tui: fix responsive layout and stream viewport chrome

12 files changed, 269 insertions, 54 deletions

diff --git a/internal/tui/common/styles.go b/internal/tui/common/styles.go
index ed6a191..d4c75ff 100644
--- a/internal/tui/common/styles.go
+++ b/internal/tui/common/styles.go
@@ -16,8 +16,7 @@ var (
 var (
 	// ScreenStyle is the base style for full-screen models.
 	ScreenStyle = lipgloss.NewStyle().
-			Foreground(ColorText).
-			Background(ColorBackground)
+			Foreground(ColorText)
 
 	// HeaderStyle is used by top-level titles and screen headers.
 	HeaderStyle = lipgloss.NewStyle().
@@ -34,7 +33,6 @@ var (
 	// TabInactiveStyle is applied to non-selected tabs.
 	TabInactiveStyle = lipgloss.NewStyle().
 				Foreground(ColorMuted).
-				Background(ColorPanel).
 				Padding(0, 1)
 
 	// PanelStyle is used for boxed sections.
diff --git a/internal/tui/dashboard/histogram.go b/internal/tui/dashboard/histogram.go
index 47942fe..7613230 100644
--- a/internal/tui/dashboard/histogram.go
+++ b/internal/tui/dashboard/histogram.go
@@ -14,8 +14,11 @@ func renderLatencyTab(snap *statsengine.Snapshot, width, height int) string {
 		return common.PanelStyle.Render("Latency: waiting for stats...")
 	}
 
+	panelInner := panelInnerWidth(width)
 	hist := renderHistogram(snap.LatencyHistogram, "Latency Histogram", width, height)
-	spark := common.PanelStyle.Render(renderLabeledSparkline("Latency sparkline:", snap.LatencySeriesNs(), sparklineWidth(width)))
+	spark := common.PanelStyle.Width(panelInner).Render(
+		renderOverviewSparkline("Latency sparkline:", snap.LatencySeriesNs(), panelInner),
+	)
 	return strings.Join([]string{hist, spark}, "\n")
 }
 
@@ -24,8 +27,11 @@ func renderGapsTab(snap *statsengine.Snapshot, width, height int) string {
 		return common.PanelStyle.Render("Gaps: waiting for stats...")
 	}
 
+	panelInner := panelInnerWidth(width)
 	hist := renderHistogram(snap.GapHistogram, "Gap Histogram", width, height)
-	spark := common.PanelStyle.Render(renderLabeledSparkline("Gap sparkline:", snap.GapSeriesNs(), sparklineWidth(width)))
+	spark := common.PanelStyle.Width(panelInner).Render(
+		renderOverviewSparkline("Gap sparkline:", snap.GapSeriesNs(), panelInner),
+	)
 	return strings.Join([]string{hist, spark}, "\n")
 }
 
@@ -47,6 +53,7 @@ func renderHistogram(hist statsengine.HistogramSnapshot, title string, width, he
 	if width <= 0 {
 		width = 80
 	}
+	panelInner := panelInnerWidth(width)
 
 	if height > 0 {
 		maxRows := height - 3
@@ -73,7 +80,7 @@ func renderHistogram(hist statsengine.HistogramSnapshot, title string, width, he
 		}
 	}
 
-	barWidth := width - labelWidth - countWidth - 10
+	barWidth := panelInner - labelWidth - countWidth - 6
 	if barWidth < 8 {
 		barWidth = 8
 	}
@@ -86,7 +93,7 @@ func renderHistogram(hist statsengine.HistogramSnapshot, title string, width, he
 	}
 	lines = append(lines, "Scale: █▓▒░")
 
-	return common.PanelStyle.Render(strings.Join(lines, "\n"))
+	return common.PanelStyle.Width(panelInner).Render(strings.Join(lines, "\n"))
 }
 
 func renderHistogramBar(count, maxCount uint64, width int) string {
diff --git a/internal/tui/dashboard/histogram_test.go b/internal/tui/dashboard/histogram_test.go
index 9da1c47..7790394 100644
--- a/internal/tui/dashboard/histogram_test.go
+++ b/internal/tui/dashboard/histogram_test.go
@@ -5,6 +5,8 @@ import (
 	"testing"
 
 	"ior/internal/statsengine"
+
+	"github.com/charmbracelet/lipgloss"
 )
 
 func TestRenderHistogramNoBuckets(t *testing.T) {
@@ -74,3 +76,32 @@ func TestRenderHistogramTruncatesForSmallHeight(t *testing.T) {
 		t.Fatalf("expected histogram rows to be truncated for small height: %q", out)
 	}
 }
+
+func TestRenderLatencyGapsTabDoesNotOverflowWidth(t *testing.T) {
+	snap := statsengine.NewSnapshot(
+		[]float64{10, 20, 15, 30, 18, 35},
+		[]float64{2, 4, 3, 5, 7, 6},
+		nil,
+		nil,
+		nil,
+		nil,
+		statsengine.NewHistogramSnapshot(6, []statsengine.HistogramBucketSnapshot{
+			{Label: "[0,1us)", Count: 1},
+			{Label: "[1us,10us)", Count: 2},
+			{Label: "[10us,100us)", Count: 3},
+		}),
+		statsengine.NewHistogramSnapshot(6, []statsengine.HistogramBucketSnapshot{
+			{Label: "[0,1us)", Count: 1},
+			{Label: "[1us,10us)", Count: 2},
+			{Label: "[10us,100us)", Count: 3},
+		}),
+	)
+
+	const width = 100
+	out := renderLatencyGapsTab(&snap, width, 24)
+	for _, line := range strings.Split(out, "\n") {
+		if lipgloss.Width(line) > width {
+			t.Fatalf("latency/gaps line exceeds width %d: got %d in %q", width, lipgloss.Width(line), line)
+		}
+	}
+}
diff --git a/internal/tui/dashboard/layout.go b/internal/tui/dashboard/layout.go
new file mode 100644
index 0000000..38cce18
--- /dev/null
+++ b/internal/tui/dashboard/layout.go
@@ -0,0 +1,3 @@
+package dashboard
+
+const panelHorizontalChrome = 4
diff --git a/internal/tui/dashboard/model.go b/internal/tui/dashboard/model.go
index 9b425b1..2ed53a1 100644
--- a/internal/tui/dashboard/model.go
+++ b/internal/tui/dashboard/model.go
@@ -14,6 +14,7 @@ import (
 
 const defaultRefreshMs = 1000
 const streamRefreshMs = 200
+const streamChromeRows = 4
 
 // SnapshotSource is the dashboard data source.
 type SnapshotSource interface {
@@ -73,7 +74,8 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	case tea.WindowSizeMsg:
 		m.width = msg.Width
 		m.height = msg.Height
-		m.streamModel.SetViewport(msg.Width, msg.Height)
+		streamWidth, streamHeight := streamViewport(msg.Width, msg.Height)
+		m.streamModel.SetViewport(streamWidth, streamHeight)
 		return m, nil
 	case refreshTickMsg:
 		snap := m.snapshot()
@@ -188,7 +190,7 @@ func (m *Model) handleScrollKey(msg tea.KeyMsg) bool {
 	case TabProcesses:
 		return scrollOffset(keyStr, &m.processesOffset, m.maxProcessesRows())
 	case TabStream:
-		streamWidth, streamHeight := common.EffectiveViewport(m.width, m.height)
+		streamWidth, streamHeight := streamViewport(m.width, m.height)
 		m.streamModel.SetViewport(streamWidth, streamHeight)
 		return m.streamModel.HandleTeaKey(msg)
 	default:
@@ -267,6 +269,10 @@ func (m *Model) SetStreamSource(source *eventstream.RingBuffer) {
 // View renders the tab bar, active tab scaffold, and help bar.
 func (m Model) View() string {
 	width, height := common.EffectiveViewport(m.width, m.height)
+	activeHeight := height
+	if m.activeTab == TabStream {
+		_, activeHeight = streamViewport(width, height)
+	}
 
 	var b strings.Builder
 	b.WriteString(renderTabBar(m.activeTab, width))
@@ -276,7 +282,7 @@ func (m Model) View() string {
 		m.latest,
 		&m.streamModel,
 		width,
-		height,
+		activeHeight,
 		m.syscallsOffset,
 		m.filesOffset,
 		m.filesDirGrouped,
@@ -286,7 +292,7 @@ func (m Model) View() string {
 	b.WriteString("\n")
 	b.WriteString(common.HighlightStyle.Render("Press ? for help"))
 	b.WriteString("\n")
-	b.WriteString(renderHelpBar(m.keys))
+	b.WriteString(renderHelpBar(m.keys, width))
 	return common.ScreenStyle.Render(b.String())
 }
 
@@ -328,3 +334,12 @@ func renderActiveTab(tab Tab, snap *statsengine.Snapshot, streamModel *eventstre
 func streamTickCmd() tea.Cmd {
 	return tea.Tick(streamRefreshMs*time.Millisecond, func(time.Time) tea.Msg { return streamTickMsg{} })
 }
+
+func streamViewport(width, height int) (int, int) {
+	width, height = common.EffectiveViewport(width, height)
+	height -= streamChromeRows
+	if height < 1 {
+		height = 1
+	}
+	return width, height
+}
diff --git a/internal/tui/dashboard/model_test.go b/internal/tui/dashboard/model_test.go
index 1e54b27..6baa62c 100644
--- a/internal/tui/dashboard/model_test.go
+++ b/internal/tui/dashboard/model_test.go
@@ -390,3 +390,25 @@ func TestRenderActiveTabUsesDirectoryFilesViewWhenGrouped(t *testing.T) {
 		t.Fatalf("expected grouped directory files view header, got %q", out)
 	}
 }
+
+func TestStreamTabViewKeepsTabAndHelpChromeVisible(t *testing.T) {
+	rb := eventstream.NewRingBuffer()
+	for i := 0; i < 200; i++ {
+		rb.Push(eventstream.StreamEvent{Syscall: "read"})
+	}
+
+	m := NewModelWithConfig(nil, rb, 1000, common.DefaultKeyMap())
+	m.activeTab = TabStream
+	m.width = 120
+	m.height = 30
+	m.streamModel.SetSource(rb)
+	m.streamModel.Refresh()
+
+	out := m.View()
+	if !strings.Contains(out, "1:Overview") {
+		t.Fatalf("expected tab bar to remain visible in stream view")
+	}
+	if !strings.Contains(out, "Press ? for help") {
+		t.Fatalf("expected help hint to remain visible in stream view")
+	}
+}
diff --git a/internal/tui/dashboard/overview.go b/internal/tui/dashboard/overview.go
index f4ec5bc..9a77da0 100644
--- a/internal/tui/dashboard/overview.go
+++ b/internal/tui/dashboard/overview.go
@@ -6,6 +6,7 @@ import (
 	common "ior/internal/tui/common"
 	"strings"
 	"time"
+	"unicode/utf8"
 
 	"github.com/charmbracelet/lipgloss"
 )
@@ -32,16 +33,17 @@ func renderOverview(snap *statsengine.Snapshot, width, height int) string {
 		trendWithArrow(snap.ThroughputTrend),
 	)
 
-	latencySpark := renderLabeledSparkline("Latency:", snap.LatencySeriesNs(), sparklineWidth(width))
-	gapSpark := renderLabeledSparkline("Gap:", snap.GapSeriesNs(), sparklineWidth(width))
-	throughputSpark := renderLabeledSparkline("Throughput:", snap.ThroughputSeriesB(), sparklineWidth(width))
+	panelInner := panelInnerWidth(width)
+	latencySpark := renderOverviewSparkline("Latency:", snap.LatencySeriesNs(), panelInner)
+	gapSpark := renderOverviewSparkline("Gap:", snap.GapSeriesNs(), panelInner)
+	throughputSpark := renderOverviewSparkline("Throughput:", snap.ThroughputSeriesB(), panelInner)
 	topSyscalls := "Top syscalls: " + summarizeTopSyscalls(snap)
 	topFiles := "Top files: " + summarizeTopFiles(snap)
 	topProcesses := "Top processes: " + summarizeTopProcesses(snap)
 	latencyHist := "Latency buckets: " + summarizeHistogramBrief(snap.LatencyHistogram)
 	gapHist := "Gap buckets: " + summarizeHistogramBrief(snap.GapHistogram)
 
-	panel := common.PanelStyle.Width(width)
+	panel := common.PanelStyle.Width(panelInner)
 	sparkPanel := panel.Render(strings.Join([]string{latencySpark, "", gapSpark, "", throughputSpark}, "\n"))
 	topPanel := panel.Render(strings.Join([]string{topSyscalls, topFiles, topProcesses}, "\n"))
 	histPanel := panel.Render(strings.Join([]string{latencyHist, gapHist}, "\n"))
@@ -70,7 +72,7 @@ func renderSyscallBox(snap *statsengine.Snapshot, width int) string {
 		snap.SyscallRatePerSec,
 		generatedAt,
 	)
-	return common.PanelStyle.Width(width).Height(5).Render(content)
+	return common.PanelStyle.Width(summaryBoxInnerWidth(width)).Height(5).Render(content)
 }
 
 func renderBytesBox(snap *statsengine.Snapshot, width int) string {
@@ -80,7 +82,7 @@ func renderBytesBox(snap *statsengine.Snapshot, width int) string {
 		formatBytes(snap.WriteBytesPerSec),
 		formatBytes(float64(snap.TotalBytes)),
 	)
-	return common.PanelStyle.Width(width).Height(5).Render(content)
+	return common.PanelStyle.Width(summaryBoxInnerWidth(width)).Height(5).Render(content)
 }
 
 func renderErrorBox(snap *statsengine.Snapshot, width int) string {
@@ -96,7 +98,7 @@ func renderErrorBox(snap *statsengine.Snapshot, width int) string {
 		snap.LatencyMeanNs,
 		snap.GapMeanNs,
 	)
-	return common.PanelStyle.Width(width).Height(5).Render(content)
+	return common.PanelStyle.Width(summaryBoxInnerWidth(width)).Height(5).Render(content)
 }
 
 func trendWithArrow(trend statsengine.Trend) string {
@@ -202,20 +204,36 @@ func summaryBoxWidth(width int) int {
 	if width <= 0 {
 		return 24
 	}
-	w := (width - 4) / 3
+	w := width / 3
 	if w < 18 {
 		return 18
 	}
 	return w
 }
 
-func sparklineWidth(width int) int {
-	if width <= 0 {
-		return 20
+func summaryBoxInnerWidth(width int) int {
+	inner := width - panelHorizontalChrome
+	if inner < 14 {
+		return 14
 	}
-	w := width - 14
+	return inner
+}
+
+func renderOverviewSparkline(label string, data []float64, panelInner int) string {
+	w := panelInner - utf8.RuneCountInString(label) - 1
 	if w < 8 {
-		return 8
+		w = 8
 	}
-	return w
+	return renderLabeledSparkline(label, data, w)
+}
+
+func panelInnerWidth(width int) int {
+	if width <= 0 {
+		width = 80
+	}
+	inner := width - panelHorizontalChrome
+	if inner < 20 {
+		return 20
+	}
+	return inner
 }
diff --git a/internal/tui/dashboard/overview_test.go b/internal/tui/dashboard/overview_test.go
index cee6cf2..89f00fb 100644
--- a/internal/tui/dashboard/overview_test.go
+++ b/internal/tui/dashboard/overview_test.go
@@ -6,6 +6,8 @@ import (
 	"time"
 
 	"ior/internal/statsengine"
+
+	"github.com/charmbracelet/lipgloss"
 )
 
 func TestRenderOverviewIncludesCoreMetrics(t *testing.T) {
@@ -94,3 +96,24 @@ func TestOverviewSummariesIncludeFilesProcessesAndHistograms(t *testing.T) {
 		}
 	}
 }
+
+func TestRenderOverviewDoesNotOverflowWidth(t *testing.T) {
+	snap := statsengine.NewSnapshot(
+		[]float64{10, 20, 15, 30, 18, 35, 40},
+		[]float64{2, 4, 3, 5, 7, 6, 8},
+		[]float64{1024, 2048, 4096, 2048, 1024},
+		[]statsengine.SyscallSnapshot{{Name: "read", Count: 20}},
+		[]statsengine.FileSnapshot{{Path: "/tmp/very/long/path/to/file.log", Accesses: 10}},
+		[]statsengine.ProcessSnapshot{{PID: 42, Comm: "proc", Syscalls: 30}},
+		statsengine.HistogramSnapshot{},
+		statsengine.HistogramSnapshot{},
+	)
+
+	const width = 120
+	out := renderOverview(&snap, width, 30)
+	for _, line := range strings.Split(out, "\n") {
+		if lipgloss.Width(line) > width {
+			t.Fatalf("overview line exceeds width %d: got %d in %q", width, lipgloss.Width(line), line)
+		}
+	}
+}
diff --git a/internal/tui/dashboard/sparkline.go b/internal/tui/dashboard/sparkline.go
index fad86e2..5cc445d 100644
--- a/internal/tui/dashboard/sparkline.go
+++ b/internal/tui/dashboard/sparkline.go
@@ -11,23 +11,15 @@ func renderSparkline(data []float64, width int) string {
 	}
 
 	samples := sampleForWidth(data, width)
-	leftPad := 0
-	if len(samples) < width {
-		leftPad = width - len(samples)
-	}
 	min, max := minMax(samples)
 	if min == max {
 		top := repeatRune(' ', width)
-		bottom := repeatRune(' ', leftPad) + repeatRune('█', len(samples))
+		bottom := repeatRune('█', width)
 		return top + "\n" + bottom
 	}
 
 	top := make([]rune, width)
 	bottom := make([]rune, width)
-	for i := 0; i < leftPad; i++ {
-		top[i] = ' '
-		bottom[i] = ' '
-	}
 	scale := 16.0
 	denom := max - min
 	for i, value := range samples {
@@ -51,7 +43,7 @@ func renderSparkline(data []float64, width int) string {
 			bottomLevel = 1
 		}
 
-		col := leftPad + i
+		col := i
 		top[col] = sparkRowChars[topLevel]
 		bottom[col] = sparkRowChars[bottomLevel]
 	}
@@ -72,12 +64,16 @@ func renderLabeledSparkline(label string, data []float64, width int) string {
 }
 
 func sampleForWidth(data []float64, width int) []float64 {
-	if width >= len(data) {
-		return append([]float64(nil), data...)
-	}
 	if width == 1 {
 		return []float64{data[len(data)-1]}
 	}
+	if len(data) == 1 {
+		out := make([]float64, width)
+		for i := range out {
+			out[i] = data[0]
+		}
+		return out
+	}
 
 	last := len(data) - 1
 	samples := make([]float64, width)
diff --git a/internal/tui/dashboard/sparkline_test.go b/internal/tui/dashboard/sparkline_test.go
index e1fb316..66d1673 100644
--- a/internal/tui/dashboard/sparkline_test.go
+++ b/internal/tui/dashboard/sparkline_test.go
@@ -16,7 +16,7 @@ func TestRenderSparklineEmptyOrInvalidWidth(t *testing.T) {
 
 func TestRenderSparklineSingleValue(t *testing.T) {
 	got := renderSparkline([]float64{10}, 8)
-	if got != "        \n       █" {
+	if got != "        \n████████" {
 		t.Fatalf("expected two-line constant sparkline, got %q", got)
 	}
 }
@@ -28,14 +28,14 @@ func TestRenderSparklineAllEqualValues(t *testing.T) {
 	}
 }
 
-func TestRenderSparklineRightAlignsShortHistory(t *testing.T) {
+func TestRenderSparklineStretchesShortHistoryToWidth(t *testing.T) {
 	got := renderSparkline([]float64{1, 2, 3}, 6)
 	lines := strings.Split(got, "\n")
 	if len(lines) != 2 {
 		t.Fatalf("expected 2 lines, got %q", got)
 	}
-	if !strings.HasPrefix(lines[1], "   ") {
-		t.Fatalf("expected left padding for short history, got %q", lines[1])
+	if strings.HasPrefix(lines[1], "   ") {
+		t.Fatalf("expected short history to fill width, got %q", lines[1])
 	}
 }
 
diff --git a/internal/tui/dashboard/tabs.go b/internal/tui/dashboard/tabs.go
index a2fe366..7f1908a 100644
--- a/internal/tui/dashboard/tabs.go
+++ b/internal/tui/dashboard/tabs.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	common "ior/internal/tui/common"
 	"strings"
+	"unicode/utf8"
 
 	"github.com/charmbracelet/lipgloss"
 )
@@ -77,28 +78,108 @@ func tabIndex(tab Tab) int {
 }
 
 func renderTabBar(active Tab, width int) string {
-	parts := make([]string, 0, len(allTabs))
-	for i, tab := range allTabs {
-		label := fmt.Sprintf("%d:%s", i+1, tab.String())
-		if tab == active {
-			parts = append(parts, common.TabActiveStyle.Render(label))
-		} else {
-			parts = append(parts, common.TabInactiveStyle.Render(label))
+	if width > 0 && width < 90 {
+		return renderTabBarPlain(active, width)
+	}
+	build := func(short bool) string {
+		parts := make([]string, 0, len(allTabs))
+		for i, tab := range allTabs {
+			label := fmt.Sprintf("%d:%s", i+1, tabLabel(tab, short))
+			if tab == active {
+				parts = append(parts, common.TabActiveStyle.Render(label))
+			} else {
+				parts = append(parts, common.TabInactiveStyle.Render(label))
+			}
 		}
+		return lipgloss.JoinHorizontal(lipgloss.Left, parts...)
 	}
 
-	bar := lipgloss.JoinHorizontal(lipgloss.Left, parts...)
+	bar := build(false)
+	if width > 0 && lipgloss.Width(bar) > width {
+		bar = build(true)
+	}
+	if width > 0 && lipgloss.Width(bar) > width {
+		label := fmt.Sprintf("%d:%s", tabIndex(active)+1, tabLabel(active, false))
+		bar = common.TabActiveStyle.Render(label)
+	}
 	if width <= 0 {
 		return bar
 	}
-	return lipgloss.NewStyle().Width(width).Render(bar)
+	styled := lipgloss.NewStyle().Width(width).Render(bar)
+	if strings.Contains(styled, "\n") {
+		return renderTabBarPlain(active, width)
+	}
+	return styled
 }
 
-func renderHelpBar(keys common.KeyMap) string {
+func renderHelpBar(keys common.KeyMap, width int) string {
 	parts := make([]string, 0, len(keys.DashboardShortHelp()))
 	for _, binding := range keys.DashboardShortHelp() {
 		help := binding.Help()
 		parts = append(parts, help.Key+" "+help.Desc)
 	}
-	return common.HelpBarStyle.Render(strings.Join(parts, " • "))
+	text := strings.Join(parts, " • ")
+	if width > 0 {
+		text = truncatePlain(text, width)
+	}
+	if width > 0 && width < 90 {
+		return text
+	}
+	return common.HelpBarStyle.Width(width).Render(text)
+}
+
+func tabLabel(tab Tab, short bool) string {
+	if !short {
+		return tab.String()
+	}
+	switch tab {
+	case TabOverview:
+		return "Ovr"
+	case TabSyscalls:
+		return "Sys"
+	case TabFiles:
+		return "Fil"
+	case TabProcesses:
+		return "Pro"
+	case TabLatency:
+		return "Lat"
+	case TabStream:
+		return "Str"
+	default:
+		return "Unk"
+	}
+}
+
+func truncatePlain(s string, width int) string {
+	if width <= 0 {
+		return ""
+	}
+	if utf8.RuneCountInString(s) <= width {
+		return s
+	}
+	if width == 1 {
+		return "…"
+	}
+	r := []rune(s)
+	return string(r[:width-1]) + "…"
+}
+
+func renderTabBarPlain(active Tab, width int) string {
+	parts := make([]string, 0, len(allTabs))
+	for i, tab := range allTabs {
+		label := fmt.Sprintf("%d:%s", i+1, tabLabel(tab, true))
+		if tab == active {
+			label = "[" + label + "]"
+		}
+		parts = append(parts, label)
+	}
+	text := strings.Join(parts, " ")
+	if width > 0 {
+		text = truncatePlain(text, width)
+		padding := width - utf8.RuneCountInString(text)
+		if padding > 0 {
+			text += strings.Repeat(" ", padding)
+		}
+	}
+	return text
 }
diff --git a/internal/tui/dashboard/tabs_test.go b/internal/tui/dashboard/tabs_test.go
index 0fc36f2..bf96864 100644
--- a/internal/tui/dashboard/tabs_test.go
+++ b/internal/tui/dashboard/tabs_test.go
@@ -3,6 +3,8 @@ package dashboard
 import (
 	"strings"
 	"testing"
+
+	common "ior/internal/tui/common"
 )
 
 func TestTabNavigationWraps(t *testing.T) {
@@ -18,10 +20,29 @@ func TestTabNavigationWraps(t *testing.T) {
 }
 
 func TestRenderTabBarContainsLabels(t *testing.T) {
-	out := renderTabBar(TabOverview, 80)
+	out := renderTabBar(TabOverview, 100)
 	for _, label := range []string{"Overview", "Syscalls", "Files", "Processes", "Latency+Gaps", "Stream"} {
 		if !strings.Contains(out, label) {
 			t.Fatalf("expected tab label %q in tab bar", label)
 		}
 	}
 }
+
+func TestRenderTabBarSmallWidthUsesSingleLine(t *testing.T) {
+	out := renderTabBar(TabOverview, 70)
+	lines := strings.Split(out, "\n")
+	if len(lines) != 1 {
+		t.Fatalf("expected single-line tab bar at width 70, got %d lines", len(lines))
+	}
+	if strings.Contains(out, "6:Strea") {
+		t.Fatalf("tab label should not be wrapped/split in small width output")
+	}
+}
+
+func TestRenderHelpBarSmallWidthUsesSingleLine(t *testing.T) {
+	out := renderHelpBar(common.DefaultKeyMap(), 70)
+	lines := strings.Split(out, "\n")
+	if len(lines) != 1 {
+		t.Fatalf("expected single-line help bar at width 70, got %d lines", len(lines))
+	}
+}