diff --git a/understand-anything-plugin/packages/dashboard/src/App.tsx b/understand-anything-plugin/packages/dashboard/src/App.tsx
index 7f4f207..2067b14 100644
--- a/understand-anything-plugin/packages/dashboard/src/App.tsx
+++ b/understand-anything-plugin/packages/dashboard/src/App.tsx
@@ -63,7 +63,7 @@ function App() {
       // Navigation
       {
         key: "Escape",
-        description: "Close panels and modals",
+        description: "Close panels / go back to overview",
         action: () => {
           // Read from store at invocation time to avoid stale closures
           const state = useDashboardStore.getState();
@@ -71,6 +71,8 @@ function App() {
             state.closeCodeViewer();
           } else if (state.selectedNodeId) {
             state.selectNode(null);
+          } else if (state.navigationLevel === "layer-detail") {
+            state.navigateToOverview();
           } else if (state.tourActive) {
             state.stopTour();
           } else {
@@ -114,15 +116,6 @@ function App() {
         category: "Tour",
       },
       // View toggles
-      {
-        key: "l",
-        description: "Toggle layer visualization",
-        action: () => {
-          const state = useDashboardStore.getState();
-          state.toggleLayers();
-        },
-        category: "View",
-      },
       {
         key: "d",
         description: "Toggle diff mode",
@@ -195,13 +188,13 @@ function App() {
   }, [setDiffOverlay]);
 
   // Determine sidebar content
-  // Learn mode shows LearnPanel + NodeInfo when a node is selected
-  // Other modes show NodeInfo when selected, ProjectOverview otherwise
+  // NodeInfo always takes priority when a node is selected.
+  // Learn mode adds LearnPanel below it; otherwise ProjectOverview shows when idle.
   const isLearnMode = tourActive || persona === "junior";
   const sidebarContent = (
     <>
-      {isLearnMode && <LearnPanel />}
       {selectedNodeId && <NodeInfo />}
+      {isLearnMode && <LearnPanel />}
       {!selectedNodeId && !isLearnMode && <ProjectOverview />}
     </>
   );
diff --git a/understand-anything-plugin/packages/dashboard/src/components/Breadcrumb.tsx b/understand-anything-plugin/packages/dashboard/src/components/Breadcrumb.tsx
index 4db7629..9bbb47b 100644
--- a/understand-anything-plugin/packages/dashboard/src/components/Breadcrumb.tsx
+++ b/understand-anything-plugin/packages/dashboard/src/components/Breadcrumb.tsx
@@ -1,4 +1,3 @@
-import { useCallback, useEffect } from "react";
 import { useDashboardStore } from "../store";
 
 export default function Breadcrumb() {
@@ -9,21 +8,6 @@ export default function Breadcrumb() {
 
   const activeLayer = graph?.layers.find((l) => l.id === activeLayerId);
 
-  // Escape key to go back to overview
-  const handleKeyDown = useCallback(
-    (e: KeyboardEvent) => {
-      if (e.key === "Escape" && navigationLevel === "layer-detail") {
-        navigateToOverview();
-      }
-    },
-    [navigationLevel, navigateToOverview],
-  );
-
-  useEffect(() => {
-    document.addEventListener("keydown", handleKeyDown);
-    return () => document.removeEventListener("keydown", handleKeyDown);
-  }, [handleKeyDown]);
-
   return (
     <div className="absolute top-4 left-4 z-10 flex items-center gap-2">
       {navigationLevel === "overview" && (
diff --git a/understand-anything-plugin/packages/dashboard/src/components/GraphView.tsx b/understand-anything-plugin/packages/dashboard/src/components/GraphView.tsx
index 4f7350a..b093f05 100644
--- a/understand-anything-plugin/packages/dashboard/src/components/GraphView.tsx
+++ b/understand-anything-plugin/packages/dashboard/src/components/GraphView.tsx
@@ -21,6 +21,7 @@ import PortalNode from "./PortalNode";
 import type { PortalFlowNode } from "./PortalNode";
 import Breadcrumb from "./Breadcrumb";
 import { useDashboardStore } from "../store";
+import type { KnowledgeGraph } from "@understand-anything/core/types";
 import { useTheme } from "../themes/index.ts";
 import {
   applyDagreLayout,
@@ -105,7 +106,6 @@ function useOverviewGraph() {
   const graph = useDashboardStore((s) => s.graph);
   const searchResults = useDashboardStore((s) => s.searchResults);
   const drillIntoLayer = useDashboardStore((s) => s.drillIntoLayer);
-  const tourHighlightedNodeIds = useDashboardStore((s) => s.tourHighlightedNodeIds);
 
   return useMemo(() => {
     if (!graph) return { nodes: [] as Node[], edges: [] as Edge[] };
@@ -181,18 +181,20 @@ function useOverviewGraph() {
     }
     const laid = applyDagreLayout(clusterNodes as unknown as Node[], flowEdges, "TB", dims);
     return { nodes: laid.nodes, edges: laid.edges };
-  }, [graph, searchResults, drillIntoLayer, tourHighlightedNodeIds]);
+  }, [graph, searchResults, drillIntoLayer]);
 }
 
-// ── Layer detail level: files + portal nodes ───────────────────────────
+// ── Layer detail level: topology (dagre) + visual overlay ───────────────
 
-function useLayerDetailGraph() {
+/**
+ * Topology memo: computes node positions via dagre. Only recomputes when
+ * the graph structure, active layer, persona, diff, or focus changes.
+ * Does NOT depend on selectedNodeId, searchResults, or tourHighlightedNodeIds.
+ */
+function useLayerDetailTopology() {
   const graph = useDashboardStore((s) => s.graph);
   const activeLayerId = useDashboardStore((s) => s.activeLayerId);
-  const selectedNodeId = useDashboardStore((s) => s.selectedNodeId);
-  const searchResults = useDashboardStore((s) => s.searchResults);
   const selectNode = useDashboardStore((s) => s.selectNode);
-  const tourHighlightedNodeIds = useDashboardStore((s) => s.tourHighlightedNodeIds);
   const persona = useDashboardStore((s) => s.persona);
   const diffMode = useDashboardStore((s) => s.diffMode);
   const changedNodeIds = useDashboardStore((s) => s.changedNodeIds);
@@ -209,22 +211,19 @@ function useLayerDetailGraph() {
 
   return useMemo(() => {
     if (!graph || !activeLayerId)
-      return { nodes: [] as Node[], edges: [] as Edge[] };
+      return { nodes: [] as CustomFlowNode[], edges: [] as Edge[], portalNodes: [] as PortalFlowNode[], portalEdges: [] as Edge[], filteredEdges: [] as KnowledgeGraph["edges"] };
 
     const activeLayer = graph.layers.find((l) => l.id === activeLayerId);
-    if (!activeLayer) return { nodes: [] as Node[], edges: [] as Edge[] };
+    if (!activeLayer) return { nodes: [] as CustomFlowNode[], edges: [] as Edge[], portalNodes: [] as PortalFlowNode[], portalEdges: [] as Edge[], filteredEdges: [] as KnowledgeGraph["edges"] };
 
     const layerNodeIds = new Set(activeLayer.nodeIds);
 
-    let filteredGraphNodes = graph.nodes.filter(
-      (n) => layerNodeIds.has(n.id) && n.type === "file",
-    );
-
-    if (persona === "non-technical") {
-      filteredGraphNodes = filteredGraphNodes.filter(
-        (n) => n.type === "concept" || n.type === "module" || n.type === "file",
-      );
-    }
+    // Non-technical persona only sees concept/module/file nodes
+    let filteredGraphNodes = persona === "non-technical"
+      ? graph.nodes.filter(
+          (n) => layerNodeIds.has(n.id) && (n.type === "concept" || n.type === "module" || n.type === "file"),
+        )
+      : graph.nodes.filter((n) => layerNodeIds.has(n.id) && n.type === "file");
 
     let filteredNodeIds = new Set(filteredGraphNodes.map((n) => n.id));
 
@@ -248,71 +247,44 @@ function useLayerDetailGraph() {
       );
     }
 
-    // Neighbor set for selection highlighting
-    const neighborNodeIds = new Set<string>();
-    if (selectedNodeId) {
-      for (const edge of filteredGraphEdges) {
-        if (edge.source === selectedNodeId) neighborNodeIds.add(edge.target);
-        if (edge.target === selectedNodeId) neighborNodeIds.add(edge.source);
-      }
-      neighborNodeIds.add(selectedNodeId);
-    }
-
-    const flowNodes: CustomFlowNode[] = filteredGraphNodes.map((node) => {
-      const matchResult = searchResults.find((r) => r.nodeId === node.id);
-      const hasSelection = !!selectedNodeId;
-      return {
-        id: node.id,
-        type: "custom" as const,
-        position: { x: 0, y: 0 },
-        data: {
-          label: node.name ?? node.filePath?.split("/").pop() ?? node.id,
-          nodeType: node.type,
-          summary: node.summary,
-          complexity: node.complexity,
-          isHighlighted: !!matchResult,
-          searchScore: matchResult?.score,
-          isSelected: selectedNodeId === node.id,
-          isTourHighlighted: tourHighlightedNodeIds.includes(node.id),
-          isDiffChanged: diffMode && changedNodeIds.has(node.id),
-          isDiffAffected: diffMode && affectedNodeIds.has(node.id),
-          isDiffFaded:
-            diffMode &&
-            !changedNodeIds.has(node.id) &&
-            !affectedNodeIds.has(node.id),
-          isNeighbor:
-            hasSelection &&
-            neighborNodeIds.has(node.id) &&
-            selectedNodeId !== node.id,
-          isSelectionFaded: hasSelection && !neighborNodeIds.has(node.id),
-          onNodeClick: handleNodeSelect,
-        },
-      };
-    });
-
     const diffNodeIds = diffMode
       ? new Set([...changedNodeIds, ...affectedNodeIds])
       : new Set<string>();
+
+    const flowNodes: CustomFlowNode[] = filteredGraphNodes.map((node) => ({
+      id: node.id,
+      type: "custom" as const,
+      position: { x: 0, y: 0 },
+      data: {
+        label: node.name ?? node.filePath?.split("/").pop() ?? node.id,
+        nodeType: node.type,
+        summary: node.summary,
+        complexity: node.complexity,
+        isHighlighted: false,
+        searchScore: undefined,
+        isSelected: false,
+        isTourHighlighted: false,
+        isDiffChanged: diffMode && changedNodeIds.has(node.id),
+        isDiffAffected: diffMode && affectedNodeIds.has(node.id),
+        isDiffFaded: diffMode && !changedNodeIds.has(node.id) && !affectedNodeIds.has(node.id),
+        isNeighbor: false,
+        isSelectionFaded: false,
+        onNodeClick: handleNodeSelect,
+      },
+    }));
+
     const flowEdges: Edge[] = filteredGraphEdges.map((edge, i) => {
       const sourceInDiff = diffMode && diffNodeIds.has(edge.source);
       const targetInDiff = diffMode && diffNodeIds.has(edge.target);
       const isImpacted = diffMode && (sourceInDiff || targetInDiff);
 
-      const isSelectedEdge =
-        !!selectedNodeId &&
-        (edge.source === selectedNodeId || edge.target === selectedNodeId);
-      const hasSelection = !!selectedNodeId;
-
       let edgeStyle: React.CSSProperties;
       let edgeLabelStyle: React.CSSProperties;
       let edgeAnimated: boolean;
 
       if (isImpacted) {
         edgeStyle = {
-          stroke:
-            sourceInDiff && targetInDiff
-              ? "rgba(224, 82, 82, 0.7)"
-              : "rgba(212, 160, 48, 0.5)",
+          stroke: sourceInDiff && targetInDiff ? "rgba(224, 82, 82, 0.7)" : "rgba(212, 160, 48, 0.5)",
           strokeWidth: 2.5,
         };
         edgeLabelStyle = { fill: "#a39787", fontSize: 10 };
@@ -321,14 +293,6 @@ function useLayerDetailGraph() {
         edgeStyle = { stroke: "rgba(212,165,116,0.08)", strokeWidth: 1 };
         edgeLabelStyle = { fill: "rgba(163,151,135,0.3)", fontSize: 10 };
         edgeAnimated = false;
-      } else if (isSelectedEdge) {
-        edgeStyle = { stroke: "rgba(212,165,116,0.8)", strokeWidth: 2.5 };
-        edgeLabelStyle = { fill: "#d4a574", fontSize: 11, fontWeight: 600 };
-        edgeAnimated = true;
-      } else if (hasSelection) {
-        edgeStyle = { stroke: "rgba(212,165,116,0.08)", strokeWidth: 1 };
-        edgeLabelStyle = { fill: "rgba(163,151,135,0.2)", fontSize: 10 };
-        edgeAnimated = false;
       } else {
         edgeStyle = { stroke: "rgba(212,165,116,0.3)", strokeWidth: 1.5 };
         edgeLabelStyle = { fill: "#a39787", fontSize: 10 };
@@ -366,11 +330,7 @@ function useLayerDetailGraph() {
     const portalEdges: Edge[] = [];
     let portalEdgeIdx = flowEdges.length;
     for (const portal of portals) {
-      const crossFiles = findCrossLayerFileNodes(
-        graph,
-        activeLayerId,
-        portal.layerId,
-      );
+      const crossFiles = findCrossLayerFileNodes(graph, activeLayerId, portal.layerId);
       for (const fileId of crossFiles) {
         if (filteredNodeIds.has(fileId)) {
           portalEdges.push({
@@ -399,21 +359,83 @@ function useLayerDetailGraph() {
     }
 
     const laid = applyDagreLayout(allFlowNodes, allFlowEdges, "TB", dims);
-    return { nodes: laid.nodes, edges: laid.edges };
-  }, [
-    graph,
-    activeLayerId,
-    selectedNodeId,
-    searchResults,
-    tourHighlightedNodeIds,
-    persona,
-    handleNodeSelect,
-    diffMode,
-    changedNodeIds,
-    affectedNodeIds,
-    focusNodeId,
-    drillIntoLayer,
-  ]);
+    return { nodes: laid.nodes, edges: laid.edges, portalNodes, portalEdges, filteredEdges: filteredGraphEdges };
+  }, [graph, activeLayerId, persona, handleNodeSelect, diffMode, changedNodeIds, affectedNodeIds, focusNodeId, drillIntoLayer]);
+}
+
+/**
+ * Visual overlay: cheap O(n) pass that applies selection, search, and tour
+ * state onto already-positioned nodes. Avoids triggering dagre relayout.
+ */
+function useLayerDetailGraph() {
+  const selectedNodeId = useDashboardStore((s) => s.selectedNodeId);
+  const searchResults = useDashboardStore((s) => s.searchResults);
+  const tourHighlightedNodeIds = useDashboardStore((s) => s.tourHighlightedNodeIds);
+
+  const topo = useLayerDetailTopology();
+
+  const nodes = useMemo(() => {
+    const searchMap = new Map(searchResults.map((r) => [r.nodeId, r.score]));
+    const tourSet = new Set(tourHighlightedNodeIds);
+
+    // Build neighbor set for selection highlighting
+    const neighborNodeIds = new Set<string>();
+    if (selectedNodeId) {
+      for (const edge of topo.filteredEdges) {
+        if (edge.source === selectedNodeId) neighborNodeIds.add(edge.target);
+        if (edge.target === selectedNodeId) neighborNodeIds.add(edge.source);
+      }
+      neighborNodeIds.add(selectedNodeId);
+    }
+
+    return topo.nodes.map((node) => {
+      // Skip portal nodes — they have no CustomNodeData
+      if (node.type === "portal") return node;
+
+      const searchScore = searchMap.get(node.id);
+      const isHighlighted = searchScore !== undefined;
+      const isSelected = selectedNodeId === node.id;
+      const isTourHighlighted = tourSet.has(node.id);
+      const hasSelection = !!selectedNodeId;
+      const isNeighbor = hasSelection && neighborNodeIds.has(node.id) && !isSelected;
+      const isSelectionFaded = hasSelection && !neighborNodeIds.has(node.id);
+
+      const data = node.data as CustomFlowNode["data"];
+
+      // Skip creating a new object if nothing visual changed
+      if (
+        data.isHighlighted === isHighlighted &&
+        data.searchScore === searchScore &&
+        data.isSelected === isSelected &&
+        data.isTourHighlighted === isTourHighlighted &&
+        data.isNeighbor === isNeighbor &&
+        data.isSelectionFaded === isSelectionFaded
+      ) {
+        return node;
+      }
+
+      return { ...node, data: { ...data, isHighlighted, searchScore, isSelected, isTourHighlighted, isNeighbor, isSelectionFaded } };
+    });
+  }, [topo.nodes, topo.filteredEdges, selectedNodeId, searchResults, tourHighlightedNodeIds]);
+
+  const edges = useMemo(() => {
+    if (!selectedNodeId) return topo.edges;
+
+    // Apply selection-based edge styling on top of topology edges
+    return topo.edges.map((edge) => {
+      const isSelectedEdge = edge.source === selectedNodeId || edge.target === selectedNodeId;
+      // Don't restyle diff-impacted or portal edges
+      if ((edge.style as Record<string, unknown>)?.strokeDasharray) return edge;
+
+      if (isSelectedEdge) {
+        return { ...edge, animated: true, style: { stroke: "rgba(212,165,116,0.8)", strokeWidth: 2.5 }, labelStyle: { fill: "#d4a574", fontSize: 11, fontWeight: 600 } };
+      }
+      // Fade unrelated edges
+      return { ...edge, animated: false, style: { stroke: "rgba(212,165,116,0.08)", strokeWidth: 1 }, labelStyle: { fill: "rgba(163,151,135,0.2)", fontSize: 10 } };
+    });
+  }, [topo.edges, selectedNodeId]);
+
+  return { nodes, edges };
 }
 
 // ── Main inner component (must be inside ReactFlowProvider) ────────────
@@ -423,6 +445,7 @@ function GraphViewInner() {
   const navigationLevel = useDashboardStore((s) => s.navigationLevel);
   const activeLayerId = useDashboardStore((s) => s.activeLayerId);
   const selectNode = useDashboardStore((s) => s.selectNode);
+  const openCodeViewer = useDashboardStore((s) => s.openCodeViewer);
   const drillIntoLayer = useDashboardStore((s) => s.drillIntoLayer);
   const focusNodeId = useDashboardStore((s) => s.focusNodeId);
   const setFocusNode = useDashboardStore((s) => s.setFocusNode);
@@ -464,9 +487,10 @@ function GraphViewInner() {
         drillIntoLayer(targetLayerId);
       } else {
         selectNode(node.id);
+        openCodeViewer(node.id);
       }
     },
-    [navigationLevel, drillIntoLayer, selectNode],
+    [navigationLevel, drillIntoLayer, selectNode, openCodeViewer],
   );
 
   const onPaneClick = useCallback(() => {
diff --git a/understand-anything-plugin/packages/dashboard/src/components/LayerClusterNode.tsx b/understand-anything-plugin/packages/dashboard/src/components/LayerClusterNode.tsx
index 20980d1..c63cad9 100644
--- a/understand-anything-plugin/packages/dashboard/src/components/LayerClusterNode.tsx
+++ b/understand-anything-plugin/packages/dashboard/src/components/LayerClusterNode.tsx
@@ -1,3 +1,4 @@
+import { memo } from "react";
 import { Handle, Position } from "@xyflow/react";
 import type { NodeProps, Node } from "@xyflow/react";
 import { getLayerColor } from "./LayerLegend";
@@ -21,7 +22,7 @@ export interface LayerClusterData extends Record<string, unknown> {
 
 export type LayerClusterFlowNode = Node<LayerClusterData, "layer-cluster">;
 
-export default function LayerClusterNode({
+function LayerClusterNode({
   data,
 }: NodeProps<LayerClusterFlowNode>) {
   const color = getLayerColor(data.layerColorIndex);
@@ -99,3 +100,5 @@ export default function LayerClusterNode({
     </div>
   );
 }
+
+export default memo(LayerClusterNode);
diff --git a/understand-anything-plugin/packages/dashboard/src/components/NodeInfo.tsx b/understand-anything-plugin/packages/dashboard/src/components/NodeInfo.tsx
index 48bdcde..b626006 100644
--- a/understand-anything-plugin/packages/dashboard/src/components/NodeInfo.tsx
+++ b/understand-anything-plugin/packages/dashboard/src/components/NodeInfo.tsx
@@ -71,6 +71,7 @@ export default function NodeInfo() {
   const [languageExpanded, setLanguageExpanded] = useState(true);
 
   const navigateToNode = useDashboardStore((s) => s.navigateToNode);
+  const navigateToHistoryIndex = useDashboardStore((s) => s.navigateToHistoryIndex);
   const setFocusNode = useDashboardStore((s) => s.setFocusNode);
   const focusNodeId = useDashboardStore((s) => s.focusNodeId);
   const node = graph?.nodes.find((n) => n.id === selectedNodeId) ?? null;
@@ -128,25 +129,8 @@ export default function NodeInfo() {
             <span key={`${h.id}-${i}`} className="flex items-center gap-1">
               <button
                 onClick={() => {
-                  // Navigate back to this point in history
                   const fullIdx = historyNodes.length - arr.length + i;
-                  // Pop history back to this point and navigate
-                  const targetId = historyNodes[fullIdx].id;
-                  // Use navigateToNode which will push current to history,
-                  // but we want to rewind. Use goBackNode repeatedly would be clunky,
-                  // so we directly set state.
-                  const newHistory = nodeHistory.slice(0, fullIdx);
-                  const layerId = graph
-                    ? graph.layers.find((l) => l.nodeIds.includes(targetId))?.id
-                    : null;
-                  useDashboardStore.setState({
-                    selectedNodeId: targetId,
-                    zoomToNodeId: targetId,
-                    nodeHistory: newHistory,
-                    ...(layerId
-                      ? { navigationLevel: "layer-detail" as const, activeLayerId: layerId }
-                      : {}),
-                  });
+                  navigateToHistoryIndex(fullIdx);
                 }}
                 className="text-[10px] text-text-muted hover:text-gold transition-colors truncate max-w-[80px]"
                 title={h.name}
diff --git a/understand-anything-plugin/packages/dashboard/src/components/PortalNode.tsx b/understand-anything-plugin/packages/dashboard/src/components/PortalNode.tsx
index 3a9a388..04f9421 100644
--- a/understand-anything-plugin/packages/dashboard/src/components/PortalNode.tsx
+++ b/understand-anything-plugin/packages/dashboard/src/components/PortalNode.tsx
@@ -1,3 +1,4 @@
+import { memo } from "react";
 import { Handle, Position } from "@xyflow/react";
 import type { NodeProps, Node } from "@xyflow/react";
 import { getLayerColor } from "./LayerLegend";
@@ -12,7 +13,7 @@ export interface PortalNodeData extends Record<string, unknown> {
 
 export type PortalFlowNode = Node<PortalNodeData, "portal">;
 
-export default function PortalNode({
+function PortalNode({
   data,
 }: NodeProps<PortalFlowNode>) {
   const color = getLayerColor(data.layerColorIndex);
@@ -59,3 +60,5 @@ export default function PortalNode({
     </div>
   );
 }
+
+export default memo(PortalNode);
diff --git a/understand-anything-plugin/packages/dashboard/src/store.ts b/understand-anything-plugin/packages/dashboard/src/store.ts
index ae6a064..fe3ed1e 100644
--- a/understand-anything-plugin/packages/dashboard/src/store.ts
+++ b/understand-anything-plugin/packages/dashboard/src/store.ts
@@ -18,6 +18,9 @@ function findNodeLayer(graph: KnowledgeGraph, nodeId: string): string | null {
   return null;
 }
 
+/** Maximum number of entries in the sidebar navigation history. */
+const MAX_HISTORY = 50;
+
 interface DashboardStore {
   graph: KnowledgeGraph | null;
   selectedNodeId: string | null;
@@ -27,8 +30,6 @@ interface DashboardStore {
   searchMode: "fuzzy" | "semantic";
   setSearchMode: (mode: "fuzzy" | "semantic") => void;
 
-  showLayers: boolean;
-
   // Lens navigation
   navigationLevel: NavigationLevel;
   activeLayerId: string | null;
@@ -46,9 +47,6 @@ interface DashboardStore {
   changedNodeIds: Set<string>;
   affectedNodeIds: Set<string>;
 
-  // Zoom-to-node: set a nodeId to trigger GraphView to pan/zoom to it
-  zoomToNodeId: string | null;
-
   // Focus mode: isolate a node's 1-hop neighborhood
   focusNodeId: string | null;
 
@@ -59,12 +57,12 @@ interface DashboardStore {
   selectNode: (nodeId: string | null) => void;
   navigateToNode: (nodeId: string) => void;
   navigateToNodeInLayer: (nodeId: string) => void;
+  navigateToHistoryIndex: (index: number) => void;
   goBackNode: () => void;
   drillIntoLayer: (layerId: string) => void;
   navigateToOverview: () => void;
   setFocusNode: (nodeId: string | null) => void;
   setSearchQuery: (query: string) => void;
-  toggleLayers: () => void;
   setPersona: (persona: Persona) => void;
   openCodeViewer: (nodeId: string) => void;
   closeCodeViewer: () => void;
@@ -109,8 +107,6 @@ export const useDashboardStore = create<DashboardStore>()((set, get) => ({
   searchEngine: null,
   searchMode: "fuzzy",
 
-  showLayers: false,
-
   navigationLevel: "overview",
   activeLayerId: null,
   codeViewerOpen: false,
@@ -126,7 +122,6 @@ export const useDashboardStore = create<DashboardStore>()((set, get) => ({
   changedNodeIds: new Set<string>(),
   affectedNodeIds: new Set<string>(),
 
-  zoomToNodeId: null,
   focusNodeId: null,
   nodeHistory: [],
 
@@ -152,7 +147,7 @@ export const useDashboardStore = create<DashboardStore>()((set, get) => ({
       // Push current node to history before navigating away
       set({
         selectedNodeId: nodeId,
-        nodeHistory: [...nodeHistory, selectedNodeId],
+        nodeHistory: [...nodeHistory, selectedNodeId].slice(-MAX_HISTORY),
       });
     } else {
       set({ selectedNodeId: nodeId });
@@ -169,14 +164,13 @@ export const useDashboardStore = create<DashboardStore>()((set, get) => ({
     const layerId = findNodeLayer(graph, nodeId);
     const newHistory =
       selectedNodeId && nodeId !== selectedNodeId
-        ? [...nodeHistory, selectedNodeId]
+        ? [...nodeHistory, selectedNodeId].slice(-MAX_HISTORY)
         : nodeHistory;
     if (layerId) {
       set({
         navigationLevel: "layer-detail",
         activeLayerId: layerId,
         selectedNodeId: nodeId,
-        zoomToNodeId: nodeId,
         focusNodeId: null,
         codeViewerOpen: false,
         codeViewerNodeId: null,
@@ -185,33 +179,40 @@ export const useDashboardStore = create<DashboardStore>()((set, get) => ({
     } else {
       set({
         selectedNodeId: nodeId,
-        zoomToNodeId: nodeId,
         nodeHistory: newHistory,
       });
     }
   },
 
+  navigateToHistoryIndex: (index) => {
+    const { nodeHistory, graph } = get();
+    if (!graph || index < 0 || index >= nodeHistory.length) return;
+    const targetId = nodeHistory[index];
+    const newHistory = nodeHistory.slice(0, index);
+    const layerId = findNodeLayer(graph, targetId);
+    set({
+      selectedNodeId: targetId,
+      nodeHistory: newHistory,
+      ...(layerId ? { navigationLevel: "layer-detail" as const, activeLayerId: layerId } : {}),
+    });
+  },
+
   goBackNode: () => {
-    const { nodeHistory } = get();
-    if (nodeHistory.length === 0) return;
+    const { nodeHistory, graph } = get();
+    if (nodeHistory.length === 0 || !graph) return;
     const prevNodeId = nodeHistory[nodeHistory.length - 1];
     const newHistory = nodeHistory.slice(0, -1);
-    // Navigate to previous node WITHOUT pushing to history
-    const { graph } = get();
-    if (!graph) return;
     const layerId = findNodeLayer(graph, prevNodeId);
     if (layerId) {
       set({
         navigationLevel: "layer-detail",
         activeLayerId: layerId,
         selectedNodeId: prevNodeId,
-        zoomToNodeId: prevNodeId,
         nodeHistory: newHistory,
       });
     } else {
       set({
         selectedNodeId: prevNodeId,
-        zoomToNodeId: prevNodeId,
         nodeHistory: newHistory,
       });
     }
@@ -253,8 +254,6 @@ export const useDashboardStore = create<DashboardStore>()((set, get) => ({
     set({ searchQuery: query, searchResults });
   },
 
-  toggleLayers: () => set((state) => ({ showLayers: !state.showLayers })),
-
   setPersona: (persona) => set({ persona }),
 
   openCodeViewer: (nodeId) => set({ codeViewerOpen: true, codeViewerNodeId: nodeId }),
diff --git a/understand-anything-plugin/packages/dashboard/src/utils/edgeAggregation.ts b/understand-anything-plugin/packages/dashboard/src/utils/edgeAggregation.ts
index 40312ff..29b72d5 100644
--- a/understand-anything-plugin/packages/dashboard/src/utils/edgeAggregation.ts
+++ b/understand-anything-plugin/packages/dashboard/src/utils/edgeAggregation.ts
@@ -72,12 +72,14 @@ export function aggregateLayerEdges(
 /**
  * Compute portal info for a given layer: which other layers are connected
  * and how many edges cross the boundary.
+ * Accepts optional pre-computed aggregation to avoid redundant work.
  */
 export function computePortals(
   graph: KnowledgeGraph,
   activeLayerId: string,
+  precomputed?: LayerEdgeAggregation[],
 ): PortalInfo[] {
-  const aggregated = aggregateLayerEdges(graph);
+  const aggregated = precomputed ?? aggregateLayerEdges(graph);
   const layerNameMap = new Map(graph.layers.map((l) => [l.id, l.name]));
 
   const portalMap = new Map<string, number>();
diff --git a/understand-anything-plugin/packages/dashboard/src/utils/layout.ts b/understand-anything-plugin/packages/dashboard/src/utils/layout.ts
index b084db8..c1644bc 100644
--- a/understand-anything-plugin/packages/dashboard/src/utils/layout.ts
+++ b/understand-anything-plugin/packages/dashboard/src/utils/layout.ts
@@ -1,6 +1,5 @@
 import dagre from "@dagrejs/dagre";
 import type { Node, Edge } from "@xyflow/react";
-import type { LayoutMessage, LayoutResult } from "./layout.worker";
 
 export const NODE_WIDTH = 280;
 export const NODE_HEIGHT = 120;
@@ -62,78 +61,4 @@ export function applyDagreLayout(
   return { nodes: layoutedNodes, edges };
 }
 
-// ── Async layout via Web Worker ────────────────────────────────────────
-
-let _worker: Worker | null = null;
-let _nextRequestId = 0;
-let _latestRequestId = -1;
-const _pending = new Map<
-  number,
-  {
-    nodes: Node[];
-    edges: Edge[];
-    resolve: (v: { nodes: Node[]; edges: Edge[] }) => void;
-    reject: (reason?: unknown) => void;
-  }
->();
-
-function getWorker(): Worker {
-  if (!_worker) {
-    _worker = new Worker(
-      new URL("./layout.worker.ts", import.meta.url),
-      { type: "module" },
-    );
-
-    _worker.onmessage = (e: MessageEvent<LayoutResult>) => {
-      const { requestId, positions } = e.data;
-      const entry = _pending.get(requestId);
-      _pending.delete(requestId);
-
-      // Discard stale results — only honour the latest request.
-      if (!entry || requestId !== _latestRequestId) return;
-
-      const layoutedNodes = entry.nodes.map((node) => ({
-        ...node,
-        position: positions[node.id] ?? { x: 0, y: 0 },
-      }));
-
-      entry.resolve({ nodes: layoutedNodes, edges: entry.edges });
-    };
-
-    _worker.onerror = (err: ErrorEvent) => {
-      for (const [, entry] of _pending) {
-        entry.reject(err);
-      }
-      _pending.clear();
-    };
-  }
-  return _worker;
-}
-
-/**
- * Async dagre layout via Web Worker — used for large graphs.
- * Keeps the main thread responsive while dagre computes positions.
- */
-export function applyDagreLayoutAsync(
-  nodes: Node[],
-  edges: Edge[],
-  direction: "TB" | "LR" = "TB",
-): Promise<{ nodes: Node[]; edges: Edge[] }> {
-  return new Promise((resolve, reject) => {
-    const worker = getWorker();
-    const requestId = _nextRequestId++;
-    _latestRequestId = requestId;
-
-    _pending.set(requestId, { nodes, edges, resolve, reject });
-
-    const msg: LayoutMessage = {
-      requestId,
-      nodes: nodes.map((n) => ({ id: n.id, width: NODE_WIDTH, height: NODE_HEIGHT })),
-      edges: edges.map((e) => ({ source: e.source, target: e.target })),
-      direction,
-    };
-
-    worker.postMessage(msg);
-  });
-}