From dc4d69c6bef2eb9d5bb02a70c3135a6fa3a1b792 Mon Sep 17 00:00:00 2001
From: master <>
Date: Thu, 2 Apr 2026 08:05:13 +0300
Subject: [PATCH] Route corridor highways to End via right-side approach

Long corridor sweeps targeting End nodes now approach from the right
face instead of dropping vertically from the top corridor. Each
successive edge gets an X-offset (nodeSizeClearance + 4) so the
vertical descent legs don't overlap.

Corridor base moved closer to graph (graphMinY - 24 instead of - 56)
for visual readability.

Both NodeSpacing=40 (1m23s) and NodeSpacing=50 (38s) pass all
44+ assertions.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 ...RouterIterative.WinnerRefinement.Hybrid.cs | 46 +++++++++++++++----
 1 file changed, 38 insertions(+), 8 deletions(-)

diff --git a/src/__Libraries/StellaOps.ElkSharp/ElkEdgeRouterIterative.WinnerRefinement.Hybrid.cs b/src/__Libraries/StellaOps.ElkSharp/ElkEdgeRouterIterative.WinnerRefinement.Hybrid.cs
index e8083bdbd..72463d688 100644
--- a/src/__Libraries/StellaOps.ElkSharp/ElkEdgeRouterIterative.WinnerRefinement.Hybrid.cs
+++ b/src/__Libraries/StellaOps.ElkSharp/ElkEdgeRouterIterative.WinnerRefinement.Hybrid.cs
@@ -298,7 +298,10 @@ internal static partial class ElkEdgeRouterIterative
         {
             var graphMinYLocal = nodes.Min(n => n.Y);
             var graphWidthLocal = nodes.Max(n => n.X + n.Width) - nodes.Min(n => n.X);
-            var baseCorridorY = graphMinYLocal - 56d;
+            var nodesById = nodes.ToDictionary(n => n.Id, StringComparer.Ordinal);
+            // Keep corridor close to graph for visual readability. 24px is
+            // enough clearance for the perpendicular exit stub.
+            var baseCorridorY = graphMinYLocal - 24d;
             var localMinSweep = graphWidthLocal * 0.4d;
             var corridorResult = current.Edges.ToArray();
             var corridorFixed = 0;
@@ -320,14 +323,41 @@ internal static partial class ElkEdgeRouterIterative
                     var src = cpath[0];
                     var tgt = cpath[^1];
                     var stubX = src.X + 24d;
-                    var newPath = new List<ElkPoint>
+
+                    // Find the target node to determine approach geometry.
+                    var tgtNode = nodesById.TryGetValue(edge.TargetNodeId ?? string.Empty, out var tn) ? tn : null;
+                    List<ElkPoint> newPath;
+                    if (tgtNode is not null && tgtNode.Kind is "End")
                     {
-                        src,
-                        new() { X = stubX, Y = src.Y },
-                        new() { X = stubX, Y = localCorridorY },
-                        new() { X = tgt.X, Y = localCorridorY },
-                        tgt,
-                    };
+                        // Enter End from the right side: corridor goes past End,
+                        // descends to End's center Y, approaches from right.
+                        // This avoids the ugly long vertical drop from corridor.
+                        // Offset both X and Y for each corridor edge so their
+                        // vertical descent legs don't overlap (parallel vertical
+                        // segments at the same X trigger target-join detection).
+                        var rightApproachX = tgtNode.X + tgtNode.Width + 24d + (corridorFixed * (nodeSizeClearance + 4d));
+                        var centerY = tgtNode.Y + (tgtNode.Height / 2d);
+                        newPath =
+                        [
+                            src,
+                            new() { X = stubX, Y = src.Y },
+                            new() { X = stubX, Y = localCorridorY },
+                            new() { X = rightApproachX, Y = localCorridorY },
+                            new() { X = rightApproachX, Y = centerY },
+                            new() { X = tgtNode.X + tgtNode.Width, Y = centerY },
+                        ];
+                    }
+                    else
+                    {
+                        newPath =
+                        [
+                            src,
+                            new() { X = stubX, Y = src.Y },
+                            new() { X = stubX, Y = localCorridorY },
+                            new() { X = tgt.X, Y = localCorridorY },
+                            tgt,
+                        ];
+                    }
                     corridorResult[ei] = new ElkRoutedEdge
                     {
                         Id = edge.Id, SourceNodeId = edge.SourceNodeId, TargetNodeId = edge.TargetNodeId,