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>

display/avatar.go

@@ -18,7 +18,7 @@ type AvatarOptions struct {
 }
 
 // Avatar shows a person as picture, initials or icon.
-func Avatar(c *ui.Context, name string, opts AvatarOptions) *ui.Element {
+func Avatar(c *ui.Context, name string, opts AvatarOptions) ui.Element {
 	size := opts.Size
 	if size < 0 {
 		panic("mujica: Avatar Size must not be negative")

display/avatar_group.go

@@ -29,7 +29,7 @@ type avatarGroupKey struct{}
 
 // AvatarGroupView is a shown AvatarGroup and its full list's state.
 type AvatarGroupView struct {
-	Element *ui.Element
+	Element ui.Element
 	// Open reports whether the full list shows.
 	Open bool
 	// Toggled reports the full list opened or closed this frame.
@@ -60,7 +60,7 @@ func AvatarGroup(c *ui.Context, items []AvatarItem, opts AvatarGroupOptions) Ava
 	was := *open
 	row.Children(func() {
 		for i, it := range items[:shown] {
-			cell := ui.Box(c).Key(i).Padding(ring).Radius(size/2 + ring).Background(k.Background).Shrink(0)
+			cell := ui.Box(c.Key(i)).Padding(ring).Radius(size/2 + ring).Background(k.Background).Shrink(0)
 			if i > 0 {
 				cell.Margin(0, 0, 0, -size/4)
 			}
@@ -72,7 +72,7 @@ func AvatarGroup(c *ui.Context, items []AvatarItem, opts AvatarGroupOptions) Ava
 			return
 		}
 		more := avatarGroupMore(c, k, open, size, ring, rest, len(items))
-		ui.PopoverBase(c, more, open, func(panel *ui.Element) {
+		ui.PopoverBase(c, more, open, func(panel ui.Element) {
 			avatarGroupList(c, k, panel, items)
 		})
 	})
@@ -84,10 +84,10 @@ func AvatarGroup(c *ui.Context, items []AvatarItem, opts AvatarGroupOptions) Ava
 }
 
 // avatarGroupMore is the "+N" disclosure toggling *open.
-func avatarGroupMore(c *ui.Context, k theme.Tokens, open *bool, size, ring float32, rest, total int) *ui.Element {
+func avatarGroupMore(c *ui.Context, k theme.Tokens, open *bool, size, ring float32, rest, total int) ui.Element {
 	hit := max(size+2*ring, theme.MinHitSize)
-	var b *ui.Element
-	ui.Box(c).Key("more").Margin(0, 0, 0, -size/4).Shrink(0).Children(func() {
+	var b ui.Element
+	ui.Box(c.Key("more")).Margin(0, 0, 0, -size/4).Shrink(0).Children(func() {
 		b = ui.CollapsibleBase(c, open).Trigger.Size(hit, hit).Center().Radius(hit / 2).
 			Label(fmt.Sprintf(core.Msg(c, "avatar_group.more"), total))
 		internal.Ring(b, k.Focus, hit/2)
@@ -111,7 +111,7 @@ func avatarGroupMore(c *ui.Context, k theme.Tokens, open *bool, size, ring float
 	return b
 }
 
-func avatarGroupList(c *ui.Context, k theme.Tokens, panel *ui.Element, items []AvatarItem) {
+func avatarGroupList(c *ui.Context, k theme.Tokens, panel ui.Element, items []AvatarItem) {
 	u := core.Density(c).Unit()
 	panel.Margin(u, 0, 0, 0).Padding(u*2).Radius(theme.PopupRadius).Background(k.Surface).
 		Border(theme.BorderWidth, k.Border).MinWidth(200)
@@ -121,7 +121,7 @@ func avatarGroupList(c *ui.Context, k theme.Tokens, panel *ui.Element, items []A
 	ui.Scroll(c).MaxHeight(240).Children(func() {
 		ui.Column(c).Gap(u * 2).Role(ui.RoleList).Children(func() {
 			for i, it := range items {
-				ui.Row(c).Key(i).Gap(u * 2).AlignItems(ui.Center).Role(ui.RoleListItem).Children(func() {
+				ui.Row(c.Key(i)).Gap(u * 2).AlignItems(ui.Center).Role(ui.RoleListItem).Children(func() {
 					Avatar(c, it.Name, AvatarOptions{Image: it.Image, Size: 24})
 					ui.Text(c, it.Name).SingleLine()
 				})

display/badge.go

@@ -48,7 +48,7 @@ type BadgeOptions struct {
 }
 
 // Badge shows text or a count, inline or cornered.
-func Badge(c *ui.Context, opts BadgeOptions, content func()) *ui.Element {
+func Badge(c *ui.Context, opts BadgeOptions, content func()) ui.Element {
 	if opts.Count < 0 || opts.Max < 0 {
 		panic("mujica: Badge Count and Max must not be negative")
 	}
@@ -92,7 +92,7 @@ func badgeText(opts BadgeOptions) (shown, full string) {
 	return full, full
 }
 
-func badgePill(c *ui.Context, opts BadgeOptions, shown, full string) *ui.Element {
+func badgePill(c *ui.Context, opts BadgeOptions, shown, full string) ui.Element {
 	k := core.Tokens(c)
 	bg, fg, border := badgeColors(k, opts.Tone)
 	label := full

display/example_display_test.go

@@ -101,7 +101,7 @@ func ExampleTag() {
 		ui.Row(c).Gap(8).Children(func() {
 			for i, t := range tags {
 				var v display.TagView
-				ui.Box(c).Key(t).Children(func() {
+				ui.Box(c.Key(t)).Children(func() {
 					v = display.Tag(c, t, display.TagOptions{Icon: "star", Clickable: true, Closable: true})
 				})
 				if v.Closed {

display/heading.go

@@ -19,7 +19,7 @@ type HeadingOptions struct {
 }
 
 // Heading shows a serif title scaled with desktop text.
-func Heading(c *ui.Context, title string, opts HeadingOptions) *ui.Element {
+func Heading(c *ui.Context, title string, opts HeadingOptions) ui.Element {
 	k := core.Tokens(c)
 	size := headingSize(opts.Level)
 	u := core.Density(c).Unit()

display/icon.go

@@ -36,7 +36,7 @@ type IconOptions struct {
 type iconMissingKey struct{}
 
 // Icon shows a named icon; missing ones show a fallback.
-func Icon(c *ui.Context, name string, opts IconOptions) *ui.Element {
+func Icon(c *ui.Context, name string, opts IconOptions) ui.Element {
 	if name == "" {
 		panic("mujica: Icon needs a name")
 	}
@@ -62,7 +62,7 @@ func Icon(c *ui.Context, name string, opts IconOptions) *ui.Element {
 	return e
 }
 
-func iconMissing(c *ui.Context, name string, size float32, k theme.Tokens) *ui.Element {
+func iconMissing(c *ui.Context, name string, size float32, k theme.Tokens) ui.Element {
 	text := fmt.Sprintf(core.Msg(c, "icon.missing"), name)
 	e := ui.Box(c).Size(size, size).Shrink(0).Role(ui.RoleImage).Label(text).Tooltip(text)
 	logged := ui.Local(e, iconMissingKey{}, func() string { return "" })

display/image.go

@@ -26,7 +26,7 @@ type ImageOptions struct {
 
 // ImageView is a shown Image and this frame's events.
 type ImageView struct {
-	Element *ui.Element
+	Element ui.Element
 	// Retry reports the error state's retry button was pressed.
 	Retry bool
 }
@@ -46,7 +46,7 @@ func Image(c *ui.Context, src ui.ImageSource, opts ImageOptions) ImageView {
 	}
 	loaded := opts.Err == nil && !opts.Loading && src != nil
 	var v ImageView
-	v.Element = imageSized(c, src, opts, func(box, pic *ui.Element) {
+	v.Element = imageSized(c, src, opts, func(box, pic ui.Element) {
 		if loaded {
 			if opts.Alt != "" {
 				pic.Label(opts.Alt)
@@ -60,7 +60,7 @@ func Image(c *ui.Context, src ui.ImageSource, opts ImageOptions) ImageView {
 }
 
 // imageLayers builds the state layers over the hidden picture.
-func imageLayers(c *ui.Context, box *ui.Element, opts ImageOptions) (retry bool) {
+func imageLayers(c *ui.Context, box ui.Element, opts ImageOptions) (retry bool) {
 	k := core.Tokens(c)
 	u := core.Density(c).Unit()
 	room := box.Bounds()
@@ -99,7 +99,7 @@ func imageLayers(c *ui.Context, box *ui.Element, opts ImageOptions) (retry bool)
 }
 
 // imageSized builds the outer box and its picture, sized alike in every state.
-func imageSized(c *ui.Context, src ui.ImageSource, opts ImageOptions, layers func(box, pic *ui.Element)) *ui.Element {
+func imageSized(c *ui.Context, src ui.ImageSource, opts ImageOptions, layers func(box, pic ui.Element)) ui.Element {
 	if src == nil {
 		src = imageBlank
 	}
@@ -123,7 +123,7 @@ func imageSized(c *ui.Context, src ui.ImageSource, opts ImageOptions, layers fun
 }
 
 // imageRetry is the 28 DIP icon-only retry button.
-func imageRetry(c *ui.Context, k theme.Tokens, problem string) *ui.Element {
+func imageRetry(c *ui.Context, k theme.Tokens, problem string) ui.Element {
 	b := ui.ButtonBase(c).Size(theme.MinHitSize, theme.MinHitSize).Shrink(0).Radius(theme.ControlRadius).
 		Label(core.Msg(c, "image.retry")).Description(problem).Tooltip(problem)
 	bg := k.Surface

display/kbd.go

@@ -11,7 +11,7 @@ import (
 )
 
 // Kbd shows keys as caps; "Mod" is Command or Ctrl.
-func Kbd(c *ui.Context, keys ...string) *ui.Element {
+func Kbd(c *ui.Context, keys ...string) ui.Element {
 	if len(keys) == 0 {
 		panic("mujica: Kbd needs at least one key")
 	}
@@ -31,7 +31,7 @@ func Kbd(c *ui.Context, keys ...string) *ui.Element {
 				ui.Text(c, "+").FontSize(core.FontSize(c, theme.CaptionSize)).TextColor(k.TextMuted)
 			}
 			face, _ := KbdKey(key, mac)
-			ui.Box(c).Key(i).Row().Center().MinWidth(core.FontSize(c, 20)).MinHeight(core.FontSize(c, 20)).Padding(0, 5).
+			ui.Box(c.Key(i)).Row().Center().MinWidth(core.FontSize(c, 20)).MinHeight(core.FontSize(c, 20)).Padding(0, 5).
 				Radius(theme.ControlRadius).Background(k.Surface).BorderColor(k.ControlBorder).
 				BorderWidth(1, 1, 2, 1).Children(func() {
 				ui.Text(c, face).Font(theme.MonoFont).FontSize(core.FontSize(c, theme.CaptionSize)).TextColor(k.Text).SingleLine()

display/link.go

@@ -21,7 +21,7 @@ type LinkOptions struct {
 }
 
 // Link is underlined text; malformed URLs show an error instead.
-func Link(c *ui.Context, label string, opts LinkOptions) *ui.Element {
+func Link(c *ui.Context, label string, opts LinkOptions) ui.Element {
 	if label == "" {
 		panic("mujica: Link needs a label")
 	}
@@ -40,7 +40,7 @@ func Link(c *ui.Context, label string, opts LinkOptions) *ui.Element {
 			}
 		}
 	}
-	var l *ui.Element
+	var l ui.Element
 	ui.Column(c).Gap(u).AlignItems(ui.Start).Children(func() {
 		ui.Row(c).Gap(u).AlignItems(ui.Center).Children(func() {
 			l = ui.Link(c, label, target).Underline().DecorationThickness(1)

display/tag.go

@@ -24,7 +24,7 @@ type TagOptions struct {
 
 // TagView is a shown Tag and this frame's events.
 type TagView struct {
-	Element *ui.Element
+	Element ui.Element
 	// Clicked reports the label was activated, not the remove button.
 	Clicked bool
 	// Closed reports the remove button, Delete or Backspace.
@@ -43,7 +43,7 @@ func Tag(c *ui.Context, label string, opts TagOptions) TagView {
 		Background(k.Surface).Border(theme.BorderWidth, k.Border).Shrink(0).Disabled(opts.Disabled)
 	v.Element = box
 	box.Children(func() {
-		var main *ui.Element
+		var main ui.Element
 		if opts.Clickable {
 			main = ui.ButtonBase(c).Label(label)
 			internal.Ring(main, k.Focus, theme.ControlRadius)
@@ -89,7 +89,7 @@ func Tag(c *ui.Context, label string, opts TagOptions) TagView {
 	return v
 }
 
-func tagClose(c *ui.Context, k theme.Tokens, label string) *ui.Element {
+func tagClose(c *ui.Context, k theme.Tokens, label string) ui.Element {
 	b := ui.ButtonBase(c).Size(theme.MinHitSize, theme.MinHitSize).
 		Radius(theme.ControlRadius).Label(fmt.Sprintf(core.Msg(c, "tag.remove"), label))
 	fg := k.TextMuted

display/text.go

@@ -19,7 +19,7 @@ type TextOptions struct {
 }
 
 // Text shows body text wrapping at its width.
-func Text(c *ui.Context, s string, opts TextOptions) *ui.Element {
+func Text(c *ui.Context, s string, opts TextOptions) ui.Element {
 	if opts.MaxLines < 0 {
 		panic("mujica: Text MaxLines must not be negative")
 	}
@@ -49,7 +49,7 @@ type EditableTextOptions struct {
 
 // EditableTextView is a shown EditableText and this frame's outcome.
 type EditableTextView struct {
-	Element *ui.Element
+	Element ui.Element
 	// Canceled reports Escape discarded an edit.
 	Canceled bool
 	changed  bool
@@ -118,7 +118,7 @@ func editableTextField(c *ui.Context, k theme.Tokens, value *string, opts Editab
 			return v
 		}
 	}
-	var in *ui.Element
+	var in ui.Element
 	box.Children(func() {
 		in = ui.TextInputBase(c, &st.draft).Grow(1).MinWidth(theme.MinHitSize*3).Padding(pad, pad*2).
 			Radius(theme.ControlRadius).Background(k.Surface).Border(theme.BorderWidth, k.Accent).TextColor(k.Text).