fix: mascot animation, makes syntax highlighting blink

difflet_test.go

@@ -72,6 +72,52 @@ func TestDiffletStylesOnlyDiffSigns(t *testing.T) {
 	}
 }
 
+func TestDiffletAnimationDoesNotChangeThreadCommentRows(t *testing.T) {
+	if err := applyTheme("dark"); err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { _ = applyTheme("dark") })
+
+	app := NewAppWithSettings(
+		&recordingService{}, "owner", "repository", false, 10, 10,
+		AppSettings{Mascot: true, MascotAnimated: true},
+	)
+	app.screen = threadScreen
+	app.loading = false
+	app.details = PRDetails{
+		PullRequest: PullRequest{
+			Owner: "owner", Repository: "repository",
+			RepoWithOwner: "owner/repository", Number: 42,
+			Title: "Stable highlighted comments",
+		},
+		Threads: []ReviewThread{{
+			ID: "thread", Path: "main.go",
+			Comments: []ReviewComment{{
+				ID: "comment", Author: "reviewer",
+				Body: "```go\nfunc main() {\n\tprintln(\"stable\")\n}\n```",
+			}},
+		}},
+	}
+	updated, _ := app.Update(tea.WindowSizeMsg{Width: 100, Height: 30})
+	app = updated.(App)
+	before := strings.Split(app.View(), "\n")
+
+	generation := app.difflet.generation
+	updated, _ = app.Update(diffletTickMsg{generation: generation})
+	app = updated.(App)
+	after := strings.Split(app.View(), "\n")
+
+	if len(before) != len(after) {
+		t.Fatalf("animation changed frame height from %d to %d", len(before), len(after))
+	}
+	for row := diffletHeight; row < len(before); row++ {
+		if before[row] != after[row] {
+			t.Fatalf("animation changed non-mascot row %d:\nbefore %q\nafter  %q",
+				row, before[row], after[row])
+		}
+	}
+}
+
 func TestDiffletEnabledSitsRightOfWrappingHeader(t *testing.T) {
 	app := NewAppWithSettings(
 		&recordingService{}, "owner", "repository", false, 10, 10,

markdown.go

@@ -97,6 +97,7 @@ func commentMarkdownRenderer(width int) (*glamour.TermRenderer, error) {
 	style.Code.Suffix = ""
 	renderer, err := glamour.NewTermRenderer(
 		glamour.WithStyles(style),
+		glamour.WithChromaFormatter("terminal16m"),
 		glamour.WithWordWrap(width),
 		glamour.WithTableWrap(true),
 		glamour.WithPreservedNewLines(),

terminal_cursor.go

@@ -49,6 +49,21 @@ func (o *terminalCursorOutput) Write(value []byte) (int, error) {
 	o.mu.Lock()
 	defer o.mu.Unlock()
 
+	// Bubble Tea v1 can expose intermediate rows from an animated partial
+	// repaint. This is especially visible when unchanged Markdown code blocks
+	// below the changed rows contain dense ANSI styling. Terminals that support
+	// synchronized output hold the completed frame until the reset sequence;
+	// terminals that do not support it safely ignore both sequences.
+	if !bytes.Equal(value, []byte(ansi.ShowCursor)) &&
+		!bytes.Equal(value, []byte(ansi.HideCursor)) {
+		if _, err := io.WriteString(o.file, ansi.SetSynchronizedOutputMode); err != nil {
+			return 0, err
+		}
+		defer func() {
+			_, _ = io.WriteString(o.file, ansi.ResetSynchronizedOutputMode)
+		}()
+	}
+
 	written, err := o.file.Write(value)
 	if err != nil || written != len(value) {
 		return written, err

terminal_cursor_test.go

@@ -25,7 +25,7 @@ func TestTerminalCursorOutputPositionsHardwareBarAfterFrame(t *testing.T) {
 		t.Fatal(err)
 	}
 	wantSuffix := ansi.SetCursorStyle(5) + ansi.CursorPosition(7, 4) + ansi.ShowCursor
-	if !strings.HasSuffix(string(content), wantSuffix) {
+	if !strings.HasSuffix(string(content), wantSuffix+ansi.ResetSynchronizedOutputMode) {
 		t.Fatalf("cursor output = %q, want suffix %q", content, wantSuffix)
 	}
 }
@@ -46,7 +46,33 @@ func TestTerminalCursorOutputHidesCursorOutsideInsertMode(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if !strings.HasSuffix(string(content), ansi.HideCursor) {
+	if !strings.HasSuffix(
+		string(content),
+		ansi.HideCursor+ansi.ResetSynchronizedOutputMode,
+	) {
 		t.Fatalf("cursor output did not hide cursor: %q", content)
 	}
 }
+
+func TestTerminalCursorOutputSynchronizesCompletedFrames(t *testing.T) {
+	file, err := os.CreateTemp(t.TempDir(), "cursor-output")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer file.Close()
+
+	output := newTerminalCursorOutput(file)
+	output.SetCursor(false, 0, 0)
+	if _, err := output.Write([]byte("animated frame")); err != nil {
+		t.Fatal(err)
+	}
+	content, err := os.ReadFile(file.Name())
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := ansi.SetSynchronizedOutputMode + "animated frame" +
+		ansi.HideCursor + ansi.ResetSynchronizedOutputMode
+	if string(content) != want {
+		t.Fatalf("synchronized frame output = %q, want %q", content, want)
+	}
+}

version.go

@@ -1,3 +1,3 @@
 package main
 
-const dipleVersion = "0.1.1"
+const dipleVersion = "0.1.2"