diff --git a/components/BuilderClientPage.tsx b/components/BuilderClientPage.tsx
index 66a27d3..a0b1e5d 100644
--- a/components/BuilderClientPage.tsx
+++ b/components/BuilderClientPage.tsx
@@ -8,6 +8,7 @@ import { AssetManager } from '@/lib/assets/assetManager'
 import { buildZip } from '@/lib/exporter/zip'
 import { buildExtrasForPage } from '@/lib/exporter/extras'
 import { buildAssetsMetadata } from '@/lib/exporter/assets.meta'
+import { buildAssetsIndex } from '@/lib/exporter/assets.index'
 import type { Section } from '@/lib/state/store'
 import { createFormStore, type FormState } from '@/lib/state/formStore'
 import FormBuilderPanel from '@/components/FormBuilderPanel'
@@ -56,6 +57,7 @@ export default function BuilderClientPage() {
   const [manifestDisplay, setManifestDisplay] = useState<string>('')
   const [manifestThemeColor, setManifestThemeColor] = useState<string>('')
   const [robotsDisallow, setRobotsDisallow] = useState<string>('')
+  const [sheetsMode, setSheetsMode] = useState<'auto' | 'include' | 'exclude'>('auto')
   const [viewport, setViewport] = useState<'desktop' | 'mobile'>(() => {
     if (typeof window !== 'undefined') {
       try {
@@ -238,14 +240,14 @@ export default function BuilderClientPage() {
       const disallowLines = lines.map((l) => (l.startsWith('Disallow:') ? l : `Disallow: ${l}`))
       return `User-agent: *\n${disallowLines.join('\n')}`
     })()
-    const baseExtras = buildExtrasForPage(valid, { robotsText: robotsTextOverride, manifest: manifestOverride })
+    const baseExtras = buildExtrasForPage(valid, { robotsText: robotsTextOverride, manifest: manifestOverride, sheetsMode })
     const extras: Record<string, Uint8Array> = {
       ...baseExtras,
-      ...(am ? { 'assets.json': buildAssetsMetadata(am) } : {}),
+      ...(am ? { 'assets.json': buildAssetsMetadata(am), 'assets.index.json': buildAssetsIndex(am) } : {}),
     }
     const zipBytes = await buildZip({ html: exported.html, css: exported.css, js: exported.js, assets, extras })
     download('landing.zip', zipBytes)
-  }, [pageData, am, manifestName, manifestShortName, manifestStartUrl, manifestDisplay, manifestThemeColor, robotsDisallow])
+  }, [pageData, am, manifestName, manifestShortName, manifestStartUrl, manifestDisplay, manifestThemeColor, robotsDisallow, sheetsMode])
 
   return (
     <div className="p-6 space-y-6">
@@ -381,6 +383,20 @@ export default function BuilderClientPage() {
                   placeholder="/private\n/tmp"
                 />
               </label>
+              <label className="block" htmlFor="ins-sheets-mode">
+                <span className="sr-only">Google Sheets Template Mode</span>
+                <select
+                  id="ins-sheets-mode"
+                  aria-label="Google Sheets Template Mode"
+                  className="border rounded px-3 py-2 w-full"
+                  value={sheetsMode}
+                  onChange={(e) => setSheetsMode(e.target.value as 'auto'|'include'|'exclude')}
+                >
+                  <option value="auto">Sheets Template: Auto</option>
+                  <option value="include">Sheets Template: Include</option>
+                  <option value="exclude">Sheets Template: Exclude</option>
+                </select>
+              </label>
             </div>
           </div>
         }
diff --git a/lib/exporter/extras.ts b/lib/exporter/extras.ts
index 84cd4dd..cfc2b1c 100644
--- a/lib/exporter/extras.ts
+++ b/lib/exporter/extras.ts
@@ -9,6 +9,7 @@ export type ExtrasOverrides = {
     display: string
     theme_color: string
   }>
+  sheetsMode?: 'auto' | 'include' | 'exclude'
 }
 
 function toBytes(s: string): Uint8Array {
@@ -42,10 +43,12 @@ export function buildExtrasForPage(page: Page, overrides?: ExtrasOverrides): Rec
   const manifestJson = JSON.stringify(manifestMerged, null, 2)
   out['site.webmanifest'] = toBytes(manifestJson)
 
-  // Google Sheets 템플릿: actionUrl 미지정 시 포함
+  // Google Sheets 템플릿: 기본 auto. overrides.sheetsMode로 강제 포함/제외 가능
+  const mode = overrides?.sheetsMode ?? 'auto'
   const action = page.form?.actionUrl?.trim()
   const hasAction = !!(action && action.length > 0)
-  if (!hasAction) {
+  const shouldInclude = mode === 'include' || (mode === 'auto' && !hasAction)
+  if (shouldInclude) {
     const code = `/**
  * Google Apps Script Web App for form submissions
  * - Deploy as Web App and set URL as form action if needed.