diff --git a/src/app/api/stores/[storeId]/route.ts b/src/app/api/stores/[storeId]/route.ts
index c7e8fd1..84977bf 100644
--- a/src/app/api/stores/[storeId]/route.ts
+++ b/src/app/api/stores/[storeId]/route.ts
@@ -137,11 +137,90 @@ export async function PATCH(
 
         await prisma.store.update({
             where: { id: storeId },
-            data: {
-                storefrontChatEnabled
-            }
+            data: { storefrontChatEnabled } as any
         })
 
+        // Best-effort: keep a Shopify ScriptTag in sync with the checkbox.
+        // Even if ScriptTag operations fail (missing scopes), the widget still
+        // won’t render because /api/storefront-chat/config returns the flag.
+        try {
+            const appBaseUrl = (process.env.NEXT_PUBLIC_APP_URL || "").trim()
+            const apiVersion = "2024-01"
+            const injectorBase = appBaseUrl ? appBaseUrl.replace(/\/$/, "") : ""
+
+            const cleanDomain = (store.shopifyDomain || "")
+                .trim()
+                .replace(/^https?:\/\//, "")
+                .replace(/\/$/, "")
+                .trim()
+
+            const accessToken = store.shopifyAccessToken
+
+            if (injectorBase && cleanDomain && accessToken) {
+                const injectorSrc = `${injectorBase}/storefront-chat/widget-injector`
+                const listUrl = `https://${cleanDomain}/admin/api/${apiVersion}/script_tags.json?src=${encodeURIComponent(injectorSrc)}`
+
+                const commonHeaders = {
+                    "X-Shopify-Access-Token": accessToken,
+                    "Content-Type": "application/json"
+                }
+
+                const listRes = await fetch(listUrl, { headers: commonHeaders })
+                const listData = await listRes.json().catch(() => ({}))
+                const existing: Array<{ id: number }> = Array.isArray(listData?.script_tags)
+                    ? listData.script_tags
+                    : []
+
+                if (storefrontChatEnabled) {
+                    if (existing.length === 0) {
+                        const createUrl = `https://${cleanDomain}/admin/api/${apiVersion}/script_tags.json`
+                        const createBody = {
+                            script_tag: {
+                                event: "onload",
+                                src: injectorSrc,
+                                display_scope: "online_store",
+                                cache: false
+                            }
+                        }
+
+                        const createRes = await fetch(createUrl, {
+                            method: "POST",
+                            headers: commonHeaders,
+                            body: JSON.stringify(createBody)
+                        })
+
+                        if (!createRes.ok) {
+                            const errText = await createRes.text().catch(() => "")
+                            console.error("[STORE_FRONT_CHAT_SCRIPTTAG_CREATE]", { storeId, status: createRes.status, errText })
+                        }
+                    }
+                } else {
+                    for (const tag of existing) {
+                        if (!tag?.id) continue
+                        const deleteUrl = `https://${cleanDomain}/admin/api/${apiVersion}/script_tags/${tag.id}.json`
+                        const delRes = await fetch(deleteUrl, {
+                            method: "DELETE",
+                            headers: { "X-Shopify-Access-Token": accessToken }
+                        })
+
+                        if (!delRes.ok) {
+                            const errText = await delRes.text().catch(() => "")
+                            console.error("[STORE_FRONT_CHAT_SCRIPTTAG_DELETE]", { storeId, tagId: tag.id, status: delRes.status, errText })
+                        }
+                    }
+                }
+            } else {
+                console.warn("[STORE_FRONT_CHAT_SCRIPTTAG_SKIP]", {
+                    storeId,
+                    hasInjectorBase: Boolean(appBaseUrl),
+                    cleanDomain,
+                    hasAccessToken: Boolean(accessToken)
+                })
+            }
+        } catch (scriptError) {
+            console.error("[STORE_FRONT_CHAT_SCRIPTTAG_ERROR]", scriptError)
+        }
+
         return NextResponse.json({
             success: true,
             storefrontChatEnabled
diff --git a/src/app/storefront-chat/widget-injector/route.ts b/src/app/storefront-chat/widget-injector/route.ts
new file mode 100644
index 0000000..04cbb6f
--- /dev/null
+++ b/src/app/storefront-chat/widget-injector/route.ts
@@ -0,0 +1,84 @@
+/**
+ * Shopify ScriptTag loader (v1).
+ *
+ * Shopify injects this JS onto the ONLINE_STORE.
+ * The script then checks our backend config for the current store and, if enabled,
+ * mounts an iframe pointing to `/storefront-chat/widget?shop=...`.
+ */
+export async function GET() {
+    const js = `
+(function () {
+  try {
+    var script = document.currentScript;
+    var baseUrl = script && script.src ? new URL(script.src).origin : window.location.origin;
+    var shop = window.location.hostname;
+
+    var containerId = "juno-storefront-chat-container";
+    var iframeId = "juno-storefront-chat-iframe";
+
+    function upsertIframe() {
+      var container = document.getElementById(containerId);
+      if (!container) {
+        container = document.createElement("div");
+        container.id = containerId;
+        container.style.position = "fixed";
+        container.style.bottom = "16px";
+        container.style.right = "16px";
+        container.style.zIndex = "2147483647";
+        container.style.width = "420px";
+        container.style.maxWidth = "calc(100vw - 32px)";
+        container.style.height = "640px";
+        container.style.maxHeight = "calc(100vh - 32px)";
+        container.style.borderRadius = "16px";
+        document.body.appendChild(container);
+      }
+
+      var existing = document.getElementById(iframeId);
+      if (existing) return;
+
+      var iframe = document.createElement("iframe");
+      iframe.id = iframeId;
+      iframe.title = "JUNO Storefront Chat";
+      iframe.style.border = "0";
+      iframe.style.width = "100%";
+      iframe.style.height = "100%";
+      iframe.style.borderRadius = "16px";
+      iframe.style.overflow = "hidden";
+      iframe.allow = "clipboard-write; fullscreen";
+      iframe.referrerPolicy = "no-referrer";
+      iframe.src = baseUrl + "/storefront-chat/widget?shop=" + encodeURIComponent(shop);
+      container.appendChild(iframe);
+    }
+
+    function removeWidget() {
+      var container = document.getElementById(containerId);
+      if (container && container.parentNode) container.parentNode.removeChild(container);
+    }
+
+    // Avoid multiple config calls if Shopify re-runs script.
+    if (window.__junoStorefrontChatConfigPromise) return;
+    window.__junoStorefrontChatConfigPromise = fetch(baseUrl + "/api/storefront-chat/config?shop=" + encodeURIComponent(shop))
+      .then(function (r) { return r.json().catch(function(){ return {}; }); })
+      .then(function (data) {
+        var enabled = !!(data && data.enabled);
+        if (enabled) upsertIframe();
+        else removeWidget();
+      })
+      .catch(function () {
+        // Fail closed: don't render widget if config check fails.
+        removeWidget();
+      });
+  } catch (e) {
+    // Fail closed: don't render widget.
+  }
+})();
+`.trimStart()
+
+    return new Response(js, {
+        headers: {
+            "Content-Type": "application/javascript; charset=utf-8",
+            "Cache-Control": "public, max-age=300"
+        }
+    })
+}
+