dashboard: clamp icicle selection by rendered tile count

3 files changed, 68 insertions, 2 deletions

diff --git a/internal/tui/dashboard/icicle.go b/internal/tui/dashboard/icicle.go
index 3761fc8..92c4834 100644
--- a/internal/tui/dashboard/icicle.go
+++ b/internal/tui/dashboard/icicle.go
@@ -79,6 +79,37 @@ func renderFilesIcicle(snap *statsengine.Snapshot, width, height int, metric bub
 	return strings.Join(lines, "\n")
 }
 
+func filesIcicleTileCount(snap *statsengine.Snapshot, width, height int, metric bubbleMetric) int {
+	if snap == nil {
+		return 0
+	}
+	if width <= 0 {
+		width = 80
+	}
+	if height <= 0 {
+		height = 18
+	}
+
+	dirs := aggregateFilesByDir(snap.Files())
+	if len(dirs) == 0 {
+		return 0
+	}
+	root := buildIcicleTree(dirs)
+	children := sortedIcicleChildren(root, metric)
+	if len(children) == 0 {
+		return 0
+	}
+
+	chartHeight := height - 2
+	if chartHeight < 4 {
+		chartHeight = 4
+	}
+
+	tiles := make([]icicleTile, 0, 64)
+	layoutIcicle(children, 0, width, 0, chartHeight, 0, metric, &tiles)
+	return len(tiles)
+}
+
 func buildIcicleTree(dirs []DirSnapshot) *icicleNode {
 	root := &icicleNode{
 		name:     "/",
diff --git a/internal/tui/dashboard/model.go b/internal/tui/dashboard/model.go
index e496776..a7d415d 100644
--- a/internal/tui/dashboard/model.go
+++ b/internal/tui/dashboard/model.go
@@ -219,7 +219,7 @@ func (m Model) handleStatsTick(msg messages.StatsTickMsg) (tea.Model, tea.Cmd) {
 	m.syscallsOffset = clampOffset(m.syscallsOffset, m.maxSyscallsRows())
 	m.syscallsTreemapSelection = clampOffset(m.syscallsTreemapSelection, m.maxSyscallsRows())
 	m.filesOffset = clampOffset(m.filesOffset, m.maxFilesRows())
-	m.filesDirOffset = clampOffset(m.filesDirOffset, m.maxFilesDirRows())
+	m.filesDirOffset = clampOffset(m.filesDirOffset, m.maxFilesDirRowsForMode())
 	m.processesOffset = clampOffset(m.processesOffset, m.maxProcessesRows())
 	m.streamModel.Refresh()
 	if m.refreshBubbleData() {
@@ -407,7 +407,7 @@ func (m *Model) handleScrollKey(msg tea.KeyPressMsg) (bool, tea.Cmd) {
 		return scrollOffset(keyStr, &m.syscallsOffset, m.maxSyscallsRows()), nil
 	case TabFiles:
 		if m.filesDirGrouped {
-			return scrollOffset(keyStr, &m.filesDirOffset, m.maxFilesDirRows()), nil
+			return scrollOffset(keyStr, &m.filesDirOffset, m.maxFilesDirRowsForMode()), nil
 		}
 		return scrollOffset(keyStr, &m.filesOffset, m.maxFilesRows()), nil
 	case TabProcesses:
@@ -470,6 +470,14 @@ func (m Model) maxFilesDirRows() int {
 	return len(aggregateFilesByDir(m.latest.Files()))
 }
 
+func (m Model) maxFilesDirRowsForMode() int {
+	if m.filesVizMode != tabVizModeIcicle {
+		return m.maxFilesDirRows()
+	}
+	width, height := flameViewport(m.width, m.height, m.showHelp)
+	return filesIcicleTileCount(m.latest, width, height, m.filesChart.Metric())
+}
+
 func (m Model) maxProcessesRows() int {
 	if m.latest == nil {
 		return 0
diff --git a/internal/tui/dashboard/model_test.go b/internal/tui/dashboard/model_test.go
index 5a3be89..f01a701 100644
--- a/internal/tui/dashboard/model_test.go
+++ b/internal/tui/dashboard/model_test.go
@@ -492,6 +492,33 @@ func TestTreemapModeUsesJKForSelection(t *testing.T) {
 	}
 }
 
+func TestFilesIcicleModeSelectionUsesIcicleTileCount(t *testing.T) {
+	snap := statsengine.NewSnapshot(nil, nil, nil, nil, []statsengine.FileSnapshot{
+		{Path: "/a/b/c/file1", Accesses: 9},
+		{Path: "/a/d/e/file2", Accesses: 7},
+	}, nil, statsengine.HistogramSnapshot{}, statsengine.HistogramSnapshot{})
+	m := NewModelWithConfig(nil, nil, 250, common.DefaultKeyMap())
+	m.activeTab = TabFiles
+	m.latest = &snap
+	m.filesDirGrouped = true
+	m.filesVizMode = tabVizModeIcicle
+	m.width = 120
+	m.height = 28
+
+	expectedMax := m.maxFilesDirRowsForMode()
+	if expectedMax <= m.maxFilesDirRows() {
+		t.Fatalf("expected icicle tile count to exceed grouped dir count: tiles=%d dirs=%d", expectedMax, m.maxFilesDirRows())
+	}
+
+	for i := 0; i < expectedMax+4; i++ {
+		next, _ := m.Update(tea.KeyPressMsg{Code: []rune{'j'}[0], Text: string([]rune{'j'})})
+		m = next.(Model)
+	}
+	if m.filesDirOffset != expectedMax-1 {
+		t.Fatalf("expected icicle selection clamped by tile count to %d, got %d", expectedMax-1, m.filesDirOffset)
+	}
+}
+
 func TestTreemapModeRendersTreemapHeader(t *testing.T) {
 	snap := statsengine.NewSnapshot(nil, nil, nil, []statsengine.SyscallSnapshot{
 		{Name: "read", Count: 9, Bytes: 512},