diff --git a/.changeset/account-button-integration.md b/.changeset/account-button-integration.md
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+++ b/.changeset/account-button-integration.md
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+---
+---
diff --git a/packages/ui/src/mosaic/account/__tests__/account-button.integration.test.tsx b/packages/ui/src/mosaic/account/__tests__/account-button.integration.test.tsx
new file mode 100644
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+++ b/packages/ui/src/mosaic/account/__tests__/account-button.integration.test.tsx
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+import type * as SharedReact from '@clerk/shared/react';
+import { fireEvent, render, screen, waitFor } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+
+import { MosaicProvider } from '../../MosaicProvider';
+import { AccountButton } from '../account-button';
+
+// End-to-end wiring test for the connected AccountButton: it renders the real view through the real
+// controller against a mocked Clerk, then drives the real popover DOM. Unlike the controller test
+// (controller -> Clerk) and the view test (props -> DOM), this proves the three layers compose —
+// including the container's close-on-success: one-shot actions close the popover, navigations leave
+// it open.
+
+interface FakeUser {
+  id: string;
+  firstName: string | null;
+  lastName: string | null;
+  username: string | null;
+  primaryEmailAddress: { emailAddress: string } | null;
+  imageUrl: string;
+}
+
+interface FakeSession {
+  id: string;
+  user: FakeUser;
+}
+
+let isUserLoaded: boolean;
+let isSessionLoaded: boolean;
+let isOrgLoaded: boolean;
+let user: FakeUser | null;
+let session: { id: string; checkAuthorization: ReturnType<typeof vi.fn> } | null;
+let organization: { id: string } | null;
+let membershipRequests: { count: number };
+let userMemberships: { data: ReturnType<typeof membership>[]; count: number; revalidate: ReturnType<typeof vi.fn> };
+let userInvitations: { data: ReturnType<typeof acceptable>[]; count: number; revalidate: ReturnType<typeof vi.fn> };
+let userSuggestions: { data: ReturnType<typeof acceptable>[]; count: number; revalidate: ReturnType<typeof vi.fn> };
+let signedInSessions: FakeSession[];
+
+let setActive: ReturnType<typeof vi.fn>;
+let signOut: ReturnType<typeof vi.fn>;
+let navigate: ReturnType<typeof vi.fn>;
+
+vi.mock('@clerk/shared/react', async importOriginal => {
+  const actual = await importOriginal<typeof SharedReact>();
+  return {
+    ...actual,
+    useUser: () => ({ isLoaded: isUserLoaded, user }),
+    useSession: () => ({ isLoaded: isSessionLoaded, session }),
+    useOrganization: () => ({ isLoaded: isOrgLoaded, organization, membershipRequests }),
+    useOrganizationList: () => ({ userMemberships, userInvitations, userSuggestions }),
+    useClerk: () => ({
+      navigate,
+      setActive,
+      signOut,
+      buildUserProfileUrl: () => '/user-profile',
+      buildOrganizationProfileUrl: () => '/org-profile',
+      buildCreateOrganizationUrl: () => '/create-org',
+      buildSignInUrl: () => '/sign-in',
+      client: { signedInSessions },
+      __internal_environment: {
+        displayConfig: {
+          afterCreateOrganizationUrl: '/after-create',
+          afterSwitchSessionUrl: '/after-switch',
+        },
+      },
+    }),
+  };
+});
+
+function acceptable(id: string, orgId: string, orgName: string, status: 'pending' | 'accepted' = 'pending') {
+  return {
+    id,
+    status,
+    accept: vi.fn().mockResolvedValue(undefined),
+    publicOrganizationData: { id: orgId, name: orgName, imageUrl: '' },
+  };
+}
+
+function membership(orgId: string, name: string, membersCount: number) {
+  return { organization: { id: orgId, name, imageUrl: '', membersCount } };
+}
+
+beforeEach(() => {
+  isUserLoaded = true;
+  isSessionLoaded = true;
+  isOrgLoaded = true;
+  user = {
+    id: 'user_1',
+    firstName: 'Alice',
+    lastName: 'Smith',
+    username: 'alice',
+    primaryEmailAddress: { emailAddress: 'alice@example.com' },
+    imageUrl: 'https://img/alice',
+  };
+  session = { id: 'sess_1', checkAuthorization: vi.fn().mockReturnValue(true) };
+  organization = { id: 'org_1' };
+  membershipRequests = { count: 4 };
+  userMemberships = {
+    data: [membership('org_1', 'Acme', 3), membership('org_9', 'Other', 1)],
+    count: 2,
+    revalidate: vi.fn().mockResolvedValue(undefined),
+  };
+  userInvitations = {
+    data: [acceptable('inv_1', 'org_3', 'Gamma')],
+    count: 1,
+    revalidate: vi.fn().mockResolvedValue(undefined),
+  };
+  userSuggestions = {
+    data: [acceptable('sug_1', 'org_2', 'Beta')],
+    count: 1,
+    revalidate: vi.fn().mockResolvedValue(undefined),
+  };
+  signedInSessions = [
+    { id: 'sess_1', user: user },
+    {
+      id: 'sess_2',
+      user: {
+        id: 'user_2',
+        firstName: 'Bob',
+        lastName: 'Jones',
+        username: null,
+        primaryEmailAddress: { emailAddress: 'bob@example.com' },
+        imageUrl: 'https://img/bob',
+      },
+    },
+  ];
+  setActive = vi.fn().mockResolvedValue(undefined);
+  signOut = vi.fn().mockResolvedValue(undefined);
+  navigate = vi.fn().mockResolvedValue(undefined);
+});
+
+afterEach(() => {
+  vi.clearAllMocks();
+});
+
+function renderAccountButton() {
+  return render(
+    <MosaicProvider>
+      <AccountButton />
+    </MosaicProvider>,
+  );
+}
+
+const trigger = () => document.querySelector('[data-cl-slot="account-button-trigger"]');
+const popup = () => document.querySelector('[data-cl-slot="account-button-popup"]');
+
+async function open() {
+  const user = userEvent.setup();
+  await user.click(screen.getByRole('button'));
+  expect(popup()).toBeInTheDocument();
+  return user;
+}
+
+describe('AccountButton (connected)', () => {
+  it('renders nothing while the controller is loading', () => {
+    isUserLoaded = false;
+    renderAccountButton();
+    expect(trigger()).toBeNull();
+  });
+
+  it('renders nothing when there is no active user', () => {
+    user = null;
+    renderAccountButton();
+    expect(trigger()).toBeNull();
+  });
+
+  it('renders the trigger and keeps the popover closed until clicked', () => {
+    renderAccountButton();
+    expect(trigger()).toBeInTheDocument();
+    expect(popup()).toBeNull();
+  });
+
+  it('opens the popover on trigger click', async () => {
+    renderAccountButton();
+    await open();
+    expect(screen.getByRole('button', { name: /Other/ })).toBeInTheDocument();
+  });
+
+  it('selecting an organization calls setActive and closes the popover', async () => {
+    renderAccountButton();
+    const user = await open();
+
+    await user.click(screen.getByRole('button', { name: /Other/ }));
+
+    expect(setActive).toHaveBeenCalledWith(
+      expect.objectContaining({ organization: 'org_9', redirectUrl: '/after-create' }),
+    );
+    await waitFor(() => expect(popup()).not.toBeInTheDocument());
+  });
+
+  it('selecting the personal workspace calls setActive with a null organization and closes', async () => {
+    renderAccountButton();
+    const user = await open();
+
+    await user.click(screen.getByRole('button', { name: /Alice Smith/ }));
+
+    expect(setActive).toHaveBeenCalledWith(expect.objectContaining({ organization: null }));
+    await waitFor(() => expect(popup()).not.toBeInTheDocument());
+  });
+
+  it('switching to an additional account calls setActive with the session and closes', async () => {
+    renderAccountButton();
+    const user = await open();
+
+    await user.click(screen.getByRole('button', { name: /Bob Jones/ }));
+
+    expect(setActive).toHaveBeenCalledWith(expect.objectContaining({ session: 'sess_2' }));
+    await waitFor(() => expect(popup()).not.toBeInTheDocument());
+  });
+
+  it('signing out of a single session calls signOut with the session id and closes', async () => {
+    renderAccountButton();
+    await open();
+
+    // The per-row "Sign out" is hover-revealed (pointer-events: none until row hover), a visual
+    // state jsdom can't apply, so dispatch the click directly rather than through userEvent.
+    fireEvent.click(screen.getByRole('button', { name: 'Sign out' }));
+
+    expect(signOut).toHaveBeenCalledWith({ sessionId: 'sess_1' });
+    await waitFor(() => expect(popup()).not.toBeInTheDocument());
+  });
+
+  it('signing out of all accounts calls signOut with no session and closes', async () => {
+    renderAccountButton();
+    const user = await open();
+
+    await user.click(screen.getByRole('button', { name: 'Sign out of all accounts' }));
+
+    expect(signOut).toHaveBeenCalledWith();
+    await waitFor(() => expect(popup()).not.toBeInTheDocument());
+  });
+
+  it('accepting an invitation accepts it, revalidates, and closes', async () => {
+    renderAccountButton();
+    const user = await open();
+    const invitation = userInvitations.data[0];
+
+    await user.click(screen.getByRole('button', { name: 'Accept' }));
+
+    await waitFor(() => expect(invitation.accept).toHaveBeenCalledTimes(1));
+    expect(userInvitations.revalidate).toHaveBeenCalledTimes(1);
+    await waitFor(() => expect(popup()).not.toBeInTheDocument());
+  });
+
+  it('accepting a suggestion accepts it, revalidates, and closes', async () => {
+    renderAccountButton();
+    const user = await open();
+    const suggestion = userSuggestions.data[0];
+
+    await user.click(screen.getByRole('button', { name: 'Join' }));
+
+    await waitFor(() => expect(suggestion.accept).toHaveBeenCalledTimes(1));
+    expect(userSuggestions.revalidate).toHaveBeenCalledTimes(1);
+    await waitFor(() => expect(popup()).not.toBeInTheDocument());
+  });
+
+  it('navigating to manage the organization navigates and leaves the popover open', async () => {
+    renderAccountButton();
+    const user = await open();
+
+    await user.click(screen.getByRole('button', { name: 'Settings' }));
+
+    expect(navigate).toHaveBeenCalledWith('/org-profile');
+    expect(popup()).toBeInTheDocument();
+  });
+
+  it('navigating to manage the account (personal mode) navigates and leaves the popover open', async () => {
+    organization = null;
+    renderAccountButton();
+    const user = await open();
+
+    await user.click(screen.getByRole('button', { name: 'Manage account' }));
+
+    expect(navigate).toHaveBeenCalledWith('/user-profile');
+    expect(popup()).toBeInTheDocument();
+  });
+
+  it('creating an organization navigates and leaves the popover open', async () => {
+    renderAccountButton();
+    const user = await open();
+
+    await user.click(screen.getByRole('button', { name: 'Add organization' }));
+
+    expect(navigate).toHaveBeenCalledWith('/create-org');
+    expect(popup()).toBeInTheDocument();
+  });
+});