fix: add UNIQUE constraint to notification preferences userId (#2429)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Yeraze

src/db/migrations.test.ts

@@ -2,8 +2,8 @@ import { describe, it, expect } from 'vitest';
 import { registry } from './migrations.js';
 
 describe('migrations registry', () => {
-  it('has all 14 migrations registered', () => {
-    expect(registry.count()).toBe(14);
+  it('has all 15 migrations registered', () => {
+    expect(registry.count()).toBe(15);
   });
 
   it('first migration is v37 baseline', () => {
@@ -12,14 +12,14 @@ describe('migrations registry', () => {
     expect(all[0].name).toContain('v37_baseline');
   });
 
-  it('last migration is the messages decrypted_by fix', () => {
+  it('last migration is the notification prefs unique constraint', () => {
     const all = registry.getAll();
     const last = all[all.length - 1];
-    expect(last.number).toBe(14);
-    expect(last.name).toContain('messages_decrypted_by');
+    expect(last.number).toBe(15);
+    expect(last.name).toContain('notification_prefs_unique');
   });
 
-  it('migrations are sequentially numbered from 1 to 12', () => {
+  it('migrations are sequentially numbered from 1 to 15', () => {
     const all = registry.getAll();
     for (let i = 0; i < all.length; i++) {
       expect(all[i].number).toBe(i + 1);

src/db/migrations.ts

@@ -26,6 +26,7 @@ import { migration as fixMessageNodeNumBigintMigration, runMigration087Postgres,
 import { migration as authAlignMigration, runMigration012Postgres, runMigration012Mysql } from '../server/migrations/012_align_sqlite_auth_schema.js';
 import { migration as auditLogColumnsMigration, runMigration013Postgres, runMigration013Mysql } from '../server/migrations/013_add_audit_log_missing_columns.js';
 import { migration as messagesDecryptedByMigration, runMigration014Postgres, runMigration014Mysql } from '../server/migrations/014_add_messages_decrypted_by.js';
+import { migration as notificationPrefsUniqueMigration, runMigration015Postgres, runMigration015Mysql } from '../server/migrations/015_add_notification_prefs_unique.js';
 
 // ============================================================================
 // Registry
@@ -184,3 +185,17 @@ registry.register({
   postgres: (client) => runMigration014Postgres(client),
   mysql: (pool) => runMigration014Mysql(pool),
 });
+
+// ---------------------------------------------------------------------------
+// 015 — Add UNIQUE constraint to user_notification_preferences.userId
+// The upsert for notification preferences requires this constraint.
+// ---------------------------------------------------------------------------
+
+registry.register({
+  number: 15,
+  name: 'add_notification_prefs_unique',
+  settingsKey: 'migration_015_add_notification_prefs_unique',
+  sqlite: (db) => notificationPrefsUniqueMigration.up(db),
+  postgres: (client) => runMigration015Postgres(client),
+  mysql: (pool) => runMigration015Mysql(pool),
+});

src/db/schema/notifications.ts

@@ -38,7 +38,7 @@ export const pushSubscriptionsPostgres = pgTable('push_subscriptions', {
 
 export const userNotificationPreferencesSqlite = sqliteTable('user_notification_preferences', {
   id: integer('id').primaryKey({ autoIncrement: true }),
-  userId: integer('user_id').notNull().references(() => usersSqlite.id, { onDelete: 'cascade' }),
+  userId: integer('user_id').notNull().unique().references(() => usersSqlite.id, { onDelete: 'cascade' }),
   notifyOnMessage: integer('enable_web_push', { mode: 'boolean' }).default(true),
   notifyOnDirectMessage: integer('enable_direct_messages', { mode: 'boolean' }).default(true),
   notifyOnEmoji: integer('notify_on_emoji', { mode: 'boolean' }).default(false),
@@ -60,7 +60,7 @@ export const userNotificationPreferencesSqlite = sqliteTable('user_notification_
 
 export const userNotificationPreferencesPostgres = pgTable('user_notification_preferences', {
   id: pgSerial('id').primaryKey(),
-  userId: pgInteger('userId').notNull().references(() => usersPostgres.id, { onDelete: 'cascade' }),
+  userId: pgInteger('userId').notNull().unique().references(() => usersPostgres.id, { onDelete: 'cascade' }),
   notifyOnMessage: pgBoolean('notifyOnMessage').default(true),
   notifyOnDirectMessage: pgBoolean('notifyOnDirectMessage').default(true),
   notifyOnChannelMessage: pgBoolean('notifyOnChannelMessage').default(false),
@@ -112,7 +112,7 @@ export const pushSubscriptionsMysql = mysqlTable('push_subscriptions', {
 
 export const userNotificationPreferencesMysql = mysqlTable('user_notification_preferences', {
   id: mySerial('id').primaryKey(),
-  userId: myInt('userId').notNull().references(() => usersMysql.id, { onDelete: 'cascade' }),
+  userId: myInt('userId').notNull().unique().references(() => usersMysql.id, { onDelete: 'cascade' }),
   notifyOnMessage: myBoolean('notifyOnMessage').default(true),
   notifyOnDirectMessage: myBoolean('notifyOnDirectMessage').default(true),
   notifyOnChannelMessage: myBoolean('notifyOnChannelMessage').default(false),

src/server/migrations/015_add_notification_prefs_unique.ts

@@ -0,0 +1,70 @@
+/**
+ * Migration 015: Add UNIQUE constraint to user_notification_preferences.userId
+ *
+ * The onConflictDoUpdate (upsert) for notification preferences requires a
+ * UNIQUE constraint on userId, but the original schema omitted it.
+ * This caused a 500 error when saving notification preferences.
+ *
+ * Fixes #2426
+ */
+import type Database from 'better-sqlite3';
+
+// SQLite migration
+export const migration = {
+  up: (db: Database.Database) => {
+    // SQLite doesn't support ADD CONSTRAINT — need to deduplicate first, then create unique index
+    try {
+      // Remove duplicate rows (keep the one with the highest id per user)
+      db.exec(`
+        DELETE FROM user_notification_preferences
+        WHERE id NOT IN (
+          SELECT MAX(id) FROM user_notification_preferences GROUP BY user_id
+        )
+      `);
+      db.exec(`CREATE UNIQUE INDEX IF NOT EXISTS idx_user_notification_preferences_user_id ON user_notification_preferences(user_id)`);
+    } catch {
+      // Index may already exist
+    }
+  }
+};
+
+// PostgreSQL migration
+export async function runMigration015Postgres(client: any): Promise<void> {
+  // Remove duplicates (keep highest id per user)
+  await client.query(`
+    DELETE FROM user_notification_preferences
+    WHERE id NOT IN (
+      SELECT MAX(id) FROM user_notification_preferences GROUP BY "userId"
+    )
+  `);
+  // Add unique constraint if not exists
+  await client.query(`
+    DO $$ BEGIN
+      IF NOT EXISTS (
+        SELECT 1 FROM pg_constraint WHERE conname = 'user_notification_preferences_userId_unique'
+      ) THEN
+        ALTER TABLE user_notification_preferences ADD CONSTRAINT "user_notification_preferences_userId_unique" UNIQUE ("userId");
+      END IF;
+    END $$;
+  `);
+}
+
+// MySQL migration
+export async function runMigration015Mysql(pool: any): Promise<void> {
+  // Remove duplicates (keep highest id per user)
+  await pool.execute(`
+    DELETE t1 FROM user_notification_preferences t1
+    INNER JOIN user_notification_preferences t2
+    WHERE t1.id < t2.id AND t1.userId = t2.userId
+  `);
+  // Add unique index if not exists
+  const [rows] = await pool.execute(`
+    SELECT COUNT(*) as cnt FROM information_schema.STATISTICS
+    WHERE TABLE_SCHEMA = DATABASE()
+    AND TABLE_NAME = 'user_notification_preferences'
+    AND INDEX_NAME = 'idx_user_notification_preferences_userId'
+  `);
+  if (rows[0].cnt === 0) {
+    await pool.execute(`CREATE UNIQUE INDEX idx_user_notification_preferences_userId ON user_notification_preferences(userId)`);
+  }
+}