diff --git a/skills/embedded-captions/scripts/preview-frames.cjs b/skills/embedded-captions/scripts/preview-frames.cjs
index 56131d7bfd..43265de85f 100644
--- a/skills/embedded-captions/scripts/preview-frames.cjs
+++ b/skills/embedded-captions/scripts/preview-frames.cjs
@@ -23,6 +23,15 @@
 const path = require("path");
 const fs = require("fs");
 const os = require("os");
+const { pathToFileURL } = require("url");
+
+function stripGsapSri(html) {
+  return html.replace(/<script\b[^>]*\bsrc=["'][^"']*gsap[^"']*["'][^>]*>/gi, (tag) =>
+    tag
+      .replace(/\s+integrity\s*=\s*(?:"[^"]*"|'[^']*')/gi, "")
+      .replace(/\s+crossorigin\s*=\s*(?:"[^"]*"|'[^']*')/gi, ""),
+  );
+}
 
 const HF_ROOTS = [
   process.env.HYPERFRAMES_ROOT,
@@ -66,7 +75,7 @@ for (const r of HF_ROOTS) {
     if (g) gsapSource = fs.readFileSync(g, "utf8");
   }
 }
-if (!puppeteer || !sharp) {
+if (require.main === module && (!puppeteer || !sharp)) {
   console.error("[preview] need puppeteer+sharp — set HYPERFRAMES_ROOT");
   process.exit(0);
 }
@@ -80,9 +89,13 @@ async function shotAt(browser, file, W, H, t) {
     // evaluation runs while document.head is still null, and gsap's init then
     // throws "appendChild of null" — which killed previews for theme projects.
     await page.setRequestInterception(true);
+    const documentUrl = pathToFileURL(file).href;
+    const documentHtml = stripGsapSri(fs.readFileSync(file, "utf8"));
     page.on("request", (req) => {
       const u = req.url();
-      if (req.resourceType() === "script" && /gsap/i.test(u) && /^https?:/i.test(u)) {
+      if (req.isNavigationRequest() && u === documentUrl) {
+        req.respond({ status: 200, contentType: "text/html", body: documentHtml });
+      } else if (req.resourceType() === "script" && /gsap/i.test(u) && /^https?:/i.test(u)) {
         if (gsapSource)
           req.respond({ status: 200, contentType: "application/javascript", body: gsapSource });
         else req.continue(); // no local bundle — let the CDN load (online machines)
@@ -90,7 +103,7 @@ async function shotAt(browser, file, W, H, t) {
         req.abort(); // a-roll pixels come from frames_bg
       else req.continue();
     });
-    await page.goto(`file://${file}`, { waitUntil: "load", timeout: 15000 });
+    await page.goto(documentUrl, { waitUntil: "load", timeout: 15000 });
     const t0 = Date.now();
     let tlReady = false;
     while (Date.now() - t0 < 15000) {
@@ -260,9 +273,13 @@ async function main() {
     await Promise.race([browser.close().catch(() => {}), new Promise((r) => setTimeout(r, 8000))]);
   }
 }
-main()
-  .then(() => process.exit(0))
-  .catch((e) => {
-    console.error("[preview]", e.message);
-    process.exit(1);
-  });
+if (require.main === module) {
+  main()
+    .then(() => process.exit(0))
+    .catch((e) => {
+      console.error("[preview]", e.message);
+      process.exit(1);
+    });
+}
+
+module.exports = { stripGsapSri };
diff --git a/skills/embedded-captions/scripts/preview-frames.test.cjs b/skills/embedded-captions/scripts/preview-frames.test.cjs
new file mode 100644
index 0000000000..5d3f8ca4a5
--- /dev/null
+++ b/skills/embedded-captions/scripts/preview-frames.test.cjs
@@ -0,0 +1,15 @@
+const assert = require("node:assert/strict");
+const test = require("node:test");
+const { stripGsapSri } = require("./preview-frames.cjs");
+
+test("removes SRI attributes only from GSAP script tags", () => {
+  const html = `
+    <script src="https://cdn.example/gsap@3.14.2/gsap.min.js" integrity="sha384-old" crossorigin="anonymous"></script>
+    <script src="https://cdn.example/app.js" integrity="sha384-app" crossorigin="anonymous"></script>
+  `;
+  const result = stripGsapSri(html);
+
+  assert.match(result, /gsap\.min\.js"><\/script>/);
+  assert.match(result, /app\.js" integrity="sha384-app" crossorigin="anonymous"/);
+  assert.doesNotMatch(result.match(/<script[^>]*gsap[^>]*>/i)[0], /integrity|crossorigin/i);
+});