From 0c129a5f8d809bf97fe13110d3c42bb764d55df0 Mon Sep 17 00:00:00 2001
From: Lucio Lelii <lucio.lelii@isti.cnr.it>
Date: Fri, 25 Sep 2026 12:58:58 +0200
Subject: [PATCH] Draw a loop's way back above its nodes, clear of how tall
 they grow

Below the ports, the way back ran through any node taller than a fixed
drop - most of them, once expanded - and its limit label sat hidden
behind the node. It now runs above the tops of the nodes at both ends,
which move only when a node is dragged, and follows them when one is.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
---
 .../custom-connection/custom-connection.ts    | 17 ++++++-----
 src/app/utilities/rete-editor.ts              | 29 ++++++++++++++++++-
 2 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/src/app/shared/custom-connection/custom-connection.ts b/src/app/shared/custom-connection/custom-connection.ts
index 844c3f2..134164b 100644
--- a/src/app/shared/custom-connection/custom-connection.ts
+++ b/src/app/shared/custom-connection/custom-connection.ts
@@ -198,20 +198,21 @@ export class CustomConnectionComponent {
 
   /**
    * A connection leading back runs from a node's output to one drawn before it, so the usual curve
-   * would double back through both nodes. It goes round underneath them instead.
+   * would double back through both nodes. It goes round above them instead.
    */
   get drawnPath(): string {
     if (!this.isLoopBack || !this.start || !this.end) return this.path;
-    const drop = this.loopDrop;
     const { x: sx, y: sy } = this.start;
     const { x: ex, y: ey } = this.end;
-    const bottom = Math.max(sy, ey) + drop;
-    return `M ${sx} ${sy} C ${sx + 140} ${sy}, ${sx + 140} ${bottom}, ${sx} ${bottom}`
-      + ` L ${ex} ${bottom} C ${ex - 140} ${bottom}, ${ex - 140} ${ey}, ${ex} ${ey}`;
+    const top = this.loopTop;
+    return `M ${sx} ${sy} C ${sx + 140} ${sy}, ${sx + 140} ${top}, ${sx} ${top}`
+      + ` L ${ex} ${top} C ${ex - 140} ${top}, ${ex - 140} ${ey}, ${ex} ${ey}`;
   }
 
-  private get loopDrop(): number {
-    return 150;
+  private get loopTop(): number {
+    const ports = Math.min(this.start?.y ?? 0, this.end?.y ?? 0) - 90;
+    const nodes = this.loopData?.__loopTop;
+    return typeof nodes === 'number' ? Math.min(nodes, ports) : ports;
   }
 
   get loopLabelX(): number {
@@ -219,7 +220,7 @@ export class CustomConnectionComponent {
   }
 
   get loopLabelY(): number {
-    return Math.max(this.start?.y ?? 0, this.end?.y ?? 0) + this.loopDrop - 17;
+    return this.loopTop - 17;
   }
 
   changeLimit(event: Event) {
diff --git a/src/app/utilities/rete-editor.ts b/src/app/utilities/rete-editor.ts
index 6879d52..5d0c614 100644
--- a/src/app/utilities/rete-editor.ts
+++ b/src/app/utilities/rete-editor.ts
@@ -77,6 +77,8 @@ export type LoopAwareConnection = HFSchemes['Connection'] & {
   loop?: FlowLoopEdgeSettings;
   __loopBack?: boolean;
   __readonly?: boolean;
+  /** Canvas y above both ends' nodes, where the way back is drawn so it crosses neither. */
+  __loopTop?: number;
 };
 
 export async function createEditor(
@@ -175,6 +177,18 @@ export async function createEditor(
     return context;
   });
 
+  area.addPipe((context: any) => {
+    if (context?.type === 'nodetranslated') {
+      const nodeId = String(context.data?.id ?? '');
+      for (const connection of editor.getConnections() as LoopAwareConnection[]) {
+        if (!connection.__loopBack || (connection.source !== nodeId && connection.target !== nodeId)) continue;
+        connection.__loopTop = loopTop(area, connection);
+        void area.update('connection', connection.id);
+      }
+    }
+    return context;
+  });
+
   connection.addPreset(ConnectionPresets.classic.setup());
 
   AreaExtensions.simpleNodesOrder(area);
@@ -765,13 +779,26 @@ export async function refreshLoopMarkers(
   for (const connection of data) {
     const loopBack = backEdges.has(connection.id);
     const readonly = resolvedRuntime?.readonly === true;
-    if (connection.__loopBack === loopBack && connection.__readonly === readonly) continue;
+    const top = loopBack ? loopTop(area, connection) : undefined;
+    if (connection.__loopBack === loopBack && connection.__readonly === readonly && connection.__loopTop === top) continue;
     connection.__loopBack = loopBack;
     connection.__readonly = readonly;
+    connection.__loopTop = top;
     await area.update('connection', connection.id);
   }
 }
 
+/**
+ * Above the tops of the nodes at both ends. Their tops, not their bottoms: a node's height changes
+ * as it is expanded or edited, its position only when it is moved.
+ */
+function loopTop(area: AreaPlugin<HFSchemes, AreaExtra>, connection: LoopAwareConnection): number | undefined {
+  const tops = [connection.source, connection.target]
+    .map((id) => area.nodeViews.get(id)?.position.y)
+    .filter((y): y is number => typeof y === 'number');
+  return tops.length ? Math.min(...tops) - 48 : undefined;
+}
+
 /**
  * Sets a loop connection's iteration limit; null goes back to the default. The settings stay on the
  * connection either way, so it remains the one its author marked as leading back.