try

d2layouts/d2cycle/layout.go

@@ -99,14 +99,53 @@ func createCircularArc(edge *d2graph.Edge) {
 	path[len(path)-1] = newDst
 
 	// Trim redundant path points that fall inside node boundaries.
+// 	path = trimPathPoints(path, edge.Src.Box)
+// 	path = trimPathPoints(path, edge.Dst.Box)
+
+// 	edge.Route = path
+// 	edge.IsCurve = true
+// }
 path = trimPathPoints(path, edge.Src.Box)
 path = trimPathPoints(path, edge.Dst.Box)
 
+// Adjust the last two points to align the arrow direction with the arc's tangent
+if len(path) >= 2 {
+	dstPoint := path[len(path)-1]
+	prevPoint := path[len(path)-2]
+
+	// Calculate the vector between the last two points
+	dx := dstPoint.X - prevPoint.X
+	dy := dstPoint.Y - prevPoint.Y
+
+	// Calculate the perpendicular vector (rotated 90 degrees counter-clockwise)
+	// This gives us the center direction of the circular arc
+	centerDirX := -dy
+	centerDirY := dx
+
+	// Normalize the center direction vector
+	centerLength := math.Hypot(centerDirX, centerDirY)
+	if centerLength > 0 {
+		centerDirX /= centerLength
+		centerDirY /= centerLength
+	}
+
+	// Calculate the tangent direction (perpendicular to center direction)
+	tangentX := -centerDirY
+	tangentY := centerDirX
+
+	// Adjust the penultimate point to create proper arrow alignment
+	step := 10.0
+	newPrevX := dstPoint.X - tangentX*step
+	newPrevY := dstPoint.Y - tangentY*step
+
+	// Update the path with the adjusted point
+	path[len(path)-2] = geo.NewPoint(newPrevX, newPrevY)
+}
+
 edge.Route = path
 edge.IsCurve = true
 }
 
-
 // clampPointOutsideBox walks forward along the path until it finds a point outside the box,
 // then replaces the point with a precise intersection.
 func clampPointOutsideBox(box *geo.Box, path []*geo.Point, startIdx int) (int, *geo.Point) {

e2etests/testdata/txtar/cycle-diagram/dagre/board.exp.json

@@ -864,8 +864,8 @@
           "y": -37.47600173950195
         },
         {
-          "x": 197.02099609375,
-          "y": -34.3849983215332
+          "x": 198.8939971923828,
+          "y": -23.135000228881836
         },
         {
           "x": 197.2519989013672,
@@ -1228,8 +1228,8 @@
           "y": 197.53700256347656
         },
         {
-          "x": 28.18000030517578,
-          "y": 198.00399780273438
+          "x": 16.589000701904297,
+          "y": 199.56100463867188
         },
         {
           "x": 26.5,
@@ -1592,8 +1592,8 @@
           "y": 37.47600173950195
         },
         {
-          "x": -197.02099609375,
-          "y": 34.3849983215332
+          "x": -198.8939971923828,
+          "y": 23.135000228881836
         },
         {
           "x": -197.2519989013672,
@@ -1972,8 +1972,8 @@
           "y": 111.8030014038086
         },
         {
-          "x": 701.875,
-          "y": 115.77300262451172
+          "x": 698.0460205078125,
+          "y": 126.40799713134766
         },
         {
           "x": 701.4329833984375,
@@ -2336,8 +2336,8 @@
           "y": 186.90899658203125
         },
         {
-          "x": 364.3710021972656,
-          "y": 183.8260040283203
+          "x": 357.02899169921875,
+          "y": 175.4980010986328
         },
         {
           "x": 363.6419982910156,
@@ -2740,8 +2740,8 @@
           "y": 196.45700073242188
         },
         {
-          "x": 1003.2860107421875,
-          "y": 197.53700256347656
+          "x": 988.5989990234375,
+          "y": 199.6269989013672
         },
         {
           "x": 998.5,

e2etests/testdata/txtar/cycle-diagram/elk/board.exp.json

@@ -864,8 +864,8 @@
           "y": -25.47599983215332
         },
         {
-          "x": 209.02099609375,
-          "y": -22.385000228881836
+          "x": 210.8939971923828,
+          "y": -11.135000228881836
         },
         {
           "x": 209.2519989013672,
@@ -1228,8 +1228,8 @@
           "y": 209.53700256347656
         },
         {
-          "x": 40.18000030517578,
-          "y": 210.00399780273438
+          "x": 28.589000701904297,
+          "y": 211.56100463867188
         },
         {
           "x": 38.5,
@@ -1592,8 +1592,8 @@
           "y": 49.47600173950195
         },
         {
-          "x": -185.02099609375,
-          "y": 46.3849983215332
+          "x": -186.8939971923828,
+          "y": 35.1349983215332
         },
         {
           "x": -185.2519989013672,
@@ -1972,8 +1972,8 @@
           "y": 123.8030014038086
         },
         {
-          "x": 674.375,
-          "y": 127.77300262451172
+          "x": 670.5460205078125,
+          "y": 138.4080047607422
         },
         {
           "x": 673.9329833984375,
@@ -2336,8 +2336,8 @@
           "y": 198.90899658203125
         },
         {
-          "x": 336.8710021972656,
-          "y": 195.8260040283203
+          "x": 329.52899169921875,
+          "y": 187.4980010986328
         },
         {
           "x": 336.1419982910156,
@@ -2740,8 +2740,8 @@
           "y": 208.45700073242188
         },
         {
-          "x": 936.197021484375,
-          "y": 209.53700256347656
+          "x": 921.5089721679688,
+          "y": 211.6269989013672
         },
         {
           "x": 931.4099731445312,