diff --git a/packages/embed-sdk/demo-my-invoices.html b/packages/embed-sdk/demo-my-invoices.html
index 6f85dfe..c54dcc4 100644
--- a/packages/embed-sdk/demo-my-invoices.html
+++ b/packages/embed-sdk/demo-my-invoices.html
@@ -211,7 +211,7 @@ <h1>My Invoices</h1>
         <!-- User menu for authentication -->
         <div class="auth-header">
           <span>Sign in to continue</span>
-          <next-user-menu mp-base-url="__MP_BASE_URL__"></next-user-menu>
+          <next-user-menu mp-base-url="__MP_BASE_URL__" api-host="__API_HOST__"></next-user-menu>
         </div>
 
         <!-- The actual widget (hidden until authenticated) -->
diff --git a/packages/embed-sdk/demo-profile.html b/packages/embed-sdk/demo-profile.html
index 3962843..5680fb8 100644
--- a/packages/embed-sdk/demo-profile.html
+++ b/packages/embed-sdk/demo-profile.html
@@ -162,7 +162,7 @@ <h1>Profile Editor</h1>
         <!-- User menu for authentication -->
         <div class="auth-header">
           <span>Sign in to continue</span>
-          <next-user-menu mp-base-url="__MP_BASE_URL__"></next-user-menu>
+          <next-user-menu mp-base-url="__MP_BASE_URL__" api-host="__API_HOST__"></next-user-menu>
         </div>
 
         <!-- The widget (hidden until authenticated) -->
diff --git a/packages/embed-sdk/src/shared/base-widget.ts b/packages/embed-sdk/src/shared/base-widget.ts
index 0a75706..06e0ecc 100644
--- a/packages/embed-sdk/src/shared/base-widget.ts
+++ b/packages/embed-sdk/src/shared/base-widget.ts
@@ -43,6 +43,18 @@ export abstract class MPNextWidget extends HTMLElement {
         return new URL(s.src).origin;
       } catch { /* continue */ }
     }
+
+    // Fall back to a sibling widget's api-host (handles Vite dev, where the SDK
+    // is a local module import — no "next-embed" script tag — and a widget
+    // without an explicit api-host would otherwise fetch the wrong origin).
+    const sibling = document.querySelector(
+      "next-user-menu, next-add-to-calendar, next-full-calendar, next-profile, next-my-invoices",
+    );
+    if (sibling && sibling !== this) {
+      const host = sibling.getAttribute("api-host");
+      if (host) return host;
+    }
+
     return "";
   }