2 files changed, 99 insertions, 2 deletions

diff --git a/internal/tui/flamegraph/model.go b/internal/tui/flamegraph/model.go
index 4453452..27e356b 100644
--- a/internal/tui/flamegraph/model.go
+++ b/internal/tui/flamegraph/model.go
@@ -194,9 +194,9 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		case key.Matches(msg, m.keys.ZoomReset):
 			m.zoomReset()
 		case key.Matches(msg, m.keys.MoveShallower):
-			m.moveVertical(-1)
+			m.moveVerticalWithFallback(-1, 1)
 		case key.Matches(msg, m.keys.MoveDeeper):
-			m.moveVertical(1)
+			m.moveVerticalWithFallback(1, -1)
 		case key.Matches(msg, m.keys.PrevSibling):
 			m.moveSibling(-1)
 		case key.Matches(msg, m.keys.NextSibling):
@@ -348,6 +348,7 @@ func (m *Model) rebuildFrames(animate bool) {
 		m.frames = append(m.frames[:0], m.targetFrames...)
 	}
 	m.clampSelection()
+	m.ensureSelectionVisible()
 	m.subtreeSet = computeSubtreeSetInto(m.frames, m.selectedIdx, m.subtreeSet)
 }
 
@@ -435,6 +436,14 @@ func (m *Model) moveVertical(delta int) {
 	m.selectedIdx = best
 }
 
+func (m *Model) moveVerticalWithFallback(primaryDelta, fallbackDelta int) {
+	before := m.selectedIdx
+	m.moveVertical(primaryDelta)
+	if m.selectedIdx == before && fallbackDelta != 0 {
+		m.moveVertical(fallbackDelta)
+	}
+}
+
 func (m *Model) moveSibling(delta int) {
 	if len(m.frames) == 0 {
 		return
@@ -517,3 +526,46 @@ func (m Model) currentRootPath() string {
 	}
 	return m.frames[0].Path
 }
+
+func (m Model) visibleRowOffset() int {
+	if len(m.frames) == 0 {
+		return 0
+	}
+	availableRows := m.height - 2 // toolbar + status
+	if availableRows <= 0 {
+		return 0
+	}
+	maxRow := maxFrameRow(m.frames)
+	if maxRow+1 <= availableRows {
+		return 0
+	}
+	return maxRow + 1 - availableRows
+}
+
+func (m *Model) ensureSelectionVisible() {
+	if len(m.frames) == 0 {
+		return
+	}
+	m.clampSelection()
+	rowOffset := m.visibleRowOffset()
+	selected := m.frames[m.selectedIdx]
+	if selected.Row >= rowOffset {
+		return
+	}
+
+	bestIdx := -1
+	bestScore := int(^uint(0) >> 1)
+	for idx, frame := range m.frames {
+		if frame.Row < rowOffset {
+			continue
+		}
+		score := abs(frame.Row-rowOffset)*1000 + abs(frame.Col-selected.Col)
+		if score < bestScore {
+			bestIdx = idx
+			bestScore = score
+		}
+	}
+	if bestIdx >= 0 {
+		m.selectedIdx = bestIdx
+	}
+}
diff --git a/internal/tui/flamegraph/model_test.go b/internal/tui/flamegraph/model_test.go
index ccb5c94..0301b93 100644
--- a/internal/tui/flamegraph/model_test.go
+++ b/internal/tui/flamegraph/model_test.go
@@ -128,6 +128,20 @@ func TestKeyboardNavigationSingleNodeClamped(t *testing.T) {
 	}
 }
 
+func TestArrowDownFallsBackToVisibleDepthFromRoot(t *testing.T) {
+	m := NewModel(nil)
+	m.frames = []tuiFrame{
+		{Name: "root", Depth: 0, Col: 0, Path: "root"},
+		{Name: "child", Depth: 1, Col: 0, Path: "root" + pathSeparator + "child"},
+	}
+	m.selectedIdx = 0
+
+	m = pressFlameKey(t, m, tea.KeyPressMsg{Code: tea.KeyDown})
+	if m.selectedIdx != 1 {
+		t.Fatalf("expected down arrow to move selection to child when root has no shallower row, got %d", m.selectedIdx)
+	}
+}
+
 func TestZoomInUndoResetAndNestedZoom(t *testing.T) {
 	m := newZoomModel()
 
@@ -399,6 +413,37 @@ func TestDataRefreshAnimationConvergesOverTicks(t *testing.T) {
 	}
 }
 
+func TestRebuildKeepsSelectionOnVisibleRowsWhenTruncated(t *testing.T) {
+	m := NewModel(nil)
+	m.width = 80
+	m.height = 4 // only 2 render rows remain after toolbar+status
+	m.snapshot = &snapshotNode{
+		Name: "root",
+		Children: []*snapshotNode{
+			{
+				Name: "a",
+				Children: []*snapshotNode{
+					{
+						Name: "b",
+						Children: []*snapshotNode{
+							{Name: "c", Total: 5},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	m.rebuildFrames(false)
+	if len(m.frames) == 0 {
+		t.Fatalf("expected rebuilt frames")
+	}
+	rowOffset := m.visibleRowOffset()
+	if m.frames[m.selectedIdx].Row < rowOffset {
+		t.Fatalf("expected selected frame row %d to be visible (offset=%d)", m.frames[m.selectedIdx].Row, rowOffset)
+	}
+}
+
 func TestResizeRecalculatesLayoutAndCullsNarrowFrames(t *testing.T) {
 	m := NewModel(nil)
 	m.width = 120