diff --git a/packages/studio/tests/e2e/edit-accuracy/case.mjs b/packages/studio/tests/e2e/edit-accuracy/case.mjs
index 5fb2dc36d3..9cf4930d9f 100644
--- a/packages/studio/tests/e2e/edit-accuracy/case.mjs
+++ b/packages/studio/tests/e2e/edit-accuracy/case.mjs
@@ -2,7 +2,7 @@
 import { spawn } from "node:child_process";
 import { readFileSync } from "node:fs";
 import { join } from "node:path";
-import { COMPOSITION, PLAYHEAD } from "./grid.mjs";
+import { COMPOSITION, FIXTURE_CDN, PLAYHEAD, localAsset } from "./grid.mjs";
 import {
   angleOf,
   centre,
@@ -772,6 +772,34 @@ async function nudgeGesture(ctx, pre) {
   };
 }
 
+const blockedCdnUrls = new Set();
+
+/** Serves the fixtures' CDN requests from the repo; any other CDN URL is blocked and named once. */
+async function serveFixtureAssetsLocally(page) {
+  const cdp = await page.createCDPSession();
+  cdp.on("Fetch.requestPaused", ({ requestId, request }) => {
+    const file = localAsset(request.url);
+    if (!file) {
+      if (!blockedCdnUrls.has(request.url)) console.warn(`edit bench: blocked ${request.url}`);
+      blockedCdnUrls.add(request.url);
+      cdp
+        .send("Fetch.failRequest", { requestId, errorReason: "BlockedByClient" })
+        .catch(() => undefined);
+      return;
+    }
+    // A request whose frame went away rejects; that must not end the run.
+    cdp
+      .send("Fetch.fulfillRequest", {
+        requestId,
+        responseCode: 200,
+        responseHeaders: [{ name: "Content-Type", value: "text/javascript" }],
+        body: readFileSync(file).toString("base64"),
+      })
+      .catch(() => undefined);
+  });
+  await cdp.send("Fetch.enable", { patterns: [{ urlPattern: `${FIXTURE_CDN}*` }] });
+}
+
 /**
  * Studio open on the case in a fresh browser context, snapping off, at the case's zoom, target selected;
  * `drive` measures the rest. A failure keeps a screenshot, and the context always closes.
@@ -779,6 +807,7 @@ async function nudgeGesture(ctx, pre) {
 export async function inStudio({ browser, spec, dir, files, url, evidence }, drive) {
   const context = await browser.createBrowserContext();
   const page = await context.newPage();
+  await serveFixtureAssetsLocally(page);
   const ctx = {
     page,
     dir,
diff --git a/packages/studio/tests/e2e/edit-accuracy/grid.mjs b/packages/studio/tests/e2e/edit-accuracy/grid.mjs
index 6c06792708..df4c5a7522 100644
--- a/packages/studio/tests/e2e/edit-accuracy/grid.mjs
+++ b/packages/studio/tests/e2e/edit-accuracy/grid.mjs
@@ -1,7 +1,8 @@
 // The edit accuracy grid: one flat-coloured element in a generated project, crossed with one gesture.
 // Projects are written to a tmp dir per case; nothing checked in is edited.
-import { mkdirSync, writeFileSync } from "node:fs";
-import { join } from "node:path";
+import { mkdirSync, statSync, writeFileSync } from "node:fs";
+import { createRequire } from "node:module";
+import { dirname, join } from "node:path";
 import { dragCases } from "./drags.mjs";
 
 export const COMPOSITION = { width: 1920, height: 1080 };
@@ -10,7 +11,19 @@ export const PLAYHEAD = 1;
 export const TARGET = { width: 240, height: 160, color: "#f0c020" };
 export const BACKGROUND = "#202020";
 const NESTED_HOST = { left: 160, top: 90, width: 1600, height: 900 };
-const GSAP_CDN = "https://cdn.jsdelivr.net/npm/gsap@3.14.2/dist/gsap.min.js";
+// Fixtures keep the CDN URL users author; the bench serves it from the repo's gsap (`localAsset`).
+const require = createRequire(import.meta.url);
+export const FIXTURE_CDN = "https://cdn.jsdelivr.net/";
+const GSAP_DIST = `${FIXTURE_CDN}npm/gsap@${require("gsap/package.json").version}/dist/`;
+const GSAP_CDN = `${GSAP_DIST}gsap.min.js`;
+const LOCAL_GSAP_DIST = dirname(require.resolve("gsap/dist/gsap.min.js"));
+
+/** The repo file a CDN URL is served from (the installed gsap's dist), so no case waits on the network. */
+export function localAsset(url) {
+  if (!url.startsWith(GSAP_DIST)) return undefined;
+  const file = join(LOCAL_GSAP_DIST, url.slice(GSAP_DIST.length));
+  return statSync(file, { throwIfNoEntry: false })?.isFile() ? file : undefined;
+}
 
 // Studio has corner handles only (ResizeHandle is nw|ne|sw|se); its edge strips crop, so there is no edge resize.
 const GESTURES = ["move", "resize", "rotate", "crop", "nudge"];
diff --git a/packages/studio/tests/e2e/edit-accuracy/grid.test.mjs b/packages/studio/tests/e2e/edit-accuracy/grid.test.mjs
new file mode 100644
index 0000000000..e10153ae85
--- /dev/null
+++ b/packages/studio/tests/e2e/edit-accuracy/grid.test.mjs
@@ -0,0 +1,30 @@
+import { mkdtempSync, readdirSync, readFileSync, rmSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { describe, expect, it } from "vitest";
+import { FIXTURE_CDN, buildGrid, localAsset, writeFixture } from "./grid.mjs";
+
+function fixtureUrls(spec) {
+  const dir = mkdtempSync(join(tmpdir(), "edit-bench-urls-"));
+  writeFixture(spec, dir);
+  const pages = readdirSync(dir, { recursive: true }).filter((f) => String(f).endsWith(".html"));
+  const urls = pages.flatMap((f) =>
+    [...readFileSync(join(dir, String(f)), "utf8").matchAll(/https?:\/\/[^"'\s)]+/g)].map(
+      (m) => m[0],
+    ),
+  );
+  rmSync(dir, { recursive: true });
+  return urls;
+}
+
+// Only the CDN host is intercepted, so a mapped URL anywhere else would still reach the network.
+const servedLocally = (url) => url.startsWith(FIXTURE_CDN) && localAsset(url) !== undefined;
+
+describe("grid fixtures", () => {
+  it("reference only URLs the bench serves from the repo", () => {
+    const unserved = buildGrid("full")
+      .flatMap(fixtureUrls)
+      .filter((url) => !servedLocally(url));
+    expect([...new Set(unserved)]).toEqual([]);
+  }, 30_000);
+});