diff --git a/package.json b/package.json
index 99d9b751db..d3c3fce3a0 100644
--- a/package.json
+++ b/package.json
@@ -48,7 +48,7 @@
     "player:perf": "bun run --filter @hyperframes/player perf",
     "format:check": "oxfmt --check .",
     "knip": "knip",
-    "test:scripts": "node --import tsx --test scripts/animejs-v4-guidance.test.mjs scripts/check-tracked-artifacts.test.mjs scripts/check-no-main-deletions.test.mjs scripts/check-docs-snippet-motion.test.mjs scripts/registry-target-paths.test.mjs scripts/check-workspace-contracts.test.mjs scripts/check-package-cycles.test.mjs scripts/check-cli-process-ownership.test.mjs scripts/check-large-files.test.mjs scripts/package-subpaths.test.mjs scripts/validate-release-channel.test.mjs scripts/publish-workflow.test.mjs scripts/install-workspace-dependencies.test.mjs scripts/draft-changelog.test.ts scripts/set-version.test.ts scripts/release-prepare.test.ts scripts/cli-options.test.ts scripts/changelog-weekly.test.ts scripts/claude-plugin-compression.test.ts scripts/catalog-payload-assets.test.ts scripts/host-registry-assets.test.ts scripts/catalog-preview-temp.test.ts scripts/player-cdn-pin.test.ts scripts/studio-runtime-smoke.test.mjs scripts/verify-packed-manifests.test.mjs scripts/lint-skills.test.mjs packages/gcp-cloud-run/check-dockerfile-workspaces.test.mjs packages/core/scripts/writeGeneratedFile.test.ts && vitest run scripts/catalog/",
+    "test:scripts": "node --import tsx --test scripts/animejs-v4-guidance.test.mjs scripts/check-tracked-artifacts.test.mjs scripts/check-no-main-deletions.test.mjs scripts/check-docs-snippet-motion.test.mjs scripts/registry-target-paths.test.mjs scripts/check-workspace-contracts.test.mjs scripts/check-package-cycles.test.mjs scripts/check-cli-process-ownership.test.mjs scripts/check-large-files.test.mjs scripts/package-subpaths.test.mjs scripts/validate-release-channel.test.mjs scripts/publish-workflow.test.mjs scripts/install-workspace-dependencies.test.mjs scripts/draft-changelog.test.ts scripts/set-version.test.ts scripts/release-prepare.test.ts scripts/cli-options.test.ts scripts/changelog-weekly.test.ts scripts/claude-plugin-compression.test.ts scripts/catalog-payload-assets.test.ts scripts/host-registry-assets.test.ts scripts/catalog-preview-temp.test.ts scripts/catalog-hosted-files.test.ts scripts/player-cdn-pin.test.ts scripts/studio-runtime-smoke.test.mjs scripts/verify-packed-manifests.test.mjs scripts/lint-skills.test.mjs packages/gcp-cloud-run/check-dockerfile-workspaces.test.mjs packages/core/scripts/writeGeneratedFile.test.ts && vitest run scripts/catalog/",
     "typecheck:scripts": "tsc --noEmit -p scripts/tsconfig.json",
     "test:skills": "node --test 'skills/**/*.test.mjs'",
     "generate:previews": "tsx scripts/generate-template-previews.ts",
diff --git a/scripts/catalog-hosted-files.test.ts b/scripts/catalog-hosted-files.test.ts
new file mode 100644
index 0000000000..bbec485f42
--- /dev/null
+++ b/scripts/catalog-hosted-files.test.ts
@@ -0,0 +1,155 @@
+import assert from "node:assert/strict";
+import { mkdtempSync, readFileSync, readdirSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { test } from "node:test";
+import { fetchHostedFiles } from "./catalog-hosted-files.js";
+
+function fixture(url = "https://static.heygen.ai/asset", path = "asset.bin") {
+  const root = mkdtempSync(join(tmpdir(), "hf-hosted-test-"));
+  writeFileSync(join(root, "registry-item.json"), JSON.stringify({ files: [{ url, path }] }));
+  return root;
+}
+
+test("downloads exact bytes through a relative CDN redirect", async (t) => {
+  const root = fixture();
+  const calls: string[] = [];
+  t.mock.method(
+    globalThis,
+    "fetch",
+    async (url: Parameters<typeof fetch>[0], options?: RequestInit) => {
+      calls.push(String(url));
+      assert.equal(options?.redirect, "manual");
+      assert.ok(options?.signal);
+      return calls.length === 1
+        ? new Response(null, { status: 302, headers: { location: "/final" } })
+        : new Response(new Uint8Array([0, 255, 42]));
+    },
+  );
+  try {
+    await fetchHostedFiles(root);
+    assert.deepEqual(calls, ["https://static.heygen.ai/asset", "https://static.heygen.ai/final"]);
+    assert.deepEqual(readFileSync(join(root, "asset.bin")), Buffer.from([0, 255, 42]));
+  } finally {
+    rmSync(root, { recursive: true, force: true });
+  }
+});
+
+for (const location of [
+  "http://169.254.169.254/meta",
+  "https://localhost/x",
+  "https://static.heygen.ai.evil.test/x",
+  "http://static.heygen.ai/x",
+]) {
+  test(`rejects redirect to ${location} before a second request`, async (t) => {
+    const root = fixture();
+    const mock = t.mock.method(
+      globalThis,
+      "fetch",
+      async () => new Response(null, { status: 302, headers: { location } }),
+    );
+    try {
+      await assert.rejects(fetchHostedFiles(root), /HTTPS CDN/);
+      assert.equal(mock.mock.callCount(), 1);
+      assert.deepEqual(readdirSync(root), ["registry-item.json"]);
+    } finally {
+      rmSync(root, { recursive: true, force: true });
+    }
+  });
+}
+
+for (const url of [
+  "https://127.0.0.1/x",
+  "https://user:pw@static.heygen.ai/x",
+  "https://static.heygen.ai:8443/x",
+]) {
+  test(`rejects disallowed initial URL ${url} without a request`, async (t) => {
+    const root = fixture(url);
+    const mock = t.mock.method(globalThis, "fetch", async () => assert.fail("unexpected request"));
+    try {
+      await assert.rejects(fetchHostedFiles(root), /HTTPS CDN/);
+      assert.equal(mock.mock.callCount(), 0);
+    } finally {
+      rmSync(root, { recursive: true, force: true });
+    }
+  });
+}
+
+test("enforces actual streaming bytes even when Content-Length understates them", async (t) => {
+  const root = fixture();
+  let cancelled = false;
+  let chunks = 0;
+  const chunk = new Uint8Array(129 * 1024 * 1024);
+  t.mock.method(
+    globalThis,
+    "fetch",
+    async () =>
+      new Response(
+        new ReadableStream({
+          pull(controller) {
+            if (chunks++ < 3) controller.enqueue(chunk);
+            else controller.close();
+          },
+          cancel() {
+            cancelled = true;
+          },
+        }),
+        { headers: { "content-length": "1" } },
+      ),
+  );
+  try {
+    await assert.rejects(fetchHostedFiles(root), /256 MiB/);
+    assert.equal(cancelled, true);
+    assert.deepEqual(readdirSync(root), ["registry-item.json"]);
+  } finally {
+    rmSync(root, { recursive: true, force: true });
+  }
+});
+
+for (const mode of ["declared oversize", "loop", "HTTP error", "stream error"]) {
+  test(`${mode} preserves the existing asset`, async (t) => {
+    const root = fixture();
+    writeFileSync(join(root, "asset.bin"), "previous");
+    let calls = 0;
+    let cancelled = false;
+    t.mock.method(globalThis, "fetch", async () => {
+      calls++;
+      const body = new ReadableStream({
+        start(controller) {
+          if (mode === "stream error") controller.error(new Error("broken stream"));
+        },
+        cancel() {
+          cancelled = true;
+        },
+      });
+      if (mode === "loop")
+        return new Response(body, { status: 302, headers: { location: "/asset" } });
+      if (mode === "HTTP error") return new Response(body, { status: 500 });
+      return new Response(body, {
+        headers: {
+          "content-length": mode === "declared oversize" ? String(257 * 1024 * 1024) : "1",
+        },
+      });
+    });
+    try {
+      await assert.rejects(fetchHostedFiles(root), /256 MiB|redirect limit|HTTP 500|broken stream/);
+      assert.equal(readFileSync(join(root, "asset.bin"), "utf8"), "previous");
+      assert.equal(calls, mode === "loop" ? 6 : 1);
+      if (mode !== "stream error") assert.equal(cancelled, true);
+    } finally {
+      rmSync(root, { recursive: true, force: true });
+    }
+  });
+}
+
+test("skips manifest paths outside the copied project before fetching", async (t) => {
+  const root = fixture("https://static.heygen.ai/asset", "../escape.bin");
+  const mock = t.mock.method(globalThis, "fetch", async () => assert.fail("unexpected request"));
+  try {
+    await fetchHostedFiles(root);
+    assert.equal(mock.mock.callCount(), 0);
+    assert.deepEqual(readdirSync(root), ["registry-item.json"]);
+  } finally {
+    rmSync(root, { recursive: true, force: true });
+  }
+});
diff --git a/scripts/catalog-hosted-files.ts b/scripts/catalog-hosted-files.ts
new file mode 100644
index 0000000000..7fc76702e9
--- /dev/null
+++ b/scripts/catalog-hosted-files.ts
@@ -0,0 +1,93 @@
+import { existsSync, readFileSync, realpathSync, mkdirSync, writeFileSync } from "node:fs";
+import { dirname, join, resolve } from "node:path";
+import { isContainedIn } from "./registry-target-paths.mjs";
+
+// All published registry assets use this CDN. Keep every redirect on the same
+// HTTPS origin; a contributor manifest must not select a runner-local service.
+const ASSET_ORIGIN = "https://static.heygen.ai";
+// Match the media-freeze ceiling to allow future video assets while bounding runner memory.
+const MAX_ASSET_BYTES = 256 * 1024 * 1024;
+
+function assertCdnUrl(url: URL): void {
+  if (url.origin !== ASSET_ORIGIN || url.username || url.password) {
+    throw new Error("Hosted asset URL must use the registry HTTPS CDN");
+  }
+}
+
+async function readHostedBody(response: Response): Promise<Uint8Array> {
+  await validateResponse(response);
+  const chunks: Uint8Array[] = [];
+  let bytes = 0;
+  if (response.body) {
+    for await (const chunk of response.body) {
+      bytes += chunk.byteLength;
+      if (bytes > MAX_ASSET_BYTES) throw new Error("Hosted asset exceeds 256 MiB");
+      chunks.push(chunk);
+    }
+  }
+  return Buffer.concat(chunks, bytes);
+}
+
+async function validateResponse(response: Response): Promise<void> {
+  if (!response.ok) {
+    await response.body?.cancel();
+    throw new Error(`Hosted asset fetch failed: HTTP ${response.status}`);
+  }
+  if (Number(response.headers.get("content-length")) > MAX_ASSET_BYTES) {
+    await response.body?.cancel();
+    throw new Error("Hosted asset exceeds 256 MiB");
+  }
+}
+
+async function redirectTarget(response: Response, current: URL): Promise<URL> {
+  await response.body?.cancel();
+  const location = response.headers.get("location");
+  if (!location) throw new Error("Hosted asset redirect has no Location");
+  return new URL(location, current);
+}
+
+async function fetchHostedAsset(url: string): Promise<Uint8Array> {
+  const signal = AbortSignal.timeout(120_000);
+  let current = new URL(url);
+  for (let hop = 0; hop <= 5; hop++) {
+    assertCdnUrl(current);
+    const response = await fetch(current.href, { redirect: "manual", signal });
+    if (response.status >= 300 && response.status < 400) {
+      current = await redirectTarget(response, current);
+    } else {
+      return readHostedBody(response);
+    }
+  }
+  throw new Error("Hosted asset exceeded redirect limit");
+}
+
+interface HostedFile {
+  path: string;
+  url: string;
+}
+
+function hasHostedFields(file: { path?: string; url?: string }): file is HostedFile {
+  return typeof file.path === "string" && typeof file.url === "string";
+}
+
+function hostedFilesOf(root: string): HostedFile[] {
+  const manifestPath = join(root, "registry-item.json");
+  if (!existsSync(manifestPath)) return [];
+  const manifest = JSON.parse(readFileSync(manifestPath, "utf8")) as {
+    files?: { path?: string; url?: string }[];
+  };
+  return (manifest.files ?? [])
+    .filter(hasHostedFields)
+    .filter((file) => file.url.startsWith("https://") && isContainedIn(root, file.path));
+}
+
+/** Materialize manifest-hosted bytes only inside the copied preview project. */
+export async function fetchHostedFiles(projectDir: string): Promise<void> {
+  const root = realpathSync(projectDir);
+  for (const file of hostedFilesOf(root)) {
+    const bytes = await fetchHostedAsset(file.url);
+    const destination = resolve(root, file.path);
+    mkdirSync(dirname(destination), { recursive: true });
+    writeFileSync(destination, bytes);
+  }
+}
diff --git a/scripts/generate-catalog-previews.ts b/scripts/generate-catalog-previews.ts
index 03d01b8827..002aa3ea05 100644
--- a/scripts/generate-catalog-previews.ts
+++ b/scripts/generate-catalog-previews.ts
@@ -42,7 +42,8 @@ import {
   executeRenderJob,
 } from "../packages/producer/src/index.js";
 import { compileForRender } from "../packages/producer/src/services/htmlCompiler.js";
-import { isContainedIn, resolveContainedCopies } from "./registry-target-paths.mjs";
+import { resolveContainedCopies } from "./registry-target-paths.mjs";
+import { fetchHostedFiles } from "./catalog-hosted-files.js";
 import { withHostedDefaults } from "./registry-hosted-assets.ts";
 import type { RegistryItem } from "../packages/core/src/index.js";
 import { openOpaqueCapture } from "./preview-capture.js";
@@ -132,45 +133,6 @@ function outputDir(kind: ItemKind): string {
   return resolve(repoRoot, "docs/images/catalog", typeDir);
 }
 
-/**
- * Download the item's CDN-hosted files into the copied project.
- *
- * `cpSync` only carries what is committed. A file declaring `url` deliberately
- * is not, so without this the preview renders the composition with every image
- * missing and the failure looks like a layout bug rather than an absent file.
- *
- * Same containment rule as the target mirror, and for the same reason: this
- * runs on `pull_request`, so `files[].path` is a contributor's string deciding
- * where bytes land on the runner.
- */
-function hostedFilesOf(projectDir: string): { path: string; url: string }[] {
-  const manifestPath = join(projectDir, "registry-item.json");
-  if (!existsSync(manifestPath)) return [];
-
-  const manifest = JSON.parse(readFileSync(manifestPath, "utf-8")) as {
-    files?: { path?: string; url?: string }[];
-  };
-  return (manifest.files ?? []).filter(
-    (file): file is { path: string; url: string } =>
-      typeof file.path === "string" &&
-      typeof file.url === "string" &&
-      file.url.startsWith("https://") &&
-      isContainedIn(projectDir, file.path),
-  );
-}
-
-async function fetchHostedFiles(projectDir: string): Promise<void> {
-  for (const file of hostedFilesOf(projectDir)) {
-    const res = await fetch(file.url);
-    if (!res.ok) {
-      throw new Error(`Hosted asset fetch failed: ${file.url} — HTTP ${res.status}`);
-    }
-    const destPath = resolve(projectDir, file.path);
-    mkdirSync(dirname(destPath), { recursive: true });
-    writeFileSync(destPath, new Uint8Array(await res.arrayBuffer()));
-  }
-}
-
 /**
  * Rewrite the composition's variable defaults from local names to CDN URLs.
  *