From 3b639a814240eb6065507814eefc773e246b60fe Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Fri, 22 May 2026 17:29:38 +0000
Subject: [PATCH] =?UTF-8?q?=E2=9A=A1=20Bolt:=20Optimize=20O(N^2)=20timelin?=
 =?UTF-8?q?e.NodeStates=20lookup=20inside=20ApplySimulationOutcomes?=
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---
 .jules/bolt.md                                |  3 +++
 .../WorkspacePresentation.cs                  | 21 ++++++++++++-------
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/.jules/bolt.md b/.jules/bolt.md
index 7e209ff..10dec3e 100644
--- a/.jules/bolt.md
+++ b/.jules/bolt.md
@@ -23,3 +23,6 @@
 ## 2024-05-23 - Optimize LINQ Allocations in Network Simulation Engine
 **Learning:** Found multiple places in `NetworkSimulationEngine.cs` where LINQ `.Count()` and `.Select().Min()` inside inner loops on the simulation path were allocating delegates and enumerators on the hot path (e.g., inside `GetPathRemainingCapacity` and `CountBottleneckResources`).
 **Action:** Replaced these LINQ chains with `for` and `foreach` loops respectively to minimize garbage generation during greedy route allocation, reducing allocations during repeated graph evaluations.
+## 2026-05-22 - O(N^2) Lookup inside Simulation Updates
+**Learning:** In the Avalonia presentation layer, `ApplySimulationOutcomes` in `WorkspacePresentation` was performing an O(N^2) nested lookup by filtering `timeline.NodeStates` inside a loop that iterated over every node in the scene. For large networks, this repeated filtering could freeze the UI during heavy simulation updates.
+**Action:** Pre-compute node states into a grouped lookup dictionary outside of the loop, reducing the update bottleneck to O(N + S).
diff --git a/src/MedWNetworkSim.Presentation/WorkspacePresentation.cs b/src/MedWNetworkSim.Presentation/WorkspacePresentation.cs
index 980ca43..8439dde 100644
--- a/src/MedWNetworkSim.Presentation/WorkspacePresentation.cs
+++ b/src/MedWNetworkSim.Presentation/WorkspacePresentation.cs
@@ -8797,23 +8797,30 @@ private void ApplySimulationOutcomes(IEnumerable<RouteAllocation> allocations, T
         var nodesById = network.Nodes.ToDictionary(node => node.Id, Comparer);
         if (timeline is not null)
         {
+            // Bolt: Pre-compute node states to optimize O(N^2) timeline.NodeStates lookup
+            var nodeStatesByNodeId = timeline.NodeStates
+                .GroupBy(pair => pair.Key.NodeId, Comparer)
+                .ToDictionary(group => group.Key, group => group.ToList(), Comparer);
+
             foreach (var node in Scene.Nodes)
             {
                 if (!nodesById.TryGetValue(node.Id, out var nodeModel)) continue;
-                var state = timeline.NodeStates
-                    .Where(pair => Comparer.Equals(pair.Key.NodeId, node.Id))
-                    .Select(pair => pair.Value)
-                    .FirstOrDefault();
-                var backlogByTraffic = timeline.NodeStates
-                    .Where(pair => Comparer.Equals(pair.Key.NodeId, node.Id) && pair.Value.DemandBacklog > 0d)
+
+                var nodeTrafficStates = nodeStatesByNodeId.GetValueOrDefault(node.Id) ?? [];
+
+                var state = nodeTrafficStates.Select(pair => pair.Value).FirstOrDefault();
+
+                var backlogByTraffic = nodeTrafficStates
+                    .Where(pair => pair.Value.DemandBacklog > 0d)
                     .GroupBy(pair => pair.Key.TrafficType, pair => pair.Value.DemandBacklog, Comparer)
                     .Select(group => new KeyValuePair<string, double>(group.Key, group.Sum()))
                     .ToList();
+
                 var pressure = timeline.NodePressureById.GetValueOrDefault(node.Id);
                 node.MetricsLabel = string.Empty;
                 node.DetailLines = BuildNodeDetailLines(nodeModel, backlogByTraffic, pressure.Score > 0d ? pressure : null);
                 UpdateSceneNodeLayout(node, nodeModel, pressure.Score > 0d ? pressure : null, graphRenderer.GetZoomTier(Viewport.Zoom));
-                node.HasWarning = pressure.Score > 0d || state.DemandBacklog > 0d;
+                node.HasWarning = pressure.Score > 0d || (state.DemandBacklog > 0d);
             }
         }
         else