diff --git a/client/src/components/Artifacts/ArtifactPreview.tsx b/client/src/components/Artifacts/ArtifactPreview.tsx
index c125889c88..8257f76887 100644
--- a/client/src/components/Artifacts/ArtifactPreview.tsx
+++ b/client/src/components/Artifacts/ArtifactPreview.tsx
@@ -6,7 +6,7 @@ import type {
 } from '@codesandbox/sandpack-react/unstyled';
 import type { TStartupConfig } from 'librechat-data-provider';
 import type { ArtifactFiles } from '~/common';
-import { sharedFiles, sharedOptions } from '~/utils/artifacts';
+import { sharedFiles, buildSandpackOptions } from '~/utils/artifacts';
 
 export const ArtifactPreview = memo(function ({
   files,
@@ -39,15 +39,10 @@ export const ArtifactPreview = memo(function ({
     };
   }, [currentCode, files, fileKey]);
 
-  const options: typeof sharedOptions = useMemo(() => {
-    if (!startupConfig) {
-      return sharedOptions;
-    }
-    return {
-      ...sharedOptions,
-      bundlerURL: template === 'static' ? startupConfig.staticBundlerURL : startupConfig.bundlerURL,
-    };
-  }, [startupConfig, template]);
+  const options: SandpackProviderProps['options'] = useMemo(
+    () => buildSandpackOptions(template, startupConfig),
+    [startupConfig, template],
+  );
 
   if (Object.keys(artifactFiles).length === 0) {
     return null;
diff --git a/client/src/utils/__tests__/artifacts.test.ts b/client/src/utils/__tests__/artifacts.test.ts
new file mode 100644
index 0000000000..bf5c1919c7
--- /dev/null
+++ b/client/src/utils/__tests__/artifacts.test.ts
@@ -0,0 +1,38 @@
+import { buildSandpackOptions } from '../artifacts';
+
+const TAILWIND_CDN = 'https://cdn.tailwindcss.com/3.4.17#tailwind.js';
+
+describe('buildSandpackOptions', () => {
+  it('includes externalResources with .js fragment hint for static template', () => {
+    const options = buildSandpackOptions('static');
+    expect(options?.externalResources).toEqual([TAILWIND_CDN]);
+  });
+
+  it('includes externalResources for react-ts template', () => {
+    const options = buildSandpackOptions('react-ts');
+    expect(options?.externalResources).toEqual([TAILWIND_CDN]);
+  });
+
+  it('uses staticBundlerURL when template is static and config is provided', () => {
+    const config = { staticBundlerURL: 'https://static.example.com' } as Parameters<
+      typeof buildSandpackOptions
+    >[1];
+    const options = buildSandpackOptions('static', config);
+    expect(options?.bundlerURL).toBe('https://static.example.com');
+    expect(options?.externalResources).toEqual([TAILWIND_CDN]);
+  });
+
+  it('uses bundlerURL when template is react-ts and config is provided', () => {
+    const config = { bundlerURL: 'https://bundler.example.com' } as Parameters<
+      typeof buildSandpackOptions
+    >[1];
+    const options = buildSandpackOptions('react-ts', config);
+    expect(options?.bundlerURL).toBe('https://bundler.example.com');
+    expect(options?.externalResources).toEqual([TAILWIND_CDN]);
+  });
+
+  it('returns base options without bundlerURL when no config is provided', () => {
+    const options = buildSandpackOptions('react-ts');
+    expect(options?.bundlerURL).toBeUndefined();
+  });
+});
diff --git a/client/src/utils/artifacts.ts b/client/src/utils/artifacts.ts
index 793bc484bc..2ca02422a2 100644
--- a/client/src/utils/artifacts.ts
+++ b/client/src/utils/artifacts.ts
@@ -4,6 +4,7 @@ import type {
   SandpackProviderProps,
   SandpackPredefinedTemplate,
 } from '@codesandbox/sandpack-react';
+import type { TStartupConfig } from 'librechat-data-provider';
 
 const artifactFilename = {
   'application/vnd.react': 'App.tsx',
@@ -138,10 +139,29 @@ export function getProps(type: string): Partial<SandpackProviderProps> {
   };
 }
 
+/** Fragment hint lets Sandpack's static-template regex detect `.js` from the URL;
+ * without it, the versioned CDN path (`/3.4.17`) has no recognised extension and
+ * `injectExternalResources` throws "Unable to determine file type". */
+const TAILWIND_CDN = 'https://cdn.tailwindcss.com/3.4.17#tailwind.js';
+
 export const sharedOptions: SandpackProviderProps['options'] = {
-  externalResources: ['https://cdn.tailwindcss.com/3.4.17'],
+  externalResources: [TAILWIND_CDN],
 };
 
+export function buildSandpackOptions(
+  template: SandpackProviderProps['template'],
+  startupConfig?: TStartupConfig,
+): SandpackProviderProps['options'] {
+  if (!startupConfig) {
+    return sharedOptions;
+  }
+
+  return {
+    ...sharedOptions,
+    bundlerURL: template === 'static' ? startupConfig.staticBundlerURL : startupConfig.bundlerURL,
+  };
+}
+
 export const sharedFiles = {
   '/lib/utils.ts': shadcnComponents.utils,
   '/components/ui/accordion.tsx': shadcnComponents.accordian,