fix(tui): repair light/dark theme switching artifacts

internal/tui/terminal.go

@@ -285,8 +285,15 @@ func NewTerminal() *Terminal {
 
 // setMarkdownStyle rebuilds the glamour renderer for the given background
 // polarity. It keeps the previous renderer when construction fails so a
-// failed swap never disables markdown rendering.
+// failed swap never disables markdown rendering, and skips the rebuild when
+// the polarity is unchanged.
 func (t *Terminal) setMarkdownStyle(dark bool) {
+	t.rendMu.Lock()
+	unchanged := t.renderer != nil && dark == t.markdownDark
+	t.rendMu.Unlock()
+	if unchanged {
+		return
+	}
 	gStyle := "light"
 	if dark {
 		gStyle = "dark"

internal/tui/theme.go

@@ -344,12 +344,30 @@ var (
 	ThemeIsDark = true
 )
 
+// terminalDark captures the terminal's actual background polarity once at
+// package init, before any ApplyTheme call overrides lipgloss's detection
+// with the selected theme's polarity. Foreground-only picker chrome keys off
+// this so opposite-polarity previews (e.g. a light theme on a dark terminal)
+// stay readable on the live terminal.
+var terminalDark = lipgloss.HasDarkBackground()
+
 // ApplyTheme rebuilds all lipgloss styles and ANSI prompt vars from t.
 // Must be called before NewTerminal() and ShowModelPicker().
 func ApplyTheme(t Theme) {
 	ThemeIsDark = t.Dark
 	lipgloss.SetHasDarkBackground(t.Dark)
 
+	// Neutral foreground-only chrome follows the terminal's real polarity,
+	// not the theme's: these styles carry no background, so a theme/terminal
+	// polarity mismatch would render its own neutrals invisible (near-black
+	// labels on a dark terminal while previewing a light theme, and vice
+	// versa). The values are identical to same-polarity themes, so matched
+	// setups render exactly as before.
+	labelFg, dimFg, subtleFg, sepFg := lipgloss.Color("252"), lipgloss.Color("242"), lipgloss.Color("240"), lipgloss.Color("237")
+	if !terminalDark {
+		labelFg, dimFg, subtleFg, sepFg = lipgloss.Color("236"), lipgloss.Color("243"), lipgloss.Color("247"), lipgloss.Color("252")
+	}
+
 	// ANSI prompt/banner vars
 	themePromptName = t.ANSIPromptName
 	themePromptArrow = t.ANSIPromptArrow
@@ -370,10 +388,9 @@ func ApplyTheme(t Theme) {
 	pickerBox = lipgloss.NewStyle().
 		Border(lipgloss.RoundedBorder()).
 		BorderForeground(lipgloss.Color(t.SurfaceBorder)).
-		Background(lipgloss.Color(t.SurfaceDark)).
 		Padding(0, 1)
 	pickerSectionHeader = lipgloss.NewStyle().
-		Foreground(lipgloss.Color(t.TextDim)).
+		Foreground(dimFg).
 		PaddingTop(1)
 	pickerRowSelected = lipgloss.NewStyle().
 		Background(lipgloss.Color(t.SurfaceSelect)).
@@ -382,7 +399,7 @@ func ApplyTheme(t Theme) {
 	pickerIcon = lipgloss.NewStyle().Foreground(lipgloss.Color(t.Brand))
 	pickerIconCodex = lipgloss.NewStyle().Foreground(lipgloss.Color(t.IconCodex))
 	pickerIconAPI = lipgloss.NewStyle().Foreground(lipgloss.Color(t.IconAPI))
-	pickerLabel = lipgloss.NewStyle().Foreground(lipgloss.Color(t.TextNormal))
+	pickerLabel = lipgloss.NewStyle().Foreground(labelFg)
 	pickerLabelSel = lipgloss.NewStyle().Foreground(lipgloss.Color(t.TextBright)).Bold(true)
 	pickerBadgeNew = lipgloss.NewStyle().
 		Foreground(lipgloss.Color("0")).
@@ -391,19 +408,19 @@ func ApplyTheme(t Theme) {
 		PaddingLeft(1).PaddingRight(1)
 	pickerBadgeCurrent = lipgloss.NewStyle().Foreground(lipgloss.Color(t.Success)).Bold(true)
 	pickerBadgeStar = lipgloss.NewStyle().Foreground(lipgloss.Color(t.Accent))
-	pickerBadgeExt = lipgloss.NewStyle().Foreground(lipgloss.Color(t.TextDim))
-	pickerShortcut = lipgloss.NewStyle().Foreground(lipgloss.Color(t.TextSubtle))
-	pickerDivider = lipgloss.NewStyle().Foreground(lipgloss.Color(t.SurfaceSep))
+	pickerBadgeExt = lipgloss.NewStyle().Foreground(dimFg)
+	pickerShortcut = lipgloss.NewStyle().Foreground(subtleFg)
+	pickerDivider = lipgloss.NewStyle().Foreground(sepFg)
 	effortLabelActive = lipgloss.NewStyle().
 		Foreground(lipgloss.Color("0")).
 		Background(lipgloss.Color(t.Brand)).
 		Bold(true).
 		PaddingLeft(2).PaddingRight(2)
 	effortLabelInactive = lipgloss.NewStyle().
-		Foreground(lipgloss.Color(t.TextDim)).
+		Foreground(dimFg).
 		PaddingLeft(2).PaddingRight(2)
 	pickerFooter = lipgloss.NewStyle().
-		Foreground(lipgloss.Color(t.TextSubtle)).
+		Foreground(subtleFg).
 		PaddingTop(1)
 	pickerStatusBar = lipgloss.NewStyle().
 		Foreground(lipgloss.Color(t.TextNormal)).
@@ -431,17 +448,16 @@ func ApplyTheme(t Theme) {
 	menuItemStyle = lipgloss.NewStyle().
 		Foreground(lipgloss.Color(t.MenuItem)).
 		PaddingLeft(1)
-	menuDescStyle = lipgloss.NewStyle().Foreground(lipgloss.Color(t.TextDim))
+	menuDescStyle = lipgloss.NewStyle().Foreground(dimFg)
 	menuDescSelSty = lipgloss.NewStyle().
 		Foreground(lipgloss.Color("0")).
 		Background(lipgloss.Color(t.Brand))
-	menuHintStyle = lipgloss.NewStyle().Foreground(lipgloss.Color(t.TextSubtle))
+	menuHintStyle = lipgloss.NewStyle().Foreground(subtleFg)
 	filterStyle = lipgloss.NewStyle().Foreground(lipgloss.Color(t.Accent)).Bold(true)
 
 	inputBoxStyle = lipgloss.NewStyle().
 		Border(lipgloss.RoundedBorder()).
 		BorderForeground(lipgloss.Color(t.SurfaceBorder)).
-		Background(lipgloss.Color(t.SurfaceDark)).
 		Padding(0, 1)
 
 	statusMetricsStyle = lipgloss.NewStyle().Foreground(lipgloss.Color(t.TextSubtle)).Background(lipgloss.Color(t.SurfaceDark))

internal/tui/theme_test.go

@@ -1,9 +1,11 @@
 package tui
 
 import (
+	"reflect"
 	"strconv"
 	"testing"
 
+	tea "github.com/charmbracelet/bubbletea"
 	"github.com/charmbracelet/lipgloss"
 )
 
@@ -129,25 +131,34 @@
 	ApplyTheme(ThemeByName("historic"))
 }
 
-// TestApplyTheme_BackgroundsFollowTheme guards the invisible-text bug: after
-// ApplyTheme, surfaces that promise a solid background must actually carry
-// the theme's SurfaceDark color, so menus stay readable when the terminal
-// background polarity mismatches the selected theme.
-func TestApplyTheme_BackgroundsFollowTheme(t *testing.T) {
+// TestApplyTheme_BackgroundOwnership guards against ANSI cutouts. Structural
+// containers stay transparent because nested styled spans emit reset sequences
+// that interrupt inherited parent backgrounds. Leaf surfaces may be solid.
+func TestApplyTheme_BackgroundOwnership(t *testing.T) {
 	for _, name := range ThemeNames() {
 		theme := ThemeByName(name)
 		ApplyTheme(theme)
 		surface := lipgloss.Color(theme.SurfaceDark)
-		cases := []struct {
+		transparent := []struct {
 			label string
 			got   lipgloss.TerminalColor
 		}{
 			{"pickerBox", pickerBox.GetBackground()},
 			{"inputBoxStyle", inputBoxStyle.GetBackground()},
+		}
+		for _, c := range transparent {
+			if _, ok := c.got.(lipgloss.NoColor); !ok {
+				t.Errorf("ApplyTheme(%q): %s background = %v, want transparent", name, c.label, c.got)
+			}
+		}
+		solid := []struct {
+			label string
+			got   lipgloss.TerminalColor
+		}{
 			{"statusBarStyle", statusBarStyle.GetBackground()},
 			{"statusMetricsStyle", statusMetricsStyle.GetBackground()},
 		}
-		for _, c := range cases {
+		for _, c := range solid {
 			if c.got != surface {
 				t.Errorf("ApplyTheme(%q): %s background = %v, want %v", name, c.label, c.got, surface)
 			}
@@ -161,7 +172,7 @@
 
 // TestThemePalette_SelectionContrastsSurface guards the picker selection
 // highlight: SurfaceSelect must be visibly distinct from SurfaceDark now
-// that pickerBox paints its own background behind every row.
+// selected rows still need a visible state transition on either polarity.
 func TestThemePalette_SelectionContrastsSurface(t *testing.T) {
 	for _, name := range ThemeNames() {
 		theme := ThemeByName(name)
@@ -221,3 +232,110 @@
 		t.Error("ApplyTheme(historic) left the renderer on light style; want dark")
 	}
 }
+
+func TestThemePicker_PolarityTransitionsRequestFullRepaint(t *testing.T) {
+	m := newThemePickerModel("aurora") // last dark theme; next is light
+
+	updated, cmd := m.Update(tea.KeyMsg{Type: tea.KeyDown})
+	m = updated.(themePickerModel)
+	if got := m.themes[m.cursor]; got != "paper" {
+		t.Fatalf("down transition selected %q, want paper", got)
+	}
+	if cmd == nil || reflect.TypeOf(cmd()) != reflect.TypeOf(tea.ClearScreen()) {
+		t.Fatal("dark-to-light preview did not request a full-screen repaint")
+	}
+
+	updated, cmd = m.Update(tea.KeyMsg{Type: tea.KeyDown})
+	m = updated.(themePickerModel)
+	if got := m.themes[m.cursor]; got != "sky" {
+		t.Fatalf("same-polarity down selected %q, want sky", got)
+	}
+	if cmd != nil {
+		t.Fatal("same-polarity move requested a full-screen repaint; clearing erases the visible transcript and must be gated on polarity flips")
+	}
+
+	updated, cmd = m.Update(tea.KeyMsg{Type: tea.KeyUp})
+	m = updated.(themePickerModel)
+	if got := m.themes[m.cursor]; got != "paper" {
+		t.Fatalf("up selected %q, want paper", got)
+	}
+	updated, cmd = m.Update(tea.KeyMsg{Type: tea.KeyUp})
+	m = updated.(themePickerModel)
+	if got := m.themes[m.cursor]; got != "aurora" {
+		t.Fatalf("up transition selected %q, want aurora", got)
+	}
+	if cmd == nil || reflect.TypeOf(cmd()) != reflect.TypeOf(tea.ClearScreen()) {
+		t.Fatal("light-to-dark preview did not request a full-screen repaint")
+	}
+
+	m = newThemePickerModel("historic")
+	updated, cmd = m.Update(tea.KeyMsg{Type: tea.KeyEsc})
+	m = updated.(themePickerModel)
+	if !m.cancelled {
+		t.Fatal("esc did not cancel")
+	}
+	if cmd == nil {
+		t.Fatal("esc produced no command")
+	}
+	if _, ok := cmd().(tea.QuitMsg); !ok {
+		t.Fatal("cancel without a polarity change must quit without a screen clear")
+	}
+	ApplyTheme(ThemeByName("historic"))
+}
+
+// TestApplyTheme_PickerChromeFollowsTerminalPolarity guards the invisible-
+// chrome regression: foreground-only picker styles must key off the
+// terminal's real polarity, so previewing (or running) an opposite-polarity
+// theme keeps labels readable on the live terminal background.
+func TestApplyTheme_PickerChromeFollowsTerminalPolarity(t *testing.T) {
+	orig := terminalDark
+	defer func() {
+		terminalDark = orig
+		ApplyTheme(ThemeByName("historic"))
+	}()
+
+	terminalDark = true
+	ApplyTheme(ThemeByName("paper")) // light theme previewed on a dark terminal
+	if got := pickerLabel.GetForeground(); got != lipgloss.Color("252") {
+		t.Errorf("pickerLabel on dark terminal = %v, want light label 252", got)
+	}
+	if got := pickerFooter.GetForeground(); got != lipgloss.Color("240") {
+		t.Errorf("pickerFooter on dark terminal = %v, want subtle 240", got)
+	}
+	if got := pickerDivider.GetForeground(); got != lipgloss.Color("237") {
+		t.Errorf("pickerDivider on dark terminal = %v, want 237", got)
+	}
+
+	terminalDark = false
+	ApplyTheme(ThemeByName("historic")) // dark theme on a light terminal
+	if got := pickerLabel.GetForeground(); got != lipgloss.Color("236") {
+		t.Errorf("pickerLabel on light terminal = %v, want dark label 236", got)
+	}
+	if got := pickerFooter.GetForeground(); got != lipgloss.Color("247") {
+		t.Errorf("pickerFooter on light terminal = %v, want subtle 247", got)
+	}
+}
+
+// TestSetMarkdownStyle_SkipsRedundantRebuild ensures a same-polarity
+// ApplyTheme does not churn the glamour renderer.
+func TestSetMarkdownStyle_SkipsRedundantRebuild(t *testing.T) {
+	term := &Terminal{}
+	term.setMarkdownStyle(true)
+	if term.renderer == nil {
+		t.Fatal("initial build did not produce a renderer")
+	}
+	first := term.renderer
+
+	term.setMarkdownStyle(true)
+	if term.renderer != first {
+		t.Error("same-polarity call rebuilt the renderer")
+	}
+
+	term.setMarkdownStyle(false)
+	if term.renderer == first {
+		t.Error("polarity flip did not rebuild the renderer")
+	}
+	if term.markdownDark {
+		t.Error("markdownDark not updated after flip")
+	}
+}

internal/tui/tui_backend.go

@@ -754,19 +754,34 @@ func (m themePickerModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		switch msg.String() {
 		case "ctrl+c", "esc", "q":
 			m.cancelled = true
+			previewed := allThemes[m.themes[m.cursor]]
 			ApplyTheme(ThemeByName(m.originalTheme))
+			// Clearing erases the visible screenful in place, so only pay
+			// that cost when the restore actually flips polarity; otherwise
+			// the renderer's line diff is enough.
+			if allThemes[m.originalTheme].Dark != previewed.Dark {
+				return m, tea.Sequence(tea.ClearScreen, tea.Quit)
+			}
 			return m, tea.Quit
 
 		case "up", "k":
 			if m.cursor > 0 {
+				prev := allThemes[m.themes[m.cursor]]
 				m.cursor--
 				ApplyTheme(ThemeByName(m.themes[m.cursor]))
+				if allThemes[m.themes[m.cursor]].Dark != prev.Dark {
+					return m, tea.ClearScreen
+				}
 			}
 
 		case "down", "j":
 			if m.cursor < len(m.themes)-1 {
+				prev := allThemes[m.themes[m.cursor]]
 				m.cursor++
 				ApplyTheme(ThemeByName(m.themes[m.cursor]))
+				if allThemes[m.themes[m.cursor]].Dark != prev.Dark {
+					return m, tea.ClearScreen
+				}
 			}
 
 		case "enter", " ":