Archify Diagram Viewer 0.1.0

VS Code extension that previews Archify diagrams from their JSON sources
(live, as you type) and opens rendered Archify HTML in a viewer tab.
Bundles the Archify 3.0.1 renderer and runs it on VS Code's Node runtime.
Adds validation diagnostics, JSON schema help, source-link navigation,
export saving, render-to-file and open-in-browser commands.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

vendor/archify/renderers/shared/spatial-grid.mjs

@@ -0,0 +1,66 @@
+/** Uniform spatial grid for "which items can this box reach" queries (#8). */
+
+// A cell box wider than this is not worth walking: the query returns every
+// inserted item instead, which stays a superset of what the box reaches.
+const DEFAULT_MAX_CELLS = 4096;
+
+export function createSpatialGrid(cellSize, { maxCells = DEFAULT_MAX_CELLS } = {}) {
+  const buckets = new Map();
+  const items = [];
+  // Items whose own box cannot be walked are candidates for every query.
+  const overflow = [];
+  const keyOf = (x, y) => x + ':' + y;
+  const rangeOf = (box) => ({
+    x0: Math.floor(box.minX / cellSize), x1: Math.floor(box.maxX / cellSize),
+    y0: Math.floor(box.minY / cellSize), y1: Math.floor(box.maxY / cellSize),
+  });
+  // Finite coordinates can still land outside the safe-integer range, where
+  // incrementing an index no longer advances it; and a legal coordinate can
+  // name more cells than the grid is worth. Both cases stay out of the buckets
+  // and are answered by the item list, so they never hang or allocate.
+  const walkable = (range) => Number.isSafeInteger(range.x0) && Number.isSafeInteger(range.x1)
+    && Number.isSafeInteger(range.y0) && Number.isSafeInteger(range.y1)
+    && (range.x1 - range.x0 + 1) * (range.y1 - range.y0 + 1) <= maxCells;
+
+  return {
+    insert(box, item) {
+      items.push(item);
+      const range = rangeOf(box);
+      if (!walkable(range)) {
+        overflow.push(item);
+        return;
+      }
+      for (let x = range.x0; x <= range.x1; x += 1) {
+        for (let y = range.y0; y <= range.y1; y += 1) {
+          const key = keyOf(x, y);
+          let bucket = buckets.get(key);
+          if (!bucket) { bucket = []; buckets.set(key, bucket); }
+          bucket.push(item);
+        }
+      }
+    },
+    query(box) {
+      const range = rangeOf(box);
+      if (!walkable(range)) return items.slice();
+      const seen = new Set();
+      const found = [];
+      for (let x = range.x0; x <= range.x1; x += 1) {
+        for (let y = range.y0; y <= range.y1; y += 1) {
+          const bucket = buckets.get(keyOf(x, y));
+          if (!bucket) continue;
+          for (const item of bucket) {
+            if (seen.has(item)) continue;
+            seen.add(item);
+            found.push(item);
+          }
+        }
+      }
+      for (const item of overflow) {
+        if (seen.has(item)) continue;
+        seen.add(item);
+        found.push(item);
+      }
+      return found;
+    },
+  };
+}