A drop asks the area the pointer already uses, so a port at the very edge is still the node

`nodeUnder()` recomputed the node's face as `0 <= x <= w`, while the pointer events follow the
`hitArea`, which reaches `PORT_HIT_RADIUS` past the edge. An input port sits at exactly x = 0, so the
global point rounded back landed a hair outside: the drop counted as one on empty canvas, the node
palette opened and swallowed every later click – four checks of step 6 at once. `NodeView` now
answers from that same `hitArea`, and the step also checks that no palette is open.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/editor/graph/GraphCanvas.ts

@@ -655,7 +655,7 @@ export class GraphCanvas extends Widget {
   private nodeUnder(globalX: number, globalY: number): string | null {
     for (const view of this.topDownViews()) {
       const p = view.toLocal({ x: globalX, y: globalY });
-      if (p.x >= 0 && p.x <= view.w && p.y >= 0 && p.y <= view.h) return view.node.id;
+      if (view.containsLocal(p.x, p.y)) return view.node.id;
     }
     return null;
   }

src/editor/graph/NodeView.ts

@@ -137,6 +137,15 @@ export class NodeView extends Widget {
     this.hitArea = new Rectangle(-PORT_HIT_RADIUS, 0, w + PORT_HIT_RADIUS * 2, h);
   }
 
+  /**
+   * Whether a local point is on this node, by the same area its pointer events use. An input port
+   * sits at exactly x = 0, and rounding a global point back can land a hair outside it – which made
+   * a drop on such a port count as a drop on empty canvas and opened the palette.
+   */
+  containsLocal(x: number, y: number): boolean {
+    return this.hitArea?.contains(x, y) ?? false;
+  }
+
   /** `project` resolves asset references (Spawn, Is asset). */
   sync(
     node: GraphNode,