FontSize(c, theme.CaptionSize)
+	ui.Text(c, t.Name).Font(theme.SerifFont).FontWeight(600).FontSize(FontSize(c, theme.H3Size))
+	if t.Description != "" {
+		ui.Text(c, t.Description).TextColor(k.TextMuted)
+	}
+	ui.Box(c).Height(1).Background(k.Ornament).Role(ui.RoleNone)
+	if len(t.Params) == 0 {
+		ui.Text(c, msg(c, "tool_registry_panel.no_params")).TextColor(k.TextMuted)
+		return
+	}
+	for _, p := range t.Params {
+		ui.Column(c).Gap(2).Children(func() {
+			ui.Row(c).Gap(u * 2).AlignItems(ui.Center).Children(func() {
+				ui.Text(c, p.Name).Font(theme.MonoFont).FontWeight(600)
+				ui.Text(c, p.Type).Font(theme.MonoFont).FontSize(small).TextColor(k.Info)
+				if p.Required {
+					ui.Text(c, msg(c, "tool_registry_panel.required")).FontSize(small).TextColor(k.AccentText).
+						Padding(0, u).Border(theme.BorderWidth, k.AccentText).Radius(theme.ControlRadius)
+				}
+			})
+			if p.Description != "" {
+				ui.Text(c, p.Description).FontSize(small).TextColor(k.TextMuted)
+			}
+		})
+	}
+}
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
new file mode 100644
index 0000000..7304c72
--- /dev/null
+++ b/trace_viewer.go
@@ -0,0 +1,195 @@
+package mujica
+
+import (
+	"cmp"
+	"fmt"
+	"log/slog"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/icons"
+	"mujicaui/internal"
+	"mujicaui/theme"
+)
+
+// TraceAttr is a key and value recorded on a span.
+type TraceAttr struct{ Key, Value string }
+
+// TraceSpan is one timed call of a trace; Start and End are offsets from the trace start.
+type TraceSpan struct {
+	ID     string
+	Parent string
+	Name   string
+	Start  time.Duration
+	End    time.Duration
+	Failed bool
+	Attrs  []TraceAttr
+}
+
+// TraceViewerState holds the tree's sort, open spans, selection and index.
+type TraceViewerState struct {
+	Tree  TreeTableState[string]
+	index traceIndex
+	src   *TraceSpan
+	n     int
+	built bool
+}
+
+type traceIndex struct {
+	byID  map[string]int
+	kids  map[string][]string
+	roots []string
+	end   time.Duration
+}
+
+// TraceViewerOptions configure a TraceViewer.
+type TraceViewerOptions struct {
+	Status DataStatus
+	Error  string
+}
+
+// TraceViewer shows a call tree with each span's time bar; the chosen span's attributes show below.
+func TraceViewer(c *ui.Context, s *TraceViewerState, spans []TraceSpan, opts TraceViewerOptions) DataTableView {
+	var first *TraceSpan
+	if len(spans) > 0 {
+		first = &spans[0]
+	}
+	if !s.built || s.src != first || s.n != len(spans) {
+		s.index = traceBuild(spans)
+		s.src, s.n, s.built = first, len(spans), true
+		for _, id := range s.index.roots {
+			s.Tree.SetOpen(id, true)
+		}
+		slog.Debug("mujica: trace viewer index", "spans", len(spans), "roots", len(s.index.roots))
+	}
+	ix := s.index
+	k := Tokens(c)
+	u := Density(c).Unit()
+	span := func(id string) TraceSpan { return spans[ix.byID[id]] }
+	cols := []TreeColumn[string]{
+		{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"))
+				}
+			}},
+		{ID: "duration", Title: msg(c, "trace_viewer.duration"), Width: 96, Align: ui.End,
+			Compare: func(a, b string) int { return cmp.Compare(span(a).End-span(a).Start, span(b).End-span(b).Start) },
+			Cell: func(id string) {
+				sp := span(id)
+				ui.Text(c, traceDuration(sp.End-sp.Start)).FontFeatures("tnum").TextColor(k.TextMuted)
+			}},
+		{ID: "timeline", Title: msg(c, "trace_viewer.timeline"), Width: 260, Compare: func(a, b string) int { return cmp.Compare(span(a).Start, span(b).Start) },
+			Cell: func(id string) {
+				sp := span(id)
+				col := k.AccentText
+				if sp.Failed {
+					col = k.Danger
+				}
+				ui.Box(c).Height(12).Grow(1).Role(ui.RoleNone).Draw(func(p *ui.Painter, r ui.Rect) {
+					p.Fill(ui.Rect{X: r.X, Y: r.Y + r.H/2, W: r.W, H: 1}, k.Border, 0)
+					if ix.end <= 0 {
+						return
+					}
+					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)))
+					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)
+				})
+			}},
+	}
+	var v DataTableView
+	col := ui.Column(c).AlignItems(ui.Stretch).Gap(u * 2)
+	col.Children(func() {
+		v = TreeTable(c, &s.Tree, TreeTableOptions[string]{Columns: cols, Roots: ix.roots,
+			Children: func(id string) []string { return ix.kids[id] },
+			Label:    func(id string) string { return span(id).Name },
+			Status:   opts.Status, Error: opts.Error, Empty: msg(c, "trace_viewer.empty")})
+		v.Element.Grow(1)
+		id, ok := s.Tree.Selected()
+		if _, known := ix.byID[id]; !ok || !known {
+			return
+		}
+		traceAttrs(c, span(id))
+	})
+	v.Element = col
+	return v
+}
+
+// traceAttrs lists the chosen span's timing and attributes.
+func traceAttrs(c *ui.Context, sp TraceSpan) {
+	k := Tokens(c)
+	u := Density(c).Unit()
+	ui.Column(c).Gap(u).Padding(u*3, u*4).Background(k.Background).Radius(theme.CardRadius).Shrink(0).Children(func() {
+		ui.Text(c, sp.Name).Font(theme.SerifFont).FontWeight(600)
+		row := func(key, val string) {
+			ui.Row(c).Gap(u * 3).Children(func() {
+				ui.Text(c, key).FontSize(FontSize(c, theme.CaptionSize)).TextColor(k.TextMuted).Width(140).Shrink(0)
+				ui.Text(c, val).Font(theme.MonoFont).FontSize(FontSize(c, theme.CaptionSize)).Grow(1).MinWidth(0)
+			})
+		}
+		row(msg(c, "trace_viewer.start"), traceDuration(sp.Start))
+		row(msg(c, "trace_viewer.duration"), traceDuration(sp.End-sp.Start))
+		for _, a := range sp.Attrs {
+			row(a.Key, a.Value)
+		}
+	})
+}
+
+// traceBuild indexes spans by ID and parent; unknown parents make roots.
+func traceBuild(spans []TraceSpan) traceIndex {
+	ix := traceIndex{byID: make(map[string]int, len(spans)), kids: map[string][]string{}}
+	for i, sp := range spans {
+		if sp.ID == "" || sp.End < sp.Start || sp.Start < 0 {
+			panic(fmt.Sprintf("mujica: TraceSpan %q needs an ID and 0 <= Start <= End", sp.ID))
+		}
+		if _, dup := ix.byID[sp.ID]; dup {
+			panic("mujica: duplicate TraceSpan ID " + sp.ID)
+		}
+		ix.byID[sp.ID] = i
+		ix.end = max(ix.end, sp.End)
+	}
+	for _, sp := range spans {
+		if _, ok := ix.byID[sp.Parent]; ok && sp.Parent != sp.ID {
+			ix.kids[sp.Parent] = append(ix.kids[sp.Parent], sp.ID)
+		} else {
+			ix.roots = append(ix.roots, sp.ID)
+		}
+	}
+	seen := 0
+	var walk func(ids []string)
+	walk = func(ids []string) {
+		for _, id := range ids {
+			seen++
+			walk(ix.kids[id])
+		}
+	}
+	walk(ix.roots)
+	if seen != len(spans) {
+		panic("mujica: TraceSpan parents form a cycle")
+	}
+	return ix
+}
+
+// traceDuration prints microseconds, milliseconds or seconds.
+func traceDuration(d time.Duration) string {
+	switch {
+	case d < time.Millisecond:
+		return fmt.Sprintf("%d µs", d.Microseconds())
+	case d < time.Second:
+		return fmt.Sprintf("%.1f ms", float64(d)/float64(time.Millisecond))
+	}
+	return fmt.Sprintf("%.2f s", d.Seconds())
+}
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
new file mode 100644
index 0000000..b1bc810
--- /dev/null
+++ b/typewriter.go
@@ -0,0 +1,87 @@
+package mujica
+
+import (
+	"log/slog"
+	"strings"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+)
+
+// TypewriterOptions configure a Typewriter.
+type TypewriterOptions struct {
+	// Speed is characters per second; zero means 40.
+	Speed float64
+	// Skippable adds a Skip button that shows the rest at once.
+	Skippable bool
+}
+
+// TypewriterResult is a built Typewriter and its events.
+type TypewriterResult struct {
+	Element *ui.Element
+	done    bool
+}
+
+// Finished reports the frame the whole text came into view.
+func (r TypewriterResult) Finished() bool { return r.done }
+
+type typewriterState struct {
+	text    []rune
+	shown   int
+	last    time.Time
+	skipped bool
+	done    bool
+}
+
+// Typewriter reveals text a character at a time; text that grows continues where it was.
+func Typewriter(c *ui.Context, text string, opts TypewriterOptions) TypewriterResult {
+	speed := opts.Speed
+	if speed == 0 {
+		speed = 40
+	}
+	if speed < 0 {
+		panic("mujica: Typewriter Speed is negative")
+	}
+	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
+	runes := []rune(text)
+	if !strings.HasPrefix(text, string(s.text)) {
+		s.shown, s.skipped, s.done = 0, false, false
+		slog.Debug("mujica: typewriter restart")
+	}
+	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()
+	if c.Preferences().ReduceMotion || s.skipped {
+		s.shown = len(runes)
+	} else if s.shown < len(runes) {
+		step := time.Duration(float64(time.Second) / speed)
+		if n := int(now.Sub(s.last) / step); n > 0 {
+			s.shown = min(len(runes), s.shown+n)
+			s.last = s.last.Add(time.Duration(n) * step)
+		}
+		if s.shown < len(runes) {
+			c.After(s.last.Add(step).Sub(now))
+		}
+	} else {
+		s.last = now
+	}
+	col.Children(func() {
+		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)
+				slog.Debug("mujica: typewriter skip")
+			}
+		}
+	})
+	if s.shown == len(runes) && !s.done {
+		s.done, res.done = true, true
+	}
+	return res
+}
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})
+		})
+	})
+}
diff --git a/wave_loader.go b/wave_loader.go
new file mode 100644
index 0000000..f82b161
--- /dev/null
+++ b/wave_loader.go
@@ -0,0 +1,30 @@
+package mujica
+
+import (
+	"math"
+
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/internal"
+)
+
+// WaveLoader draws a sine line flowing to the right.
+func WaveLoader(c *ui.Context, opts LoaderOptions) *ui.Element {
+	return loaderMark(c, opts, 2.5, 1400, func(p *ui.Painter, r ui.Rect, t float64, col ui.Color, still bool) {
+		var path ui.Path
+		amp := r.H * 0.3
+		const steps = 24
+		for i := 0; i <= steps; i++ {
+			f := float64(i) / steps
+			x := r.X + r.W*float32(f)
+			y := r.Y + r.H/2 - amp*float32(math.Sin(2*math.Pi*(1.5*f-t)))
+			x, y = internal.Snap(p, x), internal.Snap(p, y)
+			if i == 0 {
+				path.MoveTo(x, y)
+			} else {
+				path.LineTo(x, y)
+			}
+		}
+		p.StrokePath(&path, max(1.5, r.H/10), col)
+	})
+}