Merge branch 'main' into worktree-agent-ab9ba373bc47c2352

README.md

@@ -72,10 +72,10 @@ k := mujica.Tokens(c) // 当前窗口的颜色
 
 ```sh
 go run ./examples/gallery            # 原生窗口
-go run ./examples/gallery -web :8080 # 浏览器镜像
+go run ./examples/gallery -web 127.0.0.1:8080 # 浏览器镜像，仅本机
 ```
 
-浏览器镜像不在浏览器里运行组件。Go 进程用 `ui.NewTester` 驱动同一个 Gallery 视图，把帧推给页面，再把指针、键盘、输入法和剪贴板事件送回 Go。
+`-web` 按传入的地址监听；写 `:8080` 会对所有网络接口开放。浏览器镜像不在浏览器里运行组件。Go 进程用 `ui.NewTester` 驱动同一个 Gallery 视图，把帧推给页面，再把指针、键盘、输入法和剪贴板事件送回 Go。
 
 ## 文档
 

datetime_review2_test.go

@@ -169,7 +169,7 @@ func TestFormFocusesDatePickerInput(t *testing.T) {
 	tt := ui.NewTester(func(c *ui.Context) {
 		Use(c, Settings{})
 		Form(c, &st, FormOptions{}, func(f *FormScope) {
-			FormItem(f, "debut", &day, FormItemOptions[Date]{Label: "Debut date", Required: true}, func() *ui.Element {
+			FormItem(c, f, "debut", &day, FormItemOptions[Date]{Label: "Debut date", Required: true}, func() *ui.Element {
 				r := DatePicker(c, &day, DatePickerOptions{Today: calendarToday})
 				input = r.Input
 				return r.Input

docs/compat.md

@@ -22,4 +22,4 @@
 
 ## 离线
 
-库与 Gallery 不发起网络请求，无遥测、账号或远程字体。图标与角饰随代码嵌入。浏览器镜像只在本机监听调用方给定的地址。
+库与 Gallery 不发起网络请求，无遥测、账号或远程字体。图标与角饰随代码嵌入。浏览器镜像按 `-web` 传入的地址监听：`127.0.0.1:8080` 仅本机可达，`:8080` 对所有网络接口开放。

docs/components/041-form.md

@@ -14,7 +14,7 @@ name := ""
 view := func(c *ui.Context) {
 	mujica.Use(c, mujica.Settings{})
 	res := mujica.Form(c, &state, mujica.FormOptions{}, func(f *mujica.FormScope) {
-		mujica.FormItem(f, "name", &name, mujica.FormItemOptions[string]{Label: "Name", Required: true}, func() *ui.Element {
+		mujica.FormItem(c, f, "name", &name, mujica.FormItemOptions[string]{Label: "Name", Required: true}, func() *ui.Element {
 			return mujica.InputGroup(c, &name, mujica.InputGroupOptions{Invalid: state.Error("name") != ""}).Input
 		})
 	})

docs/components/054-time-picker.md

@@ -57,5 +57,4 @@ ui.Render(view, 400, 300, 1)
 - 段顺序固定为“时:分:秒 上午/下午”，zh-CN 下上午/下午也位于末尾。
 - MyGo 的 `ui.TimeInput` 只有时分且无 12 小时制、步长和范围（ui/timeinput.go:18），因此本组件自绘分段。
 - 日期与时间值不带时区：`Date`、`YearMonth`、`TimeOfDay` 只保存日历字段，组件内部计算不做 UTC 转换。
-- `Today` 为零值时读取 `c.Now()`（系统本地时区）；需要固定“今天”（测试、跨时区应用）时显式传入。
 - 无障碍：MyGo v0.2.10 没有公开设置弹出按钮展开状态（`expanded`）、数值范围（`hasRange`/`accRange`）与值（`accValue`）的接口，这些字段只在 MyGo 内部组件中赋值（ui/element.go:286-295，例如 ui/base.go:297、ui/indicators.go:61）。因此触发器只能声明为 `RolePopUpButton` 而无法报告展开状态；时间段以 `Description` 读出当前值与范围，错误通过 `Error()` 关联。

docs/components/055-time-range-picker.md

@@ -53,5 +53,4 @@ ui.Render(view, 400, 300, 1)
 - 开始等于结束视为错误。
 - `TimeRange.Overnight()` 报告是否跨午夜。
 - 日期与时间值不带时区：`Date`、`YearMonth`、`TimeOfDay` 只保存日历字段，组件内部计算不做 UTC 转换。
-- `Today` 为零值时读取 `c.Now()`（系统本地时区）；需要固定“今天”（测试、跨时区应用）时显式传入。
 - 无障碍：MyGo v0.2.10 没有公开设置弹出按钮展开状态（`expanded`）、数值范围（`hasRange`/`accRange`）与值（`accValue`）的接口，这些字段只在 MyGo 内部组件中赋值（ui/element.go:286-295，例如 ui/base.go:297、ui/indicators.go:61）。因此触发器只能声明为 `RolePopUpButton` 而无法报告展开状态；时间段以 `Description` 读出当前值与范围，错误通过 `Error()` 关联。

docs/components/059-tabs.md

@@ -7,11 +7,13 @@
 ## 最小示例
 
 ```go
-mujica.Tabs(c, &tab, []mujica.Tab{
+if mujica.Tabs(c, &tab, []mujica.Tab{
 	{Label: "General", Panel: func() { ui.Text(c, "General settings") }},
 	{Label: "Fonts", Icon: icons.Must("italic"), Panel: func() { ui.Text(c, "Fonts") }},
 	{Label: "Archive", Disabled: true},
-}, mujica.TabsOptions{Label: "Settings"})
+}, mujica.TabsOptions{Label: "Settings"}).Changed() {
+	fmt.Println("tab", tab)
+}
 ```
 
 签名：`func Tabs(c *ui.Context, selected *int, tabs []Tab, opts TabsOptions) ChoiceResult`

docs/components/060-segmented-control.md

@@ -7,10 +7,12 @@
 ## 最小示例
 
 ```go
-mujica.SegmentedControl(c, &view, []mujica.Segment{
+if mujica.SegmentedControl(c, &view, []mujica.Segment{
 	{Label: "List", Icon: icons.Must("list"), HideLabel: true},
 	{Label: "Grid", Icon: icons.Must("layout-grid"), HideLabel: true},
-}, mujica.SegmentedControlOptions{Label: "View"})
+}, mujica.SegmentedControlOptions{Label: "View"}).Changed() {
+	fmt.Println("view", view)
+}
 ```
 
 签名：`func SegmentedControl(c *ui.Context, selected *int, segments []Segment, opts SegmentedControlOptions) *ui.Element`

docs/components/068-command-palette.md

@@ -61,7 +61,7 @@ if id, ok := res.Chosen(); ok {
 
 ## 限制
 
-- MyGo `TextInputBase` 没有占位文字（`ui/editor.go:734`）；为避免与输入法组合文字重叠，说明放在底部提示栏，搜索框以无障碍名称“搜索命令”标识。
+- 操作说明放在底部提示栏而不放进输入框，避免与输入法组合文字重叠；搜索框以无障碍名称“搜索命令”标识。
 - 搜索是子串匹配，不做模糊匹配或排序打分。
 - 焦点留在搜索框以便继续输入；方向键移动高亮时用 `c.Announce` 朗读当前命令，并写入搜索框的 `Description`（MyGo 的 active descendant 不公开）。
 - 弹层打开时在 160 ms 内淡入，减少动画时直接显示。关闭时立即消失：弹层关闭后 MyGo 不再构建其元素，公开接口无法为已移除的浮层做淡出。

docs/upstream.md

@@ -33,6 +33,6 @@ PRD 第 2 节要求公开接口不足时向上游提交扩展。以下缺口在
 | `activeDescendant` 不公开 | `ui/element.go:331` | Menubar、CommandPalette |
 | `SliderBase` 方向键步长固定 1%，构建时处理指针 | `ui/base.go:111-117` | Slider |
 | `SelectBase` 高亮无设置接口 | `ui/base.go:260` | Select |
-| `TextInputBase` 无只读开关与占位符 | `ui/editor.go:139,734,811` | TextInput 只读模式、CommandPalette |
+| `TextInputBase` 无只读开关 | `ui/editor.go:139,811` | TextInput 只读模式 |
 | `ui.Stepper` 禁用时仍可步进，固定 9 位取整 | `ui/indicators.go:216`、`ui/widgets.go` `snap` | NumberInput（已改为自绘） |
 | 路径遮罩缓存按四分之一像素取键，进程内共享 | `ui/path.go:189-210` | 自绘路径以 `internal.Snap` 对齐；MyGo 自绘的箭头（Outline 等）无法对齐；快照测试因此在独立子进程中渲染，结果与测试顺序无关 |

docs_test.go

@@ -14,71 +14,93 @@ var (
 	docsPageID  = regexp.MustCompile(`ID: "(\d{3})"`)
 )
 
-// TestDocSnippetsAreCompiledExamples keeps every doc's first Go block inside a compiled Example.
+// docsLines normalizes code into its non-empty, non-comment lines without whitespace.
+func docsLines(code string) []string {
+	var out []string
+	for _, l := range strings.Split(code, "\n") {
+		s := strings.TrimSpace(l)
+		if s != "" && !strings.HasPrefix(s, "//") {
+			out = append(out, docsSpace.ReplaceAllString(s, ""))
+		}
+	}
+	return out
+}
+
+// docsContains reports whether want appears in order inside have.
+func docsContains(have, want []string) bool {
+	i := 0
+	for _, h := range have {
+		if i < len(want) && h == want[i] {
+			i++
+		}
+	}
+	return i == len(want)
+}
+
+func readGlob(t *testing.T, pattern string) map[string]string {
+	t.Helper()
+	files, err := filepath.Glob(pattern)
+	if err != nil {
+		t.Fatal(err)
+	}
+	out := map[string]string{}
+	for _, f := range files {
+		b, err := os.ReadFile(f)
+		if err != nil {
+			t.Fatal(err)
+		}
+		out[f] = string(b)
+	}
+	return out
+}
+
+// TestDocSnippetsAreCompiledExamples keeps each doc's first Go block, in order, inside one Example.
 func TestDocSnippetsAreCompiledExamples(t *testing.T) {
-	examples, err := filepath.Glob("example_*_test.go")
-	if err != nil {
-		t.Fatal(err)
-	}
-	var all strings.Builder
-	for _, f := range examples {
-		b, err := os.ReadFile(f)
-		if err != nil {
-			t.Fatal(err)
-		}
-		all.Write(b)
-	}
-	compiled := docsSpace.ReplaceAllString(all.String(), "")
-	docs, err := filepath.Glob("docs/components/*.md")
-	if err != nil {
-		t.Fatal(err)
-	}
-	pages, err := filepath.Glob("examples/gallery/pages_*.go")
-	if err != nil {
-		t.Fatal(err)
-	}
-	ids := map[string]bool{}
-	for _, f := range pages {
-		b, err := os.ReadFile(f)
-		if err != nil {
-			t.Fatal(err)
-		}
-		for _, m := range docsPageID.FindAllSubmatch(b, -1) {
-			ids[string(m[1])] = true
+	var examples [][]string
+	for _, src := range readGlob(t, "example_*_test.go") {
+		for _, fn := range strings.Split(src, "\nfunc Example")[1:] {
+			examples = append(examples, docsLines(fn))
 		}
 	}
-	documented := map[string]bool{}
-	for _, d := range docs {
-		documented[filepath.Base(d)[:3]] = true
-	}
-	for id := range ids {
-		if !documented[id] {
-			t.Errorf("gallery page %s has no doc", id)
-		}
-	}
-	for id := range documented {
-		if !ids[id] {
-			t.Errorf("doc %s has no gallery page", id)
-		}
-	}
-	for _, d := range docs {
-		b, err := os.ReadFile(d)
-		if err != nil {
-			t.Fatal(err)
-		}
-		m := docsGoBlock.FindSubmatch(b)
+	for d, src := range readGlob(t, "docs/components/*.md") {
+		m := docsGoBlock.FindStringSubmatch(src)
 		if m == nil {
 			t.Errorf("%s has no Go example", d)
 			continue
 		}
-		for _, line := range strings.Split(string(m[1]), "\n") {
-			s := strings.TrimSpace(line)
-			if s == "" || strings.HasPrefix(s, "//") {
-				continue
-			}
-			if !strings.Contains(compiled, docsSpace.ReplaceAllString(s, "")) {
-				t.Errorf("%s: %q is not in any compiled Example", d, s)
+		want, found := docsLines(m[1]), false
+		for _, ex := range examples {
+			if docsContains(ex, want) {
+				found = true
+				break
 			}
 		}
+		if !found {
+			t.Errorf("%s: its Go block is not, in order, inside any compiled Example", d)
+		}
+	}
+}
+
+// TestDocsMatchGalleryPages wants exactly one doc and one gallery page per component ID.
+func TestDocsMatchGalleryPages(t *testing.T) {
+	pages := map[string]int{}
+	for _, src := range readGlob(t, "examples/gallery/pages_*.go") {
+		for _, m := range docsPageID.FindAllStringSubmatch(src, -1) {
+			pages[m[1]]++
+		}
+	}
+	docs := map[string]int{}
+	for d := range readGlob(t, "docs/components/*.md") {
+		docs[filepath.Base(d)[:3]]++
+	}
+	for id, n := range pages {
+		if n != 1 || docs[id] != 1 {
+			t.Errorf("component %s: %d gallery pages, %d docs; want 1 and 1", id, n, docs[id])
+		}
+	}
+	for id, n := range docs {
+		if pages[id] == 0 {
+			t.Errorf("doc %s (%d files) has no gallery page", id, n)
+		}
 	}
 }

example_form_test.go

@@ -15,7 +15,7 @@ func ExampleForm() {
 	view := func(c *ui.Context) {
 		mujica.Use(c, mujica.Settings{})
 		res := mujica.Form(c, &state, mujica.FormOptions{}, func(f *mujica.FormScope) {
-			mujica.FormItem(f, "name", &name, mujica.FormItemOptions[string]{Label: "Name", Required: true}, func() *ui.Element {
+			mujica.FormItem(c, f, "name", &name, mujica.FormItemOptions[string]{Label: "Name", Required: true}, func() *ui.Element {
 				return mujica.InputGroup(c, &name, mujica.InputGroupOptions{Invalid: state.Error("name") != ""}).Input
 			})
 		})

examples/gallery/composite_form.go

@@ -110,7 +110,7 @@ func (g *gallery) formEdit(c *ui.Context, log func(string)) {
 
 func (g *gallery) formFields(c *ui.Context, f *mujica.FormScope, log func(string)) {
 	s := &g.cForm
-	mujica.FormItem(f, "name", &s.name, mujica.FormItemOptions[string]{Label: g.t("Stage name", "艺名"), Required: true,
+	mujica.FormItem(c, f, "name", &s.name, mujica.FormItemOptions[string]{Label: g.t("Stage name", "艺名"), Required: true,
 		Description: g.t("Checked against the archive; “Oblivionis” is taken.", "将与档案核对；“Oblivionis”已被占用。"),
 		Validate: func(v string) string {
 			if len([]rune(strings.TrimSpace(v))) < 2 {
@@ -134,7 +134,7 @@ func (g *gallery) formFields(c *ui.Context, f *mujica.FormScope, log func(string
 		}}, func() *ui.Element {
 		return mujica.TextInput(c, &s.name, mujica.TextInputOptions{}).Input
 	})
-	mujica.FormItem(f, "password", &s.password, mujica.FormItemOptions[string]{Label: g.t("Password", "密码"), Required: true,
+	mujica.FormItem(c, f, "password", &s.password, mujica.FormItemOptions[string]{Label: g.t("Password", "密码"), Required: true,
 		Validate: func(v string) string {
 			if len([]rune(v)) < 8 {
 				return g.t("Use at least 8 characters.", "至少 8 个字符。")
@@ -147,14 +147,14 @@ func (g *gallery) formFields(c *ui.Context, f *mujica.FormScope, log func(string
 		}
 		return r.Input
 	})
-	mujica.FormItem(f, "debut", &s.debut, mujica.FormItemOptions[mujica.Date]{Label: g.t("Debut date", "首演日期"), Required: true}, func() *ui.Element {
+	mujica.FormItem(c, f, "debut", &s.debut, mujica.FormItemOptions[mujica.Date]{Label: g.t("Debut date", "首演日期"), Required: true}, func() *ui.Element {
 		r := mujica.DatePicker(c, &s.debut, mujica.DatePickerOptions{Clearable: true})
 		if r.Changed() {
 			log("debut " + s.debut.Format("2006-01-02"))
 		}
 		return r.Input
 	})
-	mujica.FormItem(f, "roles", &s.tags, mujica.FormItemOptions[[]string]{Label: g.t("Roles", "担当"), Required: true,
+	mujica.FormItem(c, f, "roles", &s.tags, mujica.FormItemOptions[[]string]{Label: g.t("Roles", "担当"), Required: true,
 		Description: g.t("Up to 4; press Enter after each.", "最多 4 个；每个后按 Enter。")}, func() *ui.Element {
 		r := mujica.TagsInput(c, &s.tags, mujica.TagsInputOptions{Max: 4, Invalid: s.st.Error("roles") != "", Placeholder: g.t("keyboard, bass…", "键盘、贝斯…")})
 		if r.Changed() {
@@ -162,7 +162,7 @@ func (g *gallery) formFields(c *ui.Context, f *mujica.FormScope, log func(string
 		}
 		return r.Input
 	})
-	mujica.FormItem(f, "terms", &s.terms, mujica.FormItemOptions[bool]{Label: g.t("Terms", "条款"),
+	mujica.FormItem(c, f, "terms", &s.terms, mujica.FormItemOptions[bool]{Label: g.t("Terms", "条款"),
 		Validate: func(v bool) string {
 			if !v {
 				return g.t("Accept the terms to continue.", "请先同意条款。")

examples/gallery/composite_test.go

@@ -111,11 +111,11 @@ func TestCompositeFormInvalidThenValid(t *testing.T) {
 	click(t, tt, "I accept the covenant of the masquerade")
 	if s.name != "Mortis" || s.password != "hunter22secret" || s.debut.Format("2006-01-02") != "2026-12-24" ||
 		!slices.Equal(s.tags, []string{"guitar"}) || !s.terms {
-		t.Fatalf("values %q %q %v %q %v", s.name, s.password, s.debut, s.tags, s.terms)
+		t.Fatalf("values %q, password ok %v, %v %q %v", s.name, s.password == "hunter22secret", s.debut, s.tags, s.terms)
 	}
 	click(t, tt, "Submit entry")
-	await(tt, s.st.Submitting) // the name check finishes first
-	if !s.st.Submitting() || !tt.HasText("Submitting…") {
+	await(tt, func() bool { return tt.HasText("Submitting…") }) // the name check finishes first
+	if !s.st.Submitting() {
 		t.Fatalf("no loading overlay in %q", tt.Texts())
 	}
 	click(t, tt, "Submit entry") // the overlay blocks a second submit
@@ -124,9 +124,9 @@ func TestCompositeFormInvalidThenValid(t *testing.T) {
 		t.Fatalf("phase %d, texts %q", s.phase, tt.Texts())
 	}
 	submits := 0
-	for _, e := range g.events {
+	for i, e := range g.events {
 		if strings.Contains(e.text, "hunter22secret") {
-			t.Fatalf("password logged: %q", e.text)
+			t.Fatalf("password logged in event %d of page %s", i, e.page)
 		}
 		if e.page == formID && strings.HasPrefix(e.text, "submitted ") {
 			submits++

examples/gallery/main.go

@@ -1,7 +1,4 @@
-// Gallery tours every MujicaUI component in a native MyGo window.
-//
-//	go run ./examples/gallery            native window
-//	go run ./examples/gallery -web :8080 browser mirror
+// Gallery tours MujicaUI natively, or mirrored to a browser with -web.
 package main
 
 import (

examples/gallery/pages_form.go

@@ -118,7 +118,7 @@ var formPages = []page{
 			}
 			formToggles(c, []string{"Labels beside fields", "Server rejects the submit"}, &d.horizontal, &d.slowServer)
 			res := mujica.Form(c, &d.st, mujica.FormOptions{Horizontal: d.horizontal}, func(f *mujica.FormScope) {
-				mujica.FormItem(f, "name", &d.name, mujica.FormItemOptions[string]{Label: "Stage name", Required: true, Initial: "Sakiko",
+				mujica.FormItem(c, f, "name", &d.name, mujica.FormItemOptions[string]{Label: "Stage name", Required: true, Initial: "Sakiko",
 					Description: "Checked against the archive; \"Oblivionis\" is taken.",
 					Async: func(v string, version uint64) {
 						log(fmt.Sprintf("async check started v%d", version))
@@ -134,7 +134,7 @@ var formPages = []page{
 					}}, func() *ui.Element {
 					return mujica.InputGroup(c, &d.name, mujica.InputGroupOptions{Invalid: d.st.Error("name") != ""}).Input
 				})
-				mujica.FormItem(f, "email", &d.email, mujica.FormItemOptions[string]{Label: "Email", Required: true,
+				mujica.FormItem(c, f, "email", &d.email, mujica.FormItemOptions[string]{Label: "Email", Required: true,
 					Validate: func(v string) string {
 						if !strings.Contains(v, "@") {
 							return "Enter an email address."
@@ -147,7 +147,7 @@ var formPages = []page{
 					}
 					return g.Input
 				})
-				mujica.FormItem(f, "tags", &d.tags, mujica.FormItemOptions[[]string]{Label: "Roles", Required: true, Initial: []string{"keyboard"}}, func() *ui.Element {
+				mujica.FormItem(c, f, "tags", &d.tags, mujica.FormItemOptions[[]string]{Label: "Roles", Required: true, Initial: []string{"keyboard"}}, func() *ui.Element {
 					return mujica.TagsInput(c, &d.tags, mujica.TagsInputOptions{Max: 4, Invalid: d.st.Error("tags") != ""}).Input
 				})
 			})
@@ -336,7 +336,7 @@ name := ""
 view := func(c *ui.Context) {
 	mujica.Use(c, mujica.Settings{})
 	res := mujica.Form(c, &state, mujica.FormOptions{}, func(f *mujica.FormScope) {
-		mujica.FormItem(f, "name", &name, mujica.FormItemOptions[string]{Label: "Name", Required: true}, func() *ui.Element {
+		mujica.FormItem(c, f, "name", &name, mujica.FormItemOptions[string]{Label: "Name", Required: true}, func() *ui.Element {
 			return mujica.InputGroup(c, &name, mujica.InputGroupOptions{Invalid: state.Error("name") != ""}).Input
 		})
 	})

examples/gallery/web.go

@@ -20,18 +20,20 @@ var indexHTML []byte
 
 // mirror runs the gallery view headless and streams its frames.
 type mirror struct {
-	mu    sync.Mutex
-	tt    *ui.Tester
-	frame []byte
-	seq   int
-	hash  uint64
-	seed  maphash.Seed
-	subs  map[chan []byte]struct{}
-	wake  chan struct{}
-	urls  int
-	told  int
-	clip  string
-	enc   png.Encoder
+	mu     sync.Mutex
+	tt     *ui.Tester
+	frame  []byte
+	seq    int
+	hash   uint64
+	seed   maphash.Seed
+	subs   map[chan []byte]struct{}
+	wake   chan struct{}
+	urls   int
+	clip   string
+	copied bool
+	cursor ui.Cursor
+	down   *input
+	enc    png.Encoder
 }
 
 func serveWeb(addr string, view func(c *ui.Context)) error {
@@ -54,7 +56,9 @@ func newMirror(view func(c *ui.Context)) (*mirror, http.Handler) {
 	mux := http.NewServeMux()
 	mux.HandleFunc("GET /{$}", func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", "text/html; charset=utf-8")
-		w.Write(indexHTML)
+		if _, err := w.Write(indexHTML); err != nil {
+			slog.Warn("gallery: web page write failed", "err", err)
+		}
 	})
 	mux.HandleFunc("GET /frame.png", m.serveFrame)
 	mux.HandleFunc("GET /events", m.serveEvents)
@@ -62,20 +66,27 @@ func newMirror(view func(c *ui.Context)) (*mirror, http.Handler) {
 	return m, mux
 }
 
-// loop draws frames while the picture keeps changing, then sleeps.
+// loop frames at 33 ms while changing, else polls at 200 ms for timers.
 func (m *mirror) loop() {
-	for range m.wake {
-		for still := 0; still < 6; {
-			time.Sleep(33 * time.Millisecond)
-			m.mu.Lock()
-			m.tt.Frame()
-			changed := m.capture()
-			m.mu.Unlock()
-			if changed {
-				still = 0
-			} else {
-				still++
-			}
+	still := 0
+	for {
+		wait := 33 * time.Millisecond
+		if still > 30 {
+			wait = 200 * time.Millisecond
+		}
+		select {
+		case <-m.wake:
+			still = 0
+		case <-time.After(wait):
+		}
+		m.mu.Lock()
+		m.tt.Frame()
+		changed := m.capture()
+		m.mu.Unlock()
+		if changed {
+			still = 0
+		} else {
+			still++
 		}
 	}
 }
@@ -87,12 +98,12 @@ func (m *mirror) kick() {
 	}
 }
 
-// capture encodes the frame and notifies browsers; the caller holds mu.
+// capture encodes a changed frame and notifies browsers; the caller holds mu.
 func (m *mirror) capture() bool {
 	img := m.tt.Image()
 	h := maphash.Bytes(m.seed, img.Pix)
 	notice := m.notices()
-	if h == m.hash && notice == nil {
+	if h == m.hash && len(notice) == 0 {
 		return false
 	}
 	if h != m.hash {
@@ -103,11 +114,8 @@ func (m *mirror) capture() bool {
 		m.frame, m.hash = b.Bytes(), h
 		m.seq++
 	}
-	if notice == nil {
-		notice = map[string]any{}
-	}
 	notice["seq"] = m.seq
-	notice["cursor"] = cursorCSS(m.tt.Cursor())
+	notice["cursor"] = cursorCSS(m.cursor)
 	msg, err := json.Marshal(notice)
 	if err != nil {
 		panic(err)
@@ -122,20 +130,21 @@ func (m *mirror) capture() bool {
 	return true
 }
 
-// notices gathers opened URLs, announcements and clipboard changes.
+// notices gathers opened URLs, announcements, clipboard writes and cursor changes.
 func (m *mirror) notices() map[string]any {
 	n := map[string]any{}
 	if urls := m.tt.OpenedURLs(); len(urls) > m.urls {
 		n["open"], m.urls = urls[m.urls:], len(urls)
 	}
-	if told := m.tt.Announcements(); len(told) > m.told {
-		n["announce"], m.told = told[m.told:], len(told)
+	if told := m.tt.Announcements(); len(told) > 0 {
+		n["announce"] = told
 	}
-	if clip := m.tt.Clipboard(); clip != m.clip {
-		n["clipboard"], m.clip = clip, clip
+	if clip := m.tt.Clipboard(); clip != m.clip || m.copied {
+		n["clipboard"], m.clip, m.copied = clip, clip, false
 	}
-	if len(n) == 0 {
-		return nil
+	if c := m.tt.Cursor(); c != m.cursor {
+		m.cursor = c
+		n["cursorChanged"] = true
 	}
 	return n
 }
@@ -146,7 +155,9 @@ func (m *mirror) serveFrame(w http.ResponseWriter, r *http.Request) {
 	m.mu.Unlock()
 	w.Header().Set("Content-Type", "image/png")
 	w.Header().Set("Cache-Control", "no-store")
-	w.Write(frame)
+	if _, err := w.Write(frame); err != nil {
+		slog.Warn("gallery: web frame write failed", "err", err)
+	}
 }
 
 func (m *mirror) serveEvents(w http.ResponseWriter, r *http.Request) {
@@ -169,122 +180,21 @@ func (m *mirror) serveEvents(w http.ResponseWriter, r *http.Request) {
 	}()
 	w.Header().Set("Content-Type", "text/event-stream")
 	w.Header().Set("Cache-Control", "no-store")
-	fmt.Fprintf(w, "data: %s\n\n", first)
+	if _, err := fmt.Fprintf(w, "data: %s\n\n", first); err != nil {
+		slog.Warn("gallery: web events write failed", "remote", r.RemoteAddr, "err", err)
+		return
+	}
 	flusher.Flush()
 	for {
 		select {
 		case msg := <-ch:
-			fmt.Fprintf(w, "data: %s\n\n", msg)
+			if _, err := fmt.Fprintf(w, "data: %s\n\n", msg); err != nil {
+				slog.Warn("gallery: web events write failed", "remote", r.RemoteAddr, "err", err)
+				return
+			}
 			flusher.Flush()
 		case <-r.Context().Done():
 			return
 		}
 	}
 }
-
-// input is one browser event.
-type input struct {
-	Type   string  `json:"type"`
-	X      float32 `json:"x"`
-	Y      float32 `json:"y"`
-	DX     float32 `json:"dx"`
-	DY     float32 `json:"dy"`
-	Button int     `json:"button"`
-	Code   string  `json:"code"`
-	Text   string  `json:"text"`
-	Caret  int     `json:"caret"`
-	Mods   []bool  `json:"mods"`
-	W      int     `json:"w"`
-	H      int     `json:"h"`
-	Scale  float32 `json:"scale"`
-	Dark   bool    `json:"dark"`
-	Motion bool    `json:"reduceMotion"`
-	More   bool    `json:"moreContrast"`
-}
-
-func (m *mirror) serveInput(w http.ResponseWriter, r *http.Request) {
-	var in input
-	if err := json.NewDecoder(r.Body).Decode(&in); err != nil {
-		http.Error(w, err.Error(), http.StatusBadRequest)
-		return
-	}
-	m.mu.Lock()
-	err := m.apply(in)
-	if err == nil {
-		m.capture()
-	}
-	m.mu.Unlock()
-	if err != nil {
-		slog.Warn("gallery: web input rejected", "type", in.Type, "err", err)
-		http.Error(w, err.Error(), http.StatusBadRequest)
-		return
-	}
-	m.kick()
-	w.WriteHeader(http.StatusNoContent)
-}
-
-// apply sends one event to the tester; the caller holds mu.
-func (m *mirror) apply(in input) error {
-	mods := modifiers(in.Mods)
-	switch in.Type {
-	case "down":
-		if in.Button == 2 {
-			m.tt.RightClickAt(in.X, in.Y)
-		} else if mods != 0 {
-			m.tt.ClickAtWith(mods, in.X, in.Y)
-		} else {
-			m.tt.Press(in.X, in.Y)
-		}
-	case "up":
-		if in.Button == 0 && mods == 0 {
-			m.tt.Release(in.X, in.Y)
-		}
-	case "move":
-		m.tt.Move(in.X, in.Y)
-	case "wheel":
-		m.tt.Scroll(in.X, in.Y, in.DX, in.DY)
-	case "key":
-		k, ok := keyCodes[in.Code]
-		if !ok {
-			return fmt.Errorf("unmapped key code %q", in.Code)
-		}
-		if in.Text != "" && mods&^ui.Shift == 0 {
-			m.tt.TypeKey(mods, k, in.Text)
-		} else {
-			m.tt.Key(mods, k)
-		}
-	case "text":
-		m.tt.Type(in.Text)
-	case "compose":
-		m.tt.Compose(in.Text, in.Caret)
-	case "paste":
-		m.tt.SetClipboard(in.Text)
-		m.clip = in.Text
-		m.tt.Command("paste")
-	case "command":
-		m.tt.Command(in.Text)
-	case "resize":
-		if in.W < 320 || in.H < 240 || in.Scale <= 0 {
-			return fmt.Errorf("bad size %dx%d@%v", in.W, in.H, in.Scale)
-		}
-		m.tt.SetSize(in.W, in.H)
-		m.tt.SetScale(in.Scale)
-		m.tt.SetDark(in.Dark)
-		m.tt.SetPreferences(ui.Preferences{ReduceMotion: in.Motion, HighContrast: in.More, TextScale: 1})
-	case "focus":
-		m.tt.SetFocused(in.Text == "in")
-	default:
-		return fmt.Errorf("unknown input type %q", in.Type)
-	}
-	return nil
-}
-
-func modifiers(m []bool) ui.Modifiers {
-	var out ui.Modifiers
-	for i, mod := range []ui.Modifiers{ui.Shift, ui.Ctrl, ui.Alt, ui.Super} {
-		if i < len(m) && m[i] {
-			out |= mod
-		}
-	}
-	return out
-}

examples/gallery/web/index.html

@@ -139,7 +139,7 @@ canvas.addEventListener("pointermove", (e) => {
 });
 canvas.addEventListener("wheel", (e) => {
   const k = e.deltaMode === 1 ? 16 : e.deltaMode === 2 ? canvas.clientHeight : 1;
-  send({ type: "wheel", dx: -e.deltaX * k, dy: -e.deltaY * k, ...at(e) }); e.preventDefault();
+  send({ type: "wheel", dx: e.deltaX * k, dy: e.deltaY * k, ...at(e) }); e.preventDefault();
 }, { passive: false });
 canvas.addEventListener("contextmenu", (e) => e.preventDefault());
 canvas.addEventListener("focus", () => keys.focus({ preventScroll: true }));

examples/gallery/web_input.go

@@ -0,0 +1,126 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"net/http"
+
+	"github.com/egoist/mygo/ui"
+)
+
+// input is one browser event.
+type input struct {
+	Type   string  `json:"type"`
+	X      float32 `json:"x"`
+	Y      float32 `json:"y"`
+	DX     float32 `json:"dx"`
+	DY     float32 `json:"dy"`
+	Button int     `json:"button"`
+	Code   string  `json:"code"`
+	Text   string  `json:"text"`
+	Caret  int     `json:"caret"`
+	Mods   []bool  `json:"mods"`
+	W      int     `json:"w"`
+	H      int     `json:"h"`
+	Scale  float32 `json:"scale"`
+	Dark   bool    `json:"dark"`
+	Motion bool    `json:"reduceMotion"`
+	More   bool    `json:"moreContrast"`
+}
+
+func (m *mirror) serveInput(w http.ResponseWriter, r *http.Request) {
+	var in input
+	if err := json.NewDecoder(r.Body).Decode(&in); err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	m.mu.Lock()
+	err := m.apply(in)
+	if err == nil {
+		m.capture()
+	}
+	m.mu.Unlock()
+	if err != nil {
+		slog.Warn("gallery: web input rejected", "type", in.Type, "err", err)
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	m.kick()
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// apply sends one event to the tester; the caller holds mu.
+func (m *mirror) apply(in input) error {
+	mods := modifiers(in.Mods)
+	switch in.Type {
+	case "down":
+		switch {
+		case in.Button == 2:
+			m.tt.RightClickAt(in.X, in.Y)
+		case mods != 0:
+			m.down = &in
+		default:
+			m.tt.Press(in.X, in.Y)
+		}
+	case "up":
+		if d := m.down; d != nil {
+			m.down = nil
+			if dx, dy := in.X-d.X, in.Y-d.Y; dx*dx+dy*dy <= 16 {
+				m.tt.ClickAtWith(modifiers(d.Mods), d.X, d.Y)
+			} else {
+				slog.Info("gallery: modified drag ignored; tester clicks only", "mods", modifiers(d.Mods))
+			}
+		} else if in.Button == 0 {
+			m.tt.Release(in.X, in.Y)
+		}
+	case "move":
+		m.tt.Move(in.X, in.Y)
+	case "wheel":
+		m.tt.Scroll(in.X, in.Y, in.DX, in.DY)
+	case "key":
+		k, ok := keyCodes[in.Code]
+		if !ok {
+			return fmt.Errorf("unmapped key code %q", in.Code)
+		}
+		if in.Text != "" && mods&^(ui.Shift|ui.Alt) == 0 {
+			m.tt.TypeKey(mods, k, in.Text)
+		} else {
+			m.tt.Key(mods, k)
+		}
+	case "text":
+		m.tt.Type(in.Text)
+	case "compose":
+		m.tt.Compose(in.Text, in.Caret)
+	case "paste":
+		m.tt.SetClipboard(in.Text)
+		m.clip = in.Text
+		m.tt.Command("paste")
+	case "command":
+		m.tt.Command(in.Text)
+		m.copied = in.Text == "copy" || in.Text == "cut"
+	case "resize":
+		if in.W < 320 || in.H < 240 || in.Scale <= 0 {
+			return fmt.Errorf("bad size %dx%d@%v", in.W, in.H, in.Scale)
+		}
+		m.tt.SetSize(in.W, in.H)
+		m.tt.SetScale(in.Scale)
+		m.tt.SetDark(in.Dark)
+		m.tt.SetPreferences(ui.Preferences{ReduceMotion: in.Motion, HighContrast: in.More, TextScale: 1})
+	case "focus":
+		m.tt.SetFocused(in.Text == "in")
+	default:
+		return fmt.Errorf("unknown input type %q", in.Type)
+	}
+	return nil
+}
+
+func modifiers(m []bool) ui.Modifiers {
+	var out ui.Modifiers
+	for i, mod := range []ui.Modifiers{ui.Shift, ui.Ctrl, ui.Alt, ui.Super} {
+		if i < len(m) && m[i] {
+			out |= mod
+		}
+	}
+	return out
+}

examples/gallery/web_keys.go

@@ -4,6 +4,10 @@ import "github.com/egoist/mygo/ui"
 
 // keyCodes maps KeyboardEvent.code to MyGo keys.
 var keyCodes = map[string]ui.Key{
+	"Numpad0": ui.Key0, "Numpad1": ui.Key1, "Numpad2": ui.Key2, "Numpad3": ui.Key3, "Numpad4": ui.Key4,
+	"Numpad5": ui.Key5, "Numpad6": ui.Key6, "Numpad7": ui.Key7, "Numpad8": ui.Key8, "Numpad9": ui.Key9,
+	"NumpadDecimal": ui.KeyPeriod, "NumpadSubtract": ui.KeyMinus, "NumpadAdd": ui.KeyEqual,
+	"NumpadMultiply": ui.Key8, "NumpadDivide": ui.KeySlash, "NumpadEqual": ui.KeyEqual, "NumpadComma": ui.KeyComma,
 	"Enter":          ui.KeyEnter,
 	"NumpadEnter":    ui.KeyEnter,
 	"Escape":         ui.KeyEscape,

examples/gallery/web_test.go

@@ -9,6 +9,7 @@ import (
 	"net/http/httptest"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/egoist/mygo/ui"
 
@@ -133,3 +134,129 @@ func TestMirrorRejectsBadInput(t *testing.T) {
 		t.Fatalf("bad json: %d", res.StatusCode)
 	}
 }
+
+// mirrorWith serves view through a mirror for one test.
+func mirrorWith(t *testing.T, view func(c *ui.Context)) (*mirror, *httptest.Server) {
+	m, h := newMirror(view)
+	srv := httptest.NewServer(h)
+	t.Cleanup(srv.Close)
+	return m, srv
+}
+
+func postInput(t *testing.T, srv *httptest.Server, in input) {
+	t.Helper()
+	body, err := json.Marshal(in)
+	if err != nil {
+		t.Fatal(err)
+	}
+	res, err := http.Post(srv.URL+"/input", "application/json", bytes.NewReader(body))
+	if err != nil {
+		t.Fatal(err)
+	}
+	res.Body.Close()
+	if res.StatusCode != http.StatusNoContent {
+		t.Fatalf("%s: %d", in.Type, res.StatusCode)
+	}
+}
+
+func TestMirrorTimersFireWithoutInput(t *testing.T) {
+	start := time.Now()
+	var late bool
+	m, _ := mirrorWith(t, func(c *ui.Context) {
+		mujica.Use(c, mujica.Settings{})
+		late = c.Now().Sub(start) > 300*time.Millisecond
+		if !late {
+			c.After(350 * time.Millisecond)
+		}
+	})
+	time.Sleep(900 * time.Millisecond)
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if !late {
+		t.Fatal("the view was not rebuilt after its timer with no input")
+	}
+}
+
+func TestMirrorModifiedClickNeedsReleaseInPlace(t *testing.T) {
+	clicks := 0
+	_, srv := mirrorWith(t, func(c *ui.Context) {
+		mujica.Use(c, mujica.Settings{})
+		ui.Column(c).Padding(20).Children(func() {
+			if mujica.Button(c, "Seal", mujica.ButtonOptions{}).Clicked() {
+				clicks++
+			}
+		})
+	})
+	shift := []bool{true}
+	postInput(t, srv, input{Type: "down", X: 40, Y: 35, Mods: shift})
+	postInput(t, srv, input{Type: "up", X: 400, Y: 400, Mods: shift})
+	postInput(t, srv, input{Type: "down", X: 40, Y: 35, Mods: shift})
+	postInput(t, srv, input{Type: "up", X: 41, Y: 35, Mods: shift})
+	if clicks != 1 {
+		t.Fatalf("clicks %d, want 1 (released elsewhere must not click)", clicks)
+	}
+}
+
+func TestMirrorForwardsRepeatedCopy(t *testing.T) {
+	m, _ := mirrorWith(t, func(c *ui.Context) { mujica.Use(c, mujica.Settings{}) })
+	ch := make(chan []byte, 8)
+	m.mu.Lock()
+	m.subs[ch] = struct{}{}
+	notices := 0
+	for range 2 {
+		m.tt.SetClipboard("same")
+		m.copied = true
+		if m.capture() {
+			notices++
+		}
+	}
+	m.mu.Unlock()
+	if notices != 2 {
+		t.Fatalf("repeated copy of the same text notified %d times, want 2", notices)
+	}
+	for range 2 {
+		msg := <-ch
+		if !bytes.Contains(msg, []byte(`"clipboard":"same"`)) {
+			t.Fatalf("notice %s", msg)
+		}
+	}
+}
+
+func TestMirrorMapsNumpad(t *testing.T) {
+	r := newMirrorRig(t)
+	r.post(input{Type: "key", Code: "Tab"})
+	if code := r.post(input{Type: "key", Code: "Numpad7", Text: "7"}); code != http.StatusNoContent {
+		t.Fatalf("numpad: %d", code)
+	}
+	if got := r.value(); got != "7" {
+		t.Fatalf("value %q", got)
+	}
+}
+
+func TestMirrorForwardsEveryAnnouncement(t *testing.T) {
+	m, srv := mirrorWith(t, func(c *ui.Context) {
+		mujica.Use(c, mujica.Settings{})
+		ui.Column(c).Padding(20).Children(func() {
+			if mujica.Button(c, "Ring", mujica.ButtonOptions{}).Clicked() {
+				c.Announce("bell rung")
+			}
+		})
+	})
+	ch := make(chan []byte, 64)
+	m.mu.Lock()
+	m.subs[ch] = struct{}{}
+	m.mu.Unlock()
+	for range 2 {
+		postInput(t, srv, input{Type: "down", X: 40, Y: 35})
+		postInput(t, srv, input{Type: "up", X: 40, Y: 35})
+	}
+	heard := 0
+	for len(ch) > 0 {
+		if bytes.Contains(<-ch, []byte("bell rung")) {
+			heard++
+		}
+	}
+	if heard != 2 {
+		t.Fatalf("announcements forwarded %d times, want 2", heard)
+	}
+}

form.go

@@ -99,7 +99,6 @@ type FormOptions struct {
 
 // FormScope registers a Form's fields with FormItem.
 type FormScope struct {
-	c          *ui.Context
 	st         *FormState
 	horizontal bool
 }
@@ -140,7 +139,7 @@ func Form(c *ui.Context, st *FormState, opts FormOptions, fields func(f *FormSco
 	parts := FormParts{}
 	col := ui.Column(c).Gap(d.Unit() * 5)
 	parts.Element = col
-	scope := &FormScope{c: c, st: st, horizontal: opts.Horizontal}
+	scope := &FormScope{st: st, horizontal: opts.Horizontal}
 	col.Children(func() {
 		// A new key after Reset drops the controls' drafts and errors.
 		ui.Box(c).Key(st.generation).Children(func() {
@@ -242,8 +241,8 @@ func formReset(st *FormState) {
 }
 
 // FormItem registers field name around the focusable element control returns.
-func FormItem[T any](f *FormScope, name string, value *T, opts FormItemOptions[T], control func() *ui.Element) *ui.Element {
-	c, st := f.c, f.st
+func FormItem[T any](c *ui.Context, f *FormScope, name string, value *T, opts FormItemOptions[T], control func() *ui.Element) *ui.Element {
+	st := f.st
 	if name == "" || opts.Label == "" {
 		panic("mujica: FormItem needs a name and a Label")
 	}

form_test.go

@@ -25,7 +25,7 @@ func (p *formProbe) run(c *ui.Context) {
 
 func (p *formProbe) view(c *ui.Context) {
 	res := Form(c, &p.st, FormOptions{Horizontal: p.horizontal}, func(f *FormScope) {
-		FormItem(f, "name", &p.name, FormItemOptions[string]{Label: "Name", Required: true, Initial: "Sakiko"}, func() *ui.Element {
+		FormItem(c, f, "name", &p.name, FormItemOptions[string]{Label: "Name", Required: true, Initial: "Sakiko"}, func() *ui.Element {
 			return InputGroup(c, &p.name, InputGroupOptions{Invalid: p.st.Error("name") != ""}).Input
 		})
 		opts := FormItemOptions[string]{Label: "Email", Validate: func(v string) string {
@@ -40,10 +40,10 @@ func (p *formProbe) view(c *ui.Context) {
 				p.asyncValues = append(p.asyncValues, v)
 			}
 		}
-		FormItem(f, "email", &p.email, opts, func() *ui.Element {
+		FormItem(c, f, "email", &p.email, opts, func() *ui.Element {
 			return InputGroup(c, &p.email, InputGroupOptions{Invalid: p.st.Error("email") != ""}).Input
 		})
-		FormItem(f, "tags", &p.tags, FormItemOptions[[]string]{Label: "Tags", Required: true, Initial: []string{"rose"}}, func() *ui.Element {
+		FormItem(c, f, "tags", &p.tags, FormItemOptions[[]string]{Label: "Tags", Required: true, Initial: []string{"rose"}}, func() *ui.Element {
 			return TagsInput(c, &p.tags, TagsInputOptions{}).Input
 		})
 	})
@@ -222,7 +222,7 @@ func TestFormResetClearsControlState(t *testing.T) {
 	tt := ui.NewTester(func(c *ui.Context) {
 		Use(c, Settings{})
 		Form(c, &st, FormOptions{}, func(f *FormScope) {
-			FormItem(f, "tags", &tags, FormItemOptions[[]string]{Label: "Tags"}, func() *ui.Element {
+			FormItem(c, f, "tags", &tags, FormItemOptions[[]string]{Label: "Tags"}, func() *ui.Element {
 				return TagsInput(c, &tags, TagsInputOptions{Validate: func(s string) string {
 					seen = s
 					return "Invalid tag"
@@ -289,13 +289,13 @@ func TestFormCrossFieldRuleAtSettle(t *testing.T) {
 	tt := ui.NewTester(func(c *ui.Context) {
 		Use(c, Settings{})
 		res := Form(c, &st, FormOptions{}, func(f *FormScope) {
-			FormItem(f, "user", &user, FormItemOptions[string]{Label: "User", Async: func(_ string, v uint64) { version = v }}, func() *ui.Element {
+			FormItem(c, f, "user", &user, FormItemOptions[string]{Label: "User", Async: func(_ string, v uint64) { version = v }}, func() *ui.Element {
 				return InputGroup(c, &user, InputGroupOptions{}).Input
 			})
-			FormItem(f, "pw", &pw, FormItemOptions[string]{Label: "Password"}, func() *ui.Element {
+			FormItem(c, f, "pw", &pw, FormItemOptions[string]{Label: "Password"}, func() *ui.Element {
 				return InputGroup(c, &pw, InputGroupOptions{}).Input
 			})
-			FormItem(f, "confirm", &confirm, FormItemOptions[string]{Label: "Confirm", Validate: func(v string) string {
+			FormItem(c, f, "confirm", &confirm, FormItemOptions[string]{Label: "Confirm", Validate: func(v string) string {
 				if v != pw {
 					return "Passwords differ."
 				}

internal/diff.go

@@ -0,0 +1,133 @@
+package internal
+
+import "strings"
+
+// DiffOp says whether a diff line is kept, removed or added.
+type DiffOp uint8
+
+const (
+	DiffEqual DiffOp = iota
+	DiffDelete
+	DiffInsert
+)
+
+// DiffLine is one line of a line diff with its 1-based line numbers; 0 means absent.
+type DiffLine struct {
+	Op       DiffOp
+	Text     string
+	Old, New int
+}
+
+// SplitLines splits text into lines without their line breaks; "" has no lines.
+func SplitLines(s string) []string {
+	if s == "" {
+		return nil
+	}
+	return strings.Split(strings.TrimSuffix(s, "\n"), "\n")
+}
+
+// LineDiff returns a shortest edit script turning a into b (Myers, O((N+M)D)).
+func LineDiff(a, b []string) []DiffLine {
+	// Common prefix and suffix need no search.
+	pre := 0
+	for pre < len(a) && pre < len(b) && a[pre] == b[pre] {
+		pre++
+	}
+	suf := 0
+	for suf < len(a)-pre && suf < len(b)-pre && a[len(a)-1-suf] == b[len(b)-1-suf] {
+		suf++
+	}
+	out := make([]DiffLine, 0, len(a)+len(b)-pre-suf)
+	for i := range pre {
+		out = append(out, DiffLine{DiffEqual, a[i], i + 1, i + 1})
+	}
+	out = myers(out, a[pre:len(a)-suf], b[pre:len(b)-suf], pre, pre)
+	for i := range suf {
+		ai, bi := len(a)-suf+i, len(b)-suf+i
+		out = append(out, DiffLine{DiffEqual, a[ai], ai + 1, bi + 1})
+	}
+	return out
+}
+
+// myers appends the edit script of a to b, numbering from offsets ao and bo.
+func myers(out []DiffLine, a, b []string, ao, bo int) []DiffLine {
+	n, m := len(a), len(b)
+	total := n + m
+	if total == 0 {
+		return out
+	}
+	off := total + 1
+	v := make([]int, 2*total+3)
+	var trace [][]int
+	end := -1
+	for d := 0; d <= total && end < 0; d++ {
+		trace = append(trace, append([]int(nil), v[off-d:off+d+1]...)) // diagonals -d..d
+		for k := -d; k <= d; k += 2 {
+			var x int
+			if k == -d || k != d && v[off+k-1] < v[off+k+1] {
+				x = v[off+k+1]
+			} else {
+				x = v[off+k-1] + 1
+			}
+			y := x - k
+			for x < n && y < m && a[x] == b[y] {
+				x, y = x+1, y+1
+			}
+			v[off+k] = x
+			if x >= n && y >= m {
+				end = d
+				break
+			}
+		}
+	}
+	// Walk the trace back from (n, m), collecting moves in reverse.
+	var rev []DiffLine
+	x, y := n, m
+	for d := end; d >= 0; d-- {
+		vd := trace[d]
+		at := func(k int) int { return vd[k+d] }
+		k := x - y
+		var pk int
+		if k == -d || k != d && at(k-1) < at(k+1) {
+			pk = k + 1
+		} else {
+			pk = k - 1
+		}
+		px := 0
+		if d > 0 {
+			px = at(pk)
+		}
+		py := px - pk
+		for x > px && y > py {
+			x, y = x-1, y-1
+			rev = append(rev, DiffLine{DiffEqual, a[x], ao + x + 1, bo + y + 1})
+		}
+		if d == 0 {
+			break
+		}
+		if x == px {
+			y--
+			rev = append(rev, DiffLine{DiffInsert, b[y], 0, bo + y + 1})
+		} else {
+			x--
+			rev = append(rev, DiffLine{DiffDelete, a[x], ao + x + 1, 0})
+		}
+	}
+	for i := len(rev) - 1; i >= 0; i-- {
+		out = append(out, rev[i])
+	}
+	return out
+}
+
+// DiffStats counts the added and removed lines of a diff.
+func DiffStats(d []DiffLine) (added, removed int) {
+	for _, l := range d {
+		switch l.Op {
+		case DiffInsert:
+			added++
+		case DiffDelete:
+			removed++
+		}
+	}
+	return added, removed
+}

internal/diff_test.go

@@ -0,0 +1,110 @@
+package internal
+
+import (
+	"fmt"
+	"math/rand"
+	"slices"
+	"strings"
+	"testing"
+)
+
+// diffSides rebuilds both inputs from a diff and checks the line numbers.
+func diffSides(t *testing.T, d []DiffLine) (a, b []string) {
+	t.Helper()
+	for _, l := range d {
+		if l.Op != DiffInsert {
+			a = append(a, l.Text)
+			if l.Old != len(a) {
+				t.Fatalf("old number %d, want %d", l.Old, len(a))
+			}
+		}
+		if l.Op != DiffDelete {
+			b = append(b, l.Text)
+			if l.New != len(b) {
+				t.Fatalf("new number %d, want %d", l.New, len(b))
+			}
+		}
+	}
+	return a, b
+}
+
+// lcs is the reference longest common subsequence length.
+func lcs(a, b []string) int {
+	prev := make([]int, len(b)+1)
+	for i := range a {
+		cur := make([]int, len(b)+1)
+		for j := range b {
+			if a[i] == b[j] {
+				cur[j+1] = prev[j] + 1
+			} else {
+				cur[j+1] = max(prev[j+1], cur[j])
+			}
+		}
+		prev = cur
+	}
+	return prev[len(b)]
+}
+
+func TestLineDiffKnown(t *testing.T) {
+	d := LineDiff(SplitLines("a\nb\nc\nd\n"), SplitLines("a\nc\nd\ne\n"))
+	var got []string
+	for _, l := range d {
+		got = append(got, fmt.Sprintf("%d%s", l.Op, l.Text))
+	}
+	want := []string{"0a", "1b", "0c", "0d", "2e"}
+	if !slices.Equal(got, want) {
+		t.Fatalf("diff %v, want %v", got, want)
+	}
+	if add, del := DiffStats(d); add != 1 || del != 1 {
+		t.Fatalf("stats +%d -%d", add, del)
+	}
+}
+
+func TestLineDiffEdges(t *testing.T) {
+	for _, tc := range []struct{ a, b string }{{"", ""}, {"", "x\ny"}, {"x\ny", ""}, {"same\n", "same\n"}, {"a", "b"}} {
+		d := LineDiff(SplitLines(tc.a), SplitLines(tc.b))
+		a, b := diffSides(t, d)
+		if !slices.Equal(a, SplitLines(tc.a)) || !slices.Equal(b, SplitLines(tc.b)) {
+			t.Errorf("%q -> %q: rebuilt %q, %q", tc.a, tc.b, a, b)
+		}
+	}
+}
+
+func TestLineDiffMinimalRandom(t *testing.T) {
+	r := rand.New(rand.NewSource(7))
+	for range 300 {
+		a := make([]string, r.Intn(30))
+		b := make([]string, r.Intn(30))
+		for i := range a {
+			a[i] = string(rune('a' + r.Intn(4)))
+		}
+		for i := range b {
+			b[i] = string(rune('a' + r.Intn(4)))
+		}
+		d := LineDiff(a, b)
+		ra, rb := diffSides(t, d)
+		if !slices.Equal(ra, a) || !slices.Equal(rb, b) {
+			t.Fatalf("rebuilt %q %q from %q %q", ra, rb, a, b)
+		}
+		add, del := DiffStats(d)
+		if keep := len(a) - del; keep != lcs(a, b) || len(b)-add != keep {
+			t.Fatalf("%q -> %q: kept %d lines, LCS is %d", a, b, keep, lcs(a, b))
+		}
+	}
+}
+
+func TestLineDiffLargeFileSmallEdit(t *testing.T) {
+	a := make([]string, 50000)
+	for i := range a {
+		a[i] = fmt.Sprint("line ", i)
+	}
+	b := slices.Clone(a)
+	b[25000] = "changed"
+	d := LineDiff(a, b)
+	if add, del := DiffStats(d); add != 1 || del != 1 || len(d) != 50001 {
+		t.Fatalf("+%d -%d over %d lines", add, del, len(d))
+	}
+	if !strings.HasPrefix(d[25000].Text, "line 25000") || d[25000].Op != DiffDelete {
+		t.Fatalf("line 25000: %+v", d[25000])
+	}
+}

internal/display.go

@@ -6,12 +6,6 @@ import (
 	"github.com/egoist/mygo/ui"
 )
 
-// Rule draws a pixel-aligned 1 DIP horizontal line at y.
-func Rule(p *ui.Painter, x0, x1, y float32, c ui.Color) {
-	yy := ruleY(p, y)
-	p.Line(x0, yy, x1, yy, 1, c)
-}
-
 // ruleY moves y to where a 1 DIP line fills whole device pixels.
 func ruleY(p *ui.Painter, y float32) float32 {
 	s := float64(p.Scale())

navigation_review_test.go

@@ -7,6 +7,8 @@ import (
 
 	"github.com/egoist/mygo/ui"
 
+	"mujicaui/theme"
+
 	"mujicaui/icons"
 )
 
@@ -34,6 +36,7 @@ func TestNavigationPopupsFadeIn(t *testing.T) {
 			CommandPalette(c, &open, commandPaletteSample(), CommandPaletteOptions{})
 		}},
 	} {
+		opened := time.Now()
 		tt := ui.NewTester(func(c *ui.Context) {
 			Use(c, Settings{Mode: Light})
 			ui.Column(c).Fill().Padding(16).AlignItems(ui.Start).Children(func() { tc.view(c) })
@@ -49,9 +52,11 @@ func TestNavigationPopupsFadeIn(t *testing.T) {
 		}
 		x, y := int(r.X-3), int(r.Y+r.H/2)
 		early := tt.Image().RGBAAt(x, y)
+		mid := time.Since(opened) < theme.PopupDuration/2
 		time.Sleep(200 * time.Millisecond)
 		tt.Frame()
-		if late := tt.Image().RGBAAt(x, y); early == late {
+		// A slow run may finish the fade before the first sample.
+		if late := tt.Image().RGBAAt(x, y); mid && early == late {
 			t.Errorf("%s: popup appeared at once (%v)", tc.name, late)
 		}
 	}