Upgrade MyGo to v0.5.5

MyGo v0.5.5 returns ui.Element as a checked value handle instead of a
pointer. Migrated with `mygo migrate-ui`, then fixed what the codemod
leaves to review:

- Element nil checks become .Valid(); absent elements are ui.Element{}.
- Input handlers and paint callbacks run outside the build pass, where
  elements expire and Context methods are inert: read IsDisabled into a
  local during the build, keep a ui.Handle for Focus, use c.Services()
  for clipboard access, create ui.Local state during the build.
- Add core.AutoFocus: v0.5.5 records an overlay's opener after its
  content builds, so same-frame autofocus lost focus restore on close.
  It focuses one frame later; cascader rows defer their focus likewise.
- core.OverlayLayer identifies build passes by the root element, not
  c.Now(), which repeats across passes and under the Tester clock.
- Context menus survive the opening press counted as PressedOutside;
  split button tooltip no longer reorders its open menu; disabled
  menubar rows pass presses to the panel; Form defers blur-started
  async checks so the growing message no longer moves Submit away
  from the release; Combobox drops its disabled copy now that MyGo
  blocks typing under a disabled wrapper (canary flipped to a guard).
- The Tester clock is virtual: tests use Advance/Now instead of
  time.Sleep/time.Now and read element state inside the view. The web
  mirror advances the clock to wall time before each frame and input.
- AGENTS.md and docs describe the value Element API and the new pin.

Snapshot goldens are darwin-only and were not re-verified here.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

data/accordion.go

@@ -46,7 +46,7 @@ func Accordion(c *ui.Context, open *[]string, items []AccordionItem, opts Accord
 	focusTo := ui.Local(v.Element, "focus", func() int { return -1 })
 	v.Element.Children(func() {
 		for i, it := range items {
-			ui.Column(c).Key(it.ID).Children(func() {
+			ui.Column(c.Key(it.ID)).Children(func() {
 				if i > 0 {
 					ui.Box(c).Height(1).FillWidth().Background(k.Border)
 				}
@@ -75,7 +75,7 @@ func Accordion(c *ui.Context, open *[]string, items []AccordionItem, opts Accord
 					ui.Text(c, it.Title).FontWeight(600).Grow(1).MinWidth(0)
 					ui.Icon(c, icons.Must("chevron-down")).Size(16, 16).Rotate(180 * prog).TextColor(k.TextMuted).Shrink(0)
 				})
-				if panel := collapsiblePanel(c, isOpen, prog, it.Content); panel != nil {
+				if panel := collapsiblePanel(c, isOpen, prog, it.Content); panel.Valid() {
 					panel.Padding(0, u*4, u*4).Gap(u * 2)
 				}
 			})
@@ -85,7 +85,7 @@ func Accordion(c *ui.Context, open *[]string, items []AccordionItem, opts Accord
 }
 
 // accordionKey returns the header the arrows, Home or End move to from header i, or -1.
-func accordionKey(tr *ui.Element, items []AccordionItem, i int) int {
+func accordionKey(tr ui.Element, items []AccordionItem, i int) int {
 	step, from := 0, i
 	switch {
 	case tr.Shortcut(0, ui.KeyDown):

data/card.go

@@ -22,7 +22,7 @@ type CardOptions struct {
 const cardInset float32 = 4
 
 // Card groups content on a surface with an outline. It adds no click behavior.
-func Card(c *ui.Context, opts CardOptions, body func()) *ui.Element {
+func Card(c *ui.Context, opts CardOptions, body func()) ui.Element {
 	k := core.Tokens(c)
 	u := core.Density(c).Unit()
 	pad := u * 4

data/carousel.go

@@ -97,7 +97,7 @@ func Carousel(c *ui.Context, index *int, n int, opts CarouselOptions, slide func
 			ui.Column(c).Grow(1).MinWidth(0).FillHeight().Clip().Background(k.Surface).Border(theme.BorderWidth, k.Border).Radius(theme.CardRadius).
 				Role(ui.RoleGroup).Label(fmt.Sprintf(core.Msg(c, "carousel.position"), *index+1, n)).Children(func() {
 				if n > 0 {
-					ui.Column(c).Key(*index).Grow(1).Children(func() { slide(*index) })
+					ui.Column(c.Key(*index)).Grow(1).Children(func() { slide(*index) })
 				}
 			})
 			next := input.Button(c, "", input.ButtonOptions{Variant: input.Ghost, Icon: icons.Must("chevron-right"), Label: core.Msg(c, "carousel.next"), Disabled: n < 2 || !wrap && *index == n-1})
@@ -133,7 +133,7 @@ func Carousel(c *ui.Context, index *int, n int, opts CarouselOptions, slide func
 }
 
 // carouselDot is a position button: a filled diamond for the current slide.
-func carouselDot(c *ui.Context, i, n int, on bool) *ui.Element {
+func carouselDot(c *ui.Context, i, n int, on bool) ui.Element {
 	k := core.Tokens(c)
 	b := ui.ButtonBase(c).Size(theme.MinHitSize, theme.MinHitSize).Radius(theme.ControlRadius).
 		Label(fmt.Sprintf(core.Msg(c, "carousel.position"), i+1, n)).Role(ui.RoleTab).Selected(on)
@@ -154,7 +154,7 @@ func carouselDot(c *ui.Context, i, n int, on bool) *ui.Element {
 }
 
 // carouselPause is the pause button: two bars, or a play triangle while paused.
-func carouselPause(c *ui.Context, paused bool) *ui.Element {
+func carouselPause(c *ui.Context, paused bool) ui.Element {
 	k := core.Tokens(c)
 	label := core.Msg(c, "carousel.pause")
 	if paused {

data/carousel_test.go

@@ -82,8 +82,7 @@ func TestCarouselKeyboard(t *testing.T) {
 func TestCarouselNoAutoplayByDefault(t *testing.T) {
 	h := &carouselHarness{opts: CarouselOptions{Interval: 10 * time.Millisecond}}
 	tt := ui.NewTester(h.view, 420, 280)
-	time.Sleep(30 * time.Millisecond)
-	tt.Frame()
+	tt.Advance(30 * time.Millisecond)
 	if h.index != 0 || tt.HasText("Pause autoplay") {
 		t.Fatalf("advanced without Autoplay: %d", h.index)
 	}
@@ -92,8 +91,7 @@ func TestCarouselNoAutoplayByDefault(t *testing.T) {
 func TestCarouselAutoplayPause(t *testing.T) {
 	h := &carouselHarness{opts: CarouselOptions{Autoplay: true, Interval: 20 * time.Millisecond}}
 	tt := ui.NewTester(h.view, 420, 280)
-	time.Sleep(30 * time.Millisecond)
-	tt.Frame()
+	tt.Advance(30 * time.Millisecond)
 	if h.index != 1 {
 		t.Fatalf("autoplay did not advance: %d", h.index)
 	}
@@ -102,8 +100,7 @@ func TestCarouselAutoplayPause(t *testing.T) {
 	tt.SetFocused(false)
 	tt.SetFocused(true)
 	at := h.index
-	time.Sleep(50 * time.Millisecond)
-	tt.Frame()
+	tt.Advance(50 * time.Millisecond)
 	if h.index != at || !tt.HasText("") {
 		t.Fatalf("paused carousel advanced: %d -> %d", at, h.index)
 	}
@@ -113,8 +110,7 @@ func TestCarouselAutoplayPause(t *testing.T) {
 	r, _ := tt.Find("Window " + fmt.Sprint(at+1))
 	_ = tt.Click("Resume autoplay")
 	tt.Move(r.X+2, r.Y+2) // hover pauses too
-	time.Sleep(50 * time.Millisecond)
-	tt.Frame()
+	tt.Advance(50 * time.Millisecond)
 	if h.index != at {
 		t.Fatalf("hovered carousel advanced: %d -> %d", at, h.index)
 	}

data/collapsible.go

@@ -55,7 +55,7 @@ func Collapsible(c *ui.Context, open *bool, opts CollapsibleOptions, content fun
 				ui.Text(c, opts.Title).FontWeight(600).SingleLine()
 			}
 		})
-		if panel := collapsiblePanel(c, *open, prog, content); panel != nil {
+		if panel := collapsiblePanel(c, *open, prog, content); panel.Valid() {
 			panel.Padding(u*2, u*2, u*2, u*8).Gap(u * 2)
 		}
 	})
@@ -73,13 +73,13 @@ func collapsibleTarget(open bool) float32 {
 }
 
 // collapsiblePanel builds fn while open or animating, clipped to its progress.
-func collapsiblePanel(c *ui.Context, open bool, prog float32, fn func()) *ui.Element {
+func collapsiblePanel(c *ui.Context, open bool, prog float32, fn func()) ui.Element {
 	if !open && prog == 0 {
-		return nil
+		return ui.Element{}
 	}
 	// Closing content takes no input or focus while it shrinks away.
 	clip := ui.Column(c).Shrink(0).Disabled(!open)
-	var inner *ui.Element
+	var inner ui.Element
 	clip.Children(func() {
 		inner = ui.Column(c).Shrink(0)
 		inner.Children(fn)

data/data_table.go

@@ -89,7 +89,7 @@ func (s *DataTableState[K]) VisibleRows() (first, last int) { return s.rows.Visi
 
 // DataTableView is a built DataTable and what happened to it in this frame.
 type DataTableView struct {
-	Element                           *ui.Element
+	Element                           ui.Element
 	changed, submitted, sorted, retry bool
 }
 

data/data_table_columns.go

@@ -43,12 +43,12 @@ func tableColumnMenu(c *ui.Context, cols []tableColumn, sort *ui.SortOrder, layo
 			}
 		}
 	}
-	ui.PopoverBase(c, b, open, func(panel *ui.Element) {
+	ui.PopoverBase(c, b, open, func(panel ui.Element) {
 		panel.Background(k.Surface).Border(theme.BorderWidth, k.ControlBorder).Radius(theme.PopupRadius).
 			Padding(u * 2).Gap(u).MinWidth(240).MarginY(u)
 		for at, id := range order {
 			col := cols[slices.IndexFunc(cols, func(col tableColumn) bool { return col.ID == id })]
-			ui.Row(c).Key(id).Gap(u).AlignItems(ui.Center).Children(func() {
+			ui.Row(c.Key(id)).Gap(u).AlignItems(ui.Center).Children(func() {
 				if hidden != nil {
 					tableVisibility(c, col, hidden, visible)
 				} else {

data/description_list.go

@@ -33,7 +33,7 @@ type DescriptionListOptions struct {
 
 // DescriptionListView is a built DescriptionList and what happened to it in this frame.
 type DescriptionListView struct {
-	Element *ui.Element
+	Element ui.Element
 	copied  int
 }
 

data/image_viewer.go

@@ -47,7 +47,7 @@ func ImageViewer(c *ui.Context, open *bool, index *int, images []ViewerImage) co
 	k := core.Tokens(c)
 	u := core.Density(c).Unit()
 	w, h := c.Size()
-	v.Element = ui.DialogBase(c, open, func(back, panel *ui.Element) {
+	v.Element = ui.DialogBase(c, open, func(back, panel ui.Element) {
 		back.Background(ui.RGBA(0, 0, 0, 0.55))
 		panel.Background(k.Surface).Border(theme.BorderWidth, k.Border).Radius(theme.PopupRadius).
 			Size(w-u*12, h-u*12).Padding(u * 3).Gap(u * 3).Label(core.Msg(c, "image_viewer.title"))
@@ -92,7 +92,7 @@ func ImageViewer(c *ui.Context, open *bool, index *int, images []ViewerImage) co
 			if tool("chevron-left", "image_viewer.prev", *index == 0) {
 				goTo(*index - 1)
 			}
-			stage := ui.Box(c).Grow(1).FillHeight().MinWidth(0).Focusable().AutoFocus().Clip().
+			stage := core.AutoFocus(c, ui.Box(c).Grow(1).FillHeight().MinWidth(0).Focusable()).Clip().
 				Radius(theme.ControlRadius).Background(k.Background).Role(ui.RoleImage).Label(img.Alt).Cursor(ui.CursorGrab)
 			internal.Ring(stage, k.Focus, theme.ControlRadius)
 			if dx, dy, ok := stage.Dragged(); ok {
@@ -143,7 +143,7 @@ func ImageViewer(c *ui.Context, open *bool, index *int, images []ViewerImage) co
 }
 
 // viewerKeys, anywhere in the panel, zooms with + - 0, switches with Left and Right, and pans with Shift+arrows.
-func viewerKeys(panel *ui.Element, st *viewerState, zoom func(float32), goTo func(int), at int) {
+func viewerKeys(panel ui.Element, st *viewerState, zoom func(float32), goTo func(int), at int) {
 	switch {
 	case panel.Shortcut(0, ui.KeyEqual), panel.Shortcut(ui.Shift, ui.KeyEqual):
 		zoom(viewerZoomStep)

data/list.go

@@ -67,7 +67,7 @@ func (s *ListState[K]) ScrollTo(i int) {
 
 // ListView is a built List and what happened to it in this frame.
 type ListView struct {
-	Element                   *ui.Element
+	Element                   ui.Element
 	changed, submitted, retry bool
 }
 
@@ -100,7 +100,7 @@ func List[K comparable](c *ui.Context, s *ListState[K], n int, opts ListOptions[
 			v.retry = DataPlaceholder(c, opts.Status, opts.Error, opts.Empty, core.Msg(c, "list.empty"))
 			return
 		}
-		var e *ui.Element
+		var e ui.Element
 		if opts.Grid {
 			e = listGrid(c, s, n, opts, item)
 		} else {
@@ -136,7 +136,7 @@ func listLocate[K comparable](s *ListState[K], n int, key func(int) K) {
 	slog.Debug("mujica: list selection moved", "row", s.cursor)
 }
 
-func listRows[K comparable](c *ui.Context, s *ListState[K], n int, opts ListOptions[K], item func(i int)) *ui.Element {
+func listRows[K comparable](c *ui.Context, s *ListState[K], n int, opts ListOptions[K], item func(i int)) ui.Element {
 	d := core.Density(c)
 	s.Rows.Key = func(i int) any { return opts.Key(i) }
 	s.Rows.Label = opts.Label
@@ -159,7 +159,7 @@ func listRows[K comparable](c *ui.Context, s *ListState[K], n int, opts ListOpti
 	}).Padding(d.Unit())
 }
 
-func listGrid[K comparable](c *ui.Context, s *ListState[K], n int, opts ListOptions[K], item func(i int)) *ui.Element {
+func listGrid[K comparable](c *ui.Context, s *ListState[K], n int, opts ListOptions[K], item func(i int)) ui.Element {
 	d := core.Density(c)
 	w, h := opts.ItemWidth, opts.ItemHeight
 	if w <= 0 {

data/statistic.go

@@ -29,7 +29,7 @@ type StatisticOptions struct {
 }
 
 // Statistic shows a headline number with its title, unit and change.
-func Statistic(c *ui.Context, value float64, opts StatisticOptions) *ui.Element {
+func Statistic(c *ui.Context, value float64, opts StatisticOptions) ui.Element {
 	if opts.Precision < 0 {
 		panic("mujica: Statistic with negative Precision")
 	}

data/timeline.go

@@ -29,7 +29,7 @@ type TimelineItem struct {
 }
 
 // Timeline lists events top to bottom with markers joined by a line; long text wraps.
-func Timeline(c *ui.Context, items []TimelineItem) *ui.Element {
+func Timeline(c *ui.Context, items []TimelineItem) ui.Element {
 	k := core.Tokens(c)
 	u := core.Density(c).Unit()
 	return ui.Column(c).Role(ui.RoleList).Children(func() {

data/tree.go

@@ -162,7 +162,7 @@ func (t *treeCore[K]) itemStatus(c *ui.Context, item K, status func(K) DataStatu
 
 // TreeView is a built Tree and what happened to it in this frame.
 type TreeView struct {
-	Element                   *ui.Element
+	Element                   ui.Element
 	changed, submitted, retry bool
 }