fix(layout): halve the targeted pane on repeated splits

commit: 64098cd08f645b63131d67adb8f55e74e8f65ee1
author: brice · 2mo ago · 2026-08-13 02:11 UTC
parent: 99dc266
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

3 files · +66 -3

M internal/usecase/layout/layout_test.go +56 -0


@@ -43,6 +43,62 @@ func TestSolveSplitGeometry(t *testing.T) {
43	43		}
44	44		}
45	45
	46	+	func TestRepeatedSplitHalvesFocusedPane(t *testing.T) {
	47	+	t.Parallel()
	48	+
	49	+	tests := []struct {
	50	+	name string
	51	+	dir Direction
	52	+	area domain.Rect
	53	+	first map[PaneID]domain.Rect
	54	+	second map[PaneID]domain.Rect
	55	+	}{
	56	+	{
	57	+	name: "horizontal",
	58	+	dir: Right,
	59	+	area: domain.Rect{Width: 123, Height: 5},
	60	+	first: map[PaneID]domain.Rect{
	61	+	"a": {Width: 61, Height: 5},
	62	+	"b": {X: 62, Width: 61, Height: 5},
	63	+	},
	64	+	second: map[PaneID]domain.Rect{
	65	+	"a": {Width: 61, Height: 5},
	66	+	"b": {X: 62, Width: 30, Height: 5},
	67	+	"c": {X: 93, Width: 30, Height: 5},
	68	+	},
	69	+	},
	70	+	{
	71	+	name: "vertical",
	72	+	dir: Down,
	73	+	area: domain.Rect{Width: 40, Height: 15},
	74	+	first: map[PaneID]domain.Rect{
	75	+	"a": {Width: 40, Height: 7},
	76	+	"b": {Y: 8, Width: 40, Height: 7},
	77	+	},
	78	+	second: map[PaneID]domain.Rect{
	79	+	"a": {Width: 40, Height: 7},
	80	+	"b": {Y: 8, Width: 40, Height: 3},
	81	+	"c": {Y: 12, Width: 40, Height: 3},
	82	+	},
	83	+	},
	84	+	}
	85	+
	86	+	for _, tt := range tests {
	87	+	t.Run(tt.name, func(t *testing.T) {
	88	+	tr := NewTree("a")
	89	+	require.NoError(t, tr.Split("a", tt.dir, true, "b", tt.area))
	90	+	first, ok := Solve(tr.Root, tt.area)
	91	+	require.True(t, ok)
	92	+	require.Equal(t, tt.first, contents(first))
	93	+
	94	+	require.NoError(t, tr.Split("b", tt.dir, true, "c", tt.area))
	95	+	second, ok := Solve(tr.Root, tt.area)
	96	+	require.True(t, ok)
	97	+	require.Equal(t, tt.second, contents(second))
	98	+	})
	99	+	}
	100	+	}
	101	+
46	102		func TestSolveNestedTrees(t *testing.T) {
47	103		t.Parallel()
48	104		root := &Node{Kind: Split, Dir: Horizontal, Children: []*Node{


@@ -43,6 +43,62 @@ func TestSolveSplitGeometry(t *testing.T) {
43	}	43		}
44	}	44		}
45		45
		46	+	func TestRepeatedSplitHalvesFocusedPane(t *testing.T) {
		47	+	t.Parallel()
		48	+
		49	+	tests := []struct {
		50	+	name string
		51	+	dir Direction
		52	+	area domain.Rect
		53	+	first map[PaneID]domain.Rect
		54	+	second map[PaneID]domain.Rect
		55	+	}{
		56	+	{
		57	+	name: "horizontal",
		58	+	dir: Right,
		59	+	area: domain.Rect{Width: 123, Height: 5},
		60	+	first: map[PaneID]domain.Rect{
		61	+	"a": {Width: 61, Height: 5},
		62	+	"b": {X: 62, Width: 61, Height: 5},
		63	+	},
		64	+	second: map[PaneID]domain.Rect{
		65	+	"a": {Width: 61, Height: 5},
		66	+	"b": {X: 62, Width: 30, Height: 5},
		67	+	"c": {X: 93, Width: 30, Height: 5},
		68	+	},
		69	+	},
		70	+	{
		71	+	name: "vertical",
		72	+	dir: Down,
		73	+	area: domain.Rect{Width: 40, Height: 15},
		74	+	first: map[PaneID]domain.Rect{
		75	+	"a": {Width: 40, Height: 7},
		76	+	"b": {Y: 8, Width: 40, Height: 7},
		77	+	},
		78	+	second: map[PaneID]domain.Rect{
		79	+	"a": {Width: 40, Height: 7},
		80	+	"b": {Y: 8, Width: 40, Height: 3},
		81	+	"c": {Y: 12, Width: 40, Height: 3},
		82	+	},
		83	+	},
		84	+	}
		85	+
		86	+	for _, tt := range tests {
		87	+	t.Run(tt.name, func(t *testing.T) {
		88	+	tr := NewTree("a")
		89	+	require.NoError(t, tr.Split("a", tt.dir, true, "b", tt.area))
		90	+	first, ok := Solve(tr.Root, tt.area)
		91	+	require.True(t, ok)
		92	+	require.Equal(t, tt.first, contents(first))
		93	+
		94	+	require.NoError(t, tr.Split("b", tt.dir, true, "c", tt.area))
		95	+	second, ok := Solve(tr.Root, tt.area)
		96	+	require.True(t, ok)
		97	+	require.Equal(t, tt.second, contents(second))
		98	+	})
		99	+	}
		100	+	}
		101	+
46	func TestSolveNestedTrees(t *testing.T) {	102		func TestSolveNestedTrees(t *testing.T) {
47	t.Parallel()	103		t.Parallel()
48	root := &Node{Kind: Split, Dir: Horizontal, Children: []*Node{	104		root := &Node{Kind: Split, Dir: Horizontal, Children: []*Node{

M internal/usecase/layout/ops.go +7 -0


@@ -224,6 +224,13 @@ func insertSplit(n *Node, target PaneID, axis SplitDir, after bool, newID PaneID
224	224		newLeaf := NewLeaf(newID)
225	225		if n.Kind == Split && n.Dir == axis {
226	226		normalizeChildWeightsFromArea(n, area)
	227	+	targetExtent := childAreas[i].Width
	228	+	if axis == Vertical {
	229	+	targetExtent = childAreas[i].Height
	230	+	}
	231	+	firstExtent := (targetExtent - 1) / 2
	232	+	child.Weight = float64(firstExtent)
	233	+	newLeaf.Weight = float64(targetExtent - 1 - firstExtent)
227	234		at := i
228	235		if after {
229	236		at++


@@ -224,6 +224,13 @@ func insertSplit(n *Node, target PaneID, axis SplitDir, after bool, newID PaneID
224	newLeaf := NewLeaf(newID)	224		newLeaf := NewLeaf(newID)
225	if n.Kind == Split && n.Dir == axis {	225		if n.Kind == Split && n.Dir == axis {
226	normalizeChildWeightsFromArea(n, area)	226		normalizeChildWeightsFromArea(n, area)
		227	+	targetExtent := childAreas[i].Width
		228	+	if axis == Vertical {
		229	+	targetExtent = childAreas[i].Height
		230	+	}
		231	+	firstExtent := (targetExtent - 1) / 2
		232	+	child.Weight = float64(firstExtent)
		233	+	newLeaf.Weight = float64(targetExtent - 1 - firstExtent)
227	at := i	234		at := i
228	if after {	235		if after {
229	at++	236		at++

M internal/usecase/layout/weights_test.go +3 -3


@@ -159,7 +159,7 @@ func TestWeightedSplitRecursiveMinima(t *testing.T) {
159	159		}
160	160		}
161	161
162		-	func TestWeightSameAxisSplitNormalizesSolvedExtentsBeforeInsertion(t *testing.T) {
	162	+	func TestWeightSameAxisSplitHalvesTargetSolvedExtent(t *testing.T) {
163	163		t.Parallel()
164	164
165	165		tr := &Tree{Root: split(Horizontal, weightedLeaf("a", 2), weightedLeaf("b", 1)), Focus: "a"}

@@ -167,8 +167,8 @@ func TestWeightSameAxisSplitNormalizesSolvedExtentsBeforeInsertion(t *testing.T)
167	167		require.NoError(t, tr.Split("b", Right, true, "c", area))
168	168
169	169		require.Equal(t, 54.0, tr.Root.Children[0].Weight)
170		-	require.Equal(t, 27.0, tr.Root.Children[1].Weight)
171		-	require.Zero(t, tr.Root.Children[2].Weight)
	170	+	require.Equal(t, 13.0, tr.Root.Children[1].Weight)
	171	+	require.Equal(t, 13.0, tr.Root.Children[2].Weight)
172	172		placements, ok := Solve(tr.Root, area)
173	173		require.True(t, ok)
174	174		require.Equal(t, map[PaneID]int{"a": 40, "b": 20, "c": 20}, placementWidths(placements))


@@ -159,7 +159,7 @@ func TestWeightedSplitRecursiveMinima(t *testing.T) {
159		}	159		}
160		}	160		}
161			161
162	-	func TestWeightSameAxisSplitNormalizesSolvedExtentsBeforeInsertion(t *testing.T) {	162	+	func TestWeightSameAxisSplitHalvesTargetSolvedExtent(t *testing.T) {
163		t.Parallel()	163		t.Parallel()
164			164
165		tr := &Tree{Root: split(Horizontal, weightedLeaf("a", 2), weightedLeaf("b", 1)), Focus: "a"}	165		tr := &Tree{Root: split(Horizontal, weightedLeaf("a", 2), weightedLeaf("b", 1)), Focus: "a"}

@@ -167,8 +167,8 @@ func TestWeightSameAxisSplitNormalizesSolvedExtentsBeforeInsertion(t *testing.T)
167		require.NoError(t, tr.Split("b", Right, true, "c", area))	167		require.NoError(t, tr.Split("b", Right, true, "c", area))
168			168
169		require.Equal(t, 54.0, tr.Root.Children[0].Weight)	169		require.Equal(t, 54.0, tr.Root.Children[0].Weight)
170	-	require.Equal(t, 27.0, tr.Root.Children[1].Weight)	170	+	require.Equal(t, 13.0, tr.Root.Children[1].Weight)
171	-	require.Zero(t, tr.Root.Children[2].Weight)	171	+	require.Equal(t, 13.0, tr.Root.Children[2].Weight)
172		placements, ok := Solve(tr.Root, area)	172		placements, ok := Solve(tr.Root, area)
173		require.True(t, ok)	173		require.True(t, ok)
174		require.Equal(t, map[PaneID]int{"a": 40, "b": 20, "c": 20}, placementWidths(placements))	174		require.Equal(t, map[PaneID]int{"a": 40, "b": 20, "c": 20}, placementWidths(placements))