diff --git a/.changeset/safe-phrasing-hosts.md b/.changeset/safe-phrasing-hosts.md
new file mode 100644
index 00000000..5b2eb826
--- /dev/null
+++ b/.changeset/safe-phrasing-hosts.md
@@ -0,0 +1,5 @@
+---
+'@youversion/platform-react-ui': patch
+---
+
+Keep auth-button and Bible-picker Shadow DOM hosts valid in server-rendered phrasing content.
diff --git a/docs/adr/0010-automatic-shadow-dom-style-isolation.md b/docs/adr/0010-automatic-shadow-dom-style-isolation.md
index 97fa65c7..19e8e727 100644
--- a/docs/adr/0010-automatic-shadow-dom-style-isolation.md
+++ b/docs/adr/0010-automatic-shadow-dom-style-isolation.md
@@ -108,6 +108,10 @@ ordinary boundary's declarative display:
 <div data-yv-shadow-host="true" style="display:contents"></div>
 ```
 
+Components that can be in phrasing content (`YouVersionAuthButton`, the picker
+roots, `Separator`, and `ProfileAvatar`) use a `span` host with the same
+attributes.
+
 The first client render matches that markup. A layout effect applies the
 protected host reset before paint. After hydration, a passive effect attaches
 or reuses one open shadow root, installs the SDK stylesheet, and then portals
diff --git a/docs/shadow-dom-isolation-plan.md b/docs/shadow-dom-isolation-plan.md
index b19266f1..25ec623f 100644
--- a/docs/shadow-dom-isolation-plan.md
+++ b/docs/shadow-dom-isolation-plan.md
@@ -178,6 +178,10 @@ per-story results, screenshots, raw terminal output, or other local test
 artifacts. Repeat actual-Safari validation after future rollout-policy trigger
 changes.
 
+YPE-6218 repeated the targeted actual-Safari gate for the host-tag change at
+commit `1d1bddb`; all 42 stories passed, with the YPE-6214 limitations
+unchanged.
+
 ### Assistive-technology evidence
 
 Record versions from the tested machines rather than naming only the product
diff --git a/packages/ui/src/components/YouVersionAuthButton.ssr.test.tsx b/packages/ui/src/components/YouVersionAuthButton.ssr.test.tsx
new file mode 100644
index 00000000..965ea89d
--- /dev/null
+++ b/packages/ui/src/components/YouVersionAuthButton.ssr.test.tsx
@@ -0,0 +1,93 @@
+/**
+ * @vitest-environment jsdom
+ */
+import { PassThrough } from 'node:stream';
+import { act, waitFor } from '@testing-library/react';
+import { YouVersionProvider } from '@youversion/platform-react-hooks';
+import type { ReactElement } from 'react';
+import { hydrateRoot, type Root } from 'react-dom/client';
+import { renderToPipeableStream } from 'react-dom/server';
+import { expect, it, vi } from 'vitest';
+import { requireShadowRoot } from '@/test/dom-stubs';
+import { YouVersionAuthButton } from './YouVersionAuthButton';
+
+function renderAfterAllReady(element: ReactElement): Promise<string> {
+  return new Promise((resolve, reject) => {
+    const destination = new PassThrough();
+    let html = '';
+
+    destination.setEncoding('utf8');
+    destination.on('data', (chunk: string) => {
+      html += chunk;
+    });
+    destination.on('end', () => resolve(html));
+    destination.on('error', reject);
+
+    const { pipe } = renderToPipeableStream(element, {
+      onAllReady() {
+        pipe(destination);
+      },
+      onShellError: reject,
+    });
+  });
+}
+
+it('preserves auth-button phrasing content through streaming SSR and hydration', async () => {
+  const element = (
+    <YouVersionProvider
+      appKey="test-app-key"
+      authRedirectUrl="https://example.com/callback"
+      includeAuth
+    >
+      <p>
+        Before <YouVersionAuthButton /> after
+      </p>
+    </YouVersionProvider>
+  );
+  const serverMarkup = await renderAfterAllReady(element);
+
+  expect(serverMarkup).toContain(
+    '<span data-yv-shadow-host="true" style="display:contents"></span>',
+  );
+
+  const container = document.createElement('div');
+  container.innerHTML = serverMarkup;
+  document.body.append(container);
+  const paragraph = container.querySelector('p');
+  const serverHost = container.querySelector<HTMLElement>('[data-yv-shadow-host]');
+  const recoverableErrors: unknown[] = [];
+  const consoleError = vi.spyOn(console, 'error').mockImplementation(() => undefined);
+  let root: Root | undefined;
+
+  try {
+    expect(container.querySelectorAll('p')).toHaveLength(1);
+    expect(paragraph).toContainElement(serverHost);
+    expect(paragraph).toHaveTextContent('Before after');
+
+    await act(async () => {
+      root = hydrateRoot(container, element, {
+        onRecoverableError: (error) => recoverableErrors.push(error),
+      });
+    });
+
+    const shadowRoot = await waitFor(() => requireShadowRoot(container));
+    expect(container.querySelector('[data-yv-shadow-host]')).toBe(serverHost);
+    expect(shadowRoot.querySelector('button')).not.toBeNull();
+    expect(recoverableErrors).toEqual([]);
+
+    // The provider can emit unrelated multiple-renderer errors when server and client
+    // renderers share this process, so only reject diagnostics for this regression.
+    const invalidNestingDiagnostics = consoleError.mock.calls.filter((call) =>
+      call.some((value) =>
+        /cannot be a (?:child|descendant) of|cannot contain a nested|validateDOMNesting/i.test(
+          String(value),
+        ),
+      ),
+    );
+    expect(invalidNestingDiagnostics).toEqual([]);
+  } finally {
+    if (root) await act(async () => root?.unmount());
+    consoleError.mockRestore();
+    container.remove();
+  }
+});
diff --git a/packages/ui/src/components/YouVersionAuthButton.tsx b/packages/ui/src/components/YouVersionAuthButton.tsx
index e076541d..22d27449 100644
--- a/packages/ui/src/components/YouVersionAuthButton.tsx
+++ b/packages/ui/src/components/YouVersionAuthButton.tsx
@@ -276,7 +276,7 @@ YouVersionAuthButtonImpl.displayName = 'YouVersionAuthButtonImpl';
  */
 export const YouVersionAuthButton = React.forwardRef<HTMLButtonElement, YouVersionAuthButtonProps>(
   (props, ref) => (
-    <ShadowIsolationBoundary theme={props.background}>
+    <ShadowIsolationBoundary hostElement="span" theme={props.background}>
       <YouVersionAuthButtonImpl {...props} ref={ref} />
     </ShadowIsolationBoundary>
   ),
diff --git a/packages/ui/src/components/bible-chapter-picker.tsx b/packages/ui/src/components/bible-chapter-picker.tsx
index 188f256f..891eb3d8 100644
--- a/packages/ui/src/components/bible-chapter-picker.tsx
+++ b/packages/ui/src/components/bible-chapter-picker.tsx
@@ -272,7 +272,11 @@ function RootImplementation({
 
 function Root(props: RootProps) {
   return (
-    <ShadowIsolationBoundary portalStrategy="local-top-layer" theme={props.background}>
+    <ShadowIsolationBoundary
+      hostElement="span"
+      portalStrategy="local-top-layer"
+      theme={props.background}
+    >
       <RootImplementation {...props} />
     </ShadowIsolationBoundary>
   );
diff --git a/packages/ui/src/components/bible-picker-shadow-isolation.test.tsx b/packages/ui/src/components/bible-picker-shadow-isolation.test.tsx
index ffec32b7..851ac597 100644
--- a/packages/ui/src/components/bible-picker-shadow-isolation.test.tsx
+++ b/packages/ui/src/components/bible-picker-shadow-isolation.test.tsx
@@ -90,24 +90,52 @@ describe('Bible picker public shadow boundaries', () => {
   it.each([
     ['BibleChapterPicker.Root', chapterPicker],
     ['BibleVersionPicker.Root', versionPicker],
-  ])('%s owns one childless styled SSR host and reuses it during hydration', async (_, picker) => {
+  ])('%s preserves phrasing content around its SSR host during hydration', async (_, picker) => {
     const fixture = picker();
     const element = (
-      <HookOverrideProvider overrides={overrides}>{fixture.element}</HookOverrideProvider>
+      <p>
+        Before <HookOverrideProvider overrides={overrides}>{fixture.element}</HookOverrideProvider>{' '}
+        after
+      </p>
     );
     const serverMarkup = renderToString(element);
 
-    expect(serverMarkup).toBe('<div data-yv-shadow-host="true" style="display:contents"></div>');
+    expect(serverMarkup).toContain(
+      '<span data-yv-shadow-host="true" style="display:contents"></span>',
+    );
 
     const container = document.createElement('div');
     container.innerHTML = serverMarkup;
     document.body.append(container);
-    const serverHost = container.firstElementChild;
+    const paragraph = container.querySelector('p');
+    const serverHost = container.querySelector<HTMLElement>('[data-yv-shadow-host]');
+    if (!paragraph || !serverHost) throw new Error('parsed picker phrasing fixture is incomplete');
     const recoverableErrors: unknown[] = [];
     const consoleError = vi.spyOn(console, 'error').mockImplementation(() => undefined);
     let root: Root | undefined;
 
     try {
+      expect(container.querySelectorAll('p')).toHaveLength(1);
+      expect(paragraph).toContainElement(serverHost);
+      expect(paragraph).toHaveTextContent('Before after');
+      const phrasingNodes = Array.from(paragraph.childNodes).filter(
+        (node) => node.nodeType !== Node.COMMENT_NODE,
+      );
+      const hostIndex = phrasingNodes.indexOf(serverHost);
+      expect(hostIndex).toBeGreaterThan(0);
+      expect(
+        phrasingNodes
+          .slice(0, hostIndex)
+          .map((node) => node.textContent)
+          .join(''),
+      ).toBe('Before ');
+      expect(
+        phrasingNodes
+          .slice(hostIndex + 1)
+          .map((node) => node.textContent)
+          .join(''),
+      ).toBe(' after');
+
       await act(async () => {
         root = hydrateRoot(container, element, {
           onRecoverableError: (error) => recoverableErrors.push(error),
diff --git a/packages/ui/src/components/bible-version-picker.tsx b/packages/ui/src/components/bible-version-picker.tsx
index 0c15d30d..97345236 100644
--- a/packages/ui/src/components/bible-version-picker.tsx
+++ b/packages/ui/src/components/bible-version-picker.tsx
@@ -521,7 +521,11 @@ function RootImplementation({
 
 function Root(props: RootProps) {
   return (
-    <ShadowIsolationBoundary portalStrategy="local-top-layer" theme={props.background}>
+    <ShadowIsolationBoundary
+      hostElement="span"
+      portalStrategy="local-top-layer"
+      theme={props.background}
+    >
       <RootImplementation {...props} />
     </ShadowIsolationBoundary>
   );