diff --git a/.changeset/react-tests-mock-svg.md b/.changeset/react-tests-mock-svg.md
new file mode 100644
index 0000000000..a845151cc8
--- /dev/null
+++ b/.changeset/react-tests-mock-svg.md
@@ -0,0 +1,2 @@
+---
+---
diff --git a/packages/joint-react/__mocks__/jest-setup.ts b/packages/joint-react/__mocks__/jest-setup.ts
index 29102e11ef..9dd78e0418 100644
--- a/packages/joint-react/__mocks__/jest-setup.ts
+++ b/packages/joint-react/__mocks__/jest-setup.ts
@@ -4,6 +4,10 @@
 // learn more: https://github.com/testing-library/jest-dom
 import '@testing-library/jest-dom';
 import { configure } from '@testing-library/react';
+// Installs the SVG globals JSDOM does not implement but JointJS relies on.
+// Note: it mocks `checkVisibility()` on SVG elements only (an empty `getBBox()`
+// reads as not rendered); HTML elements have none in JSDOM.
+import '@joint/mock-svg';
 
 configure({ reactStrictMode: true });
 
@@ -11,13 +15,8 @@ configure({ reactStrictMode: true });
 // -----
 
 /**
- * @description Mock method which is not implemented in JSDOM
- * @see https://developer.mozilla.org/en-US/docs/Web/API/SVGPathElement
- */
-globalThis.SVGPathElement = jest.fn();
-
-/**
- * @description Minimal DOMMatrix polyfill — JSDOM doesn't ship it.
+ * @description Minimal DOMMatrix polyfill — JSDOM doesn't ship it, and
+ * `@joint/mock-svg` does not mock it.
  * Always returns the identity matrix. Tests don't validate transform math;
  * they only need the constructor to not throw and produce a/b/c/d/e/f
  * fields readable by `V.createSVGMatrix`.
@@ -36,162 +35,10 @@ Object.defineProperty(globalThis, 'DOMMatrix', {
   value: MockDOMMatrix,
 });
 
-/**
- * @description Mock SVGAngle which is used for sanity checks in Vectorizer library
- * @see https://developer.mozilla.org/en-US/docs/Web/API/SVGAngle
- */
-Object.defineProperty(globalThis, 'SVGAngle', {
-  writable: true,
-  value: jest.fn().mockImplementation(() => SVGAngle),
-});
-
+// `@joint/mock-svg` installs its mocks once per test file. Tests that drive
+// their own `ResizeObserver` replace the global, so restore the library one
+// before every test to keep each test isolated from the previous one.
+const { ResizeObserver: MockResizeObserver } = globalThis;
 beforeEach(() => {
-  /**
-   * @see https://developer.mozilla.org/en-US/docs/Web/API/ResizeObserver
-   */
-  globalThis.ResizeObserver = jest.fn().mockImplementation(() => ({
-    observe: jest.fn(),
-    unobserve: jest.fn(),
-    disconnect: jest.fn(),
-  }));
-
-  /**
-   * @see https://developer.mozilla.org/en-US/docs/Web/API/SVGSVGElement/createSVGMatrix
-   */
-  Object.defineProperty(globalThis.SVGSVGElement.prototype, 'createSVGMatrix', {
-    writable: true,
-    value: jest.fn().mockImplementation(() => SVGMatrix),
-  });
-
-  /**
-   * @see https://developer.mozilla.org/en-US/docs/Web/API/SVGTransform
-   */
-  Object.defineProperty(globalThis.SVGSVGElement.prototype, 'createSVGTransform', {
-    writable: true,
-    value: jest.fn().mockImplementation(() => SVGTransform),
-  });
-
-  /**
-   * @see https://developer.mozilla.org/en-US/docs/Web/API/SVGPoint
-   */
-  Object.defineProperty(globalThis.SVGSVGElement.prototype, 'createSVGPoint', {
-    writable: true,
-    value: jest.fn().mockImplementation(() => SVGPoint),
-  });
-
-  /**
-   * @description used in `util.breakText()` method
-   * @see https://developer.mozilla.org/en-US/docs/Web/API/SVGTextContentElement/getComputedTextLength
-   */
-  Object.defineProperty(globalThis.SVGElement.prototype, 'getComputedTextLength', {
-    writable: true,
-    value: jest.fn().mockImplementation(() => 0),
-  });
-
-  /**
-   * @see https://developer.mozilla.org/en-US/docs/Web/API/SVGGraphicsElement/getScreenCTM
-   * Note: JSDOM SVGGraphicsElement does not encompass all SVG elements that might be needed,
-   * whereas SVGElement provides broader compatibility.
-   */
-  Object.defineProperty(globalThis.SVGElement.prototype, 'getScreenCTM', {
-    writable: true,
-    value: jest.fn().mockImplementation(() => SVGMatrix),
-  });
-
-  /**
-   * @description used in `util.breakText()` method
-   * @see https://developer.mozilla.org/en-US/docs/Web/API/SVGGraphicsElement/getBBox
-   */
-  Object.defineProperty(globalThis.SVGElement.prototype, 'getBBox', {
-    writable: true,
-    value: jest.fn().mockImplementation(() => SVGRect),
-  });
-
-  /**
-   * @description Mock checkVisibility method which is not implemented in JSDOM
-   * @see https://developer.mozilla.org/en-US/docs/Web/API/Element/checkVisibility
-   */
-  Object.defineProperty(globalThis.Element.prototype, 'checkVisibility', {
-    writable: true,
-    value: jest.fn().mockImplementation(() => true),
-  });
+  globalThis.ResizeObserver = MockResizeObserver;
 });
-
-// Interfaces
-// ----------
-
-/**
- * @see https://developer.mozilla.org/en-US/docs/Web/API/SVGAngle
- */
-const SVGAngle = {
-  SVG_ANGLETYPE_UNKNOWN: 0,
-  SVG_ANGLETYPE_UNSPECIFIED: 1,
-  SVG_ANGLETYPE_DEG: 2,
-  SVG_ANGLETYPE_RAD: 3,
-  SVG_ANGLETYPE_GRAD: 4,
-};
-
-/**
- * @description SVGMatrix is deprecated, we should use DOMMatrix instead
- * @see https://developer.mozilla.org/en-US/docs/Web/API/SVGMatrix
- */
-const SVGMatrix = {
-  a: 0,
-  b: 0,
-  c: 0,
-  d: 0,
-  e: 0,
-  f: 0,
-  flipX: jest.fn().mockImplementation(() => SVGMatrix),
-  flipY: jest.fn().mockImplementation(() => SVGMatrix),
-  inverse: jest.fn().mockImplementation(() => SVGMatrix),
-  multiply: jest.fn().mockImplementation(() => SVGMatrix),
-  rotate: jest.fn().mockImplementation(() => SVGMatrix),
-  rotateFromVector: jest.fn().mockImplementation(() => SVGMatrix),
-  scale: jest.fn().mockImplementation(() => SVGMatrix),
-  scaleNonUniform: jest.fn().mockImplementation(() => SVGMatrix),
-  skewX: jest.fn().mockImplementation(() => SVGMatrix),
-  skewY: jest.fn().mockImplementation(() => SVGMatrix),
-  translate: jest.fn().mockImplementation(() => SVGMatrix),
-};
-
-/**
- * @see https://developer.mozilla.org/en-US/docs/Web/API/SVGTransform
- */
-const SVGTransform = {
-  type: 0,
-  angle: 0,
-  matrix: SVGMatrix,
-  SVG_TRANSFORM_UNKNOWN: 0,
-  SVG_TRANSFORM_MATRIX: 1,
-  SVG_TRANSFORM_TRANSLATE: 2,
-  SVG_TRANSFORM_SCALE: 3,
-  SVG_TRANSFORM_ROTATE: 4,
-  SVG_TRANSFORM_SKEWX: 5,
-  SVG_TRANSFORM_SKEWY: 6,
-  setMatrix: jest.fn(),
-  setRotate: jest.fn(),
-  setScale: jest.fn(),
-  setSkewX: jest.fn(),
-  setSkewY: jest.fn(),
-  setTranslate: jest.fn(),
-};
-
-/**
- * @see https://developer.mozilla.org/en-US/docs/Web/API/SVGPoint
- */
-const SVGPoint = {
-  x: 0,
-  y: 0,
-  matrixTransform: jest.fn().mockImplementation(() => SVGPoint),
-};
-
-/**
- * @see https://developer.mozilla.org/en-US/docs/Web/API/SVGRect
- */
-const SVGRect = {
-  x: 0,
-  y: 0,
-  width: 0,
-  height: 0,
-};
diff --git a/packages/joint-react/package.json b/packages/joint-react/package.json
index d039bd864c..2a963922e4 100644
--- a/packages/joint-react/package.json
+++ b/packages/joint-react/package.json
@@ -92,6 +92,7 @@
     "@jest/globals": "30.1.2",
     "@joint/eslint-config": "workspace:*",
     "@joint/layout-directed-graph": "workspace:^",
+    "@joint/mock-svg": "workspace:~",
     "@reduxjs/toolkit": "^2.11.0",
     "@storybook/addon-a11y": "^10.6.2",
     "@storybook/addon-docs": "^10.6.2",
diff --git a/packages/joint-react/src/presets/__tests__/anchors.test.ts b/packages/joint-react/src/presets/__tests__/anchors.test.ts
index fa21d3ccb3..0accc2735c 100644
--- a/packages/joint-react/src/presets/__tests__/anchors.test.ts
+++ b/packages/joint-react/src/presets/__tests__/anchors.test.ts
@@ -75,6 +75,17 @@ function setupPaper(targetWithPort = false, portSide: PortSide = 'left'): Setup
   };
 }
 
+// `@joint/mock-svg` counts a node as part of the render tree only when its mocked
+// `getBBox()` is non-empty, and the mock is always empty. These suites measure magnets
+// through the DOM-measured branches, so every node is treated as rendered.
+let checkVisibilitySpy: jest.SpyInstance;
+beforeEach(() => {
+  checkVisibilitySpy = jest.spyOn(SVGElement.prototype, 'checkVisibility').mockReturnValue(true);
+});
+afterEach(() => {
+  checkVisibilitySpy.mockRestore();
+});
+
 describe('presets / anchors / centerAnchor', () => {
   it('returns center for root element magnet (uses model geometry path)', () => {
     const ctx = setupPaper();
diff --git a/packages/joint-react/src/presets/__tests__/extra-coverage.test.ts b/packages/joint-react/src/presets/__tests__/extra-coverage.test.ts
index e299e3d3fe..c51ad711c4 100644
--- a/packages/joint-react/src/presets/__tests__/extra-coverage.test.ts
+++ b/packages/joint-react/src/presets/__tests__/extra-coverage.test.ts
@@ -8,6 +8,17 @@ import { boundaryPoint, anchorPoint } from '../connection-points';
 import { LinkView } from '../link-view';
 import { Paper } from '../paper';
 
+// `@joint/mock-svg` counts a node as part of the render tree only when its mocked
+// `getBBox()` is non-empty, and the mock is always empty. These suites measure magnets
+// through the DOM-measured branches, so every node is treated as rendered.
+let checkVisibilitySpy: jest.SpyInstance;
+beforeEach(() => {
+  checkVisibilitySpy = jest.spyOn(SVGElement.prototype, 'checkVisibility').mockReturnValue(true);
+});
+afterEach(() => {
+  checkVisibilitySpy.mockRestore();
+});
+
 describe('presets / element-ports / elementPort — group-positioned', () => {
   it('omits position when neither cx nor cy is supplied', () => {
     const port = elementPort({ shape: 'rect' });
diff --git a/packages/joint-react/src/presets/__tests__/paper-button-interactions.test.tsx b/packages/joint-react/src/presets/__tests__/paper-button-interactions.test.tsx
index e0f7a2ca35..91770b1236 100644
--- a/packages/joint-react/src/presets/__tests__/paper-button-interactions.test.tsx
+++ b/packages/joint-react/src/presets/__tests__/paper-button-interactions.test.tsx
@@ -1,5 +1,6 @@
 import { useCallback } from 'react';
 import { render, waitFor } from '@testing-library/react';
+import { g, type dia } from '@joint/core';
 import { GraphProvider, Paper } from '../../components';
 import { usePaper } from '../../hooks/use-paper';
 import type { PaperView } from '../../mvc/paper';
@@ -62,6 +63,14 @@ function NodeWithButton() {
 
 const renderElement = () => <NodeWithButton />;
 
+// jsdom has no layout, so `@joint/mock-svg` maps every client point to the origin.
+// The paper sits unscaled at the client origin, so client and local points are equal.
+function clientToLocalIdentity(x: number, y: number): g.Point;
+function clientToLocalIdentity(point: dia.Point): g.Point;
+function clientToLocalIdentity(xOrPoint: number | dia.Point, y?: number): g.Point {
+  return typeof xOrPoint === 'number' ? new g.Point(xOrPoint, y) : new g.Point(xOrPoint);
+}
+
 /**
  * Mount a paper holding one element whose markup contains a `<button>`.
  * @param clickSpy - Spy for the button's React `onClick`.
@@ -87,7 +96,10 @@ async function renderNodeWithButton(
   const paper = capturedPaper;
   const button = capturedButton;
   if (!paper || !button) throw new Error('paper or button not mounted');
-  return { paper, button };
+  // Typed explicitly: the narrowing above cannot see the assignments made while rendering.
+  const mounted: { paper: PaperView; button: HTMLButtonElement } = { paper, button };
+  mounted.paper.clientToLocalPoint = clientToLocalIdentity;
+  return mounted;
 }
 
 function dispatchAt(node: EventTarget, type: string, clientX: number, clientY: number) {
diff --git a/packages/joint-react/src/store/__tests__/graph-store.test.ts b/packages/joint-react/src/store/__tests__/graph-store.test.ts
index 00d4528989..cfbc6fef33 100644
--- a/packages/joint-react/src/store/__tests__/graph-store.test.ts
+++ b/packages/joint-react/src/store/__tests__/graph-store.test.ts
@@ -129,10 +129,10 @@ describe('GraphStore', () => {
 
       // The observer measures the same size, so it writes nothing to the graph.
       const node = document.createElement('div');
+      const resizeObserverSpy = jest.spyOn(globalThis, 'ResizeObserver');
       store.measurement.observe({ id: 'a', node });
-      const [callback] = (globalThis.ResizeObserver as jest.Mock).mock.calls.at(-1) as [
-        ResizeObserverCallback,
-      ];
+      const [callback] = resizeObserverSpy.mock.calls.at(-1) as [ResizeObserverCallback];
+      resizeObserverSpy.mockRestore();
       const entry = { target: node, borderBoxSize: [{ inlineSize: 120, blockSize: 40 }] };
       callback([entry as unknown as ResizeObserverEntry], {} as ResizeObserver);
       await flush();
diff --git a/yarn.lock b/yarn.lock
index bb7cdec86d..bb90f7c32a 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -6064,6 +6064,7 @@ __metadata:
     "@joint/core": "workspace:^"
     "@joint/eslint-config": "workspace:*"
     "@joint/layout-directed-graph": "workspace:^"
+    "@joint/mock-svg": "workspace:~"
     "@reduxjs/toolkit": "npm:^2.11.0"
     "@storybook/addon-a11y": "npm:^10.6.2"
     "@storybook/addon-docs": "npm:^10.6.2"