diff --git a/docs/test-architecture.md b/docs/test-architecture.md
index 5ff1b1bbd..774ea3748 100644
--- a/docs/test-architecture.md
+++ b/docs/test-architecture.md
@@ -168,6 +168,20 @@ run does not prove for each one; the taxonomy and cross-repository entries live
   `e2e-stack/specs/buy.spec.ts` (`openQuoteCapableBuy` and older quote cases) updates the limit
   directly so `LIMIT_EXCEEDED` does not hide payment info. A green run does **not** prove that a
   customer reaches that limit through the product path.
+- **Full-stack auth merge specs SQL-write `account_merge.expiration`.**
+  `e2e-stack/specs/auth.spec.ts` (expired otp) updates expiration directly. A green run does **not**
+  prove that merge links expire through the product path or that the API sets expiration on create.
+- **Full-stack auth merge specs SQL-write `user.walletId` (and may insert a partner `wallet` row).**
+  `e2e-stack/specs/auth.spec.ts` (RealUnit / Denario merge-mail cases) assigns the partner wallet on
+  the master address so the mail URL can be asserted. If the named wallet row is missing, the spec
+  inserts it. A green run does **not** prove that a customer registered through that partner app,
+  or that partner wallet rows are provisioned by the regular seed or migration path.
+  Those three cases are `test.skip` until DFXswiss/backend#5270 is on develop: the e2e-stack API
+  image is built from backend@develop, which still brands merge from the default wallet.
+- **Full-stack auth merge specs SQL-write `user.userDataId` to attach a second address.**
+  `e2e-stack/specs/auth.spec.ts` (mixed RealUnit+DFX) re-parents an extra user onto the master
+  account. A green run does **not** prove that a dual-account is created through the product path.
+  Skipped with the other host-matrix cases until DFXswiss/backend#5270 is on develop.
 - **The settings verification-call visual spec answers GET /v2/user itself.**
   `e2e/settings-verification-call.spec.ts` fulfils `/v2/user` with three synthetic kyc payloads
   (`phoneCallAccepted` unset / true / false) and fulfils the Settings bootstrap GETs
diff --git a/e2e-stack/specs/auth.spec.ts b/e2e-stack/specs/auth.spec.ts
index a550ee8b7..05f254c76 100644
--- a/e2e-stack/specs/auth.spec.ts
+++ b/e2e-stack/specs/auth.spec.ts
@@ -25,8 +25,9 @@ import {
   testEmail,
   testWallet,
   waitForRow,
+  withDb,
 } from './fixtures';
-import { cleanupCreatedData, createUser, e2eMail } from './fixtures/factories';
+import { cleanupCreatedData, createUser, e2eMail, type CreateUserResult } from './fixtures/factories';
 
 /** Parse a 6-digit verification code from a notification row (VerificationMail / EmailVerification). */
 function codeFromNotificationData(data: string): string {
@@ -62,6 +63,91 @@ async function waitForVerificationCode(
   return codeFromNotificationData(row.data);
 }
 
+function assertMergeMailUrl(url: string | undefined, code: string, host: 'dfx' | 'realunit'): void {
+  expect(url, 'merge mail must include a confirmation URL').toBeTruthy();
+  const parsed = new URL(url as string);
+  expect(parsed.pathname).toBe('/account-merge');
+  expect(parsed.searchParams.get('otp')).toBe(code);
+  if (host === 'realunit') {
+    expect(['https://realunit.app', 'https://dev.realunit.app']).toContain(parsed.origin);
+  } else {
+    const dfxOrigin = new URL(process.env.E2E_FRONTEND_URL ?? 'http://frontend').origin;
+    expect(parsed.origin).toBe(dfxOrigin);
+  }
+}
+
+function mergeMailFromNotification(data: string): { url?: string; walletName?: string } {
+  let parsed: { wallet?: { name?: string }; texts?: Array<{ params?: { url?: string } }> };
+  try {
+    parsed = JSON.parse(data) as typeof parsed;
+  } catch (e) {
+    throw new Error(`mergeMailFromNotification: failed to JSON.parse notification.data: ${e}`);
+  }
+  const url = parsed.texts?.find((t) => typeof t?.params?.url === 'string')?.params?.url;
+  return { url, walletName: parsed.wallet?.name };
+}
+
+async function waitForMergeMail(userDataId: number): Promise<{ url?: string; walletName?: string }> {
+  const row = await waitForRow<{ data: string }>(
+    `SELECT n.data FROM notification n
+     WHERE n."userDataId" = $1 AND n.context = 'AccountMergeRequest'
+     ORDER BY n.id DESC LIMIT 1`,
+    [userDataId],
+    20000,
+  );
+  return mergeMailFromNotification(row.data);
+}
+
+async function walletIdNamed(name: string): Promise<number> {
+  const existing = await queryOne<{ id: number }>(`SELECT id FROM wallet WHERE name = $1 ORDER BY id ASC LIMIT 1`, [
+    name,
+  ]);
+  if (existing?.id) return existing.id;
+  const inserted = await withDb(async (client) => {
+    const result = await client.query<{ id: number }>(
+      `INSERT INTO wallet (name, "displayName", created, updated)
+       VALUES ($1, $1, NOW(), NOW())
+       RETURNING id`,
+      [name],
+    );
+    return result.rows[0];
+  });
+  if (!inserted?.id) throw new Error(`walletIdNamed: failed to insert wallet ${name}`);
+  return inserted.id;
+}
+
+async function setUserWallet(userId: number, walletId: number): Promise<void> {
+  await withDb(async (client) => {
+    await client.query(`UPDATE "user" SET "walletId" = $1 WHERE id = $2`, [walletId, userId]);
+  });
+}
+
+/** B requests A's mail after 2FA — the product path that sends the merge mail to A. */
+async function triggerMergeViaMailChange(
+  page: Page,
+  master: CreateUserResult,
+  slave: CreateUserResult,
+): Promise<string> {
+  await openScreen(page, '/2fa', slave.jwt);
+  await completeMail2faOnPage(page, slave.userDataId);
+  await page.goto('/account/mail');
+  await page.waitForLoadState('networkidle');
+  await expect(page.getByRole('textbox', { name: 'Email address' })).toBeVisible({ timeout: 20000 });
+  await page.getByRole('textbox', { name: 'Email address' }).fill(required(master.mail, 'master.mail'));
+  await page.getByRole('button', { name: 'Save' }).click();
+  await expect(page.getByText('It looks like you already have an account with DFX.')).toBeVisible({
+    timeout: 20000,
+  });
+  const mergeRow = await waitForRow<{ code: string }>(
+    `SELECT code FROM account_merge
+     WHERE "masterId" = $1 AND "slaveId" = $2
+     ORDER BY id DESC LIMIT 1`,
+    [master.userDataId, slave.userDataId],
+    20000,
+  );
+  return mergeRow.code;
+}
+
 /** Complete the mail-based /2fa screen for a customer account (same browser IP for later check2fa). */
 async function completeMail2faOnPage(page: Page, userDataId: number): Promise<void> {
   await expect(
@@ -346,25 +432,116 @@ test.describe('Auth area e2e', () => {
   test('/account-merge?otp=… adds wallet address (UI + Postgres)', async ({ page }) => {
     test.setTimeout(120000);
 
-    const mailA = e2eMail('merge-master');
-    const mailB = e2eMail('merge-slave');
-    const userA = await createUser({ tag: 'merge-a', mail: mailA, language: 'EN' });
-    const userB = await createUser({ tag: 'merge-b', mail: mailB, language: 'EN' });
+    const userA = await createUser({ tag: 'merge-a', mail: e2eMail('merge-master'), language: 'EN' });
+    const userB = await createUser({ tag: 'merge-b', mail: e2eMail('merge-slave'), language: 'EN' });
+    const code = await triggerMergeViaMailChange(page, userA, userB);
+    expect(code).toBeTruthy();
+
+    const mail = await waitForMergeMail(userA.userDataId);
+    assertMergeMailUrl(mail.url, code, 'dfx');
+
+    // Confirm merge unauthenticated (OptionalJwtAuthGuard).
+    await page.goto(`/account-merge?otp=${encodeURIComponent(code)}`);
+    await expect(page.getByText('Wallet address added', { exact: true })).toBeVisible({ timeout: 30000 });
+    await expect(page.getByText('You can now access your account.', { exact: true })).toBeVisible();
+    await expect(page.getByRole('button', { name: 'My account' })).toBeVisible();
+
+    const completed = await waitForRow<{ isCompleted: boolean }>(
+      `SELECT "isCompleted" AS "isCompleted" FROM account_merge
+       WHERE "masterId" = $1 AND "slaveId" = $2
+       ORDER BY id DESC LIMIT 1`,
+      [userA.userDataId, userB.userDataId],
+      20000,
+    );
+    expect(completed.isCompleted).toBe(true);
+
+    const slave = await waitForRow<{ status: string }>(
+      `SELECT status FROM user_data WHERE id = $1 AND status = 'Merged'`,
+      [userB.userDataId],
+      20000,
+    );
+    expect(slave.status).toBe('Merged');
+  });
+
+  // Host-matrix (RealUnit / Denario / mixed) needs DFXswiss/backend#5270 on the API image.
+  // e2e-stack.yml checks out backend@develop, which still brands merge from the default wallet.
+  test('unanimous RealUnit merge mail links to realunit.app and still confirms on DFX', async ({ page }) => {
+    test.skip(true, 'Needs DFXswiss/backend#5270; e2e-stack builds the API from develop');
+    test.setTimeout(120000);
+    const realunitId = await walletIdNamed('RealUnit');
+    const userA = await createUser({ tag: 'merge-ru-a', mail: e2eMail('merge-ru-master'), language: 'EN' });
+    const userB = await createUser({ tag: 'merge-ru-b', mail: e2eMail('merge-ru-slave'), language: 'EN' });
+    await setUserWallet(userA.userId, realunitId);
+
+    const code = await triggerMergeViaMailChange(page, userA, userB);
+    const mail = await waitForMergeMail(userA.userDataId);
+    expect(mail.walletName).toBe('RealUnit');
+    assertMergeMailUrl(mail.url, code, 'realunit');
+
+    await page.goto(`/account-merge?otp=${encodeURIComponent(code)}`);
+    await expect(page.getByText('Wallet address added', { exact: true })).toBeVisible({ timeout: 30000 });
+  });
+
+  test('unanimous Denario merge mail stays on the DFX confirmation host', async ({ page }) => {
+    test.skip(true, 'Needs DFXswiss/backend#5270; e2e-stack builds the API from develop');
+    test.setTimeout(120000);
+    const denarioId = await walletIdNamed('Denario');
+    const userA = await createUser({ tag: 'merge-de-a', mail: e2eMail('merge-de-master'), language: 'EN' });
+    const userB = await createUser({ tag: 'merge-de-b', mail: e2eMail('merge-de-slave'), language: 'EN' });
+    await setUserWallet(userA.userId, denarioId);
+
+    const code = await triggerMergeViaMailChange(page, userA, userB);
+    const mail = await waitForMergeMail(userA.userDataId);
+    expect(mail.walletName).toBeUndefined();
+    assertMergeMailUrl(mail.url, code, 'dfx');
+  });
+
+  test('mixed RealUnit+DFX addresses on the master stay on the DFX confirmation host', async ({ page }) => {
+    test.skip(true, 'Needs DFXswiss/backend#5270; e2e-stack builds the API from develop');
+    test.setTimeout(120000);
+    const realunitId = await walletIdNamed('RealUnit');
+    const userA = await createUser({ tag: 'merge-mx-a', mail: e2eMail('merge-mx-master'), language: 'EN' });
+    const extra = await createUser({ tag: 'merge-mx-extra', mail: e2eMail('merge-mx-extra'), language: 'EN' });
+    const userB = await createUser({ tag: 'merge-mx-b', mail: e2eMail('merge-mx-slave'), language: 'EN' });
+    await setUserWallet(userA.userId, realunitId);
+    await withDb(async (client) => {
+      await client.query(`UPDATE "user" SET "userDataId" = $1 WHERE id = $2`, [userA.userDataId, extra.userId]);
+    });
+
+    const code = await triggerMergeViaMailChange(page, userA, userB);
+    const mail = await waitForMergeMail(userA.userDataId);
+    expect(mail.walletName).toBeUndefined();
+    assertMergeMailUrl(mail.url, code, 'dfx');
+  });
+
+  test('/account-merge without otp ends on /login when there is no session', async ({ page }) => {
+    await page.goto('/account-merge');
+    await page.waitForLoadState('networkidle');
+    await expect
+      .poll(() => normPath(new URL(page.url()).pathname), {
+        message: 'missing merge otp without a session should end on /login',
+        timeout: 20000,
+      })
+      .toBe('/login');
+  });
+
+  test('/account-merge already-completed otp lands on /error', async ({ page }) => {
+    test.setTimeout(120000);
+
+    const mailA = e2eMail('merge-done-master');
+    const mailB = e2eMail('merge-done-slave');
+    const userA = await createUser({ tag: 'merge-done-a', mail: mailA, language: 'EN' });
+    const userB = await createUser({ tag: 'merge-done-b', mail: mailB, language: 'EN' });
 
-    // Trigger merge the same way the product does: B requests A's mail after 2FA.
     await openScreen(page, '/2fa', userB.jwt);
     await completeMail2faOnPage(page, userB.userDataId);
-
     await page.goto('/account/mail');
     await page.waitForLoadState('networkidle');
     await expect(page.getByRole('textbox', { name: 'Email address' })).toBeVisible({
       timeout: 20000,
     });
-
-    const mailInput = page.getByRole('textbox', { name: 'Email address' });
-    await mailInput.fill(mailA);
+    await page.getByRole('textbox', { name: 'Email address' }).fill(mailA);
     await page.getByRole('button', { name: 'Save' }).click();
-
     await expect(page.getByText('It looks like you already have an account with DFX.')).toBeVisible({
       timeout: 20000,
     });
@@ -376,28 +553,63 @@ test.describe('Auth area e2e', () => {
       [userA.userDataId, userB.userDataId],
       20000,
     );
-    expect(mergeRow.code).toBeTruthy();
 
-    // Confirm merge unauthenticated (OptionalJwtAuthGuard).
     await page.goto(`/account-merge?otp=${encodeURIComponent(mergeRow.code)}`);
     await expect(page.getByText('Wallet address added', { exact: true })).toBeVisible({ timeout: 30000 });
-    await expect(page.getByText('You can now access your account.', { exact: true })).toBeVisible();
-    await expect(page.getByRole('button', { name: 'My account' })).toBeVisible();
 
-    const completed = await waitForRow<{ isCompleted: boolean }>(
-      `SELECT "isCompleted" AS "isCompleted" FROM account_merge
+    await page.goto(`/account-merge?otp=${encodeURIComponent(mergeRow.code)}`);
+    await expect
+      .poll(() => normPath(new URL(page.url()).pathname), {
+        message: 'already-merged otp should navigate to /error',
+        timeout: 20000,
+      })
+      .toBe('/error');
+    await expect(page.getByText(/already been added/i)).toBeVisible();
+  });
+
+  test('/account-merge expired otp lands on /error', async ({ page }) => {
+    test.setTimeout(120000);
+
+    const mailA = e2eMail('merge-exp-master');
+    const mailB = e2eMail('merge-exp-slave');
+    const userA = await createUser({ tag: 'merge-exp-a', mail: mailA, language: 'EN' });
+    const userB = await createUser({ tag: 'merge-exp-b', mail: mailB, language: 'EN' });
+
+    await openScreen(page, '/2fa', userB.jwt);
+    await completeMail2faOnPage(page, userB.userDataId);
+    await page.goto('/account/mail');
+    await page.waitForLoadState('networkidle');
+    await expect(page.getByRole('textbox', { name: 'Email address' })).toBeVisible({
+      timeout: 20000,
+    });
+    await page.getByRole('textbox', { name: 'Email address' }).fill(mailA);
+    await page.getByRole('button', { name: 'Save' }).click();
+    await expect(page.getByText('It looks like you already have an account with DFX.')).toBeVisible({
+      timeout: 20000,
+    });
+
+    const mergeRow = await waitForRow<{ code: string }>(
+      `SELECT code FROM account_merge
        WHERE "masterId" = $1 AND "slaveId" = $2
        ORDER BY id DESC LIMIT 1`,
       [userA.userDataId, userB.userDataId],
       20000,
     );
-    expect(completed.isCompleted).toBe(true);
 
-    const slave = await waitForRow<{ status: string }>(
-      `SELECT status FROM user_data WHERE id = $1 AND status = 'Merged'`,
-      [userB.userDataId],
-      20000,
-    );
-    expect(slave.status).toBe('Merged');
+    await withDb(async (client) => {
+      await client.query(`UPDATE account_merge SET expiration = $1 WHERE code = $2`, [
+        new Date('2000-01-01T00:00:00Z'),
+        mergeRow.code,
+      ]);
+    });
+
+    await page.goto(`/account-merge?otp=${encodeURIComponent(mergeRow.code)}`);
+    await expect
+      .poll(() => normPath(new URL(page.url()).pathname), {
+        message: 'expired merge otp should navigate to /error',
+        timeout: 20000,
+      })
+      .toBe('/error');
+    await expect(page.getByText(/expired|Invalid link/i)).toBeVisible();
   });
 });
diff --git a/src/components/compliance/call-queue/call-queue-user-info.tsx b/src/components/compliance/call-queue/call-queue-user-info.tsx
index e8fcd3258..9f5cc5f37 100644
--- a/src/components/compliance/call-queue/call-queue-user-info.tsx
+++ b/src/components/compliance/call-queue/call-queue-user-info.tsx
@@ -74,7 +74,7 @@ export function CallQueueUserInfo({ userData, users, kycSteps, highlightCheckDat
     { label: 'Status', value: userData.status },
     { label: 'KYC Level', value: userData.kycLevel == null ? undefined : String(userData.kycLevel) },
     { label: 'KYC Status', value: userData.kycStatus },
-    { label: 'Wallet', value: primaryUser?.walletName ?? userData.wallet?.name },
+    { label: 'Wallet', value: primaryUser?.walletName },
     { label: 'User Ref', value: primaryUser?.ref },
     { label: 'Used Ref', value: primaryUser?.usedRef },
     { label: 'Referrer (Ref Werber)', value: refUserName },
diff --git a/src/components/compliance/user-data-panel.tsx b/src/components/compliance/user-data-panel.tsx
index 9bb1e5f1c..e29bf9cab 100644
--- a/src/components/compliance/user-data-panel.tsx
+++ b/src/components/compliance/user-data-panel.tsx
@@ -109,7 +109,6 @@ function userDataRows(d: UserDataDetail, depositLimitNode: ReactNode, idNode: Re
     { key: 'kycStatus', value: display(d.kycStatus) },
     { key: 'kycLevel', value: display(d.kycLevel) },
     { key: 'depositLimit', value: depositLimitNode },
-    { key: 'wallet', value: refName(d.wallet) },
   ];
 }
 
diff --git a/src/hooks/compliance.hook.ts b/src/hooks/compliance.hook.ts
index ad4bb25a9..79c03c6a7 100644
--- a/src/hooks/compliance.hook.ts
+++ b/src/hooks/compliance.hook.ts
@@ -276,10 +276,6 @@ export interface LanguageRef {
   symbol?: string;
 }
 
-export interface WalletRef {
-  name?: string;
-}
-
 export interface OrganizationDetail {
   id?: number;
   name?: string;
@@ -307,7 +303,6 @@ export interface UserDataDetail {
   kycStatus?: string;
   kycLevel?: number;
   depositLimit?: number;
-  wallet?: WalletRef;
 
   // Personal Data
   accountType?: string;