From 4b865762a1cb6a6a12515acd3af6435e54cf1924 Mon Sep 17 00:00:00 2001
From: Jan-Henrik Bruhn <jan-henrik.bruhn@offis.de>
Date: Sat, 24 Jan 2026 16:17:23 +0100
Subject: [PATCH] Address PR review comments

Edge calculation improvements:
- Add zero radius/radii guards in circle and ellipse intersection functions
- Add clamping for pill straight edge intersections to prevent overflow
- Ensure intersection points stay within valid pill boundaries

Handle improvements:
- Add bidirectional connection support with overlapping source/target handles
- Each edge now has both source and target handles (8 total per node)
- Allows edges to connect in any direction from any side
- Fixes handle type restrictions that prevented flexible connections

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
---
 src/components/Nodes/CustomNode.tsx | 85 +++++++++++++++++++++++++++--
 src/components/Nodes/GroupNode.tsx  | 85 +++++++++++++++++++++++++++--
 src/utils/edgeUtils.ts              | 20 ++++++-
 3 files changed, 180 insertions(+), 10 deletions(-)

diff --git a/src/components/Nodes/CustomNode.tsx b/src/components/Nodes/CustomNode.tsx
index 820302d..8b76947 100644
--- a/src/components/Nodes/CustomNode.tsx
+++ b/src/components/Nodes/CustomNode.tsx
@@ -82,10 +82,13 @@ const CustomNode = ({ data, selected }: NodeProps<Actor>) => {
       }}
     >
       {/* Invisible handles positioned around edges - center remains free for dragging */}
-      {/* Top edge handle */}
+      {/* Bidirectional handles (source + target overlapping at each edge) */}
+
+      {/* Top edge handles */}
       <Handle
         type="target"
         position={Position.Top}
+        id="top-target"
         isConnectable={true}
         style={{
           width: "100%",
@@ -99,10 +102,29 @@ const CustomNode = ({ data, selected }: NodeProps<Actor>) => {
           cursor: "crosshair",
         }}
       />
-      {/* Right edge handle */}
       <Handle
         type="source"
+        position={Position.Top}
+        id="top-source"
+        isConnectable={true}
+        style={{
+          width: "100%",
+          height: "30px",
+          top: 0,
+          left: 0,
+          opacity: 0,
+          border: "none",
+          background: "transparent",
+          transform: "none",
+          cursor: "crosshair",
+        }}
+      />
+
+      {/* Right edge handles */}
+      <Handle
+        type="target"
         position={Position.Right}
+        id="right-target"
         isConnectable={true}
         style={{
           width: "30px",
@@ -116,10 +138,29 @@ const CustomNode = ({ data, selected }: NodeProps<Actor>) => {
           cursor: "crosshair",
         }}
       />
-      {/* Bottom edge handle */}
       <Handle
         type="source"
+        position={Position.Right}
+        id="right-source"
+        isConnectable={true}
+        style={{
+          width: "30px",
+          height: "100%",
+          top: 0,
+          right: 0,
+          opacity: 0,
+          border: "none",
+          background: "transparent",
+          transform: "none",
+          cursor: "crosshair",
+        }}
+      />
+
+      {/* Bottom edge handles */}
+      <Handle
+        type="target"
         position={Position.Bottom}
+        id="bottom-target"
         isConnectable={true}
         style={{
           width: "100%",
@@ -133,10 +174,46 @@ const CustomNode = ({ data, selected }: NodeProps<Actor>) => {
           cursor: "crosshair",
         }}
       />
-      {/* Left edge handle */}
+      <Handle
+        type="source"
+        position={Position.Bottom}
+        id="bottom-source"
+        isConnectable={true}
+        style={{
+          width: "100%",
+          height: "30px",
+          bottom: 0,
+          left: 0,
+          opacity: 0,
+          border: "none",
+          background: "transparent",
+          transform: "none",
+          cursor: "crosshair",
+        }}
+      />
+
+      {/* Left edge handles */}
       <Handle
         type="target"
         position={Position.Left}
+        id="left-target"
+        isConnectable={true}
+        style={{
+          width: "30px",
+          height: "100%",
+          top: 0,
+          left: 0,
+          opacity: 0,
+          border: "none",
+          background: "transparent",
+          transform: "none",
+          cursor: "crosshair",
+        }}
+      />
+      <Handle
+        type="source"
+        position={Position.Left}
+        id="left-source"
         isConnectable={true}
         style={{
           width: "30px",
diff --git a/src/components/Nodes/GroupNode.tsx b/src/components/Nodes/GroupNode.tsx
index 0650ce2..8d4b877 100644
--- a/src/components/Nodes/GroupNode.tsx
+++ b/src/components/Nodes/GroupNode.tsx
@@ -221,10 +221,13 @@ const GroupNode = ({ id, data, selected }: NodeProps<Group>) => {
       }}
     >
       {/* Invisible handles positioned around edges - center remains free for dragging */}
-      {/* Top edge handle */}
+      {/* Bidirectional handles (source + target overlapping at each edge) */}
+
+      {/* Top edge handles */}
       <Handle
         type="target"
         position={Position.Top}
+        id="top-target"
         isConnectable={true}
         style={{
           width: '100%',
@@ -238,10 +241,29 @@ const GroupNode = ({ id, data, selected }: NodeProps<Group>) => {
           cursor: 'crosshair',
         }}
       />
-      {/* Right edge handle */}
       <Handle
         type="source"
+        position={Position.Top}
+        id="top-source"
+        isConnectable={true}
+        style={{
+          width: '100%',
+          height: '30px',
+          top: 0,
+          left: 0,
+          opacity: 0,
+          border: 'none',
+          background: 'transparent',
+          transform: 'none',
+          cursor: 'crosshair',
+        }}
+      />
+
+      {/* Right edge handles */}
+      <Handle
+        type="target"
         position={Position.Right}
+        id="right-target"
         isConnectable={true}
         style={{
           width: '30px',
@@ -255,10 +277,29 @@ const GroupNode = ({ id, data, selected }: NodeProps<Group>) => {
           cursor: 'crosshair',
         }}
       />
-      {/* Bottom edge handle */}
       <Handle
         type="source"
+        position={Position.Right}
+        id="right-source"
+        isConnectable={true}
+        style={{
+          width: '30px',
+          height: '100%',
+          top: 0,
+          right: 0,
+          opacity: 0,
+          border: 'none',
+          background: 'transparent',
+          transform: 'none',
+          cursor: 'crosshair',
+        }}
+      />
+
+      {/* Bottom edge handles */}
+      <Handle
+        type="target"
         position={Position.Bottom}
+        id="bottom-target"
         isConnectable={true}
         style={{
           width: '100%',
@@ -272,10 +313,46 @@ const GroupNode = ({ id, data, selected }: NodeProps<Group>) => {
           cursor: 'crosshair',
         }}
       />
-      {/* Left edge handle */}
+      <Handle
+        type="source"
+        position={Position.Bottom}
+        id="bottom-source"
+        isConnectable={true}
+        style={{
+          width: '100%',
+          height: '30px',
+          bottom: 0,
+          left: 0,
+          opacity: 0,
+          border: 'none',
+          background: 'transparent',
+          transform: 'none',
+          cursor: 'crosshair',
+        }}
+      />
+
+      {/* Left edge handles */}
       <Handle
         type="target"
         position={Position.Left}
+        id="left-target"
+        isConnectable={true}
+        style={{
+          width: '30px',
+          height: '100%',
+          top: 0,
+          left: 0,
+          opacity: 0,
+          border: 'none',
+          background: 'transparent',
+          transform: 'none',
+          cursor: 'crosshair',
+        }}
+      />
+      <Handle
+        type="source"
+        position={Position.Left}
+        id="left-source"
         isConnectable={true}
         style={{
           width: '30px',
diff --git a/src/utils/edgeUtils.ts b/src/utils/edgeUtils.ts
index 14a8c3a..17665f3 100644
--- a/src/utils/edgeUtils.ts
+++ b/src/utils/edgeUtils.ts
@@ -20,6 +20,11 @@ function getCircleIntersection(
   targetY: number,
   offset: number = 3
 ): { x: number; y: number; angle: number } {
+  // Guard against zero radius
+  if (radius === 0) {
+    return { x: centerX + offset, y: centerY, angle: 0 };
+  }
+
   const dx = targetX - centerX;
   const dy = targetY - centerY;
   const distance = Math.sqrt(dx * dx + dy * dy);
@@ -53,6 +58,11 @@ function getEllipseIntersection(
   targetY: number,
   offset: number = 3
 ): { x: number; y: number; angle: number } {
+  // Guard against zero radii
+  if (radiusX === 0 || radiusY === 0) {
+    return { x: centerX + offset, y: centerY, angle: 0 };
+  }
+
   const dx = targetX - centerX;
   const dy = targetY - centerY;
 
@@ -131,10 +141,13 @@ function getPillIntersection(
       // Calculate x position where line from target to center intersects the horizontal edge
       // Line equation: (y - centerY) / (x - centerX) = dy / dx
       // Solving for x when y = intersectY: x = centerX + dx * (intersectY - centerY) / dy
-      const intersectX = Math.abs(dy) > 0.001
+      let intersectX = Math.abs(dy) > 0.001
         ? centerX + dx * (intersectY - centerY) / dy
         : centerX;
 
+      // Clamp intersection to the straight horizontal segment between the caps
+      intersectX = Math.min(Math.max(intersectX, leftCapX), rightCapX);
+
       const normalAngle = side < 0 ? -Math.PI / 2 : Math.PI / 2;
 
       return {
@@ -164,10 +177,13 @@ function getPillIntersection(
       // Calculate y position where line from target to center intersects the vertical edge
       // Line equation: (y - centerY) / (x - centerX) = dy / dx
       // Solving for y when x = intersectX: y = centerY + dy * (intersectX - centerX) / dx
-      const intersectY = Math.abs(dx) > 0.001
+      let intersectY = Math.abs(dx) > 0.001
         ? centerY + dy * (intersectX - centerX) / dx
         : centerY;
 
+      // Clamp intersection to the straight vertical segment between the caps
+      intersectY = Math.min(Math.max(intersectY, topCapY), bottomCapY);
+
       const normalAngle = side < 0 ? Math.PI : 0;
 
       return {