diff --git a/TODO.txt b/TODO.txt
--- a/TODO.txt
+++ b/TODO.txt
@@ -128,23 +128,191 @@
 and history-driven syncing.
 
 ================================================================================
-14. Milestone N: Desktop packaging (Tauri)                                *wb-N*
+14. Milestone N: Status Bar (Editor HUD)                                  *wb-N*
 ================================================================================
 
-Goal: same app works as a desktop app with filesystem access.
+Goal:
+Add a bottom status bar that surfaces the "always-useful" editor telemetry:
+cursor position, zoom, active tool/mode, selection summary, and persistence
+state - with a clean core → UI boundary.
 
-Tauri + SvelteKit integration:
-[ ] Configure SvelteKit for static/SPA output
-[ ] Ensure SSR is disabled for desktop build
-[ ] Configure Tauri to load the built assets
+Design inspirations:
+- Zoom controls commonly expose percentage + "zoom to fit/selection" shortcuts.
+Svelte integration detail:
+- Use $effect to subscribe/unsubscribe to external sources (runs client-side;
+  cleanup function runs on re-run/unmount).
 
-File dialogs + FS:
-[ ] Implement "Save As…" using Tauri dialog + fs APIs
-[ ] Implement "Open…" using Tauri dialog + fs APIs
-[ ] Add recent files list (v0: store paths in Tauri local storage)
+------------------------------------------------------------------------------
+N1. Define the StatusBar view model (core, pure TS)
+------------------------------------------------------------------------------
+
+/packages/core/src/ui/statusbar/types.ts
+[ ] Define StatusBarVM (single object the UI renders):
+    - cursorWorld: { x, y }         " world coords (always)
+    - cursorScreen: { x, y }?       " optional dev-only
+    - zoomPct: number               " e.g. 100, 67, 250
+    - toolId: ToolId                " select/rect/pen/...
+    - mode: string                  " 'idle'|'dragging'|'panning'|'text-edit'
+    - selection:
+        - count: number
+        - kind?: string             " optional: 'rect', 'mixed', etc.
+        - bounds?: { w, h }         " optional v1
+    - snap:
+        - enabled: boolean
+        - gridSize?: number         " if grid enabled
+        - angleStepDeg?: number     " if angle snapping exists
+    - persistence:
+        - backend: 'indexeddb'
+        - state: 'saved'|'saving'|'error'
+        - lastSavedAt?: number      " epoch ms
+        - pendingWrites?: number    " queue depth if you batch writes
+        - errorMsg?: string
+
+Notes:
+- This VM is intentionally READ-ONLY and derived from existing editor state,
+  input state, and persistence sink state.
 
 (DoD):
-- Desktop app opens/saves JSON files on disk and reopens them correctly.
+- StatusBarVM compiles and is stable enough to render even before UI exists.
+
+------------------------------------------------------------------------------
+N2. Provide selectors / derivations for StatusBarVM
+------------------------------------------------------------------------------
+
+/packages/core/src/ui/statusbar/selectors.ts
+[ ] Implement pure functions:
+    - getZoomPct(state) -> number
+    - getToolId(state) -> ToolId
+    - getSelectionSummary(state) -> { count, kind?, bounds? }
+    - getSnapSummary(state) -> snap summary (default safe values)
+
+Cursor position source:
+[ ] Define a minimal CursorState in core (NOT persisted):
+    - cursorWorld: Vec2
+    - cursorScreen?: Vec2
+    - lastMoveAt: number
+
+[ ] Add updateCursor(world, screen?) action + reducer handler (or direct setter)
+    that ONLY touches CursorState (no history command, no persistence).
+
+(DoD):
+- You can compute StatusBarVM from (EditorState + CursorState + PersistState).
+
+------------------------------------------------------------------------------
+N3. Wire cursor updates from pointer movement (apps/web)
+------------------------------------------------------------------------------
+
+/apps/web/src/lib/pointer.ts
+[ ] On pointermove (or mousemove when not captured):
+    - compute world coords using camera.screenToWorld
+    - dispatch updateCursor(world, screen)
+
+Performance:
+[ ] Throttle cursor updates:
+    - v0: requestAnimationFrame coalescing (only publish latest per frame)
+    - avoid flooding render/history/persistence
+
+(DoD):
+- Cursor world coordinates update smoothly while moving the mouse.
+
+------------------------------------------------------------------------------
+N4. Add persistence status signals (Dexie + persistence sink integration)
+------------------------------------------------------------------------------
+
+Goal:
+Expose persistence state without touching the history system (Milestone L is
+done; persistence is already hooked to history in Milestone M).
+
+/apps/web/src/lib/status.ts
+[ ] Extend your persistence sink (from Milestone M) to expose a small status:
+    - pendingWrites counter (increment on enqueue, decrement on commit)
+    - lastSavedAt timestamp (set on successful commit)
+    - lastError (set on failed commit)
+[ ] Use Dexie liveQuery to observe the current board’s updatedAt from IndexedDB
+    and reflect it in the UI (helps confirm persisted state across tabs).
+
+(DoD):
+- Status bar can show: "Saving…" when pendingWrites > 0, and "Saved" with time
+  when pendingWrites reaches 0.
+
+------------------------------------------------------------------------------
+N5. Implement StatusBar.svelte using runes
+------------------------------------------------------------------------------
+
+/apps/web/src/lib/components/StatusBar.svelte
+[ ] Render left → right (suggested):
+    - Tool + mode
+    - Cursor: X,Y (world)
+    - Selection summary
+    - Snap/grid summary
+    - Zoom %
+    - Save state ("Saved 3s ago" / "Saving…" / "Error")
+
+[ ] Consume state via runes:
+    - keep a local $state(snapshot) for EditorState
+    - keep a local $state(cursor) for CursorState
+    - keep a local $state(persist) for PersistStatus
+
+Subscriptions:
+[ ] Use $effect to subscribe to any external streams and return cleanup
+    unsubscribe.
+
+Formatting:
+[ ] Cursor formatting:
+    - v0: integers
+    - v1: configurable precision (e.g. 0.1 units when zoomed in)
+
+(DoD):
+- Status bar is visible, updates live, and never causes noticeable jank.
+
+------------------------------------------------------------------------------
+N6. Interactions (small, high-value)
+------------------------------------------------------------------------------
+
+Zoom control:
+[ ] Clicking zoomPct opens a tiny menu:
+    - 50%, 100%, 200%
+    - Zoom to fit
+    - Zoom to selection
+(Inspiration: zoom/view options + shortcuts in Figma/FigJam.)
+
+Snap toggles:
+[ ] Add quick toggles (optional v0, recommended v1):
+    - snap enabled
+    - grid enabled
+
+(DoD):
+- Zoom is discoverable and controllable from the status bar.
+
+------------------------------------------------------------------------------
+N7. Tests
+------------------------------------------------------------------------------
+
+Core unit tests (/packages/core/test/statusbar.test.ts):
+[ ] getZoomPct returns expected values from camera zoom
+[ ] selection summary is correct (0, 1, many)
+[ ] snap summary defaults safe when features disabled
+
+Web integration tests (optional v0):
+[ ] cursor update throttling: 100 pointermoves in a tick results in <= 1 state
+    publication per frame (if you implement rAF coalescing)
+
+Persistence tests (web):
+[ ] pendingWrites transitions: 0 -> N -> 0 yields state 'saving' then 'saved'
+[ ] error sets 'error' state and preserves lastSavedAt
+
+------------------------------------------------------------------------------
+Definition of Done
+------------------------------------------------------------------------------
+
+- Status bar shows:
+    - cursor world position
+    - zoom percentage
+    - active tool/mode
+    - selection count
+    - persistence state (Saved/Saving/Error + lastSavedAt)
+- Cursor updates are throttled and do not spam history or persistence.
+- UI subscriptions use $effect with cleanup.
 
 ================================================================================
 15. Milestone O: Export (PNG/SVG)                                         *wb-O*
@@ -165,9 +333,27 @@
 (DoD):
 - One-click export works in both web and desktop.
 
+================================================================================
+16. Milestone P: Desktop packaging (Tauri)                                *wb-P*
+================================================================================
+
+Goal: same app works as a desktop app with filesystem access.
+
+Tauri + SvelteKit integration:
+[ ] Configure SvelteKit for static/SPA output
+[ ] Ensure SSR is disabled for desktop build
+[ ] Configure Tauri to load the built assets
+
+File dialogs + FS:
+[ ] Implement "Save As…" using Tauri dialog + fs APIs
+[ ] Implement "Open…" using Tauri dialog + fs APIs
+[ ] Add recent files list (v0: store paths in Tauri local storage)
+
+(DoD):
+- Desktop app opens/saves JSON files on disk and reopens them correctly.
 
 ================================================================================
-16. Milestone P: Performance + big docs (pragmatic)                       *wb-P*
+17. Milestone Q: Performance + big docs (pragmatic)                       *wb-Q*
 ================================================================================
 
 Goal: the editor stays responsive with many shapes.
@@ -175,15 +361,12 @@
 [ ] Add spatial index (v0: simple grid buckets):
     - rebuild index on doc changes
     - query nearby shapes for hit testing
-
 [ ] Add view culling:
     - compute viewport bounds in world space
     - render only shapes whose bounds intersect viewport
-
 [ ] Reduce redraw frequency:
     - rAF only while dirty
     - optionally batch multiple store updates into one redraw
-
 [ ] Add microbench harness:
     - generate 10k shapes doc
     - measure hit test and render time
@@ -192,15 +375,15 @@
 - 10k simple shapes pans/zooms smoothly on a typical machine.
 
 ================================================================================
-17. Milestone Q: File Browser (web: Dexie inspector, desktop: FS)         *wb-Q*
+18. Milestone R: File Browser (web: Dexie inspector, desktop: FS)         *wb-R*
 ================================================================================
 
-Goal: A unified “Open board” experience:
+Goal: A unified "Open board" experience:
 - Web: browse Dexie-backed boards + a useful persistence/migration inspector
 - Desktop: browse real directories/files (native file browser semantics)
 
 --------------------------------------------------------------------------------
-Q1. Shared UX contracts
+R1. Shared UX contracts
 --------------------------------------------------------------------------------
 
 /packages/core/src/persist/DocRepo.ts:
@@ -219,7 +402,7 @@
 - Svelte UI can render the browser purely from the ViewModel.
 
 --------------------------------------------------------------------------------
-Q2. Web: Boards list + Dexie “Inspector” drawer
+R2. Web: Boards list + Dexie "Inspector" drawer
 --------------------------------------------------------------------------------
 
 /apps/web/src/lib/filebrowser/FileBrowser.svelte:
@@ -229,7 +412,7 @@
     - open / create / rename / delete
 
 Inspector drawer (selected board):
-[ ] Show “Storage: IndexedDB (Dexie)”
+[ ] Show "Storage: IndexedDB (Dexie)"
 [ ] Show schema info:
     - declared schema version (your constant)
     - installed schema version (best-effort display)
@@ -239,7 +422,7 @@
     - last updatedAt
 [ ] Show migration info:
     - list applied migrations from migrations table (id + appliedAt)
-    - show “pending” migrations if any (based on known list vs applied)
+    - show "pending" migrations if any (based on known list vs applied)
 
 Safe deletes:
 [ ] deleteBoard must be a single atomic transaction (boards + related tables)
@@ -248,10 +431,10 @@
 - Web: you can browse boards, open one, and verify migrations + row counts.
 
 --------------------------------------------------------------------------------
-Q3. Desktop: real directory + files (Tauri)
+R3. Desktop: real directory + files (Tauri)
 --------------------------------------------------------------------------------
 
-[ ] Add “Workspace folder” concept:
+[ ] Add "Workspace folder" concept:
     - pick directory
     - remember last workspace path
 [ ] Implement directory listing:
@@ -268,7 +451,7 @@
 - Desktop: pick a folder, browse files, open/save boards from disk.
 
 --------------------------------------------------------------------------------
-Q4. Parity behaviors
+R4. Parity behaviors
 --------------------------------------------------------------------------------
 
 [ ] Same shortcuts:
@@ -281,7 +464,7 @@
 - Web and desktop feel like the same app, with storage differences made explicit.
 
 ================================================================================
-18. Milestone R: Quality polish (what makes it feel "real")               *wb-R*
+19. Milestone S: Quality polish (what makes it feel "real")               *wb-S*
 ================================================================================
 
 Goal: the UX crosses the "this is legit" threshold.
diff --git a/packages/core/src/cursor.ts b/packages/core/src/cursor.ts
new file mode 100644
--- /dev/null
+++ b/packages/core/src/cursor.ts
@@ -0,0 +1,63 @@
+import { BehaviorSubject, type Subscription } from "rxjs";
+import { Vec2 } from "./math";
+
+/**
+ * Cursor position + timing in world/screen space.
+ *
+ * CursorState is intentionally separate from EditorState so it can be updated
+ * with high frequency (e.g., on pointer move) without touching history or
+ * triggering document persistence.
+ */
+export type CursorState = { cursorWorld: Vec2; cursorScreen?: Vec2; lastMoveAt: number };
+
+export const CursorState = {
+  /**
+   * Create a cursor state positioned at origin with no screen point.
+   */
+  create(world?: Vec2, screen?: Vec2, timestamp = Date.now()): CursorState {
+    return {
+      cursorWorld: Vec2.clone(world ?? { x: 0, y: 0 }),
+      cursorScreen: screen ? Vec2.clone(screen) : undefined,
+      lastMoveAt: timestamp,
+    };
+  },
+};
+
+export type CursorListener = (state: CursorState) => void;
+
+/**
+ * Store that tracks cursor movement separately from the undoable editor state.
+ */
+export class CursorStore {
+  private readonly state$: BehaviorSubject<CursorState>;
+
+  constructor(initialState?: CursorState) {
+    this.state$ = new BehaviorSubject(initialState ?? CursorState.create());
+  }
+
+  /**
+   * Read the latest cursor snapshot.
+   */
+  getState(): CursorState {
+    return this.state$.value;
+  }
+
+  /**
+   * Subscribe to cursor updates.
+   */
+  subscribe(listener: CursorListener): () => void {
+    const subscription: Subscription = this.state$.subscribe(listener);
+    return () => subscription.unsubscribe();
+  }
+
+  /**
+   * Update the cursor position without touching editor history/persistence.
+   */
+  updateCursor(world: Vec2, screen?: Vec2, timestamp = Date.now()): void {
+    this.state$.next({
+      cursorWorld: Vec2.clone(world),
+      cursorScreen: screen ? Vec2.clone(screen) : undefined,
+      lastMoveAt: timestamp,
+    });
+  }
+}
diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -1,5 +1,6 @@
 export * from "./actions";
 export * from "./camera";
+export * from "./cursor";
 export * from "./geom";
 export * from "./history";
 export * from "./math";
@@ -8,3 +9,4 @@
 export * from "./persistence/web";
 export * from "./reactivity";
 export * from "./tools";
+export * from "./ui/statusbar";
diff --git a/packages/core/tests/statusbar.test.ts b/packages/core/tests/statusbar.test.ts
new file mode 100644
--- /dev/null
+++ b/packages/core/tests/statusbar.test.ts
@@ -0,0 +1,142 @@
+import { describe, expect, it } from "vitest";
+import { CursorState as CursorStateOps } from "../src/cursor";
+import { ShapeRecord } from "../src/model";
+import type { ShapeRecord as ShapeRecordType } from "../src/model";
+import { EditorState } from "../src/reactivity";
+import {
+  buildStatusBarVM,
+  getSelectionSummary,
+  getSnapSummary,
+  getToolId,
+  getZoomPct,
+  type PersistenceStatus,
+} from "../src/ui/statusbar";
+
+describe("Status bar selectors", () => {
+  describe("getZoomPct", () => {
+    it("rounds zoom values to percentages", () => {
+      const state = { ...EditorState.create(), camera: { x: 0, y: 0, zoom: 1.234 } };
+      expect(getZoomPct(state)).toBe(123);
+    });
+
+    it("falls back to 100 for invalid zoom", () => {
+      const state = { ...EditorState.create(), camera: { x: 0, y: 0, zoom: Number.NaN } };
+      expect(getZoomPct(state)).toBe(100);
+    });
+  });
+
+  describe("getToolId", () => {
+    it("returns the active tool id", () => {
+      const base = EditorState.create();
+      const state: EditorState = { ...base, ui: { ...base.ui, toolId: "rect", currentPageId: null, selectionIds: [] } };
+      expect(getToolId(state)).toBe("rect");
+    });
+  });
+
+  describe("getSelectionSummary", () => {
+    it("returns zero summary when nothing is selected", () => {
+      const state = buildState([], []);
+      expect(getSelectionSummary(state)).toEqual({ count: 0 });
+    });
+
+    it("describes a single selected shape", () => {
+      const rect = ShapeRecord.createRect(
+        "page-1",
+        10,
+        20,
+        { w: 40, h: 20, fill: "#000", stroke: "#fff", radius: 0 },
+        "shape-rect",
+      );
+      const state = buildState([rect], ["shape-rect"]);
+      expect(getSelectionSummary(state)).toEqual({ count: 1, kind: "rect", bounds: { w: 40, h: 20 } });
+    });
+
+    it("summarizes multiple selections with combined bounds and mixed kind", () => {
+      const rect = ShapeRecord.createRect(
+        "page-1",
+        10,
+        20,
+        { w: 40, h: 20, fill: "#000", stroke: "#fff", radius: 0 },
+        "shape-rect",
+      );
+      const ellipse = ShapeRecord.createEllipse(
+        "page-1",
+        100,
+        50,
+        { w: 20, h: 20, fill: "#f00", stroke: "#111" },
+        "shape-ellipse",
+      );
+      const state = buildState([rect, ellipse], ["shape-rect", "shape-ellipse"]);
+
+      expect(getSelectionSummary(state)).toEqual({ count: 2, kind: "mixed", bounds: { w: 110, h: 50 } });
+    });
+
+    it("marks kind when all selected shapes match", () => {
+      const rectA = ShapeRecord.createRect(
+        "page-1",
+        0,
+        0,
+        { w: 10, h: 10, fill: "#000", stroke: "#fff", radius: 0 },
+        "shape-1",
+      );
+      const rectB = ShapeRecord.createRect(
+        "page-1",
+        20,
+        20,
+        { w: 10, h: 10, fill: "#111", stroke: "#eee", radius: 0 },
+        "shape-2",
+      );
+      const state = buildState([rectA, rectB], ["shape-1", "shape-2"]);
+
+      expect(getSelectionSummary(state)).toEqual({ count: 2, kind: "rect", bounds: { w: 30, h: 30 } });
+    });
+  });
+
+  describe("getSnapSummary", () => {
+    it("returns safe defaults when snapping is disabled", () => {
+      const state = buildState([], []);
+      expect(getSnapSummary(state)).toEqual({ enabled: false });
+    });
+  });
+
+  describe("buildStatusBarVM", () => {
+    it("composes slices into a status bar view model", () => {
+      const rect = ShapeRecord.createRect(
+        "page-1",
+        0,
+        0,
+        { w: 50, h: 50, fill: "#000", stroke: "#fff", radius: 0 },
+        "shape-rect",
+      );
+      const state = buildState([rect], ["shape-rect"]);
+      const cursorState = CursorStateOps.create({ x: 5, y: 6 }, { x: 1, y: 2 }, 42);
+      const persistence: PersistenceStatus = { backend: "indexeddb", state: "saving", pendingWrites: 1 };
+
+      const vm = buildStatusBarVM(state, cursorState, persistence, "dragging");
+
+      expect(vm.cursorWorld).toEqual({ x: 5, y: 6 });
+      expect(vm.cursorScreen).toEqual({ x: 1, y: 2 });
+      expect(vm.zoomPct).toBe(100);
+      expect(vm.toolId).toBe("select");
+      expect(vm.mode).toBe("dragging");
+      expect(vm.selection).toEqual({ count: 1, kind: "rect", bounds: { w: 50, h: 50 } });
+      expect(vm.snap).toEqual({ enabled: false });
+      expect(vm.persistence).toEqual({ backend: "indexeddb", state: "saving", pendingWrites: 1 });
+      expect(vm.cursorWorld).not.toBe(cursorState.cursorWorld);
+      expect(vm.persistence).not.toBe(persistence);
+    });
+  });
+});
+
+function buildState(shapes: ShapeRecordType[], selectionIds: string[]) {
+  const base = EditorState.create();
+  const pageId = "page-1";
+  const docShapes = Object.fromEntries(shapes.map((shape) => [shape.id, shape]));
+  const page = { id: pageId, name: "Page 1", shapeIds: shapes.map((shape) => shape.id) };
+
+  return {
+    ...base,
+    doc: { pages: { [pageId]: page }, shapes: docShapes, bindings: {} },
+    ui: { ...base.ui, currentPageId: pageId, selectionIds },
+  };
+}
diff --git a/packages/core/src/ui/statusbar.ts b/packages/core/src/ui/statusbar.ts
new file mode 100644
--- /dev/null
+++ b/packages/core/src/ui/statusbar.ts
@@ -0,0 +1,115 @@
+import type { CursorState } from "../cursor";
+import { shapeBounds } from "../geom";
+import { type Box2, Box2 as Box2Ops, type Vec2, Vec2 as Vec2Ops } from "../math";
+import type { EditorState, ToolId } from "../reactivity";
+import { getSelectedShapes } from "../reactivity";
+
+export type SelectionSummary = { count: number; kind?: string; bounds?: { w: number; h: number } };
+
+export type SnapSummary = { enabled: boolean; gridSize?: number; angleStepDeg?: number };
+
+export type PersistenceStatus = {
+  backend: "indexeddb";
+  state: "saved" | "saving" | "error";
+  lastSavedAt?: number;
+  pendingWrites?: number;
+  errorMsg?: string;
+};
+
+export type StatusBarVM = {
+  cursorWorld: Vec2;
+  cursorScreen?: Vec2;
+  zoomPct: number;
+  toolId: ToolId;
+  mode: "idle" | "dragging" | "panning" | "text-edit" | string;
+  selection: SelectionSummary;
+  snap: SnapSummary;
+  persistence: PersistenceStatus;
+};
+
+/**
+ * Convert the current camera zoom factor into a human-friendly percentage.
+ */
+export function getZoomPct(state: EditorState): number {
+  const pct = state.camera.zoom * 100;
+  if (!Number.isFinite(pct)) {
+    return 100;
+  }
+  return Math.round(pct);
+}
+
+/**
+ * Get the active tool identifier from UI state.
+ */
+export function getToolId(state: EditorState): ToolId {
+  return state.ui.toolId;
+}
+
+/**
+ * Summarize the current selection for display.
+ */
+export function getSelectionSummary(state: EditorState): SelectionSummary {
+  const shapes = getSelectedShapes(state);
+  const count = shapes.length;
+
+  if (count === 0) {
+    return { count: 0 };
+  }
+
+  const combinedBounds = combineBounds(shapes.map((shape) => shapeBounds(shape)));
+
+  const kind = count === 1
+    ? shapes[0].type
+    : (shapes.every((shape) => shape.type === shapes[0].type) ? shapes[0].type : "mixed");
+
+  return {
+    count,
+    kind,
+    bounds: combinedBounds ? { w: Box2Ops.width(combinedBounds), h: Box2Ops.height(combinedBounds) } : undefined,
+  };
+}
+
+const SNAP_DEFAULT: SnapSummary = { enabled: false };
+
+/**
+ * Provide safe defaults for snap/grid summary until features are enabled.
+ */
+export function getSnapSummary(_: EditorState): SnapSummary {
+  return { ...SNAP_DEFAULT };
+}
+
+/**
+ * Compose the full StatusBar view model from editor/cursor/persistence state.
+ */
+export function buildStatusBarVM(
+  editorState: EditorState,
+  cursorState: CursorState,
+  persistence: PersistenceStatus,
+  mode: StatusBarVM["mode"] = "idle",
+): StatusBarVM {
+  return {
+    cursorWorld: Vec2Ops.clone(cursorState.cursorWorld),
+    cursorScreen: cursorState.cursorScreen ? Vec2Ops.clone(cursorState.cursorScreen) : undefined,
+    zoomPct: getZoomPct(editorState),
+    toolId: getToolId(editorState),
+    mode,
+    selection: getSelectionSummary(editorState),
+    snap: getSnapSummary(editorState),
+    persistence: { ...persistence },
+  };
+}
+
+function combineBounds(boxes: Box2[]): Box2 | null {
+  if (boxes.length === 0) {
+    return null;
+  }
+  let combined = Box2Ops.clone(boxes[0]);
+  for (let index = 1; index < boxes.length; index++) {
+    const box = boxes[index];
+    combined = {
+      min: { x: Math.min(combined.min.x, box.min.x), y: Math.min(combined.min.y, box.min.y) },
+      max: { x: Math.max(combined.max.x, box.max.x), y: Math.max(combined.max.y, box.max.y) },
+    };
+  }
+  return combined;
+}