Refine overview layout and right-align sparkline history

3 files changed, 44 insertions, 18 deletions

diff --git a/internal/tui/dashboard/overview.go b/internal/tui/dashboard/overview.go
index 7cbc7fe..f4ec5bc 100644
--- a/internal/tui/dashboard/overview.go
+++ b/internal/tui/dashboard/overview.go
@@ -15,6 +15,9 @@ func renderOverview(snap *statsengine.Snapshot, width, height int) string {
 	if snap == nil {
 		return common.PanelStyle.Render("Overview: waiting for stats...")
 	}
+	if width <= 0 {
+		width = 80
+	}
 
 	boxWidth := summaryBoxWidth(width)
 	box1 := renderSyscallBox(snap, boxWidth)
@@ -38,18 +41,18 @@ func renderOverview(snap *statsengine.Snapshot, width, height int) string {
 	latencyHist := "Latency buckets: " + summarizeHistogramBrief(snap.LatencyHistogram)
 	gapHist := "Gap buckets: " + summarizeHistogramBrief(snap.GapHistogram)
 
+	panel := common.PanelStyle.Width(width)
+	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"))
+
 	return strings.Join(
 		[]string{
 			row,
 			common.HighlightStyle.Render(trends),
-			common.PanelStyle.Render(latencySpark),
-			common.PanelStyle.Render(gapSpark),
-			common.PanelStyle.Render(throughputSpark),
-			common.PanelStyle.Render(topSyscalls),
-			common.PanelStyle.Render(topFiles),
-			common.PanelStyle.Render(topProcesses),
-			common.PanelStyle.Render(latencyHist),
-			common.PanelStyle.Render(gapHist),
+			sparkPanel,
+			topPanel,
+			histPanel,
 		},
 		"\n",
 	)
@@ -67,7 +70,7 @@ func renderSyscallBox(snap *statsengine.Snapshot, width int) string {
 		snap.SyscallRatePerSec,
 		generatedAt,
 	)
-	return common.PanelStyle.Width(width).Render(content)
+	return common.PanelStyle.Width(width).Height(5).Render(content)
 }
 
 func renderBytesBox(snap *statsengine.Snapshot, width int) string {
@@ -77,7 +80,7 @@ func renderBytesBox(snap *statsengine.Snapshot, width int) string {
 		formatBytes(snap.WriteBytesPerSec),
 		formatBytes(float64(snap.TotalBytes)),
 	)
-	return common.PanelStyle.Width(width).Render(content)
+	return common.PanelStyle.Width(width).Height(5).Render(content)
 }
 
 func renderErrorBox(snap *statsengine.Snapshot, width int) string {
@@ -93,7 +96,7 @@ func renderErrorBox(snap *statsengine.Snapshot, width int) string {
 		snap.LatencyMeanNs,
 		snap.GapMeanNs,
 	)
-	return common.PanelStyle.Width(width).Render(content)
+	return common.PanelStyle.Width(width).Height(5).Render(content)
 }
 
 func trendWithArrow(trend statsengine.Trend) string {
diff --git a/internal/tui/dashboard/sparkline.go b/internal/tui/dashboard/sparkline.go
index b94d84f..fad86e2 100644
--- a/internal/tui/dashboard/sparkline.go
+++ b/internal/tui/dashboard/sparkline.go
@@ -11,15 +11,23 @@ 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(' ', len(samples))
-		bottom := repeatRune('█', len(samples))
+		top := repeatRune(' ', width)
+		bottom := repeatRune(' ', leftPad) + repeatRune('█', len(samples))
 		return top + "\n" + bottom
 	}
 
-	top := make([]rune, len(samples))
-	bottom := make([]rune, len(samples))
+	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 {
@@ -39,9 +47,13 @@ func renderSparkline(data []float64, width int) string {
 		if bottomLevel > 8 {
 			bottomLevel = 8
 		}
+		if bottomLevel == 0 {
+			bottomLevel = 1
+		}
 
-		top[i] = sparkRowChars[topLevel]
-		bottom[i] = sparkRowChars[bottomLevel]
+		col := leftPad + i
+		top[col] = sparkRowChars[topLevel]
+		bottom[col] = sparkRowChars[bottomLevel]
 	}
 	return string(top) + "\n" + string(bottom)
 }
diff --git a/internal/tui/dashboard/sparkline_test.go b/internal/tui/dashboard/sparkline_test.go
index 97dac03..e1fb316 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)
 	}
 }
@@ -28,6 +28,17 @@ func TestRenderSparklineAllEqualValues(t *testing.T) {
 	}
 }
 
+func TestRenderSparklineRightAlignsShortHistory(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])
+	}
+}
+
 func TestRenderSparklineRespectsWidthTruncation(t *testing.T) {
 	got := renderSparkline([]float64{1, 2, 3, 4, 5, 6, 7, 8}, 4)
 	lines := strings.Split(got, "\n")