flamegraph: use full viewport with capped bar height and preserve footer/status

5 files changed, 140 insertions, 14 deletions

diff --git a/internal/tui/dashboard/model.go b/internal/tui/dashboard/model.go
index b1d23bb..10d8b49 100644
--- a/internal/tui/dashboard/model.go
+++ b/internal/tui/dashboard/model.go
@@ -19,6 +19,9 @@ const defaultRefreshMs = 1000
 const streamRefreshMs = 200
 const flameRefreshMs = 200
 const streamChromeRows = 4
+const dashboardHelpHintRows = 1
+const dashboardExpandedHelpRows = 2
+const dashboardTabBarRows = 1
 
 // SnapshotSource is the dashboard data source.
 type SnapshotSource interface {
@@ -106,7 +109,8 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		m.height = msg.Height
 		streamWidth, streamHeight := streamViewport(msg.Width, msg.Height)
 		m.streamModel.SetViewport(streamWidth, streamHeight)
-		m.flamegraphModel.SetViewport(msg.Width, msg.Height)
+		flameWidth, flameHeight := flameViewport(msg.Width, msg.Height, m.showHelp)
+		m.flamegraphModel.SetViewport(flameWidth, flameHeight)
 		return m, nil
 	case refreshTickMsg:
 		if !m.focused {
@@ -171,6 +175,8 @@ func (m Model) handleKey(msg tea.KeyPressMsg) (tea.Model, tea.Cmd) {
 	keyStr := msg.String()
 	if keyStr == "H" {
 		m.showHelp = !m.showHelp
+		flameWidth, flameHeight := flameViewport(m.width, m.height, m.showHelp)
+		m.flamegraphModel.SetViewport(flameWidth, flameHeight)
 		return m, nil
 	}
 	if m.activeTab == TabFlame && m.flamegraphModel.ConsumesKey(msg) {
@@ -396,7 +402,7 @@ func (m *Model) SetPidFilter(pid int) {
 // View renders the tab bar, active tab scaffold, and help bar.
 func (m Model) View() tea.View {
 	width, height := common.EffectiveViewport(m.width, m.height)
-	activeHeight := height
+	_, activeHeight := flameViewport(width, height, m.showHelp)
 	streamModel := m.streamModel
 	streamModel.SetFooterVisible(m.showHelp)
 	if m.activeTab == TabStream {
@@ -487,3 +493,16 @@ func streamViewport(width, height int) (int, int) {
 	}
 	return width, height
 }
+
+func flameViewport(width, height int, showHelp bool) (int, int) {
+	width, height = common.EffectiveViewport(width, height)
+	chromeRows := dashboardTabBarRows + dashboardHelpHintRows
+	if showHelp {
+		chromeRows = dashboardTabBarRows + dashboardExpandedHelpRows
+	}
+	height -= chromeRows
+	if height < 1 {
+		height = 1
+	}
+	return width, height
+}
diff --git a/internal/tui/flamegraph/model.go b/internal/tui/flamegraph/model.go
index 2f40a30..2b974fe 100644
--- a/internal/tui/flamegraph/model.go
+++ b/internal/tui/flamegraph/model.go
@@ -284,7 +284,16 @@ func (m Model) ConsumesKey(msg tea.KeyPressMsg) bool {
 
 // View renders the flamegraph viewport.
 func (m Model) View() tea.View {
-	content := RenderTerminalView(m.frames, m.width, m.height, m.selectedIdx, m.subtreeSet, m.matchIndices, m.filterVisible, m.globalTotal, m.isDark, m.searchActive, m.searchQuery)
+	extraLines := 1 // selection status line
+	if m.showHelp {
+		extraLines++
+	}
+	renderHeight := m.height - extraLines
+	if renderHeight < 3 {
+		renderHeight = 3
+	}
+
+	content := RenderTerminalView(m.frames, m.width, renderHeight, m.selectedIdx, m.subtreeSet, m.matchIndices, m.filterVisible, m.globalTotal, m.isDark, m.searchActive, m.searchQuery)
 	content = replaceHeaderLine(content, m.toolbarLine())
 	if m.searchActive {
 		content = replaceFooterLine(content, m.searchFooter())
diff --git a/internal/tui/flamegraph/model_test.go b/internal/tui/flamegraph/model_test.go
index 093bf34..355facc 100644
--- a/internal/tui/flamegraph/model_test.go
+++ b/internal/tui/flamegraph/model_test.go
@@ -666,6 +666,32 @@ func TestViewIncludesSelectionStatusBar(t *testing.T) {
 	}
 }
 
+func TestViewFitsViewportHeightAndKeepsSearchFooterVisible(t *testing.T) {
+	m := NewModel(nil)
+	m.width = 100
+	m.height = 12
+	m.frames = []tuiFrame{
+		{Name: "root", Depth: 0, Col: 0, Row: 0, Width: 100, Total: 100, Percent: 100, Path: "root"},
+		{Name: "child", Depth: 1, Col: 0, Row: 1, Width: 80, Total: 80, Percent: 80, Path: "root" + pathSeparator + "child"},
+	}
+	m.selectedIdx = 1
+	m.globalTotal = 100
+	m.searchActive = true
+	m.searchInput.SetValue("child")
+
+	view := m.View().Content
+	lines := strings.Split(view, "\n")
+	if got, max := len(lines), m.height; got > max {
+		t.Fatalf("expected flame view to fit viewport height <=%d, got %d lines", max, got)
+	}
+	if !strings.Contains(view, "matches") {
+		t.Fatalf("expected search footer to remain visible in viewport, got %q", view)
+	}
+	if !strings.Contains(view, "[LIVE] sel:2/2 child") {
+		t.Fatalf("expected selection status line to remain visible, got %q", view)
+	}
+}
+
 func TestViewFilterSelectionStatusUsesFilteredTotalAndKeepsContextVisible(t *testing.T) {
 	snapshot := &snapshotNode{
 		Name:  "root",
diff --git a/internal/tui/flamegraph/renderer.go b/internal/tui/flamegraph/renderer.go
index f2ab08e..3ae9a11 100644
--- a/internal/tui/flamegraph/renderer.go
+++ b/internal/tui/flamegraph/renderer.go
@@ -17,6 +17,7 @@ import (
 const pathSeparator = "\x1f"
 const pathSeparatorByte = '\x1f'
 const minFlameWidth = 60
+const maxBarVisualHeight = 3
 
 // BuildTerminalLayout converts a live trie snapshot into terminal frame cells.
 func BuildTerminalLayout(snapshot *snapshotNode, width, height int) []tuiFrame {
@@ -223,10 +224,16 @@ func RenderTerminalView(frames []tuiFrame, width, height, selectedIdx int, subtr
 
 	availableRows := height - 2 // toolbar + status
 	maxRow := maxFrameRowForSet(frames, nil)
+	totalDepthRows := maxRow + 1
+	barHeight := computeBarHeight(availableRows, totalDepthRows, maxBarVisualHeight)
+	visibleDepthRows := availableRows / barHeight
+	if visibleDepthRows < 1 {
+		visibleDepthRows = 1
+	}
 	rowOffset := 0
 	truncated := false
-	if maxRow+1 > availableRows {
-		rowOffset = maxRow + 1 - availableRows
+	if maxRow+1 > visibleDepthRows {
+		rowOffset = maxRow + 1 - visibleDepthRows
 		truncated = true
 	}
 
@@ -263,16 +270,16 @@ func RenderTerminalView(frames []tuiFrame, width, height, selectedIdx int, subtr
 		status := fmt.Sprintf("Filter %q: %.1f%% system (%d/%d matches, %.1f%% frames shown) | Selected: %s total=%d depth=%d %.2f%% filter",
 			searchQuery, filterSystemShare, pos, len(matches), frameCoverage,
 			selected.Name, selected.Total, selected.Depth, selectedFilterShare)
-		return renderViewRows(toolbar, status, rowsForRender(frames, width, rowOffset, maxRow, selected.Path, subtreeSet, matchSet, selectedIdx, isDark, searchActive, filterActive), width)
+		return renderViewRows(toolbar, status, rowsForRender(frames, width, rowOffset, maxRow, barHeight, availableRows, selected.Path, subtreeSet, matchSet, selectedIdx, isDark, searchActive, filterActive), width)
 	} else {
 		status := fmt.Sprintf("Selected: %s [%s] total=%d depth=%d col=%d width=%d share=%.2f%%",
 			selected.Name, compactFramePath(selected.Path), selected.Total, selected.Depth, selected.Col, selected.Width, selectedSystemShare)
-		return renderViewRows(toolbar, status, rowsForRender(frames, width, rowOffset, maxRow, selected.Path, subtreeSet, matchSet, selectedIdx, isDark, searchActive, filterActive), width)
+		return renderViewRows(toolbar, status, rowsForRender(frames, width, rowOffset, maxRow, barHeight, availableRows, selected.Path, subtreeSet, matchSet, selectedIdx, isDark, searchActive, filterActive), width)
 	}
 }
 
-func rowsForRender(frames []tuiFrame, width, rowOffset, maxRow int, selectedPath string, subtreeSet, matchSet map[int]bool, selectedIdx int, isDark, searchActive, filterActive bool) []string {
-	return buildRenderRows(frames, width, rowOffset, maxRow, selectedPath, subtreeSet, matchSet, selectedIdx, isDark, searchActive, filterActive)
+func rowsForRender(frames []tuiFrame, width, rowOffset, maxRow, barHeight, availableRows int, selectedPath string, subtreeSet, matchSet map[int]bool, selectedIdx int, isDark, searchActive, filterActive bool) []string {
+	return buildRenderRows(frames, width, rowOffset, maxRow, barHeight, availableRows, selectedPath, subtreeSet, matchSet, selectedIdx, isDark, searchActive, filterActive)
 }
 
 func renderViewRows(toolbar, status string, rows []string, width int) string {
@@ -294,7 +301,7 @@ type indexedFrame struct {
 	frame tuiFrame
 }
 
-func buildRenderRows(frames []tuiFrame, width, rowOffset, maxRow int, selectedPath string, subtreeSet, matchSet map[int]bool, selectedIdx int, isDark, searchActive, filterActive bool) []string {
+func buildRenderRows(frames []tuiFrame, width, rowOffset, maxRow, barHeight, availableRows int, selectedPath string, subtreeSet, matchSet map[int]bool, selectedIdx int, isDark, searchActive, filterActive bool) []string {
 	rowsByDepth := make(map[int][]indexedFrame)
 	for idx, frame := range frames {
 		if frame.Row < rowOffset || frame.Row > maxRow {
@@ -303,18 +310,40 @@ func buildRenderRows(frames []tuiFrame, width, rowOffset, maxRow int, selectedPa
 		rowsByDepth[frame.Row] = append(rowsByDepth[frame.Row], indexedFrame{idx: idx, frame: frame})
 	}
 
-	rows := make([]string, 0, maxRow-rowOffset+1)
+	if barHeight < 1 {
+		barHeight = 1
+	}
+
+	rows := make([]string, 0, (maxRow-rowOffset+1)*barHeight)
 	for row := maxRow; row >= rowOffset; row-- {
 		framesAtRow := rowsByDepth[row]
 		sort.Slice(framesAtRow, func(i, j int) bool {
 			return framesAtRow[i].frame.Col < framesAtRow[j].frame.Col
 		})
-		rows = append(rows, renderRow(framesAtRow, width, selectedPath, subtreeSet, matchSet, selectedIdx, isDark, searchActive, filterActive))
+		for repeat := 0; repeat < barHeight; repeat++ {
+			showLabels := repeat == barHeight/2
+			rows = append(rows, renderRow(framesAtRow, width, selectedPath, subtreeSet, matchSet, selectedIdx, isDark, searchActive, filterActive, showLabels))
+		}
+	}
+
+	if availableRows > 0 {
+		if len(rows) > availableRows {
+			rows = rows[:availableRows]
+		}
+		if len(rows) < availableRows {
+			blank := strings.Repeat(" ", width)
+			pad := make([]string, 0, availableRows)
+			for i := 0; i < availableRows-len(rows); i++ {
+				pad = append(pad, blank)
+			}
+			pad = append(pad, rows...)
+			rows = pad
+		}
 	}
 	return rows
 }
 
-func renderRow(frames []indexedFrame, width int, selectedPath string, subtreeSet, matchSet map[int]bool, selectedIdx int, isDark, searchActive, filterActive bool) string {
+func renderRow(frames []indexedFrame, width int, selectedPath string, subtreeSet, matchSet map[int]bool, selectedIdx int, isDark, searchActive, filterActive, showLabels bool) string {
 	if len(frames) == 0 {
 		return strings.Repeat(" ", width)
 	}
@@ -339,7 +368,10 @@ func renderRow(frames []indexedFrame, width int, selectedPath string, subtreeSet
 		if cellWidth <= 0 {
 			continue
 		}
-		label := frameLabel(frame.Name, cellWidth, item.idx == selectedIdx, matchSet != nil && matchSet[item.idx])
+		label := strings.Repeat(" ", cellWidth)
+		if showLabels {
+			label = frameLabel(frame.Name, cellWidth, item.idx == selectedIdx, matchSet != nil && matchSet[item.idx])
+		}
 		style := styleForFrame(item.idx, frame, selectedPath, subtreeSet, matchSet, selectedIdx, isDark, searchActive, filterActive)
 		cell := style.Render(label)
 		b.WriteString(cell)
@@ -569,6 +601,20 @@ func filterSampleCoverage(frames []tuiFrame, matchSet map[int]bool, totalBase ui
 	return percentOfTotal(coveredTotal, rootTotal)
 }
 
+func computeBarHeight(availableRows, depthRows, maxHeight int) int {
+	if availableRows <= 0 || depthRows <= 0 {
+		return 1
+	}
+	height := availableRows / depthRows
+	if height < 1 {
+		height = 1
+	}
+	if maxHeight > 0 && height > maxHeight {
+		height = maxHeight
+	}
+	return height
+}
+
 func filterCoverageTotals(frames []tuiFrame, matchSet map[int]bool, totalBase uint64) (coveredTotal uint64, rootTotal uint64) {
 	if len(frames) == 0 || len(matchSet) == 0 {
 		return 0, 0
diff --git a/internal/tui/flamegraph/renderer_test.go b/internal/tui/flamegraph/renderer_test.go
index b85bceb..091aeec 100644
--- a/internal/tui/flamegraph/renderer_test.go
+++ b/internal/tui/flamegraph/renderer_test.go
@@ -158,6 +158,15 @@ func TestRenderTerminalViewShowsNarrowMessage(t *testing.T) {
 	}
 }
 
+func TestComputeBarHeightCappedAtThree(t *testing.T) {
+	if got := computeBarHeight(30, 4, 3); got != 3 {
+		t.Fatalf("expected bar height cap at 3, got %d", got)
+	}
+	if got := computeBarHeight(5, 10, 3); got != 1 {
+		t.Fatalf("expected bar height minimum 1 when depth exceeds rows, got %d", got)
+	}
+}
+
 func TestRenderTerminalViewIncludesToolbarAndStatus(t *testing.T) {
 	snapshot := &snapshotNode{
 		Name:  "root",
@@ -177,6 +186,23 @@ func TestRenderTerminalViewIncludesToolbarAndStatus(t *testing.T) {
 	}
 }
 
+func TestRenderTerminalViewFillsAvailableHeightForShallowTree(t *testing.T) {
+	snapshot := &snapshotNode{
+		Name:  "root",
+		Total: 10,
+		Children: []*snapshotNode{
+			{Name: "child", Total: 10},
+		},
+	}
+	frames := BuildTerminalLayout(snapshot, 100, 20)
+
+	out := RenderTerminalView(frames, 100, 20, 1, nil, nil, nil, 0, true, false, "")
+	lines := strings.Split(out, "\n")
+	if got, want := len(lines), 20; got != want {
+		t.Fatalf("expected render to fill viewport height (%d lines), got %d", want, got)
+	}
+}
+
 func TestFrameLabelAddsSelectionAndMatchMarkers(t *testing.T) {
 	if got := frameLabel("child", 7, true, false); got != ">child<" {
 		t.Fatalf("expected selected marker label, got %q", got)