fix: aggregate large ink groups safely

src/onenote/one/content.ts

@@ -623,7 +623,7 @@ function parseInk(
       id: exGuidKey(object.id),
       strokes: [],
       children,
-      boundingBox: unionBoundingBoxes(
+      boundingBox: unionInkBoundingBoxes(
         children.map((child) => child.boundingBox)
       ),
       layout: parseLayout(object),
@@ -915,18 +915,24 @@ function boundingBoxFromStrokes(
     : undefined;
 }
 
-function unionBoundingBoxes(
+/** @internal Exported so the bounded aggregation path can be stress-tested. */
+export function unionInkBoundingBoxes(
   boxes: readonly (OneNoteInkBoundingBox | undefined)[]
 ): OneNoteInkBoundingBox | undefined {
-  const present = boxes.filter(
-    (box): box is OneNoteInkBoundingBox => box !== undefined
-  );
-  if (present.length === 0) return undefined;
-  const x = Math.min(...present.map((box) => box.x));
-  const y = Math.min(...present.map((box) => box.y));
-  const x2 = Math.max(...present.map((box) => box.x + box.width));
-  const y2 = Math.max(...present.map((box) => box.y + box.height));
-  return { x, y, width: x2 - x, height: y2 - y };
+  let x = Infinity;
+  let y = Infinity;
+  let x2 = -Infinity;
+  let y2 = -Infinity;
+  for (const box of boxes) {
+    if (!box) continue;
+    x = Math.min(x, box.x);
+    y = Math.min(y, box.y);
+    x2 = Math.max(x2, box.x + box.width);
+    y2 = Math.max(y2, box.y + box.height);
+  }
+  return Number.isFinite(x)
+    ? { x, y, width: x2 - x, height: y2 - y }
+    : undefined;
 }
 
 function parseLayout(object: StoreObject): OneNoteLayout {

tests/content-model.test.ts

@@ -15,7 +15,10 @@ import {
   type OneNoteTextBlock,
 } from '../src/onenote/index.js';
 import type { ParserDiagnostic } from '../src/onenote/model/diagnostics.js';
-import { parseContentObjects } from '../src/onenote/one/content.js';
+import {
+  parseContentObjects,
+  unionInkBoundingBoxes,
+} from '../src/onenote/one/content.js';
 import { JCID, PROPERTY } from '../src/onenote/one/constants.js';
 import type {
   ExGuid,
@@ -209,6 +212,22 @@ describe('OneNote rich-content model', () => {
     expect(parsedPoints).toBeLessThanOrEqual(100);
   });
 
+  it('combines a large number of child ink bounds without argument spreading', () => {
+    const boxes = Array.from({ length: 200_000 }, (_, index) => ({
+      x: index,
+      y: -index,
+      width: 2,
+      height: 3,
+    }));
+
+    expect(unionInkBoundingBoxes([undefined, ...boxes])).toEqual({
+      x: 0,
+      y: -199_999,
+      width: 200_001,
+      height: 200_002,
+    });
+  });
+
   it('bounds retained rich text across content blocks', () => {
     const guid = '{33333333-3333-3333-3333-333333333333}';
     const firstId = id(guid, 1);