vo: fix flamegraph click mapping for expanded leaf rows

3 files changed, 80 insertions, 7 deletions

diff --git a/internal/tui/flamegraph/frame_animator.go b/internal/tui/flamegraph/frame_animator.go
index 26755e8..86e52ec 100644
--- a/internal/tui/flamegraph/frame_animator.go
+++ b/internal/tui/flamegraph/frame_animator.go
@@ -82,7 +82,7 @@ func (fa *FrameAnimator) reset() {
 // frameIndexAt returns the index of the frame rendered at terminal coordinates
 // (x, y), or -1 if no frame occupies that cell. showHelp adds one extra line
 // to the UI chrome so the frame area row calculations account for it.
-func frameIndexAt(frames []tuiFrame, x, y, width, height int, showHelp bool) int {
+func frameIndexAt(frames []tuiFrame, x, y, width, height int, showHelp, heightMetricActive bool) int {
 	if len(frames) == 0 || width <= 0 || height <= 0 {
 		return -1
 	}
@@ -105,7 +105,7 @@ func frameIndexAt(frames []tuiFrame, x, y, width, height int, showHelp bool) int
 	if y < 1 || y > availableRows {
 		return -1
 	}
-	targetRow := frameCoordToTargetRow(frames, y-1, availableRows)
+	targetRow := frameCoordToTargetRow(frames, y-1, availableRows, heightMetricActive)
 	if targetRow < 0 {
 		return -1
 	}
@@ -115,10 +115,15 @@ func frameIndexAt(frames []tuiFrame, x, y, width, height int, showHelp bool) int
 // frameCoordToTargetRow converts a data-area row offset (0-based, after
 // stripping the toolbar row) into the logical frame row index. Returns -1 when
 // the coordinate falls in the top padding above the first visible row.
-func frameCoordToTargetRow(frames []tuiFrame, dataRow, availableRows int) int {
+func frameCoordToTargetRow(frames []tuiFrame, dataRow, availableRows int, heightMetricActive bool) int {
 	maxRow := maxFrameRowForSet(frames, nil)
 	barHeight := computeBarHeight(availableRows, maxRow+1, maxBarVisualHeight)
+	leafBarHeight := barHeight
 	visibleDepthRows := availableRows / barHeight
+	if heightMetricActive {
+		barHeight = 1
+		visibleDepthRows = availableRows
+	}
 	if visibleDepthRows < 1 {
 		visibleDepthRows = 1
 	}
@@ -126,7 +131,17 @@ func frameCoordToTargetRow(frames []tuiFrame, dataRow, availableRows int) int {
 	if maxRow+1 > visibleDepthRows {
 		rowOffset = maxRow + 1 - visibleDepthRows
 	}
+	if heightMetricActive {
+		visibleNonLeafRows := max(0, maxRow-rowOffset)
+		leafBarHeight = availableRows - visibleNonLeafRows
+		if leafBarHeight < 1 {
+			leafBarHeight = 1
+		}
+	}
 	renderedRows := (maxRow - rowOffset + 1) * barHeight
+	if heightMetricActive {
+		renderedRows = leafBarHeight + max(0, maxRow-rowOffset)*barHeight
+	}
 	padTop := 0
 	if renderedRows < availableRows {
 		padTop = availableRows - renderedRows
@@ -134,8 +149,18 @@ func frameCoordToTargetRow(frames []tuiFrame, dataRow, availableRows int) int {
 	if dataRow < padTop {
 		return -1
 	}
-	depthFromTop := (dataRow - padTop) / barHeight
-	return maxRow - depthFromTop
+	rowInRender := dataRow - padTop
+	for row := maxRow; row >= rowOffset; row-- {
+		rowHeight := barHeight
+		if heightMetricActive && row == maxRow {
+			rowHeight = leafBarHeight
+		}
+		if rowInRender < rowHeight {
+			return row
+		}
+		rowInRender -= rowHeight
+	}
+	return -1
 }
 
 // findFrameAtRow scans frames for the narrowest one that occupies logical row
diff --git a/internal/tui/flamegraph/frame_animator_test.go b/internal/tui/flamegraph/frame_animator_test.go
new file mode 100644
index 0000000..6b4d4f7
--- /dev/null
+++ b/internal/tui/flamegraph/frame_animator_test.go
@@ -0,0 +1,48 @@
+package flamegraph
+
+import "testing"
+
+func TestFrameCoordToTargetRowKeepsUniformBarMapping(t *testing.T) {
+	frames := []tuiFrame{
+		{Name: "root", Row: 0, Col: 0, Width: 20, Path: "root"},
+		{Name: "a", Row: 1, Col: 0, Width: 20, Path: "root" + pathSeparator + "a"},
+		{Name: "b", Row: 2, Col: 0, Width: 20, Path: "root" + pathSeparator + "a" + pathSeparator + "b"},
+		{Name: "leaf", Row: 3, Col: 0, Width: 20, Path: "root" + pathSeparator + "a" + pathSeparator + "b" + pathSeparator + "leaf"},
+	}
+	availableRows := 8
+	want := []int{3, 3, 2, 2, 1, 1, 0, 0}
+	for dataRow, expected := range want {
+		if got := frameCoordToTargetRow(frames, dataRow, availableRows, false); got != expected {
+			t.Fatalf("dataRow=%d: got row=%d want=%d", dataRow, got, expected)
+		}
+	}
+}
+
+func TestFrameCoordToTargetRowHeightMetricMapsExpandedLeafBand(t *testing.T) {
+	frames := []tuiFrame{
+		{Name: "root", Row: 0, Col: 0, Width: 20, Path: "root"},
+		{Name: "leaf", Row: 1, Col: 0, Width: 20, Path: "root" + pathSeparator + "leaf", HeightTotal: 100},
+	}
+	availableRows := 6
+	want := []int{1, 1, 1, 1, 1, 0}
+	for dataRow, expected := range want {
+		if got := frameCoordToTargetRow(frames, dataRow, availableRows, true); got != expected {
+			t.Fatalf("dataRow=%d: got row=%d want=%d", dataRow, got, expected)
+		}
+	}
+}
+
+func TestFrameIndexAtHeightMetricMapsClicksInExpandedLeafBand(t *testing.T) {
+	frames := []tuiFrame{
+		{Name: "root", Row: 0, Col: 0, Width: 20, Path: "root"},
+		{Name: "leaf", Row: 1, Col: 0, Width: 20, Path: "root" + pathSeparator + "leaf", HeightTotal: 100},
+	}
+	for y := 1; y <= 5; y++ {
+		if got := frameIndexAt(frames, 10, y, 20, 9, false, true); got != 1 {
+			t.Fatalf("y=%d: expected leaf frame index 1, got %d", y, got)
+		}
+	}
+	if got := frameIndexAt(frames, 10, 6, 20, 9, false, true); got != 0 {
+		t.Fatalf("y=6: expected root frame index 0, got %d", got)
+	}
+}
diff --git a/internal/tui/flamegraph/model.go b/internal/tui/flamegraph/model.go
index fe9b73b..81fcb7b 100644
--- a/internal/tui/flamegraph/model.go
+++ b/internal/tui/flamegraph/model.go
@@ -1088,12 +1088,12 @@ func (m Model) rootSnapshotPath() string {
 // frameIndexAt delegates to the FrameAnimator package-level helper to convert
 // terminal coordinates (x, y) to a frame index, accounting for UI chrome.
 func (m Model) frameIndexAt(x, y int) int {
-	return frameIndexAt(m.frames, x, y, m.width, m.height, m.showHelp)
+	return frameIndexAt(m.frames, x, y, m.width, m.height, m.showHelp, strings.TrimSpace(m.heightField) != "")
 }
 
 // frameCoordToTargetRow delegates to the FrameAnimator package-level helper.
 func (m Model) frameCoordToTargetRow(dataRow, availableRows int) int {
-	return frameCoordToTargetRow(m.frames, dataRow, availableRows)
+	return frameCoordToTargetRow(m.frames, dataRow, availableRows, strings.TrimSpace(m.heightField) != "")
 }
 
 func (m Model) withZoomLineage(frames []tuiFrame) []tuiFrame {