feat(cardav): add Migration 30 for CardDAV contacts schema

Add comprehensive database schema for CardDAV multi-account contacts sync:

New tables:
- cardav_accounts: Store CardDAV server credentials
- cardav_addressbook_selection: Per-account addressbook enable/disable
- contact_phones: Multiple phone numbers per contact with labels
- contact_emails: Multiple email addresses per contact with labels
- contact_addresses: Multiple postal addresses per contact with labels

Extended contacts table with 9 new columns:
- organization, job_title, birthday, website, photo, nickname
- cardav_account_id (FK to cardav_accounts, ON DELETE SET NULL)
- cardav_uid (vCard UID from server)
- cardav_addressbook_url (source addressbook URL)

Features:
- UNIQUE constraints on (cardav_url, username) and (account_id, addressbook_url)
- CASCADE delete for addressbook selection and contact sub-tables
- Performance indices for cardav_uid and email lookups
- Support for manual contacts (NULL cardav_account_id)
- is_primary flag for phone/email/address selection

Test coverage:
- 23 comprehensive tests verify all tables, constraints, indices
- FK CASCADE delete behavior validated
- UNIQUE constraints enforced
- Data integrity scenarios tested

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "oikos",
-  "version": "0.43.0",
+  "version": "0.44.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "oikos",
-      "version": "0.43.0",
+      "version": "0.44.0",
       "license": "MIT",
       "dependencies": {
         "bcrypt": "^6.0.0",

package.json

@@ -28,7 +28,8 @@
     "test:ics-sub": "node --experimental-sqlite test-ics-subscription.js",
     "test:backup-scheduler": "node --experimental-sqlite test-backup-scheduler.js",
     "test:caldav": "node --experimental-sqlite test-caldav-sync.js",
-    "test": "node --experimental-sqlite test-db.js && node --experimental-sqlite test-dashboard.js && node --experimental-sqlite test-tasks.js && node --experimental-sqlite test-shopping.js && node --experimental-sqlite test-meals.js && node --experimental-sqlite test-calendar.js && node --experimental-sqlite test-notes-contacts-budget.js && npm run test:ux-utils && npm run test:modal-utils && npm run test:reminders && npm run test:api && npm run test:ics-parser && npm run test:ics-sub && npm run test:setup && npm run test:kitchen-tabs && npm run test:backup-scheduler && npm run test:caldav"
+    "test:cardav": "node --experimental-sqlite test-cardav.js",
+    "test": "node --experimental-sqlite test-db.js && node --experimental-sqlite test-dashboard.js && node --experimental-sqlite test-tasks.js && node --experimental-sqlite test-shopping.js && node --experimental-sqlite test-meals.js && node --experimental-sqlite test-calendar.js && node --experimental-sqlite test-notes-contacts-budget.js && npm run test:ux-utils && npm run test:modal-utils && npm run test:reminders && npm run test:api && npm run test:ics-parser && npm run test:ics-sub && npm run test:setup && npm run test:kitchen-tabs && npm run test:backup-scheduler && npm run test:caldav && npm run test:cardav"
   },
   "dependencies": {
     "bcrypt": "^6.0.0",

server/db.js

@@ -1075,6 +1075,107 @@ const MIGRATIONS = [
       db.exec(`CREATE UNIQUE INDEX idx_calendar_sub_extid ON calendar_events (subscription_id, external_calendar_id)`);
     },
   },
+  {
+    version: 30,
+    description: 'CardDAV multi-account contacts sync',
+    up: `
+      -- ========================================
+      -- CardDAV Accounts
+      -- ========================================
+      CREATE TABLE cardav_accounts (
+        id         INTEGER PRIMARY KEY AUTOINCREMENT,
+        name       TEXT NOT NULL,
+        cardav_url TEXT NOT NULL,
+        username   TEXT NOT NULL,
+        password   TEXT NOT NULL,
+        created_at TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
+        last_sync  TEXT,
+        UNIQUE(cardav_url, username)
+      );
+
+      -- ========================================
+      -- CardDAV Addressbook Selection
+      -- ========================================
+      CREATE TABLE cardav_addressbook_selection (
+        id              INTEGER PRIMARY KEY AUTOINCREMENT,
+        account_id      INTEGER NOT NULL,
+        addressbook_url TEXT NOT NULL,
+        addressbook_name TEXT NOT NULL,
+        enabled         INTEGER NOT NULL DEFAULT 1,
+        created_at      TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
+        UNIQUE(account_id, addressbook_url),
+        FOREIGN KEY(account_id) REFERENCES cardav_accounts(id) ON DELETE CASCADE
+      );
+
+      CREATE INDEX idx_cardav_addressbook_account
+        ON cardav_addressbook_selection(account_id, enabled);
+
+      -- ========================================
+      -- Extend Contacts Table for CardDAV
+      -- ========================================
+      ALTER TABLE contacts ADD COLUMN organization TEXT;
+      ALTER TABLE contacts ADD COLUMN job_title TEXT;
+      ALTER TABLE contacts ADD COLUMN birthday TEXT;
+      ALTER TABLE contacts ADD COLUMN website TEXT;
+      ALTER TABLE contacts ADD COLUMN photo TEXT;
+      ALTER TABLE contacts ADD COLUMN nickname TEXT;
+      ALTER TABLE contacts ADD COLUMN cardav_account_id INTEGER
+        REFERENCES cardav_accounts(id) ON DELETE SET NULL;
+      ALTER TABLE contacts ADD COLUMN cardav_uid TEXT;
+      ALTER TABLE contacts ADD COLUMN cardav_addressbook_url TEXT;
+
+      CREATE INDEX idx_contacts_cardav_uid ON contacts(cardav_uid);
+      CREATE INDEX idx_contacts_email ON contacts(email);
+
+      -- ========================================
+      -- Contact Phones (Multiple per Contact)
+      -- ========================================
+      CREATE TABLE contact_phones (
+        id         INTEGER PRIMARY KEY AUTOINCREMENT,
+        contact_id INTEGER NOT NULL,
+        label      TEXT,
+        value      TEXT NOT NULL,
+        is_primary INTEGER NOT NULL DEFAULT 0,
+        FOREIGN KEY(contact_id) REFERENCES contacts(id) ON DELETE CASCADE
+      );
+
+      CREATE INDEX idx_contact_phones_contact ON contact_phones(contact_id);
+      CREATE INDEX idx_contact_phones_value ON contact_phones(value);
+
+      -- ========================================
+      -- Contact Emails (Multiple per Contact)
+      -- ========================================
+      CREATE TABLE contact_emails (
+        id         INTEGER PRIMARY KEY AUTOINCREMENT,
+        contact_id INTEGER NOT NULL,
+        label      TEXT,
+        value      TEXT NOT NULL,
+        is_primary INTEGER NOT NULL DEFAULT 0,
+        FOREIGN KEY(contact_id) REFERENCES contacts(id) ON DELETE CASCADE
+      );
+
+      CREATE INDEX idx_contact_emails_contact ON contact_emails(contact_id);
+      CREATE INDEX idx_contact_emails_value ON contact_emails(value);
+
+      -- ========================================
+      -- Contact Addresses (Multiple per Contact)
+      -- ========================================
+      CREATE TABLE contact_addresses (
+        id          INTEGER PRIMARY KEY AUTOINCREMENT,
+        contact_id  INTEGER NOT NULL,
+        label       TEXT,
+        street      TEXT,
+        city        TEXT,
+        state       TEXT,
+        postal_code TEXT,
+        country     TEXT,
+        is_primary  INTEGER NOT NULL DEFAULT 0,
+        FOREIGN KEY(contact_id) REFERENCES contacts(id) ON DELETE CASCADE
+      );
+
+      CREATE INDEX idx_contact_addresses_contact ON contact_addresses(contact_id);
+    `,
+  },
 ];
 
 /**

test-cardav.js

@@ -0,0 +1,469 @@
+/**
+ * Test: CardDAV Contacts Schema
+ * Purpose: Verify Migration 30 - CardDAV multi-account contacts sync tables
+ */
+
+import { describe, it, before } from 'node:test';
+import assert from 'node:assert/strict';
+import { DatabaseSync } from 'node:sqlite';
+
+const TEST_DB = ':memory:';
+
+describe('CardDAV Contacts Schema (Migration 30)', () => {
+  let db;
+
+  before(() => {
+    // Create in-memory DB
+    db = new DatabaseSync(TEST_DB);
+    db.exec('PRAGMA foreign_keys = ON;');
+
+    // Create base contacts table (from Migration 1) and family_user_id (Migration 23)
+    db.exec(`
+      CREATE TABLE users (
+        id INTEGER PRIMARY KEY AUTOINCREMENT,
+        username TEXT NOT NULL
+      );
+
+      CREATE TABLE contacts (
+        id         INTEGER PRIMARY KEY AUTOINCREMENT,
+        name       TEXT NOT NULL,
+        category   TEXT NOT NULL DEFAULT 'Sonstiges',
+        phone      TEXT,
+        email      TEXT,
+        address    TEXT,
+        notes      TEXT,
+        family_user_id INTEGER REFERENCES users(id) ON DELETE CASCADE,
+        created_at TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
+        updated_at TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now'))
+      );
+
+      INSERT INTO users (username) VALUES ('testuser');
+    `);
+
+    // Apply Migration 30
+    db.exec(`
+      -- CardDAV Accounts
+      CREATE TABLE cardav_accounts (
+        id         INTEGER PRIMARY KEY AUTOINCREMENT,
+        name       TEXT NOT NULL,
+        cardav_url TEXT NOT NULL,
+        username   TEXT NOT NULL,
+        password   TEXT NOT NULL,
+        created_at TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
+        last_sync  TEXT,
+        UNIQUE(cardav_url, username)
+      );
+
+      -- CardDAV Addressbook Selection
+      CREATE TABLE cardav_addressbook_selection (
+        id              INTEGER PRIMARY KEY AUTOINCREMENT,
+        account_id      INTEGER NOT NULL,
+        addressbook_url TEXT NOT NULL,
+        addressbook_name TEXT NOT NULL,
+        enabled         INTEGER NOT NULL DEFAULT 1,
+        created_at      TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
+        UNIQUE(account_id, addressbook_url),
+        FOREIGN KEY(account_id) REFERENCES cardav_accounts(id) ON DELETE CASCADE
+      );
+
+      CREATE INDEX idx_cardav_addressbook_account
+        ON cardav_addressbook_selection(account_id, enabled);
+
+      -- Extend Contacts Table
+      ALTER TABLE contacts ADD COLUMN organization TEXT;
+      ALTER TABLE contacts ADD COLUMN job_title TEXT;
+      ALTER TABLE contacts ADD COLUMN birthday TEXT;
+      ALTER TABLE contacts ADD COLUMN website TEXT;
+      ALTER TABLE contacts ADD COLUMN photo TEXT;
+      ALTER TABLE contacts ADD COLUMN nickname TEXT;
+      ALTER TABLE contacts ADD COLUMN cardav_account_id INTEGER
+        REFERENCES cardav_accounts(id) ON DELETE SET NULL;
+      ALTER TABLE contacts ADD COLUMN cardav_uid TEXT;
+      ALTER TABLE contacts ADD COLUMN cardav_addressbook_url TEXT;
+
+      CREATE INDEX idx_contacts_cardav_uid ON contacts(cardav_uid);
+      CREATE INDEX idx_contacts_email ON contacts(email);
+
+      -- Contact Phones
+      CREATE TABLE contact_phones (
+        id         INTEGER PRIMARY KEY AUTOINCREMENT,
+        contact_id INTEGER NOT NULL,
+        label      TEXT,
+        value      TEXT NOT NULL,
+        is_primary INTEGER NOT NULL DEFAULT 0,
+        FOREIGN KEY(contact_id) REFERENCES contacts(id) ON DELETE CASCADE
+      );
+
+      CREATE INDEX idx_contact_phones_contact ON contact_phones(contact_id);
+      CREATE INDEX idx_contact_phones_value ON contact_phones(value);
+
+      -- Contact Emails
+      CREATE TABLE contact_emails (
+        id         INTEGER PRIMARY KEY AUTOINCREMENT,
+        contact_id INTEGER NOT NULL,
+        label      TEXT,
+        value      TEXT NOT NULL,
+        is_primary INTEGER NOT NULL DEFAULT 0,
+        FOREIGN KEY(contact_id) REFERENCES contacts(id) ON DELETE CASCADE
+      );
+
+      CREATE INDEX idx_contact_emails_contact ON contact_emails(contact_id);
+      CREATE INDEX idx_contact_emails_value ON contact_emails(value);
+
+      -- Contact Addresses
+      CREATE TABLE contact_addresses (
+        id          INTEGER PRIMARY KEY AUTOINCREMENT,
+        contact_id  INTEGER NOT NULL,
+        label       TEXT,
+        street      TEXT,
+        city        TEXT,
+        state       TEXT,
+        postal_code TEXT,
+        country     TEXT,
+        is_primary  INTEGER NOT NULL DEFAULT 0,
+        FOREIGN KEY(contact_id) REFERENCES contacts(id) ON DELETE CASCADE
+      );
+
+      CREATE INDEX idx_contact_addresses_contact ON contact_addresses(contact_id);
+    `);
+  });
+
+  // ========================================
+  // Table Existence Tests
+  // ========================================
+
+  it('should create cardav_accounts table', () => {
+    const result = db.prepare("SELECT name FROM sqlite_master WHERE type='table' AND name='cardav_accounts'").get();
+    assert.ok(result, 'cardav_accounts table should exist');
+  });
+
+  it('should create cardav_addressbook_selection table', () => {
+    const result = db.prepare("SELECT name FROM sqlite_master WHERE type='table' AND name='cardav_addressbook_selection'").get();
+    assert.ok(result, 'cardav_addressbook_selection table should exist');
+  });
+
+  it('should create contact_phones table', () => {
+    const result = db.prepare("SELECT name FROM sqlite_master WHERE type='table' AND name='contact_phones'").get();
+    assert.ok(result, 'contact_phones table should exist');
+  });
+
+  it('should create contact_emails table', () => {
+    const result = db.prepare("SELECT name FROM sqlite_master WHERE type='table' AND name='contact_emails'").get();
+    assert.ok(result, 'contact_emails table should exist');
+  });
+
+  it('should create contact_addresses table', () => {
+    const result = db.prepare("SELECT name FROM sqlite_master WHERE type='table' AND name='contact_addresses'").get();
+    assert.ok(result, 'contact_addresses table should exist');
+  });
+
+  // ========================================
+  // Contacts Table Extension Tests
+  // ========================================
+
+  it('should extend contacts table with CardDAV columns', () => {
+    const cols = db.prepare("PRAGMA table_info(contacts)").all();
+    const colNames = cols.map(c => c.name);
+
+    assert.ok(colNames.includes('organization'), 'Should have organization column');
+    assert.ok(colNames.includes('job_title'), 'Should have job_title column');
+    assert.ok(colNames.includes('birthday'), 'Should have birthday column');
+    assert.ok(colNames.includes('website'), 'Should have website column');
+    assert.ok(colNames.includes('photo'), 'Should have photo column');
+    assert.ok(colNames.includes('nickname'), 'Should have nickname column');
+    assert.ok(colNames.includes('cardav_account_id'), 'Should have cardav_account_id column');
+    assert.ok(colNames.includes('cardav_uid'), 'Should have cardav_uid column');
+    assert.ok(colNames.includes('cardav_addressbook_url'), 'Should have cardav_addressbook_url column');
+  });
+
+  // ========================================
+  // Index Tests
+  // ========================================
+
+  it('should create index on contacts.cardav_uid', () => {
+    const result = db.prepare("SELECT name FROM sqlite_master WHERE type='index' AND name='idx_contacts_cardav_uid'").get();
+    assert.ok(result, 'Index on cardav_uid should exist');
+  });
+
+  it('should create index on contacts.email', () => {
+    const result = db.prepare("SELECT name FROM sqlite_master WHERE type='index' AND name='idx_contacts_email'").get();
+    assert.ok(result, 'Index on email should exist');
+  });
+
+  it('should create index on contact_phones.contact_id', () => {
+    const result = db.prepare("SELECT name FROM sqlite_master WHERE type='index' AND name='idx_contact_phones_contact'").get();
+    assert.ok(result, 'Index on contact_phones.contact_id should exist');
+  });
+
+  it('should create index on contact_phones.value', () => {
+    const result = db.prepare("SELECT name FROM sqlite_master WHERE type='index' AND name='idx_contact_phones_value'").get();
+    assert.ok(result, 'Index on contact_phones.value should exist');
+  });
+
+  it('should create index on contact_emails.contact_id', () => {
+    const result = db.prepare("SELECT name FROM sqlite_master WHERE type='index' AND name='idx_contact_emails_contact'").get();
+    assert.ok(result, 'Index on contact_emails.contact_id should exist');
+  });
+
+  it('should create index on contact_emails.value', () => {
+    const result = db.prepare("SELECT name FROM sqlite_master WHERE type='index' AND name='idx_contact_emails_value'").get();
+    assert.ok(result, 'Index on contact_emails.value should exist');
+  });
+
+  it('should create index on contact_addresses.contact_id', () => {
+    const result = db.prepare("SELECT name FROM sqlite_master WHERE type='index' AND name='idx_contact_addresses_contact'").get();
+    assert.ok(result, 'Index on contact_addresses.contact_id should exist');
+  });
+
+  // ========================================
+  // UNIQUE Constraint Tests
+  // ========================================
+
+  it('should enforce UNIQUE(cardav_url, username) on cardav_accounts', () => {
+    db.prepare(`
+      INSERT INTO cardav_accounts (name, cardav_url, username, password)
+      VALUES (?, ?, ?, ?)
+    `).run('Test Account', 'https://cardav.example.com', 'user1', 'pass1');
+
+    const account = db.prepare('SELECT * FROM cardav_accounts WHERE name = ?').get('Test Account');
+    assert.ok(account, 'Account should be inserted');
+
+    // Duplicate should fail
+    assert.throws(() => {
+      db.prepare(`
+        INSERT INTO cardav_accounts (name, cardav_url, username, password)
+        VALUES (?, ?, ?, ?)
+      `).run('Duplicate', 'https://cardav.example.com', 'user1', 'pass2');
+    }, 'UNIQUE constraint should prevent duplicate cardav_url+username');
+  });
+
+  it('should enforce UNIQUE(account_id, addressbook_url) on addressbook_selection', () => {
+    const accountId = db.prepare('SELECT id FROM cardav_accounts WHERE name = ?').get('Test Account').id;
+
+    db.prepare(`
+      INSERT INTO cardav_addressbook_selection (account_id, addressbook_url, addressbook_name)
+      VALUES (?, ?, ?)
+    `).run(accountId, 'https://cardav.example.com/addressbooks/main', 'Main Addressbook');
+
+    // Duplicate should fail
+    assert.throws(() => {
+      db.prepare(`
+        INSERT INTO cardav_addressbook_selection (account_id, addressbook_url, addressbook_name)
+        VALUES (?, ?, ?)
+      `).run(accountId, 'https://cardav.example.com/addressbooks/main', 'Duplicate');
+    }, 'UNIQUE constraint should prevent duplicate account_id+addressbook_url');
+  });
+
+  // ========================================
+  // Foreign Key Cascade Tests
+  // ========================================
+
+  it('should CASCADE delete addressbook_selection when account deleted', () => {
+    const accountId = db.prepare('SELECT id FROM cardav_accounts WHERE name = ?').get('Test Account').id;
+
+    // Verify addressbook exists
+    const beforeDelete = db.prepare('SELECT * FROM cardav_addressbook_selection WHERE account_id = ?').get(accountId);
+    assert.ok(beforeDelete, 'Addressbook selection should exist before delete');
+
+    // Delete account
+    db.prepare('DELETE FROM cardav_accounts WHERE id = ?').run(accountId);
+
+    // Addressbook selection should be deleted
+    const afterDelete = db.prepare('SELECT * FROM cardav_addressbook_selection WHERE account_id = ?').get(accountId);
+    assert.strictEqual(afterDelete, undefined, 'Addressbook selection should CASCADE delete');
+  });
+
+  it('should CASCADE delete contact_phones when contact deleted', () => {
+    // Create contact
+    db.prepare(`
+      INSERT INTO contacts (name, category)
+      VALUES (?, ?)
+    `).run('John Doe', 'Sonstiges');
+
+    const contactId = db.prepare('SELECT id FROM contacts WHERE name = ?').get('John Doe').id;
+
+    // Add phones
+    db.prepare(`
+      INSERT INTO contact_phones (contact_id, label, value, is_primary)
+      VALUES (?, ?, ?, ?)
+    `).run(contactId, 'mobile', '+1234567890', 1);
+
+    db.prepare(`
+      INSERT INTO contact_phones (contact_id, label, value)
+      VALUES (?, ?, ?)
+    `).run(contactId, 'work', '+0987654321');
+
+    // Verify phones exist
+    const phonesBefore = db.prepare('SELECT * FROM contact_phones WHERE contact_id = ?').all(contactId);
+    assert.strictEqual(phonesBefore.length, 2, 'Should have 2 phone numbers');
+
+    // Delete contact
+    db.prepare('DELETE FROM contacts WHERE id = ?').run(contactId);
+
+    // Phones should be deleted
+    const phonesAfter = db.prepare('SELECT * FROM contact_phones WHERE contact_id = ?').all(contactId);
+    assert.strictEqual(phonesAfter.length, 0, 'Phone numbers should CASCADE delete');
+  });
+
+  it('should CASCADE delete contact_emails when contact deleted', () => {
+    // Create contact
+    db.prepare(`
+      INSERT INTO contacts (name, category)
+      VALUES (?, ?)
+    `).run('Jane Smith', 'Sonstiges');
+
+    const contactId = db.prepare('SELECT id FROM contacts WHERE name = ?').get('Jane Smith').id;
+
+    // Add emails
+    db.prepare(`
+      INSERT INTO contact_emails (contact_id, label, value, is_primary)
+      VALUES (?, ?, ?, ?)
+    `).run(contactId, 'work', 'jane@work.com', 1);
+
+    db.prepare(`
+      INSERT INTO contact_emails (contact_id, label, value)
+      VALUES (?, ?, ?)
+    `).run(contactId, 'home', 'jane@home.com');
+
+    // Verify emails exist
+    const emailsBefore = db.prepare('SELECT * FROM contact_emails WHERE contact_id = ?').all(contactId);
+    assert.strictEqual(emailsBefore.length, 2, 'Should have 2 email addresses');
+
+    // Delete contact
+    db.prepare('DELETE FROM contacts WHERE id = ?').run(contactId);
+
+    // Emails should be deleted
+    const emailsAfter = db.prepare('SELECT * FROM contact_emails WHERE contact_id = ?').all(contactId);
+    assert.strictEqual(emailsAfter.length, 0, 'Email addresses should CASCADE delete');
+  });
+
+  it('should CASCADE delete contact_addresses when contact deleted', () => {
+    // Create contact
+    db.prepare(`
+      INSERT INTO contacts (name, category)
+      VALUES (?, ?)
+    `).run('Bob Johnson', 'Sonstiges');
+
+    const contactId = db.prepare('SELECT id FROM contacts WHERE name = ?').get('Bob Johnson').id;
+
+    // Add addresses
+    db.prepare(`
+      INSERT INTO contact_addresses (contact_id, label, street, city, is_primary)
+      VALUES (?, ?, ?, ?, ?)
+    `).run(contactId, 'home', '123 Main St', 'Springfield', 1);
+
+    db.prepare(`
+      INSERT INTO contact_addresses (contact_id, label, street, city)
+      VALUES (?, ?, ?, ?)
+    `).run(contactId, 'work', '456 Office Blvd', 'Metropolis');
+
+    // Verify addresses exist
+    const addressesBefore = db.prepare('SELECT * FROM contact_addresses WHERE contact_id = ?').all(contactId);
+    assert.strictEqual(addressesBefore.length, 2, 'Should have 2 addresses');
+
+    // Delete contact
+    db.prepare('DELETE FROM contacts WHERE id = ?').run(contactId);
+
+    // Addresses should be deleted
+    const addressesAfter = db.prepare('SELECT * FROM contact_addresses WHERE contact_id = ?').all(contactId);
+    assert.strictEqual(addressesAfter.length, 0, 'Addresses should CASCADE delete');
+  });
+
+  it('should SET NULL on contacts.cardav_account_id when account deleted', () => {
+    // Create new account
+    db.prepare(`
+      INSERT INTO cardav_accounts (name, cardav_url, username, password)
+      VALUES (?, ?, ?, ?)
+    `).run('iCloud', 'https://contacts.icloud.com', 'user@icloud.com', 'pass');
+
+    const accountId = db.prepare('SELECT id FROM cardav_accounts WHERE name = ?').get('iCloud').id;
+
+    // Create contact linked to account
+    db.prepare(`
+      INSERT INTO contacts (name, category, cardav_account_id, cardav_uid)
+      VALUES (?, ?, ?, ?)
+    `).run('Alice Cooper', 'Sonstiges', accountId, 'urn:uuid:12345');
+
+    const contactId = db.prepare('SELECT id FROM contacts WHERE name = ?').get('Alice Cooper').id;
+
+    // Verify link
+    const beforeDelete = db.prepare('SELECT cardav_account_id FROM contacts WHERE id = ?').get(contactId);
+    assert.strictEqual(beforeDelete.cardav_account_id, accountId, 'Contact should be linked to account');
+
+    // Delete account
+    db.prepare('DELETE FROM cardav_accounts WHERE id = ?').run(accountId);
+
+    // Contact should remain but link should be NULL
+    const afterDelete = db.prepare('SELECT * FROM contacts WHERE id = ?').get(contactId);
+    assert.ok(afterDelete, 'Contact should still exist');
+    assert.strictEqual(afterDelete.cardav_account_id, null, 'cardav_account_id should be SET NULL');
+  });
+
+  // ========================================
+  // Data Integrity Tests
+  // ========================================
+
+  it('should handle enabled/disabled addressbook selection', () => {
+    // Create account
+    db.prepare(`
+      INSERT INTO cardav_accounts (name, cardav_url, username, password)
+      VALUES (?, ?, ?, ?)
+    `).run('Nextcloud', 'https://nextcloud.example.com/dav', 'user@example.com', 'pass');
+
+    const accountId = db.prepare('SELECT id FROM cardav_accounts WHERE name = ?').get('Nextcloud').id;
+
+    // Add addressbooks
+    db.prepare(`
+      INSERT INTO cardav_addressbook_selection (account_id, addressbook_url, addressbook_name, enabled)
+      VALUES (?, ?, ?, ?), (?, ?, ?, ?)
+    `).run(
+      accountId, 'https://nextcloud.example.com/dav/contacts/private', 'Private', 1,
+      accountId, 'https://nextcloud.example.com/dav/contacts/work', 'Work', 0
+    );
+
+    // Query enabled only
+    const enabled = db.prepare('SELECT * FROM cardav_addressbook_selection WHERE account_id = ? AND enabled = 1').all(accountId);
+    assert.strictEqual(enabled.length, 1, 'Should have 1 enabled addressbook');
+    assert.strictEqual(enabled[0].addressbook_name, 'Private');
+
+    // Query all
+    const all = db.prepare('SELECT * FROM cardav_addressbook_selection WHERE account_id = ?').all(accountId);
+    assert.strictEqual(all.length, 2, 'Should have 2 total addressbooks');
+  });
+
+  it('should handle is_primary flag on contact phones', () => {
+    // Create contact
+    db.prepare(`
+      INSERT INTO contacts (name, category)
+      VALUES (?, ?)
+    `).run('Test Primary', 'Sonstiges');
+
+    const contactId = db.prepare('SELECT id FROM contacts WHERE name = ?').get('Test Primary').id;
+
+    // Add multiple phones with one primary
+    db.prepare(`
+      INSERT INTO contact_phones (contact_id, label, value, is_primary)
+      VALUES (?, ?, ?, ?), (?, ?, ?, ?)
+    `).run(
+      contactId, 'mobile', '+1111111111', 1,
+      contactId, 'home', '+2222222222', 0
+    );
+
+    // Query primary
+    const primary = db.prepare('SELECT * FROM contact_phones WHERE contact_id = ? AND is_primary = 1').get(contactId);
+    assert.ok(primary, 'Should have a primary phone');
+    assert.strictEqual(primary.value, '+1111111111');
+    assert.strictEqual(primary.label, 'mobile');
+  });
+
+  it('should allow manual contacts (NULL cardav_account_id)', () => {
+    db.prepare(`
+      INSERT INTO contacts (name, category, phone, email, cardav_account_id)
+      VALUES (?, ?, ?, ?, ?)
+    `).run('Manual Contact', 'Sonstiges', '+9999999999', 'manual@example.com', null);
+
+    const contact = db.prepare('SELECT * FROM contacts WHERE name = ?').get('Manual Contact');
+    assert.ok(contact, 'Manual contact should be created');
+    assert.strictEqual(contact.cardav_account_id, null, 'Manual contact should have NULL cardav_account_id');
+  });
+});