routing optimization

src/lib/components/FlowCanvas.svelte

@@ -54,7 +54,17 @@
 		colorMode = theme;
 	});
 
-
+	// Debounced routing context update — coalesces rapid connection changes
+	// (e.g. paste, undo, bulk delete) into a single recalculation
+	let routingContextTimer: ReturnType<typeof setTimeout> | null = null;
+	function scheduleRoutingUpdate() {
+		if (routingContextTimer !== null) clearTimeout(routingContextTimer);
+		routingContextTimer = setTimeout(() => {
+			routingContextTimer = null;
+			updateRoutingContext();
+		}, 0);
+	}
+
 	// Track mouse position for waypoint placement
 	let mousePosition = { x: 0, y: 0 };
 
@@ -238,7 +248,10 @@
 
 	// Cleanup function - will add subscriptions as they're defined
 	const cleanups: (() => void)[] = [unsubscribeTheme, unsubscribeNodeUpdates, unsubscribeClearSelection, unsubscribeNudge, unsubscribeSelectNode];
-	onDestroy(() => cleanups.forEach(fn => fn()));
+	onDestroy(() => {
+		cleanups.forEach(fn => fn());
+		if (routingContextTimer !== null) clearTimeout(routingContextTimer);
+	});
 
 	function clearPendingUpdates() {
 		pendingNodeUpdates = [];
@@ -248,7 +261,7 @@
 	// Returns handle tip position (accounting for handle offset from block edge)
 	// For inputs, also accounts for arrowhead so stub starts within arrow
 	function getPortInfo(nodeId: string, portIndex: number, isOutput: boolean): PortInfo | null {
-		const node = nodes.find(n => n.id === nodeId);
+		const node = nodeMap.get(nodeId);
 		if (!node) return null;
 
 		const nodeData = node.data as NodeInstance;
@@ -382,6 +395,8 @@
 	// Combined nodes for SvelteFlow
 	let nodes = $state<Node[]>([]);
 	let edges = $state<Edge[]>([]);
+	// O(1) node lookup map — kept in sync with nodes array via $effect
+	let nodeMap = $derived(new Map(nodes.map(n => [n.id, n])));
 
 	// Merge block, event, and annotation nodes when any changes
 	// Preserve position and selection from SvelteFlow's current state (except during undo/redo)
@@ -640,8 +655,8 @@
 			return edge;
 		});
 		// Recalculate routes when connections change
-		// Use setTimeout to ensure nodes are updated first
-		setTimeout(() => updateRoutingContext(), 0);
+		// Debounced to coalesce rapid changes (paste, undo, bulk operations)
+		scheduleRoutingUpdate();
 	}));
 
 	// Track last snapped positions during drag for discrete routing updates

src/lib/routing/gridBuilder.ts

@@ -1,6 +1,9 @@
 /**
  * Sparse grid for pathfinding - stores only obstacles, computes walkability on demand
  * Supports incremental updates for efficient node dragging
+ *
+ * Performance: spatial hash uses numeric bucket keys to avoid string GC
+ * in the hot isWalkableAt path (called thousands of times per A* run).
  */
 
 import type { RoutingContext, Bounds, PortStub } from './types';
@@ -10,6 +13,14 @@ import { GRID_SIZE, ROUTING_MARGIN } from './constants';
 /** Size of spatial hash buckets (in grid cells) */
 const SPATIAL_BUCKET_SIZE = 10;
 
+/**
+ * Encode bucket coordinates into a single number.
+ * Bucket coords are small (typically -50..+50), so 10_000 offset is plenty.
+ */
+function encodeBucket(bx: number, by: number): number {
+	return (bx + 10_000) * 20_001 + (by + 10_000);
+}
+
 /**
  * Convert world coordinates to grid coordinates
  * Since everything is grid-aligned, this is a simple division
@@ -57,7 +68,7 @@ function boundsToObstacle(bounds: Bounds, offsetX: number, offsetY: number): Gri
 
 /**
  * Sparse grid that computes walkability on-demand from obstacle list
- * No matrix storage - O(obstacles) memory instead of O(width × height)
+ * No matrix storage - O(obstacles) memory instead of O(width x height)
  * Supports incremental updates - O(1) to update a single node
  * Effectively unbounded - only obstacles block movement
  */
@@ -71,33 +82,33 @@ export class SparseGrid {
 	/** Port stub obstacles (rebuilt when stubs change) */
 	private portStubObstacles: GridObstacle[] = [];
 
-	/** Spatial hash: bucket key -> set of node IDs with obstacles in that bucket */
-	private spatialHash: Map<string, Set<string>> = new Map();
+	/** Spatial hash: numeric bucket key -> set of node IDs with obstacles in that bucket */
+	private spatialHash: Map<number, Set<string>> = new Map();
 
 	constructor(context?: RoutingContext) {
 		if (context) {
 			this.initFromContext(context);
 		}
 	}
 
-	/** Get bucket key for a grid coordinate */
-	private getBucketKey(gx: number, gy: number): string {
+	/** Get numeric bucket key for a grid coordinate */
+	private getBucketKey(gx: number, gy: number): number {
 		const bx = Math.floor(gx / SPATIAL_BUCKET_SIZE);
 		const by = Math.floor(gy / SPATIAL_BUCKET_SIZE);
-		return `${bx},${by}`;
+		return encodeBucket(bx, by);
 	}
 
 	/** Get all bucket keys that an obstacle overlaps */
-	private getObstacleBuckets(obs: GridObstacle): string[] {
-		const keys: string[] = [];
+	private getObstacleBuckets(obs: GridObstacle): number[] {
+		const keys: number[] = [];
 		const minBx = Math.floor(obs.minGx / SPATIAL_BUCKET_SIZE);
 		const maxBx = Math.floor(obs.maxGx / SPATIAL_BUCKET_SIZE);
 		const minBy = Math.floor(obs.minGy / SPATIAL_BUCKET_SIZE);
 		const maxBy = Math.floor(obs.maxGy / SPATIAL_BUCKET_SIZE);
 
 		for (let bx = minBx; bx <= maxBx; bx++) {
 			for (let by = minBy; by <= maxBy; by++) {
-				keys.push(`${bx},${by}`);
+				keys.push(encodeBucket(bx, by));
 			}
 		}
 		return keys;