diff --git a/pages/app-layout-toolbar/without-toolbar-nested.page.tsx b/pages/app-layout-toolbar/without-toolbar-nested.page.tsx
new file mode 100644
index 0000000000..d656d30793
--- /dev/null
+++ b/pages/app-layout-toolbar/without-toolbar-nested.page.tsx
@@ -0,0 +1,168 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+import React, { useContext, useRef, useState } from 'react';
+
+import { AppLayoutToolbar, Button, ContentLayout, Header, HelpPanel, Link, SpaceBetween, Toggle } from '~components';
+import { AppLayoutToolbarProps } from '~components/app-layout-toolbar';
+import { registerLeftDrawer, updateDrawer } from '~components/internal/plugins/widget';
+
+import AppContext, { AppContextType } from '../app/app-context';
+import { Containers, CustomDrawerContent, Navigation } from '../app-layout/utils/content-blocks';
+import { drawerLabels } from '../app-layout/utils/drawers';
+import { leftDrawerPayload } from '../app-layout/utils/external-global-left-panel-widget';
+import appLayoutLabels from '../app-layout/utils/labels';
+import { IframeWrapper } from '../utils/iframe-wrapper';
+import ScreenshotArea from '../utils/screenshot-area';
+
+registerLeftDrawer({ ...leftDrawerPayload, defaultActive: true });
+
+type DemoContext = React.Context<
+  AppContextType<{
+    hasNestedIframe: boolean | undefined;
+  }>
+>;
+
+export default function WithoutToolbar() {
+  const [activeDrawerId, setActiveDrawerId] = useState<string | null>(null);
+  const [helpPathSlug, setHelpPathSlug] = useState<string>('default');
+  const [isToolsOpen, setIsToolsOpen] = useState(false);
+  const [isNavigationOpen, setIsNavigationOpen] = useState(true);
+  const pageLayoutRef = useRef<AppLayoutToolbarProps.Ref>(null);
+  const { urlParams, setUrlParams } = useContext(AppContext as DemoContext);
+
+  const drawersProps: Pick<AppLayoutToolbarProps, 'activeDrawerId' | 'onDrawerChange' | 'drawers'> | null = {
+    activeDrawerId: activeDrawerId,
+    drawers: [
+      {
+        ariaLabels: {
+          closeButton: 'ProHelp close button',
+          drawerName: 'ProHelp drawer content',
+          triggerButton: 'ProHelp trigger button',
+          resizeHandle: 'ProHelp resize handle',
+        },
+        content: <CustomDrawerContent />,
+        id: 'pro-help',
+      },
+    ],
+    onDrawerChange: event => {
+      setActiveDrawerId(event.detail.activeDrawerId);
+    },
+  };
+
+  const renderInternalAppLayout = () => (
+    <AppLayoutToolbar
+      toolsHide={true}
+      navigationHide={true}
+      navigationTriggerHide={true}
+      content={
+        <ContentLayout
+          disableOverlap={true}
+          header={
+            <SpaceBetween size="m">
+              <Header
+                variant="h1"
+                description="Sometimes you need custom triggers for drawers and navigation to get the job done."
+                info={
+                  <Link
+                    data-testid="info-link-header"
+                    variant="info"
+                    onFollow={() => {
+                      setHelpPathSlug('header');
+                      setIsToolsOpen(true);
+                      pageLayoutRef.current?.focusToolsClose();
+                    }}
+                  >
+                    Info
+                  </Link>
+                }
+              >
+                Page layout without the toolbar
+              </Header>
+
+              <SpaceBetween size="xs">
+                <Toggle
+                  checked={urlParams.hasNestedIframe ?? false}
+                  onChange={event => {
+                    setUrlParams({ hasNestedIframe: event.detail.checked });
+                  }}
+                >
+                  Has nested iframe
+                </Toggle>
+                <Button
+                  onClick={() => {
+                    setIsNavigationOpen(current => !current);
+                    pageLayoutRef.current?.focusNavigation();
+                  }}
+                >
+                  Toggle navigation
+                </Button>
+
+                <Button
+                  onClick={() => {
+                    setActiveDrawerId('pro-help');
+                    pageLayoutRef.current?.focusActiveDrawer();
+                  }}
+                >
+                  Open a drawer without trigger
+                </Button>
+                <Button onClick={() => setActiveDrawerId(null)}>Close a drawer without trigger</Button>
+                <Button onClick={() => updateDrawer({ type: 'openDrawer', payload: { id: 'ai-panel' } })}>
+                  Open the left panel
+                </Button>
+              </SpaceBetween>
+            </SpaceBetween>
+          }
+        >
+          <Header
+            info={
+              <Link
+                data-testid="info-link-content"
+                variant="info"
+                onFollow={() => {
+                  setHelpPathSlug('content');
+                  setIsToolsOpen(true);
+                }}
+              >
+                Info
+              </Link>
+            }
+          >
+            Content
+          </Header>
+          <Containers />
+        </ContentLayout>
+      }
+    />
+  );
+
+  return (
+    <ScreenshotArea gutters={false}>
+      <AppLayoutToolbar
+        {...{ __forceEnableRuntimeMessages: true }}
+        ariaLabels={{ ...appLayoutLabels, ...drawerLabels }}
+        ref={pageLayoutRef}
+        content={
+          urlParams.hasNestedIframe ? (
+            <IframeWrapper id="smth" AppComponent={renderInternalAppLayout} />
+          ) : (
+            renderInternalAppLayout()
+          )
+        }
+        onToolsChange={event => {
+          setIsToolsOpen(event.detail.open);
+        }}
+        tools={<Info helpPathSlug={helpPathSlug} />}
+        toolsOpen={isToolsOpen}
+        navigationTriggerHide={true}
+        navigationOpen={isNavigationOpen}
+        navigation={<Navigation />}
+        onNavigationChange={event => setIsNavigationOpen(event.detail.open)}
+        {...drawersProps}
+      />
+    </ScreenshotArea>
+  );
+}
+
+function Info({ helpPathSlug }: { helpPathSlug: string }) {
+  return <HelpPanel header={<h2>Info</h2>}>Here is some info for you: {helpPathSlug}</HelpPanel>;
+}
diff --git a/pages/app-layout-toolbar/without-toolbar.page.tsx b/pages/app-layout-toolbar/without-toolbar.page.tsx
index 48dfbfc880..648b2b2b9f 100644
--- a/pages/app-layout-toolbar/without-toolbar.page.tsx
+++ b/pages/app-layout-toolbar/without-toolbar.page.tsx
@@ -4,12 +4,16 @@ import React, { useRef, useState } from 'react';
 
 import { AppLayoutToolbar, Button, ContentLayout, Header, HelpPanel, Link, SpaceBetween } from '~components';
 import { AppLayoutToolbarProps } from '~components/app-layout-toolbar';
+import { registerLeftDrawer, updateDrawer } from '~components/internal/plugins/widget';
 
 import { Containers, CustomDrawerContent, Navigation } from '../app-layout/utils/content-blocks';
 import { drawerLabels } from '../app-layout/utils/drawers';
+import { leftDrawerPayload } from '../app-layout/utils/external-global-left-panel-widget';
 import appLayoutLabels from '../app-layout/utils/labels';
 import ScreenshotArea from '../utils/screenshot-area';
 
+registerLeftDrawer({ ...leftDrawerPayload, defaultActive: true });
+
 export default function WithDrawers() {
   const [activeDrawerId, setActiveDrawerId] = useState<string | null>(null);
   const [helpPathSlug, setHelpPathSlug] = useState<string>('default');
@@ -39,6 +43,7 @@ export default function WithDrawers() {
   return (
     <ScreenshotArea gutters={false}>
       <AppLayoutToolbar
+        {...{ __forceEnableRuntimeMessages: true }}
         ariaLabels={{ ...appLayoutLabels, ...drawerLabels }}
         ref={pageLayoutRef}
         content={
@@ -85,6 +90,9 @@ export default function WithDrawers() {
                     Open a drawer without trigger
                   </Button>
                   <Button onClick={() => setActiveDrawerId(null)}>Close a drawer without trigger</Button>
+                  <Button onClick={() => updateDrawer({ type: 'openDrawer', payload: { id: 'ai-panel' } })}>
+                    Open the left panel
+                  </Button>
                 </SpaceBetween>
               </SpaceBetween>
             }
diff --git a/src/__a11y__/a11y-app-layout-toolbar.test.ts b/src/__a11y__/a11y-app-layout-toolbar.test.ts
index b2e47addb0..3658bd44ee 100644
--- a/src/__a11y__/a11y-app-layout-toolbar.test.ts
+++ b/src/__a11y__/a11y-app-layout-toolbar.test.ts
@@ -11,6 +11,7 @@ const EXCLUDED_PAGES = [
   // Not a use case that's encouraged.
   'app-layout/multi-layout-global-drawer-child-layout',
   'app-layout/with-error-boundaries',
+  'app-layout-toolbar/without-toolbar-nested',
 ];
 
 describe('A11y checks for app layout toolbar', () => {
diff --git a/src/__a11y__/run-a11y-tests.ts b/src/__a11y__/run-a11y-tests.ts
index a7e6411493..0f83c77e4f 100644
--- a/src/__a11y__/run-a11y-tests.ts
+++ b/src/__a11y__/run-a11y-tests.ts
@@ -34,6 +34,8 @@ export default function runA11yTests(theme: Theme, mode: Mode, skip: string[] =
         // this page intentionally has issues to test the helper
         'undefined-texts',
         'app-layout/with-error-boundaries',
+        // nested app layouts aren't accessible, as every page should contain a level-one heading
+        'app-layout-toolbar/without-toolbar-nested',
       ];
       const testFunction =
         skipPages.includes(inputUrl) ||
diff --git a/src/app-layout/__tests__/runtime-drawers-widgetized.test.tsx b/src/app-layout/__tests__/runtime-drawers-widgetized.test.tsx
index 7c5d0e5488..a67edb7d1a 100644
--- a/src/app-layout/__tests__/runtime-drawers-widgetized.test.tsx
+++ b/src/app-layout/__tests__/runtime-drawers-widgetized.test.tsx
@@ -302,6 +302,65 @@ describeEachAppLayout({ themes: ['refresh-toolbar'] }, ({ size }) => {
     }
   });
 
+  describe('left drawer without toolbar', () => {
+    test('should not render left drawer when toolbar is not present', () => {
+      awsuiWidgetPlugins.registerLeftDrawer({ ...drawerDefaults, trigger: undefined, defaultActive: true });
+      const { globalDrawersWrapper, wrapper } = renderComponent(<AppLayout navigationHide={true} toolsHide={true} />);
+
+      expect(wrapper.findToolbar()).toBeFalsy();
+      expect(globalDrawersWrapper.findDrawerById(drawerDefaults.id)).toBeFalsy();
+    });
+
+    test('should render left drawer when toolbar is not present (__forceEnableRuntimeMessages is provided)', () => {
+      awsuiWidgetPlugins.registerLeftDrawer({ ...drawerDefaults, trigger: undefined, defaultActive: true });
+      const { globalDrawersWrapper, wrapper } = renderComponent(
+        <AppLayout {...{ __forceEnableRuntimeMessages: true }} navigationHide={true} toolsHide={true} />
+      );
+
+      expect(wrapper.findToolbar()).toBeFalsy();
+      expect(globalDrawersWrapper.findDrawerById(drawerDefaults.id)!.isActive()).toBe(true);
+    });
+
+    test('should open left drawer via API when toolbar is not present (__forceEnableRuntimeMessages is provided)', () => {
+      awsuiWidgetPlugins.registerLeftDrawer({ ...drawerDefaults, trigger: undefined });
+      const { globalDrawersWrapper, wrapper } = renderComponent(
+        <AppLayout {...{ __forceEnableRuntimeMessages: true }} navigationHide={true} toolsHide={true} />
+      );
+
+      expect(wrapper.findToolbar()).toBeFalsy();
+      expect(globalDrawersWrapper.findDrawerById(drawerDefaults.id)).toBeFalsy();
+
+      act(() => awsuiWidgetPlugins.updateDrawer({ type: 'openDrawer', payload: { id: drawerDefaults.id } }));
+
+      expect(globalDrawersWrapper.findDrawerById(drawerDefaults.id)!.isActive()).toBe(true);
+    });
+
+    test('should render left drawer when toolbar is not present and has a nested app layout (__forceEnableRuntimeMessages is provided)', () => {
+      awsuiWidgetPlugins.registerLeftDrawer({ ...drawerDefaults, trigger: undefined, defaultActive: true });
+      const { container } = render(
+        <AppLayout
+          {...{ __forceEnableRuntimeMessages: true }}
+          data-testid="outer"
+          navigationHide={true}
+          toolsHide={true}
+          content={<AppLayout data-testid="inner" navigationHide={true} toolsHide={true} />}
+        />
+      );
+
+      const outerWrapper = createWrapper(container).find('[data-testid="outer"]')!.findAppLayout()!;
+      const innerWrapper = createWrapper(container).find('[data-testid="inner"]')!.findAppLayout()!;
+      const outerDrawersUtils = getGlobalDrawersTestUtils(outerWrapper);
+      const innerDrawersUtils = getGlobalDrawersTestUtils(innerWrapper);
+
+      expect(outerWrapper.findToolbar()).toBeFalsy();
+      expect(innerWrapper.findToolbar()).toBeFalsy();
+      expect(outerDrawersUtils.findDrawerById(drawerDefaults.id)!.isActive()).toBe(true);
+      expect(outerDrawersUtils.findActiveDrawers().length).toBe(1);
+      expect(innerDrawersUtils.findDrawerById(drawerDefaults.id)).toBeFalsy();
+      expect(innerDrawersUtils.findActiveDrawers().length).toBe(0);
+    });
+  });
+
   describe('metrics', () => {
     let sendPanoramaMetricSpy: jest.SpyInstance;
     beforeEach(() => {
diff --git a/src/app-layout/visual-refresh-toolbar/skeleton/styles.scss b/src/app-layout/visual-refresh-toolbar/skeleton/styles.scss
index c0713f92bb..92879161e7 100644
--- a/src/app-layout/visual-refresh-toolbar/skeleton/styles.scss
+++ b/src/app-layout/visual-refresh-toolbar/skeleton/styles.scss
@@ -214,6 +214,64 @@
   box-sizing: border-box;
 }
 
+/**
+ * A zero-height sticky element placed in the toolbar grid area when the toolbar is absent
+ * and the left panel (AI drawer) is open. It reuses the toolbar's pseudo-element technique
+ * to render the border-radius corner between the AI drawer and the content area.
+ * In light mode: inverse radius trick (dark square + white square with radius).
+ * In dark mode: a vertical border line with a rounded top corner + top border on the element itself.
+ */
+.pseudo-toolbar {
+  grid-area: toolbar;
+  position: sticky;
+  z-index: constants.$toolbar-z-index;
+
+  &:before {
+    @include theming.dark-mode-only {
+      content: '';
+      position: absolute;
+      inline-size: awsui.$border-divider-section-width;
+      block-size: 100vh;
+      background: awsui.$color-border-layout;
+    }
+  }
+}
+
+.pseudo-toolbar-content {
+  position: relative;
+
+  @include theming.dark-mode-only {
+    border-block-start: awsui.$border-divider-section-width solid awsui.$color-border-layout;
+    border-start-start-radius: awsui.$space-xxs;
+  }
+
+  &:before,
+  &:after {
+    content: '';
+    position: absolute;
+    inset-block-start: 0;
+    inset-inline-start: 0;
+    inline-size: 5px;
+    block-size: 5px;
+    background: constants.$ai-drawer-background;
+
+    @include theming.dark-mode-only {
+      inset-block-start: -1px;
+    }
+  }
+
+  &::after {
+    background-color: awsui.$color-background-layout-toolbar;
+    border-start-start-radius: awsui.$space-xxs;
+
+    @include theming.dark-mode-only {
+      background-color: transparent;
+      border-inline-start: awsui.$border-divider-section-width solid awsui.$color-border-layout;
+      border-block-start: awsui.$border-divider-section-width solid awsui.$color-border-layout;
+    }
+  }
+}
+
 .notifications-container {
   grid-area: notifications;
 }
diff --git a/src/app-layout/visual-refresh-toolbar/state/props-merger.ts b/src/app-layout/visual-refresh-toolbar/state/props-merger.ts
index 37299c2b4a..d903f780ff 100644
--- a/src/app-layout/visual-refresh-toolbar/state/props-merger.ts
+++ b/src/app-layout/visual-refresh-toolbar/state/props-merger.ts
@@ -42,7 +42,7 @@ export const mergeProps: MergeProps = (ownProps, additionalProps) => {
       toolbar.onActiveGlobalDrawersChange = props.onActiveGlobalDrawersChange;
     }
     if (
-      props.aiDrawer &&
+      props.aiDrawer?.trigger &&
       props.aiDrawerFocusRef &&
       !checkAlreadyExists(!!toolbar.aiDrawerFocusRef, 'aiDrawerFocusRef')
     ) {
diff --git a/src/app-layout/visual-refresh-toolbar/state/use-app-layout.tsx b/src/app-layout/visual-refresh-toolbar/state/use-app-layout.tsx
index aafb2b36c1..e94554d007 100644
--- a/src/app-layout/visual-refresh-toolbar/state/use-app-layout.tsx
+++ b/src/app-layout/visual-refresh-toolbar/state/use-app-layout.tsx
@@ -79,6 +79,7 @@ export const useAppLayout = (
   const onMountRootRef = useCallback(node => {
     setIsNested(getIsNestedInAppLayout(node));
   }, []);
+  const { __forceEnableRuntimeMessages: forceEnableRuntimeMessages } = rest as any;
 
   const [toolsOpen = false, setToolsOpen] = useControllable(controlledToolsOpen, onToolsChange, false, {
     componentName: 'AppLayout',
@@ -239,7 +240,7 @@ export const useAppLayout = (
     }
   };
 
-  useWidgetMessages(hasToolbar, message => {
+  useWidgetMessages(hasToolbar || forceEnableRuntimeMessages, message => {
     if (message.type === 'expandDrawer' || message.type === 'exitExpandedMode') {
       drawerGenericMessageHandler(message);
       return;
diff --git a/src/app-layout/visual-refresh-toolbar/widget-areas/before-main-slot.tsx b/src/app-layout/visual-refresh-toolbar/widget-areas/before-main-slot.tsx
index 3ab05d0d04..e18d304b3d 100644
--- a/src/app-layout/visual-refresh-toolbar/widget-areas/before-main-slot.tsx
+++ b/src/app-layout/visual-refresh-toolbar/widget-areas/before-main-slot.tsx
@@ -68,6 +68,16 @@ export const BeforeMainSlotImplementationInternal = ({
           featureNotificationsProps={featureNotificationsProps}
         />
       )}
+      {!toolbarProps && !!activeAiDrawerId && (
+        <div
+          className={styles['pseudo-toolbar']}
+          style={{
+            insetBlockStart: appLayoutState.appLayoutInternals?.verticalOffsets?.toolbar,
+          }}
+        >
+          <div className={styles['pseudo-toolbar-content']} />
+        </div>
+      )}
       {aiDrawer && (
         <div
           className={clsx(