tui: align overview sparkline columns

2 files changed, 73 insertions, 3 deletions

diff --git a/internal/tui/dashboard/overview.go b/internal/tui/dashboard/overview.go
index 990e36d..5b8fab8 100644
--- a/internal/tui/dashboard/overview.go
+++ b/internal/tui/dashboard/overview.go
@@ -34,9 +34,10 @@ func renderOverview(snap *statsengine.Snapshot, width, height int) string {
 	)
 
 	panelInner := panelInnerWidth(width)
-	latencySpark := renderOverviewSparkline("Latency:", snap.LatencySeriesNs(), panelInner)
-	gapSpark := renderOverviewSparkline("Gap:", snap.GapSeriesNs(), panelInner)
-	throughputSpark := renderOverviewSparkline("Throughput:", snap.ThroughputSeriesB(), panelInner)
+	labelWidth := maxLabelWidth("Latency:", "Gap:", "Throughput:")
+	latencySpark := renderOverviewSparklineAligned("Latency:", snap.LatencySeriesNs(), panelInner, labelWidth)
+	gapSpark := renderOverviewSparklineAligned("Gap:", snap.GapSeriesNs(), panelInner, labelWidth)
+	throughputSpark := renderOverviewSparklineAligned("Throughput:", snap.ThroughputSeriesB(), panelInner, labelWidth)
 	topSyscalls := "Top syscalls: " + summarizeTopSyscalls(snap)
 	topFiles := "Top files: " + summarizeTopFiles(snap)
 	topProcesses := "Top processes: " + summarizeTopProcesses(snap)
@@ -221,12 +222,46 @@ func summaryBoxInnerWidth(width int) int {
 
 func renderOverviewSparkline(label string, data []float64, panelInner int) string {
 	w := panelInner - utf8.RuneCountInString(label) - 1 - sparklineSafetyMargin
+	if w > sparklineMaxWidth {
+		w = sparklineMaxWidth
+	}
 	if w < 8 {
 		w = 8
 	}
 	return renderLabeledSparkline(label, data, w)
 }
 
+func renderOverviewSparklineAligned(label string, data []float64, panelInner int, labelWidth int) string {
+	paddedLabel := padLabelRight(label, labelWidth)
+	w := panelInner - labelWidth - 1 - sparklineSafetyMargin
+	if w > sparklineMaxWidth {
+		w = sparklineMaxWidth
+	}
+	if w < 8 {
+		w = 8
+	}
+	return renderLabeledSparkline(paddedLabel, data, w)
+}
+
+func maxLabelWidth(labels ...string) int {
+	max := 0
+	for _, label := range labels {
+		w := utf8.RuneCountInString(label)
+		if w > max {
+			max = w
+		}
+	}
+	return max
+}
+
+func padLabelRight(label string, width int) string {
+	pad := width - utf8.RuneCountInString(label)
+	if pad <= 0 {
+		return label
+	}
+	return label + strings.Repeat(" ", pad)
+}
+
 func panelInnerWidth(width int) int {
 	if width <= 0 {
 		width = 80
diff --git a/internal/tui/dashboard/overview_test.go b/internal/tui/dashboard/overview_test.go
index 706661e..9895490 100644
--- a/internal/tui/dashboard/overview_test.go
+++ b/internal/tui/dashboard/overview_test.go
@@ -129,3 +129,38 @@ func TestRenderOverviewSparklineHasSafetyMargin(t *testing.T) {
 		t.Fatalf("expected sparkline width <= %d with safety margin, got %d", max, got)
 	}
 }
+
+func TestRenderOverviewSparklineCapsWidth(t *testing.T) {
+	out := renderOverviewSparkline("Latency:", make([]float64, 120), 400)
+	lines := strings.Split(out, "\n")
+	if len(lines) != 2 {
+		t.Fatalf("expected 2-line sparkline, got %q", out)
+	}
+	if got := lipgloss.Width(lines[0]) - len("Latency: "); got > sparklineMaxWidth {
+		t.Fatalf("expected capped sparkline width <= %d, got %d", sparklineMaxWidth, got)
+	}
+}
+
+func TestRenderOverviewSparklineAlignedUsesSameSparkStartColumn(t *testing.T) {
+	const panelInner = 80
+	labelWidth := maxLabelWidth("Latency:", "Gap:", "Throughput:")
+	lat := renderOverviewSparklineAligned("Latency:", []float64{1, 2, 3}, panelInner, labelWidth)
+	gap := renderOverviewSparklineAligned("Gap:", []float64{1, 2, 3}, panelInner, labelWidth)
+	thr := renderOverviewSparklineAligned("Throughput:", []float64{1, 2, 3}, panelInner, labelWidth)
+
+	latTop := strings.Split(lat, "\n")[0]
+	gapTop := strings.Split(gap, "\n")[0]
+	thrTop := strings.Split(thr, "\n")[0]
+
+	prefix := strings.Repeat(" ", labelWidth-len("Latency:"))
+	if !strings.HasPrefix(latTop, "Latency:"+prefix+" ") {
+		t.Fatalf("unexpected latency prefix: %q", latTop)
+	}
+	prefix = strings.Repeat(" ", labelWidth-len("Gap:"))
+	if !strings.HasPrefix(gapTop, "Gap:"+prefix+" ") {
+		t.Fatalf("unexpected gap prefix: %q", gapTop)
+	}
+	if !strings.HasPrefix(thrTop, "Throughput: ") {
+		t.Fatalf("unexpected throughput prefix: %q", thrTop)
+	}
+}