Fix zoom display regression: split viewport change concerns

Pass popoverVisible flag from graph-canvas tick loop to the
onViewportChange callback. The handler always updates zoomDisplay
(so NavigationControls shows correct zoom %) but only increments
viewportVersion (triggering popover repositioning) when a node is
actually selected or hovered. This avoids 60fps React reconciliation
during plain panning while keeping the zoom indicator responsive.

packages/memory-graph/src/components/graph-canvas.tsx

@@ -234,17 +234,14 @@ export const GraphCanvas = memo<ExtendedGraphCanvasProps>(function GraphCanvas({
 				return
 			renderNeeded.current = false
 
-			// Report viewport changes so popover positions update.
-			// Only fire when a popover is actually visible (selected or hovered node)
-			// to avoid triggering React re-renders at 60fps during plain panning.
+			// Report viewport changes so zoom display and popover positions update.
 			const vpChanged =
 				vp.panX !== prevVpX || vp.panY !== prevVpY || vp.zoom !== prevVpZoom
-			if (
-				(vpChanged || simActive) &&
-				(cur.selectedNodeId || cur.hoveredNodeId) &&
-				cb.current.onViewportChange
-			) {
-				cb.current.onViewportChange(vp.zoom)
+			if ((vpChanged || simActive) && cb.current.onViewportChange) {
+				cb.current.onViewportChange(
+					vp.zoom,
+					!!(cur.selectedNodeId || cur.hoveredNodeId),
+				)
 			}
 			if (vpChanged) {
 				prevVpX = vp.panX

packages/memory-graph/src/components/memory-graph.tsx

@@ -170,10 +170,18 @@ export function MemoryGraph({
 		// Drag end handled by InputHandler
 	}, [])
 
-	const handleViewportChange = useCallback((zoom: number) => {
-		setZoomDisplay(Math.round(zoom * 100))
-		setViewportVersion((v) => v + 1)
-	}, [])
+	const handleViewportChange = useCallback(
+		(zoom: number, popoverVisible: boolean) => {
+			setZoomDisplay(Math.round(zoom * 100))
+			// Only increment viewportVersion (which triggers popover repositioning
+			// via activePopoverPosition useMemo) when a popover is actually visible.
+			// This avoids 60fps React reconciliation during plain panning/zooming.
+			if (popoverVisible) {
+				setViewportVersion((v) => v + 1)
+			}
+		},
+		[],
+	)
 
 	// Navigation
 	const handleAutoFit = useCallback(() => {

packages/memory-graph/src/types.ts

@@ -163,7 +163,7 @@ export interface GraphCanvasProps {
 	onNodeClick: (nodeId: string | null) => void
 	onNodeDragStart: (nodeId: string) => void
 	onNodeDragEnd: () => void
-	onViewportChange?: (zoom: number) => void
+	onViewportChange?: (zoom: number, popoverVisible: boolean) => void
 	canvasRef?: React.RefObject<HTMLCanvasElement | null>
 	simulation?: import("./canvas/simulation").ForceSimulation
 	viewportRef?: React.RefObject<