feat(server): notification system (#10053)

closes CLOUD-52
2026-02-13 21:05:19 +00:00 · 2025-03-06 15:25:05 +00:00
parent 81694a1144
commit 7302c4f954
20 changed files with 2356 additions and 14 deletions
--- a/packages/backend/server/src/tests/utils/index.ts
+++ b/packages/backend/server/src/tests/utils/index.ts
@@ -1,5 +1,6 @@
 export * from './blobs';
 export * from './invite';
+export * from './notification';
 export * from './permission';
 export * from './testing-app';
 export * from './testing-module';
--- a/packages/backend/server/src/tests/utils/notification.ts
+++ b/packages/backend/server/src/tests/utils/notification.ts
@@ -0,0 +1,86 @@
+import { PaginationInput } from '../../base/graphql/pagination';
+import type {
+  MentionInput,
+  PaginatedNotificationObjectType,
+} from '../../core/notification/types';
+import type { TestingApp } from './testing-app';
+
+export async function listNotifications(
+  app: TestingApp,
+  pagination: PaginationInput
+): Promise<PaginatedNotificationObjectType> {
+  const res = await app.gql(
+    `
+    query listNotifications($pagination: PaginationInput!) {
+      currentUser {
+        notifications(pagination: $pagination) {
+          totalCount
+          edges {
+            cursor
+            node {
+              id
+              type
+              level
+              read
+              createdAt
+              updatedAt
+              body
+            }
+          }
+          pageInfo {
+            startCursor
+            endCursor
+            hasNextPage
+            hasPreviousPage
+          }
+        }
+      }
+    }
+    `,
+    { pagination }
+  );
+  return res.currentUser.notifications;
+}
+
+export async function getNotificationCount(app: TestingApp): Promise<number> {
+  const res = await app.gql(
+    `
+    query notificationCount {
+      currentUser {
+        notificationCount
+      }
+    }
+    `
+  );
+  return res.currentUser.notificationCount;
+}
+
+export async function mentionUser(
+  app: TestingApp,
+  input: MentionInput
+): Promise<string> {
+  const res = await app.gql(
+    `
+    mutation mentionUser($input: MentionInput!) {
+      mentionUser(input: $input)
+    }
+    `,
+    { input }
+  );
+  return res.mentionUser;
+}
+
+export async function readNotification(
+  app: TestingApp,
+  id: string
+): Promise<boolean> {
+  const res = await app.gql(
+    `
+    mutation readNotification($id: String!) {
+      readNotification(id: $id)
+    }
+    `,
+    { id }
+  );
+  return res.readNotification;
+}
--- a/packages/backend/server/src/tests/utils/testing-app.ts
+++ b/packages/backend/server/src/tests/utils/testing-app.ts
@@ -1,3 +1,5 @@
+import { randomUUID } from 'node:crypto';
+
 import { INestApplication, ModuleMetadata } from '@nestjs/common';
 import type { NestExpressApplication } from '@nestjs/platform-express';
 import { TestingModuleBuilder } from '@nestjs/testing';
@@ -182,12 +184,19 @@ export class TestingApp extends ApplyType<INestApplication>() {
    return res.body.data;
  }

-  async createUser(email: string, override?: Partial<User>): Promise<TestUser> {
+  private randomEmail() {
+    return `test-${randomUUID()}@affine.pro`;
+  }
+
+  async createUser(
+    email?: string,
+    override?: Partial<User>
+  ): Promise<TestUser> {
    const model = this.get(UserModel);
    // TODO(@forehalo): model factories
    //   TestingData.user.create()
    const user = await model.create({
-      email,
+      email: email ?? this.randomEmail(),
      password: '1',
      name: email,
      emailVerifiedAt: new Date(),
@@ -200,8 +209,8 @@ export class TestingApp extends ApplyType<INestApplication>() {
    return user as Omit<User, 'password'> & { password: string };
  }

-  async signup(email: string, override?: Partial<User>) {
-    const user = await this.createUser(email, override);
+  async signup(email?: string, override?: Partial<User>) {
+    const user = await this.createUser(email ?? this.randomEmail(), override);
    await this.login(user);
    return user;
  }
--- a/packages/backend/server/src/app.module.ts
+++ b/packages/backend/server/src/app.module.ts
@@ -43,6 +43,7 @@ import { DocStorageModule } from './core/doc';
 import { DocRendererModule } from './core/doc-renderer';
 import { DocServiceModule } from './core/doc-service';
 import { FeatureModule } from './core/features';
+import { NotificationModule } from './core/notification';
 import { PermissionModule } from './core/permission';
 import { QuotaModule } from './core/quota';
 import { SelfhostModule } from './core/selfhost';
@@ -218,7 +219,7 @@ export function buildAppModule() {
    .use(UserModule, AuthModule, PermissionModule)

    // business modules
-    .use(FeatureModule, QuotaModule, DocStorageModule)
+    .use(FeatureModule, QuotaModule, DocStorageModule, NotificationModule)

    // sync server only
    .useIf(config => config.flavor.sync, SyncModule)
--- a/packages/backend/server/src/base/error/def.ts
+++ b/packages/backend/server/src/base/error/def.ts
@@ -767,4 +767,19 @@ export const USER_FRIENDLY_ERRORS = {
    message: ({ clientVersion, requiredVersion }) =>
      `Unsupported client with version [${clientVersion}], required version is [${requiredVersion}].`,
  },
+
+  // Notification Errors
+  notification_not_found: {
+    type: 'resource_not_found',
+    message: 'Notification not found.',
+  },
+  mention_user_doc_access_denied: {
+    type: 'no_permission',
+    args: { docId: 'string' },
+    message: ({ docId }) => `Mentioned user can not access doc ${docId}.`,
+  },
+  mention_user_oneself_denied: {
+    type: 'action_forbidden',
+    message: 'You can not mention yourself.',
+  },
 } satisfies Record<string, UserFriendlyErrorOptions>;
--- a/packages/backend/server/src/base/error/errors.gen.ts
+++ b/packages/backend/server/src/base/error/errors.gen.ts
@@ -855,6 +855,28 @@ export class UnsupportedClientVersion extends UserFriendlyError {
    super('action_forbidden', 'unsupported_client_version', message, args);
  }
 }
+
+export class NotificationNotFound extends UserFriendlyError {
+  constructor(message?: string) {
+    super('resource_not_found', 'notification_not_found', message);
+  }
+}
+@ObjectType()
+class MentionUserDocAccessDeniedDataType {
+  @Field() docId!: string
+}
+
+export class MentionUserDocAccessDenied extends UserFriendlyError {
+  constructor(args: MentionUserDocAccessDeniedDataType, message?: string | ((args: MentionUserDocAccessDeniedDataType) => string)) {
+    super('no_permission', 'mention_user_doc_access_denied', message, args);
+  }
+}
+
+export class MentionUserOneselfDenied extends UserFriendlyError {
+  constructor(message?: string) {
+    super('action_forbidden', 'mention_user_oneself_denied', message);
+  }
+}
 export enum ErrorNames {
  INTERNAL_SERVER_ERROR,
  NETWORK_ERROR,
@@ -963,7 +985,10 @@ export enum ErrorNames {
  INVALID_LICENSE_TO_ACTIVATE,
  INVALID_LICENSE_UPDATE_PARAMS,
  WORKSPACE_MEMBERS_EXCEED_LIMIT_TO_DOWNGRADE,
-  UNSUPPORTED_CLIENT_VERSION
+  UNSUPPORTED_CLIENT_VERSION,
+  NOTIFICATION_NOT_FOUND,
+  MENTION_USER_DOC_ACCESS_DENIED,
+  MENTION_USER_ONESELF_DENIED
 }
 registerEnumType(ErrorNames, {
  name: 'ErrorNames'
@@ -972,5 +997,5 @@ registerEnumType(ErrorNames, {
 export const ErrorDataUnionType = createUnionType({
  name: 'ErrorDataUnion',
  types: () =>
-    [GraphqlBadRequestDataType, QueryTooLongDataType, ValidationErrorDataType, WrongSignInCredentialsDataType, UnknownOauthProviderDataType, InvalidOauthCallbackCodeDataType, MissingOauthQueryParameterDataType, InvalidEmailDataType, InvalidPasswordLengthDataType, WorkspacePermissionNotFoundDataType, SpaceNotFoundDataType, MemberNotFoundInSpaceDataType, NotInSpaceDataType, AlreadyInSpaceDataType, SpaceAccessDeniedDataType, SpaceOwnerNotFoundDataType, SpaceShouldHaveOnlyOneOwnerDataType, DocNotFoundDataType, DocActionDeniedDataType, DocUpdateBlockedDataType, VersionRejectedDataType, InvalidHistoryTimestampDataType, DocHistoryNotFoundDataType, BlobNotFoundDataType, ExpectToGrantDocUserRolesDataType, ExpectToRevokeDocUserRolesDataType, ExpectToUpdateDocUserRoleDataType, UnsupportedSubscriptionPlanDataType, SubscriptionAlreadyExistsDataType, SubscriptionNotExistsDataType, SameSubscriptionRecurringDataType, SubscriptionPlanNotFoundDataType, CopilotDocNotFoundDataType, CopilotMessageNotFoundDataType, CopilotPromptNotFoundDataType, CopilotProviderSideErrorDataType, CopilotInvalidContextDataType, CopilotContextFileNotSupportedDataType, CopilotFailedToModifyContextDataType, CopilotFailedToMatchContextDataType, RuntimeConfigNotFoundDataType, InvalidRuntimeConfigTypeDataType, InvalidLicenseUpdateParamsDataType, WorkspaceMembersExceedLimitToDowngradeDataType, UnsupportedClientVersionDataType] as const,
+    [GraphqlBadRequestDataType, QueryTooLongDataType, ValidationErrorDataType, WrongSignInCredentialsDataType, UnknownOauthProviderDataType, InvalidOauthCallbackCodeDataType, MissingOauthQueryParameterDataType, InvalidEmailDataType, InvalidPasswordLengthDataType, WorkspacePermissionNotFoundDataType, SpaceNotFoundDataType, MemberNotFoundInSpaceDataType, NotInSpaceDataType, AlreadyInSpaceDataType, SpaceAccessDeniedDataType, SpaceOwnerNotFoundDataType, SpaceShouldHaveOnlyOneOwnerDataType, DocNotFoundDataType, DocActionDeniedDataType, DocUpdateBlockedDataType, VersionRejectedDataType, InvalidHistoryTimestampDataType, DocHistoryNotFoundDataType, BlobNotFoundDataType, ExpectToGrantDocUserRolesDataType, ExpectToRevokeDocUserRolesDataType, ExpectToUpdateDocUserRoleDataType, UnsupportedSubscriptionPlanDataType, SubscriptionAlreadyExistsDataType, SubscriptionNotExistsDataType, SameSubscriptionRecurringDataType, SubscriptionPlanNotFoundDataType, CopilotDocNotFoundDataType, CopilotMessageNotFoundDataType, CopilotPromptNotFoundDataType, CopilotProviderSideErrorDataType, CopilotInvalidContextDataType, CopilotContextFileNotSupportedDataType, CopilotFailedToModifyContextDataType, CopilotFailedToMatchContextDataType, RuntimeConfigNotFoundDataType, InvalidRuntimeConfigTypeDataType, InvalidLicenseUpdateParamsDataType, WorkspaceMembersExceedLimitToDowngradeDataType, UnsupportedClientVersionDataType, MentionUserDocAccessDeniedDataType] as const,
 });
--- a/packages/backend/server/src/base/graphql/pagination.ts
+++ b/packages/backend/server/src/base/graphql/pagination.ts
@@ -15,8 +15,8 @@ export class PaginationInput {
    transform: value => {
      return {
        ...value,
-        after: value.after ? decode(value.after) : null,
-        // before: value.before ? decode(value.before) : null,
+        after: decode(value.after),
+        // before: decode(value.before),
      };
    },
  };
@@ -51,9 +51,19 @@ export class PaginationInput {
  // before?: string | null;
 }

-const encode = (input: string) => Buffer.from(input).toString('base64');
-const decode = (base64String: string) =>
-  Buffer.from(base64String, 'base64').toString('utf-8');
+const encode = (input: unknown) => {
+  let inputStr: string;
+  if (input instanceof Date) {
+    inputStr = input.toISOString();
+  } else if (typeof input === 'string') {
+    inputStr = input;
+  } else {
+    inputStr = String(input);
+  }
+  return Buffer.from(inputStr).toString('base64');
+};
+const decode = (base64String?: string | null) =>
+  base64String ? Buffer.from(base64String, 'base64').toString('utf-8') : null;

 export function paginate<T>(
  list: T[],
@@ -63,7 +73,7 @@ export function paginate<T>(
 ): PaginatedType<T> {
  const edges = list.map(item => ({
    node: item,
-    cursor: encode(String(item[cursorField])),
+    cursor: encode(item[cursorField]),
  }));

  return {
--- a/packages/backend/server/src/core/notification/tests/resolver.e2e.ts
+++ b/packages/backend/server/src/core/notification/tests/resolver.e2e.ts
@@ -0,0 +1,516 @@
+import { randomUUID } from 'node:crypto';
+
+import test from 'ava';
+
+import {
+  acceptInviteById,
+  createTestingApp,
+  createWorkspace,
+  getNotificationCount,
+  inviteUser,
+  listNotifications,
+  mentionUser,
+  readNotification,
+  TestingApp,
+} from '../../../__tests__/utils';
+import { Models, NotificationType } from '../../../models';
+import { MentionNotificationBodyType, NotificationObjectType } from '../types';
+
+let app: TestingApp;
+let models: Models;
+
+test.before(async () => {
+  app = await createTestingApp();
+  models = app.get(Models);
+});
+
+test.after.always(async () => {
+  await app.close();
+});
+
+test('should mention user in a doc', async t => {
+  const member = await app.signup();
+  const owner = await app.signup();
+
+  await app.switchUser(owner);
+  const workspace = await createWorkspace(app);
+  await models.workspace.update(workspace.id, {
+    name: 'test-workspace-name',
+    avatarKey: 'test-avatar-key',
+  });
+  const inviteId = await inviteUser(app, workspace.id, member.email);
+  await app.switchUser(member);
+  await acceptInviteById(app, workspace.id, inviteId);
+
+  await app.switchUser(owner);
+  const mentionId = await mentionUser(app, {
+    userId: member.id,
+    workspaceId: workspace.id,
+    doc: {
+      id: 'doc-id-1',
+      title: 'doc-title-1',
+      blockId: 'block-id-1',
+    },
+  });
+  t.truthy(mentionId);
+  // mention user at another doc
+  await mentionUser(app, {
+    userId: member.id,
+    workspaceId: workspace.id,
+    doc: {
+      id: 'doc-id-2',
+      title: 'doc-title-2',
+      elementId: 'element-id-2',
+    },
+  });
+
+  await app.switchUser(member);
+  const result = await listNotifications(app, {
+    first: 10,
+    offset: 0,
+  });
+  t.is(result.totalCount, 2);
+  const notifications = result.edges.map(edge => edge.node);
+  t.is(notifications.length, 2);
+
+  const notification = notifications[1] as NotificationObjectType;
+  t.is(notification.read, false);
+  t.truthy(notification.createdAt);
+  t.truthy(notification.updatedAt);
+  const body = notification.body as MentionNotificationBodyType;
+  t.is(body.workspace!.id, workspace.id);
+  t.is(body.doc.id, 'doc-id-1');
+  t.is(body.doc.title, 'doc-title-1');
+  t.is(body.doc.blockId, 'block-id-1');
+  t.is(body.createdByUser!.id, owner.id);
+  t.is(body.createdByUser!.name, owner.name);
+  t.is(body.workspace!.id, workspace.id);
+  t.is(body.workspace!.name, 'test-workspace-name');
+  t.truthy(body.workspace!.avatarUrl);
+
+  const notification2 = notifications[0] as NotificationObjectType;
+  t.is(notification2.read, false);
+  t.truthy(notification2.createdAt);
+  t.truthy(notification2.updatedAt);
+  const body2 = notification2.body as MentionNotificationBodyType;
+  t.is(body2.workspace!.id, workspace.id);
+  t.is(body2.doc.id, 'doc-id-2');
+  t.is(body2.doc.title, 'doc-title-2');
+  t.is(body2.doc.elementId, 'element-id-2');
+  t.is(body2.createdByUser!.id, owner.id);
+  t.is(body2.workspace!.id, workspace.id);
+  t.is(body2.workspace!.name, 'test-workspace-name');
+  t.truthy(body2.workspace!.avatarUrl);
+});
+
+test('should throw error when mention user has no Doc.Read role', async t => {
+  const member = await app.signup();
+  const owner = await app.signup();
+
+  await app.switchUser(owner);
+  const workspace = await createWorkspace(app);
+
+  await app.switchUser(owner);
+  const docId = randomUUID();
+  await t.throwsAsync(
+    mentionUser(app, {
+      userId: member.id,
+      workspaceId: workspace.id,
+      doc: {
+        id: docId,
+        title: 'doc-title-1',
+        blockId: 'block-id-1',
+      },
+    }),
+    {
+      message: `Mentioned user can not access doc ${docId}.`,
+    }
+  );
+});
+
+test('should throw error when mention a not exists user', async t => {
+  const owner = await app.signup();
+  const workspace = await createWorkspace(app);
+  await app.switchUser(owner);
+  const docId = randomUUID();
+  await t.throwsAsync(
+    mentionUser(app, {
+      userId: 'user-id-not-exists',
+      workspaceId: workspace.id,
+      doc: {
+        id: docId,
+        title: 'doc-title-1',
+        blockId: 'block-id-1',
+      },
+    }),
+    {
+      message: `Mentioned user can not access doc ${docId}.`,
+    }
+  );
+});
+
+test('should not mention user oneself', async t => {
+  const owner = await app.signup();
+  const workspace = await createWorkspace(app);
+  await app.switchUser(owner);
+  await t.throwsAsync(
+    mentionUser(app, {
+      userId: owner.id,
+      workspaceId: workspace.id,
+      doc: {
+        id: 'doc-id-1',
+        title: 'doc-title-1',
+        blockId: 'block-id-1',
+      },
+    }),
+    {
+      message: 'You can not mention yourself.',
+    }
+  );
+});
+
+test('should mark notification as read', async t => {
+  const member = await app.signup();
+  const owner = await app.signup();
+
+  await app.switchUser(owner);
+  const workspace = await createWorkspace(app);
+  const inviteId = await inviteUser(app, workspace.id, member.email);
+  await app.switchUser(member);
+  await acceptInviteById(app, workspace.id, inviteId);
+
+  await app.switchUser(owner);
+  const mentionId = await mentionUser(app, {
+    userId: member.id,
+    workspaceId: workspace.id,
+    doc: {
+      id: 'doc-id-1',
+      title: 'doc-title-1',
+      blockId: 'block-id-1',
+    },
+  });
+  t.truthy(mentionId);
+
+  await app.switchUser(member);
+  const result = await listNotifications(app, {
+    first: 10,
+    offset: 0,
+  });
+  t.is(result.totalCount, 1);
+
+  const notifications = result.edges.map(edge => edge.node);
+  const notification = notifications[0] as NotificationObjectType;
+  t.is(notification.read, false);
+
+  await readNotification(app, notification.id);
+
+  const count = await getNotificationCount(app);
+  t.is(count, 0);
+
+  // read again should work
+  await readNotification(app, notification.id);
+});
+
+test('should throw error when read the other user notification', async t => {
+  const member = await app.signup();
+  const owner = await app.signup();
+
+  await app.switchUser(owner);
+  const workspace = await createWorkspace(app);
+  const inviteId = await inviteUser(app, workspace.id, member.email);
+  await app.switchUser(member);
+  await acceptInviteById(app, workspace.id, inviteId);
+
+  await app.switchUser(owner);
+  const mentionId = await mentionUser(app, {
+    userId: member.id,
+    workspaceId: workspace.id,
+    doc: {
+      id: 'doc-id-1',
+      title: 'doc-title-1',
+      blockId: 'block-id-1',
+    },
+  });
+  t.truthy(mentionId);
+
+  await app.switchUser(member);
+  const result = await listNotifications(app, {
+    first: 10,
+    offset: 0,
+  });
+  const notifications = result.edges.map(edge => edge.node);
+  const notification = notifications[0] as NotificationObjectType;
+  t.is(notification.read, false);
+
+  await app.switchUser(owner);
+  await t.throwsAsync(readNotification(app, notification.id), {
+    message: 'Notification not found.',
+  });
+  // notification not exists
+  await t.throwsAsync(readNotification(app, 'notification-id-not-exists'), {
+    message: 'Notification not found.',
+  });
+});
+
+test.skip('should throw error when mention call with invalid params', async t => {
+  const owner = await app.signup();
+  await app.switchUser(owner);
+  await t.throwsAsync(
+    mentionUser(app, {
+      userId: '',
+      workspaceId: '',
+      doc: {
+        id: '',
+        title: '',
+        blockId: '',
+      },
+    }),
+    {
+      message: 'Mention user not found.',
+    }
+  );
+});
+
+test('should list and count notifications', async t => {
+  const member = await app.signup();
+  const owner = await app.signup();
+
+  {
+    await app.switchUser(member);
+    const result = await listNotifications(app, {
+      first: 10,
+      offset: 0,
+    });
+    const notifications = result.edges.map(edge => edge.node);
+    t.is(notifications.length, 0);
+    t.is(result.totalCount, 0);
+  }
+
+  await app.switchUser(owner);
+  const workspace = await createWorkspace(app);
+  await models.workspace.update(workspace.id, {
+    name: 'test-workspace-name1',
+    avatarKey: 'test-avatar-key1',
+  });
+  const inviteId = await inviteUser(app, workspace.id, member.email);
+  const workspace2 = await createWorkspace(app);
+  await models.workspace.update(workspace2.id, {
+    name: 'test-workspace-name2',
+    avatarKey: 'test-avatar-key2',
+  });
+  const inviteId2 = await inviteUser(app, workspace2.id, member.email);
+  await app.switchUser(member);
+  await acceptInviteById(app, workspace.id, inviteId);
+  await acceptInviteById(app, workspace2.id, inviteId2);
+
+  await app.switchUser(owner);
+  await mentionUser(app, {
+    userId: member.id,
+    workspaceId: workspace.id,
+    doc: {
+      id: 'doc-id-1',
+      title: 'doc-title-1',
+      blockId: 'block-id-1',
+    },
+  });
+  await mentionUser(app, {
+    userId: member.id,
+    workspaceId: workspace.id,
+    doc: {
+      id: 'doc-id-2',
+      title: 'doc-title-2',
+      blockId: 'block-id-2',
+    },
+  });
+  await mentionUser(app, {
+    userId: member.id,
+    workspaceId: workspace.id,
+    doc: {
+      id: 'doc-id-3',
+      title: 'doc-title-3',
+      blockId: 'block-id-3',
+    },
+  });
+  // mention user in another workspace
+  await mentionUser(app, {
+    userId: member.id,
+    workspaceId: workspace2.id,
+    doc: {
+      id: 'doc-id-4',
+      title: 'doc-title-4',
+      blockId: 'block-id-4',
+    },
+  });
+
+  {
+    await app.switchUser(member);
+    const result = await listNotifications(app, {
+      first: 10,
+      offset: 0,
+    });
+    const notifications = result.edges.map(
+      edge => edge.node
+    ) as NotificationObjectType[];
+    t.is(notifications.length, 4);
+    t.is(result.totalCount, 4);
+
+    const notification = notifications[0];
+    t.is(notification.read, false);
+    const body = notification.body as MentionNotificationBodyType;
+    t.is(body.type, NotificationType.Mention);
+    t.is(body.workspace!.id, workspace2.id);
+    t.is(body.doc.id, 'doc-id-4');
+    t.is(body.doc.title, 'doc-title-4');
+    t.is(body.doc.blockId, 'block-id-4');
+    t.is(body.createdByUser!.id, owner.id);
+    t.is(body.workspace!.id, workspace2.id);
+    t.is(body.workspace!.name, 'test-workspace-name2');
+    t.truthy(body.workspace!.avatarUrl);
+
+    const notification2 = notifications[1];
+    t.is(notification2.read, false);
+    const body2 = notification2.body as MentionNotificationBodyType;
+    t.is(body2.type, NotificationType.Mention);
+    t.is(body2.workspace!.id, workspace.id);
+    t.is(body2.doc.id, 'doc-id-3');
+    t.is(body2.doc.title, 'doc-title-3');
+    t.is(body2.doc.blockId, 'block-id-3');
+    t.is(body2.createdByUser!.id, owner.id);
+    t.is(body2.workspace!.id, workspace.id);
+    t.is(body2.workspace!.name, 'test-workspace-name1');
+    t.truthy(body2.workspace!.avatarUrl);
+  }
+
+  {
+    await app.switchUser(member);
+    const result = await listNotifications(app, {
+      first: 10,
+      offset: 2,
+    });
+    t.is(result.totalCount, 4);
+    t.is(result.pageInfo.hasNextPage, false);
+    t.is(result.pageInfo.hasPreviousPage, true);
+    const notifications = result.edges.map(
+      edge => edge.node
+    ) as NotificationObjectType[];
+    t.is(notifications.length, 2);
+
+    const notification = notifications[0];
+    t.is(notification.read, false);
+    const body = notification.body as MentionNotificationBodyType;
+    t.is(body.workspace!.id, workspace.id);
+    t.is(body.doc.id, 'doc-id-2');
+    t.is(body.doc.title, 'doc-title-2');
+    t.is(body.doc.blockId, 'block-id-2');
+    t.is(body.createdByUser!.id, owner.id);
+    t.is(body.workspace!.id, workspace.id);
+    t.is(body.workspace!.name, 'test-workspace-name1');
+    t.truthy(body.workspace!.avatarUrl);
+
+    const notification2 = notifications[1];
+    t.is(notification2.read, false);
+    const body2 = notification2.body as MentionNotificationBodyType;
+    t.is(body2.workspace!.id, workspace.id);
+    t.is(body2.doc.id, 'doc-id-1');
+    t.is(body2.doc.title, 'doc-title-1');
+    t.is(body2.doc.blockId, 'block-id-1');
+    t.is(body2.createdByUser!.id, owner.id);
+    t.is(body2.workspace!.id, workspace.id);
+    t.is(body2.workspace!.name, 'test-workspace-name1');
+    t.truthy(body2.workspace!.avatarUrl);
+  }
+
+  {
+    await app.switchUser(member);
+    const result = await listNotifications(app, {
+      first: 2,
+      offset: 0,
+    });
+    t.is(result.totalCount, 4);
+    t.is(result.pageInfo.hasNextPage, true);
+    t.is(result.pageInfo.hasPreviousPage, false);
+    const notifications = result.edges.map(
+      edge => edge.node
+    ) as NotificationObjectType[];
+    t.is(notifications.length, 2);
+
+    const notification = notifications[0];
+    t.is(notification.read, false);
+    const body = notification.body as MentionNotificationBodyType;
+    t.is(body.workspace!.id, workspace2.id);
+    t.is(body.doc.id, 'doc-id-4');
+    t.is(body.doc.title, 'doc-title-4');
+    t.is(body.doc.blockId, 'block-id-4');
+    t.is(body.createdByUser!.id, owner.id);
+    t.is(body.workspace!.id, workspace2.id);
+    t.is(body.workspace!.name, 'test-workspace-name2');
+    t.truthy(body.workspace!.avatarUrl);
+    t.is(
+      notification.createdAt.toString(),
+      Buffer.from(result.pageInfo.startCursor!, 'base64').toString('utf-8')
+    );
+    const notification2 = notifications[1];
+    t.is(notification2.read, false);
+    const body2 = notification2.body as MentionNotificationBodyType;
+    t.is(body2.workspace!.id, workspace.id);
+    t.is(body2.doc.id, 'doc-id-3');
+    t.is(body2.doc.title, 'doc-title-3');
+    t.is(body2.doc.blockId, 'block-id-3');
+    t.is(body2.createdByUser!.id, owner.id);
+    t.is(body2.workspace!.id, workspace.id);
+    t.is(body2.workspace!.name, 'test-workspace-name1');
+    t.truthy(body2.workspace!.avatarUrl);
+
+    await app.switchUser(owner);
+    await mentionUser(app, {
+      userId: member.id,
+      workspaceId: workspace.id,
+      doc: {
+        id: 'doc-id-5',
+        title: 'doc-title-5',
+        blockId: 'block-id-5',
+      },
+    });
+
+    // get new notifications
+    await app.switchUser(member);
+    const result2 = await listNotifications(app, {
+      first: 2,
+      offset: 0,
+      after: result.pageInfo.startCursor,
+    });
+    t.is(result2.totalCount, 5);
+    t.is(result2.pageInfo.hasNextPage, false);
+    t.is(result2.pageInfo.hasPreviousPage, true);
+    const notifications2 = result2.edges.map(
+      edge => edge.node
+    ) as NotificationObjectType[];
+    t.is(notifications2.length, 1);
+
+    const notification3 = notifications2[0];
+    t.is(notification3.read, false);
+    const body3 = notification3.body as MentionNotificationBodyType;
+    t.is(body3.workspace!.id, workspace.id);
+    t.is(body3.doc.id, 'doc-id-5');
+    t.is(body3.doc.title, 'doc-title-5');
+    t.is(body3.doc.blockId, 'block-id-5');
+    t.is(body3.createdByUser!.id, owner.id);
+    t.is(body3.createdByUser!.name, owner.name);
+    t.is(body3.workspace!.id, workspace.id);
+    t.is(body3.workspace!.name, 'test-workspace-name1');
+    t.truthy(body3.workspace!.avatarUrl);
+
+    // no new notifications
+    const result3 = await listNotifications(app, {
+      first: 2,
+      offset: 0,
+      after: result2.pageInfo.startCursor,
+    });
+    t.is(result3.totalCount, 5);
+    t.is(result3.pageInfo.hasNextPage, false);
+    t.is(result3.pageInfo.hasPreviousPage, true);
+    t.is(result3.pageInfo.startCursor, null);
+    t.is(result3.pageInfo.endCursor, null);
+    t.is(result3.edges.length, 0);
+  }
+});
--- a/packages/backend/server/src/core/notification/tests/service.spec.ts
+++ b/packages/backend/server/src/core/notification/tests/service.spec.ts
@@ -0,0 +1,314 @@
+import { randomUUID } from 'node:crypto';
+import { mock } from 'node:test';
+
+import ava, { TestFn } from 'ava';
+
+import {
+  createTestingModule,
+  type TestingModule,
+} from '../../../__tests__/utils';
+import { NotificationNotFound } from '../../../base';
+import {
+  MentionNotificationBody,
+  Models,
+  NotificationType,
+  User,
+  Workspace,
+} from '../../../models';
+import { DocReader } from '../../doc';
+import { NotificationService } from '../service';
+interface Context {
+  module: TestingModule;
+  notificationService: NotificationService;
+  models: Models;
+  docReader: DocReader;
+}
+
+const test = ava as TestFn<Context>;
+
+test.before(async t => {
+  const module = await createTestingModule();
+  t.context.module = module;
+  t.context.notificationService = module.get(NotificationService);
+  t.context.models = module.get(Models);
+  t.context.docReader = module.get(DocReader);
+});
+
+let owner: User;
+let member: User;
+let workspace: Workspace;
+
+test.beforeEach(async t => {
+  await t.context.module.initTestingDB();
+  owner = await t.context.models.user.create({
+    email: `${randomUUID()}@affine.pro`,
+  });
+  member = await t.context.models.user.create({
+    email: `${randomUUID()}@affine.pro`,
+  });
+  workspace = await t.context.models.workspace.create(owner.id);
+  await t.context.models.workspace.update(workspace.id, {
+    name: 'Test Workspace',
+    avatarKey: 'test-avatar-key',
+  });
+});
+
+test.afterEach.always(() => {
+  mock.reset();
+  mock.timers.reset();
+});
+
+test.after.always(async t => {
+  await t.context.module.close();
+});
+
+test('should create invitation notification', async t => {
+  const { notificationService } = t.context;
+  const inviteId = randomUUID();
+  const notification = await notificationService.createInvitation({
+    userId: member.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: owner.id,
+      inviteId,
+    },
+  });
+  t.truthy(notification);
+  t.is(notification!.type, NotificationType.Invitation);
+  t.is(notification!.userId, member.id);
+  t.is(notification!.body.workspaceId, workspace.id);
+  t.is(notification!.body.createdByUserId, owner.id);
+  t.is(notification!.body.inviteId, inviteId);
+});
+
+test('should not create invitation notification if user is already a member', async t => {
+  const { notificationService, models } = t.context;
+  const inviteId = randomUUID();
+  mock.method(models.workspaceUser, 'getActive', async () => ({
+    id: inviteId,
+  }));
+  const notification = await notificationService.createInvitation({
+    userId: member.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: owner.id,
+      inviteId,
+    },
+  });
+  t.is(notification, undefined);
+});
+
+test('should create invitation accepted notification', async t => {
+  const { notificationService } = t.context;
+  const inviteId = randomUUID();
+  const notification = await notificationService.createInvitationAccepted({
+    userId: owner.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: member.id,
+      inviteId,
+    },
+  });
+  t.truthy(notification);
+  t.is(notification!.type, NotificationType.InvitationAccepted);
+  t.is(notification!.userId, owner.id);
+  t.is(notification!.body.workspaceId, workspace.id);
+  t.is(notification!.body.createdByUserId, member.id);
+  t.is(notification!.body.inviteId, inviteId);
+});
+
+test('should create invitation blocked notification', async t => {
+  const { notificationService } = t.context;
+  const inviteId = randomUUID();
+  const notification = await notificationService.createInvitationBlocked({
+    userId: owner.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: member.id,
+      inviteId,
+    },
+  });
+  t.truthy(notification);
+  t.is(notification!.type, NotificationType.InvitationBlocked);
+  t.is(notification!.userId, owner.id);
+  t.is(notification!.body.workspaceId, workspace.id);
+  t.is(notification!.body.createdByUserId, member.id);
+  t.is(notification!.body.inviteId, inviteId);
+});
+
+test('should create invitation rejected notification', async t => {
+  const { notificationService } = t.context;
+  const inviteId = randomUUID();
+  const notification = await notificationService.createInvitationRejected({
+    userId: owner.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: member.id,
+      inviteId,
+    },
+  });
+  t.truthy(notification);
+  t.is(notification!.type, NotificationType.InvitationRejected);
+  t.is(notification!.userId, owner.id);
+  t.is(notification!.body.workspaceId, workspace.id);
+  t.is(notification!.body.createdByUserId, member.id);
+  t.is(notification!.body.inviteId, inviteId);
+});
+
+test('should clean expired notifications', async t => {
+  const { notificationService } = t.context;
+  await notificationService.createInvitation({
+    userId: member.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: owner.id,
+      inviteId: randomUUID(),
+    },
+  });
+  let count = await notificationService.countByUserId(member.id);
+  t.is(count, 1);
+  // wait for 100 days
+  mock.timers.enable({
+    apis: ['Date'],
+    now: Date.now() + 1000 * 60 * 60 * 24 * 100,
+  });
+  await t.context.models.notification.cleanExpiredNotifications();
+  count = await notificationService.countByUserId(member.id);
+  t.is(count, 1);
+  mock.timers.reset();
+  // wait for 1 year
+  mock.timers.enable({
+    apis: ['Date'],
+    now: Date.now() + 1000 * 60 * 60 * 24 * 365,
+  });
+  await t.context.models.notification.cleanExpiredNotifications();
+  count = await notificationService.countByUserId(member.id);
+  t.is(count, 0);
+});
+
+test('should mark notification as read', async t => {
+  const { notificationService } = t.context;
+  const notification = await notificationService.createInvitation({
+    userId: member.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: owner.id,
+      inviteId: randomUUID(),
+    },
+  });
+  await notificationService.markAsRead(member.id, notification!.id);
+  const updatedNotification = await t.context.models.notification.get(
+    notification!.id
+  );
+  t.is(updatedNotification!.read, true);
+});
+
+test('should throw error on mark notification as read if notification is not found', async t => {
+  const { notificationService } = t.context;
+  await t.throwsAsync(notificationService.markAsRead(member.id, randomUUID()), {
+    instanceOf: NotificationNotFound,
+  });
+});
+
+test('should throw error on mark notification as read if notification user is not the same', async t => {
+  const { notificationService } = t.context;
+  const notification = await notificationService.createInvitation({
+    userId: member.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: owner.id,
+      inviteId: randomUUID(),
+    },
+  });
+  const otherUser = await t.context.models.user.create({
+    email: `${randomUUID()}@affine.pro`,
+  });
+  await t.throwsAsync(
+    notificationService.markAsRead(otherUser.id, notification!.id),
+    {
+      instanceOf: NotificationNotFound,
+    }
+  );
+});
+
+test('should use latest doc title in mention notification', async t => {
+  const { notificationService, models } = t.context;
+  const docId = randomUUID();
+  await notificationService.createMention({
+    userId: member.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: owner.id,
+      doc: { id: docId, title: 'doc-title-1', blockId: 'block-id-1' },
+    },
+  });
+  const mentionNotification = await notificationService.createMention({
+    userId: member.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: owner.id,
+      doc: { id: docId, title: 'doc-title-2', blockId: 'block-id-2' },
+    },
+  });
+  t.truthy(mentionNotification);
+  mock.method(models.doc, 'findMetas', async () => [
+    {
+      title: 'doc-title-2-updated',
+    },
+    {
+      title: 'doc-title-1-updated',
+    },
+  ]);
+  const notifications = await notificationService.findManyByUserId(member.id);
+  t.is(notifications.length, 2);
+  const mention = notifications[0];
+  t.is(mention.body.workspace!.id, workspace.id);
+  t.is(mention.body.workspace!.name, 'Test Workspace');
+  t.truthy(mention.body.workspace!.avatarUrl);
+  t.is(mention.body.type, NotificationType.Mention);
+  const body = mention.body as MentionNotificationBody;
+  t.is(body.doc.title, 'doc-title-2-updated');
+
+  const mention2 = notifications[1];
+  t.is(mention2.body.workspace!.id, workspace.id);
+  t.is(mention2.body.workspace!.name, 'Test Workspace');
+  t.truthy(mention2.body.workspace!.avatarUrl);
+  t.is(mention2.body.type, NotificationType.Mention);
+  const body2 = mention2.body as MentionNotificationBody;
+  t.is(body2.doc.title, 'doc-title-1-updated');
+});
+
+test('should raw doc title in mention notification if no doc found', async t => {
+  const { notificationService, models } = t.context;
+  const docId = randomUUID();
+  await notificationService.createMention({
+    userId: member.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: owner.id,
+      doc: { id: docId, title: 'doc-title-1', blockId: 'block-id-1' },
+    },
+  });
+  await notificationService.createMention({
+    userId: member.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: owner.id,
+      doc: { id: docId, title: 'doc-title-2', blockId: 'block-id-2' },
+    },
+  });
+  mock.method(models.doc, 'findMetas', async () => [null, null]);
+  const notifications = await notificationService.findManyByUserId(member.id);
+  t.is(notifications.length, 2);
+  const mention = notifications[0];
+  t.is(mention.body.workspace!.name, 'Test Workspace');
+  t.is(mention.body.type, NotificationType.Mention);
+  const body = mention.body as MentionNotificationBody;
+  t.is(body.doc.title, 'doc-title-2');
+
+  const mention2 = notifications[1];
+  t.is(mention2.body.workspace!.name, 'Test Workspace');
+  t.is(mention2.body.type, NotificationType.Mention);
+  const body2 = mention2.body as MentionNotificationBody;
+  t.is(body2.doc.title, 'doc-title-1');
+});
--- a/packages/backend/server/src/core/notification/index.ts
+++ b/packages/backend/server/src/core/notification/index.ts
@@ -0,0 +1,20 @@
+import { Module } from '@nestjs/common';
+
+import { DocStorageModule } from '../doc';
+import { PermissionModule } from '../permission';
+import { StorageModule } from '../storage';
+import { NotificationJob } from './job';
+import { NotificationResolver, UserNotificationResolver } from './resolver';
+import { NotificationService } from './service';
+
+@Module({
+  imports: [PermissionModule, DocStorageModule, StorageModule],
+  providers: [
+    UserNotificationResolver,
+    NotificationResolver,
+    NotificationService,
+    NotificationJob,
+  ],
+  exports: [NotificationService],
+})
+export class NotificationModule {}
--- a/packages/backend/server/src/core/notification/job.ts
+++ b/packages/backend/server/src/core/notification/job.ts
@@ -0,0 +1,35 @@
+import { Injectable } from '@nestjs/common';
+import { Cron, CronExpression } from '@nestjs/schedule';
+
+import { JobQueue, OnJob } from '../../base';
+import { NotificationService } from './service';
+
+declare global {
+  interface Jobs {
+    'nightly.cleanExpiredNotifications': {};
+  }
+}
+
+@Injectable()
+export class NotificationJob {
+  constructor(
+    private readonly service: NotificationService,
+    private readonly queue: JobQueue
+  ) {}
+
+  @Cron(CronExpression.EVERY_DAY_AT_MIDNIGHT)
+  async nightlyJob() {
+    await this.queue.add(
+      'nightly.cleanExpiredNotifications',
+      {},
+      {
+        jobId: 'nightly-notification-clean-expired',
+      }
+    );
+  }
+
+  @OnJob('nightly.cleanExpiredNotifications')
+  async cleanExpiredNotifications() {
+    await this.service.cleanExpiredNotifications();
+  }
+}
--- a/packages/backend/server/src/core/notification/resolver.ts
+++ b/packages/backend/server/src/core/notification/resolver.ts
@@ -0,0 +1,114 @@
+import {
+  Args,
+  ID,
+  Int,
+  Mutation,
+  ResolveField,
+  Resolver,
+} from '@nestjs/graphql';
+
+import {
+  MentionUserDocAccessDenied,
+  MentionUserOneselfDenied,
+} from '../../base/error';
+import { paginate, PaginationInput } from '../../base/graphql';
+import { MentionNotificationCreateSchema } from '../../models';
+import { CurrentUser } from '../auth/session';
+import { AccessController } from '../permission';
+import { UserType } from '../user';
+import { NotificationService } from './service';
+import {
+  MentionInput,
+  NotificationObjectType,
+  PaginatedNotificationObjectType,
+  UnionNotificationBodyType,
+} from './types';
+
+@Resolver(() => UserType)
+export class UserNotificationResolver {
+  constructor(
+    private readonly service: NotificationService,
+    private readonly ac: AccessController
+  ) {}
+
+  @ResolveField(() => PaginatedNotificationObjectType, {
+    description: 'Get current user notifications',
+  })
+  async notifications(
+    @CurrentUser() me: UserType,
+    @Args('pagination', PaginationInput.decode) pagination: PaginationInput
+  ): Promise<PaginatedNotificationObjectType> {
+    const [notifications, totalCount] = await Promise.all([
+      this.service.findManyByUserId(me.id, pagination),
+      this.service.countByUserId(me.id),
+    ]);
+    return paginate(notifications, 'createdAt', pagination, totalCount);
+  }
+
+  @ResolveField(() => Int, {
+    description: 'Get user notification count',
+  })
+  async notificationCount(@CurrentUser() me: UserType): Promise<number> {
+    return await this.service.countByUserId(me.id);
+  }
+
+  @Mutation(() => ID, {
+    description: 'mention user in a doc',
+  })
+  async mentionUser(
+    @CurrentUser() me: UserType,
+    @Args('input') input: MentionInput
+  ) {
+    const parsedInput = MentionNotificationCreateSchema.parse({
+      userId: input.userId,
+      body: {
+        workspaceId: input.workspaceId,
+        doc: input.doc,
+        createdByUserId: me.id,
+      },
+    });
+    if (parsedInput.userId === me.id) {
+      throw new MentionUserOneselfDenied();
+    }
+    // currentUser can update the doc
+    await this.ac
+      .user(me.id)
+      .doc(parsedInput.body.workspaceId, parsedInput.body.doc.id)
+      .assert('Doc.Update');
+    // mention user can read the doc
+    if (
+      !(await this.ac
+        .user(parsedInput.userId)
+        .doc(parsedInput.body.workspaceId, parsedInput.body.doc.id)
+        .can('Doc.Read'))
+    ) {
+      throw new MentionUserDocAccessDenied({
+        docId: parsedInput.body.doc.id,
+      });
+    }
+    const notification = await this.service.createMention(parsedInput);
+    return notification.id;
+  }
+
+  @Mutation(() => Boolean, {
+    description: 'mark notification as read',
+  })
+  async readNotification(
+    @CurrentUser() me: UserType,
+    @Args('id') notificationId: string
+  ) {
+    await this.service.markAsRead(me.id, notificationId);
+    return true;
+  }
+}
+
+@Resolver(() => NotificationObjectType)
+export class NotificationResolver {
+  @ResolveField(() => UnionNotificationBodyType, {
+    description:
+      "Just a placeholder to export UnionNotificationBodyType, don't use it",
+  })
+  async _placeholderForUnionNotificationBodyType() {
+    return null;
+  }
+}
--- a/packages/backend/server/src/core/notification/service.ts
+++ b/packages/backend/server/src/core/notification/service.ts
@@ -0,0 +1,171 @@
+import { Injectable, Logger } from '@nestjs/common';
+import { PrismaClientKnownRequestError } from '@prisma/client/runtime/library';
+
+import { NotificationNotFound, PaginationInput } from '../../base';
+import {
+  InvitationNotificationCreate,
+  MentionNotification,
+  MentionNotificationCreate,
+  Models,
+  NotificationType,
+  UnionNotificationBody,
+} from '../../models';
+import { DocReader } from '../doc';
+import { WorkspaceBlobStorage } from '../storage';
+
+@Injectable()
+export class NotificationService {
+  private readonly logger = new Logger(NotificationService.name);
+
+  constructor(
+    private readonly models: Models,
+    private readonly docReader: DocReader,
+    private readonly workspaceBlobStorage: WorkspaceBlobStorage
+  ) {}
+
+  async cleanExpiredNotifications() {
+    return await this.models.notification.cleanExpiredNotifications();
+  }
+
+  async createMention(input: MentionNotificationCreate) {
+    return await this.models.notification.createMention(input);
+  }
+
+  async createInvitation(input: InvitationNotificationCreate) {
+    const isActive = await this.models.workspaceUser.getActive(
+      input.body.workspaceId,
+      input.userId
+    );
+    if (isActive) {
+      this.logger.debug(
+        `User ${input.userId} is already a active member of workspace ${input.body.workspaceId}, skip creating notification`
+      );
+      return;
+    }
+    await this.ensureWorkspaceContentExists(input.body.workspaceId);
+    return await this.models.notification.createInvitation(
+      input,
+      NotificationType.Invitation
+    );
+  }
+
+  async createInvitationAccepted(input: InvitationNotificationCreate) {
+    await this.ensureWorkspaceContentExists(input.body.workspaceId);
+    return await this.models.notification.createInvitation(
+      input,
+      NotificationType.InvitationAccepted
+    );
+  }
+
+  async createInvitationBlocked(input: InvitationNotificationCreate) {
+    await this.ensureWorkspaceContentExists(input.body.workspaceId);
+    return await this.models.notification.createInvitation(
+      input,
+      NotificationType.InvitationBlocked
+    );
+  }
+
+  async createInvitationRejected(input: InvitationNotificationCreate) {
+    await this.ensureWorkspaceContentExists(input.body.workspaceId);
+    return await this.models.notification.createInvitation(
+      input,
+      NotificationType.InvitationRejected
+    );
+  }
+
+  private async ensureWorkspaceContentExists(workspaceId: string) {
+    const workspace = await this.models.workspace.get(workspaceId);
+    if (!workspace || workspace.name) {
+      return;
+    }
+    const content = await this.docReader.getWorkspaceContent(workspaceId);
+    if (!content?.name) {
+      return;
+    }
+    await this.models.workspace.update(workspaceId, {
+      name: content.name,
+      avatarKey: content.avatarKey,
+    });
+  }
+
+  async markAsRead(userId: string, notificationId: string) {
+    try {
+      await this.models.notification.markAsRead(notificationId, userId);
+    } catch (err) {
+      if (
+        err instanceof PrismaClientKnownRequestError &&
+        err.code === 'P2025'
+      ) {
+        // https://www.prisma.io/docs/orm/reference/error-reference#p2025
+        throw new NotificationNotFound();
+      }
+      throw err;
+    }
+  }
+
+  /**
+   * Find notifications by user id, order by createdAt desc
+   */
+  async findManyByUserId(userId: string, options?: PaginationInput) {
+    const notifications = await this.models.notification.findManyByUserId(
+      userId,
+      options
+    );
+
+    // fill user info
+    const userIds = new Set(notifications.map(n => n.body.createdByUserId));
+    const users = await this.models.user.getPublicUsers(Array.from(userIds));
+    const userInfos = new Map(users.map(u => [u.id, u]));
+
+    // fill workspace info
+    const workspaceIds = new Set(notifications.map(n => n.body.workspaceId));
+    const workspaces = await this.models.workspace.findMany(
+      Array.from(workspaceIds)
+    );
+    const workspaceInfos = new Map(
+      workspaces.map(w => [
+        w.id,
+        {
+          id: w.id,
+          name: w.name ?? '',
+          avatarUrl: w.avatarKey
+            ? this.workspaceBlobStorage.getAvatarUrl(w.id, w.avatarKey)
+            : undefined,
+        },
+      ])
+    );
+
+    // fill latest doc title
+    const mentions = notifications.filter(
+      n => n.type === NotificationType.Mention
+    ) as MentionNotification[];
+    const mentionDocs = await this.models.doc.findMetas(
+      mentions.map(m => ({
+        workspaceId: m.body.workspaceId,
+        docId: m.body.doc.id,
+      }))
+    );
+    for (const [index, mention] of mentions.entries()) {
+      const doc = mentionDocs[index];
+      if (doc?.title) {
+        // use the latest doc title
+        mention.body.doc.title = doc.title;
+      }
+    }
+
+    return notifications.map(n => ({
+      ...n,
+      body: {
+        ...(n.body as UnionNotificationBody),
+        // set type to body.type to improve type inference on frontend
+        type: n.type,
+        workspace: workspaceInfos.get(n.body.workspaceId),
+        createdByUser: userInfos.get(n.body.createdByUserId),
+      },
+    }));
+  }
+
+  async countByUserId(userId: string) {
+    return await this.models.notification.countByUserId(userId);
+  }
+}
--- a/packages/backend/server/src/core/notification/types.ts
+++ b/packages/backend/server/src/core/notification/types.ts
@@ -0,0 +1,196 @@
+import {
+  createUnionType,
+  Field,
+  ID,
+  InputType,
+  ObjectType,
+  registerEnumType,
+} from '@nestjs/graphql';
+import { GraphQLJSONObject } from 'graphql-scalars';
+
+import { Paginated } from '../../base';
+import {
+  InvitationNotificationBody,
+  Notification,
+  NotificationLevel,
+  NotificationType,
+} from '../../models';
+import { WorkspaceDocInfo } from '../doc/reader';
+import { PublicUserType } from '../user';
+
+registerEnumType(NotificationLevel, {
+  name: 'NotificationLevel',
+  description: 'Notification level',
+});
+
+registerEnumType(NotificationType, {
+  name: 'NotificationType',
+  description: 'Notification type',
+});
+
+@ObjectType()
+export class NotificationWorkspaceType implements WorkspaceDocInfo {
+  @Field(() => ID)
+  id!: string;
+
+  @Field({ description: 'Workspace name' })
+  name!: string;
+
+  @Field(() => String, {
+    description: 'Workspace avatar url',
+    nullable: true,
+  })
+  avatarUrl?: string;
+}
+
+@ObjectType()
+export abstract class BaseNotificationBodyType {
+  @Field(() => NotificationType, {
+    description: 'The type of the notification',
+  })
+  type!: NotificationType;
+
+  @Field(() => PublicUserType, {
+    nullable: true,
+    description:
+      'The user who created the notification, maybe null when user is deleted or sent by system',
+  })
+  createdByUser?: PublicUserType;
+
+  @Field(() => NotificationWorkspaceType, {
+    nullable: true,
+  })
+  workspace?: NotificationWorkspaceType;
+}
+
+@ObjectType()
+export class MentionDocType {
+  @Field(() => String)
+  id!: string;
+
+  @Field(() => String)
+  title!: string;
+
+  @Field(() => String, {
+    nullable: true,
+  })
+  blockId?: string;
+
+  @Field(() => String, {
+    nullable: true,
+  })
+  elementId?: string;
+}
+
+@ObjectType()
+export class MentionNotificationBodyType extends BaseNotificationBodyType {
+  @Field(() => MentionDocType)
+  doc!: MentionDocType;
+}
+
+@ObjectType()
+export class InvitationNotificationBodyType
+  extends BaseNotificationBodyType
+  implements Partial<InvitationNotificationBody>
+{
+  @Field(() => ID)
+  inviteId!: string;
+}
+
+@ObjectType()
+export class InvitationAcceptedNotificationBodyType
+  extends BaseNotificationBodyType
+  implements Partial<InvitationNotificationBody>
+{
+  @Field(() => String)
+  inviteId!: string;
+}
+
+@ObjectType()
+export class InvitationBlockedNotificationBodyType
+  extends BaseNotificationBodyType
+  implements Partial<InvitationNotificationBody>
+{
+  @Field(() => String)
+  inviteId!: string;
+}
+
+export const UnionNotificationBodyType = createUnionType({
+  name: 'UnionNotificationBodyType',
+  types: () =>
+    [
+      MentionNotificationBodyType,
+      InvitationNotificationBodyType,
+      InvitationAcceptedNotificationBodyType,
+      InvitationBlockedNotificationBodyType,
+    ] as const,
+});
+
+@ObjectType()
+export class NotificationObjectType implements Partial<Notification> {
+  @Field(() => ID)
+  id!: string;
+
+  @Field(() => NotificationLevel, {
+    description: 'The level of the notification',
+  })
+  level!: NotificationLevel;
+
+  @Field(() => NotificationType, {
+    description: 'The type of the notification',
+  })
+  type!: NotificationType;
+
+  @Field({ description: 'Whether the notification has been read' })
+  read!: boolean;
+
+  @Field({ description: 'The created at time of the notification' })
+  createdAt!: Date;
+
+  @Field({ description: 'The updated at time of the notification' })
+  updatedAt!: Date;
+
+  @Field(() => GraphQLJSONObject, {
+    description:
+      'The body of the notification, different types have different fields, see UnionNotificationBodyType',
+  })
+  body!: object;
+}
+
+@ObjectType()
+export class PaginatedNotificationObjectType extends Paginated(
+  NotificationObjectType
+) {}
+
+@InputType()
+export class MentionDocInput {
+  @Field(() => String)
+  id!: string;
+
+  @Field(() => String)
+  title!: string;
+
+  @Field(() => String, {
+    description: 'The block id in the doc',
+    nullable: true,
+  })
+  blockId?: string;
+
+  @Field(() => String, {
+    description: 'The element id in the doc',
+    nullable: true,
+  })
+  elementId?: string;
+}
+
+@InputType()
+export class MentionInput {
+  @Field()
+  userId!: string;
+
+  @Field()
+  workspaceId!: string;
+
+  @Field(() => MentionDocInput)
+  doc!: MentionDocInput;
+}
--- a/packages/backend/server/src/models/tests/notification.spec.ts
+++ b/packages/backend/server/src/models/tests/notification.spec.ts
@@ -0,0 +1,407 @@
+import { randomUUID } from 'node:crypto';
+import { mock } from 'node:test';
+
+import ava, { TestFn } from 'ava';
+
+import { createTestingModule, type TestingModule } from '../../__tests__/utils';
+import { Config } from '../../base/config';
+import {
+  Models,
+  NotificationLevel,
+  NotificationType,
+  User,
+  Workspace,
+} from '../../models';
+
+interface Context {
+  config: Config;
+  module: TestingModule;
+  models: Models;
+}
+
+const test = ava as TestFn<Context>;
+
+test.before(async t => {
+  const module = await createTestingModule();
+
+  t.context.models = module.get(Models);
+  t.context.config = module.get(Config);
+  t.context.module = module;
+});
+
+let user: User;
+let createdBy: User;
+let workspace: Workspace;
+let docId: string;
+
+test.beforeEach(async t => {
+  await t.context.module.initTestingDB();
+  user = await t.context.models.user.create({
+    email: 'test@affine.pro',
+  });
+  createdBy = await t.context.models.user.create({
+    email: 'createdBy@affine.pro',
+  });
+  workspace = await t.context.models.workspace.create(user.id);
+  docId = randomUUID();
+  await t.context.models.doc.upsert({
+    spaceId: user.id,
+    docId,
+    blob: Buffer.from('hello'),
+    timestamp: Date.now(),
+    editorId: user.id,
+  });
+});
+
+test.afterEach.always(() => {
+  mock.reset();
+  mock.timers.reset();
+});
+
+test.after(async t => {
+  await t.context.module.close();
+});
+
+test('should create a mention notification with default level', async t => {
+  const notification = await t.context.models.notification.createMention({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      doc: {
+        id: docId,
+        title: 'doc-title',
+        blockId: 'blockId',
+      },
+      createdByUserId: createdBy.id,
+    },
+  });
+  t.is(notification.level, NotificationLevel.Default);
+  t.is(notification.body.workspaceId, workspace.id);
+  t.is(notification.body.doc.id, docId);
+  t.is(notification.body.doc.title, 'doc-title');
+  t.is(notification.body.doc.blockId, 'blockId');
+  t.is(notification.body.createdByUserId, createdBy.id);
+  t.is(notification.type, NotificationType.Mention);
+  t.is(notification.read, false);
+});
+
+test('should create a mention notification with custom level', async t => {
+  const notification = await t.context.models.notification.createMention({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      doc: {
+        id: docId,
+        title: 'doc-title',
+        elementId: 'elementId',
+      },
+      createdByUserId: createdBy.id,
+    },
+    level: NotificationLevel.High,
+  });
+  t.is(notification.level, NotificationLevel.High);
+  t.is(notification.body.workspaceId, workspace.id);
+  t.is(notification.body.doc.id, docId);
+  t.is(notification.body.doc.title, 'doc-title');
+  t.is(notification.body.doc.elementId, 'elementId');
+  t.is(notification.body.createdByUserId, createdBy.id);
+  t.is(notification.type, NotificationType.Mention);
+  t.is(notification.read, false);
+});
+
+test('should mark a mention notification as read', async t => {
+  const notification = await t.context.models.notification.createMention({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      doc: {
+        id: docId,
+        title: 'doc-title',
+        blockId: 'blockId',
+      },
+      createdByUserId: createdBy.id,
+    },
+  });
+  t.is(notification.read, false);
+  await t.context.models.notification.markAsRead(notification.id, user.id);
+  const updatedNotification = await t.context.models.notification.get(
+    notification.id
+  );
+  t.is(updatedNotification!.read, true);
+});
+
+test('should create an invite notification', async t => {
+  const inviteId = randomUUID();
+  const notification = await t.context.models.notification.createInvitation({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: createdBy.id,
+      inviteId,
+    },
+  });
+  t.is(notification.type, NotificationType.Invitation);
+  t.is(notification.body.workspaceId, workspace.id);
+  t.is(notification.body.createdByUserId, createdBy.id);
+  t.is(notification.body.inviteId, inviteId);
+  t.is(notification.read, false);
+});
+
+test('should mark an invite notification as read', async t => {
+  const inviteId = randomUUID();
+  const notification = await t.context.models.notification.createInvitation({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: createdBy.id,
+      inviteId,
+    },
+  });
+  t.is(notification.read, false);
+  await t.context.models.notification.markAsRead(notification.id, user.id);
+  const updatedNotification = await t.context.models.notification.get(
+    notification.id
+  );
+  t.is(updatedNotification!.read, true);
+});
+
+test('should find many notifications by user id, order by createdAt descending', async t => {
+  const notification1 = await t.context.models.notification.createMention({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      doc: {
+        id: docId,
+        title: 'doc-title',
+        blockId: 'blockId',
+      },
+      createdByUserId: createdBy.id,
+    },
+  });
+  const inviteId = randomUUID();
+  const notification2 = await t.context.models.notification.createInvitation({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: createdBy.id,
+      inviteId,
+    },
+  });
+  const notifications = await t.context.models.notification.findManyByUserId(
+    user.id
+  );
+  t.is(notifications.length, 2);
+  t.is(notifications[0].id, notification2.id);
+  t.is(notifications[1].id, notification1.id);
+});
+
+test('should find many notifications by user id, filter read notifications', async t => {
+  const notification1 = await t.context.models.notification.createMention({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      doc: {
+        id: docId,
+        title: 'doc-title',
+        blockId: 'blockId',
+      },
+      createdByUserId: createdBy.id,
+    },
+  });
+  const inviteId = randomUUID();
+  const notification2 = await t.context.models.notification.createInvitation({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: createdBy.id,
+      inviteId,
+    },
+  });
+  await t.context.models.notification.markAsRead(notification2.id, user.id);
+  const notifications = await t.context.models.notification.findManyByUserId(
+    user.id
+  );
+  t.is(notifications.length, 1);
+  t.is(notifications[0].id, notification1.id);
+});
+
+test('should clean expired notifications', async t => {
+  const notification = await t.context.models.notification.createMention({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      doc: {
+        id: docId,
+        title: 'doc-title',
+        blockId: 'blockId',
+      },
+      createdByUserId: createdBy.id,
+    },
+  });
+  t.truthy(notification);
+  let notifications = await t.context.models.notification.findManyByUserId(
+    user.id
+  );
+  t.is(notifications.length, 1);
+  let count = await t.context.models.notification.cleanExpiredNotifications();
+  t.is(count, 0);
+  notifications = await t.context.models.notification.findManyByUserId(user.id);
+  t.is(notifications.length, 1);
+  t.is(notifications[0].id, notification.id);
+
+  await t.context.models.notification.markAsRead(notification.id, user.id);
+  // wait for 1 year
+  mock.timers.enable({
+    apis: ['Date'],
+    now: Date.now() + 1000 * 60 * 60 * 24 * 365,
+  });
+  count = await t.context.models.notification.cleanExpiredNotifications();
+  t.is(count, 1);
+  notifications = await t.context.models.notification.findManyByUserId(user.id);
+  t.is(notifications.length, 0);
+});
+
+test('should not clean unexpired notifications', async t => {
+  const notification = await t.context.models.notification.createMention({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      doc: {
+        id: docId,
+        title: 'doc-title',
+        blockId: 'blockId',
+      },
+      createdByUserId: createdBy.id,
+    },
+  });
+  let count = await t.context.models.notification.cleanExpiredNotifications();
+  t.is(count, 0);
+  await t.context.models.notification.markAsRead(notification.id, user.id);
+  count = await t.context.models.notification.cleanExpiredNotifications();
+  t.is(count, 0);
+});
+
+test('should find many notifications by user id, order by createdAt descending, with pagination', async t => {
+  const notification1 = await t.context.models.notification.createMention({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      doc: {
+        id: docId,
+        title: 'doc-title',
+        blockId: 'blockId',
+      },
+      createdByUserId: createdBy.id,
+    },
+  });
+  const notification2 = await t.context.models.notification.createInvitation({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: createdBy.id,
+      inviteId: randomUUID(),
+    },
+  });
+  const notification3 = await t.context.models.notification.createInvitation({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: createdBy.id,
+      inviteId: randomUUID(),
+    },
+  });
+  const notification4 = await t.context.models.notification.createInvitation({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: createdBy.id,
+      inviteId: randomUUID(),
+    },
+  });
+  const notifications = await t.context.models.notification.findManyByUserId(
+    user.id,
+    {
+      offset: 0,
+      first: 2,
+    }
+  );
+  t.is(notifications.length, 2);
+  t.is(notifications[0].id, notification4.id);
+  t.is(notifications[1].id, notification3.id);
+  const notifications2 = await t.context.models.notification.findManyByUserId(
+    user.id,
+    {
+      offset: 2,
+      first: 2,
+    }
+  );
+  t.is(notifications2.length, 2);
+  t.is(notifications2[0].id, notification2.id);
+  t.is(notifications2[1].id, notification1.id);
+  const notifications3 = await t.context.models.notification.findManyByUserId(
+    user.id,
+    {
+      offset: 4,
+      first: 2,
+    }
+  );
+  t.is(notifications3.length, 0);
+});
+
+test('should count notifications by user id, exclude read notifications', async t => {
+  const notification1 = await t.context.models.notification.createMention({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      doc: {
+        id: docId,
+        title: 'doc-title',
+        blockId: 'blockId',
+      },
+      createdByUserId: createdBy.id,
+    },
+  });
+  t.truthy(notification1);
+  const notification2 = await t.context.models.notification.createInvitation({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: createdBy.id,
+      inviteId: randomUUID(),
+    },
+  });
+  t.truthy(notification2);
+  await t.context.models.notification.markAsRead(notification2.id, user.id);
+  const count = await t.context.models.notification.countByUserId(user.id);
+  t.is(count, 1);
+});
+
+test('should count notifications by user id, include read notifications', async t => {
+  const notification1 = await t.context.models.notification.createMention({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      doc: {
+        id: docId,
+        title: 'doc-title',
+        blockId: 'blockId',
+      },
+      createdByUserId: createdBy.id,
+    },
+  });
+  t.truthy(notification1);
+  const notification2 = await t.context.models.notification.createInvitation({
+    userId: user.id,
+    body: {
+      workspaceId: workspace.id,
+      createdByUserId: createdBy.id,
+      inviteId: randomUUID(),
+    },
+  });
+  t.truthy(notification2);
+  await t.context.models.notification.markAsRead(notification2.id, user.id);
+  const count = await t.context.models.notification.countByUserId(user.id, {
+    includeRead: true,
+  });
+  t.is(count, 2);
+});
--- a/packages/backend/server/src/models/index.ts
+++ b/packages/backend/server/src/models/index.ts
@@ -11,6 +11,7 @@ import { DocModel } from './doc';
 import { DocUserModel } from './doc-user';
 import { FeatureModel } from './feature';
 import { HistoryModel } from './history';
+import { NotificationModel } from './notification';
 import { MODELS_SYMBOL } from './provider';
 import { SessionModel } from './session';
 import { UserModel } from './user';
@@ -34,6 +35,7 @@ const MODELS = {
  workspaceUser: WorkspaceUserModel,
  docUser: DocUserModel,
  history: HistoryModel,
+  notification: NotificationModel,
 };

 type ModelsType = {
@@ -90,6 +92,7 @@ export * from './doc';
 export * from './doc-user';
 export * from './feature';
 export * from './history';
+export * from './notification';
 export * from './session';
 export * from './user';
 export * from './user-doc';
--- a/packages/backend/server/src/models/notification.ts
+++ b/packages/backend/server/src/models/notification.ts
@@ -0,0 +1,200 @@
+import { Injectable } from '@nestjs/common';
+import {
+  Notification,
+  NotificationLevel,
+  NotificationType,
+  Prisma,
+} from '@prisma/client';
+import { z } from 'zod';
+
+import { PaginationInput } from '../base';
+import { BaseModel } from './base';
+
+export { NotificationLevel, NotificationType };
+export type { Notification };
+
+// #region input
+
+export const ONE_YEAR = 1000 * 60 * 60 * 24 * 365;
+const IdSchema = z.string().trim().min(1).max(100);
+
+export const BaseNotificationCreateSchema = z.object({
+  userId: IdSchema,
+  level: z
+    .nativeEnum(NotificationLevel)
+    .optional()
+    .default(NotificationLevel.Default),
+});
+
+export const MentionDocSchema = z.object({
+  id: IdSchema,
+  // Allow empty string, will display as `Untitled` at frontend
+  title: z.string().trim().max(255),
+  // blockId or elementId is required at least one
+  blockId: IdSchema.optional(),
+  elementId: IdSchema.optional(),
+});
+
+const MentionNotificationBodySchema = z.object({
+  workspaceId: IdSchema,
+  createdByUserId: IdSchema,
+  doc: MentionDocSchema,
+});
+
+export type MentionNotificationBody = z.infer<
+  typeof MentionNotificationBodySchema
+>;
+
+export const MentionNotificationCreateSchema =
+  BaseNotificationCreateSchema.extend({
+    body: MentionNotificationBodySchema,
+  });
+
+export type MentionNotificationCreate = z.input<
+  typeof MentionNotificationCreateSchema
+>;
+
+const InvitationNotificationBodySchema = z.object({
+  workspaceId: IdSchema,
+  createdByUserId: IdSchema,
+  inviteId: IdSchema,
+});
+
+export type InvitationNotificationBody = z.infer<
+  typeof InvitationNotificationBodySchema
+>;
+
+export const InvitationNotificationCreateSchema =
+  BaseNotificationCreateSchema.extend({
+    body: InvitationNotificationBodySchema,
+  });
+
+export type InvitationNotificationCreate = z.input<
+  typeof InvitationNotificationCreateSchema
+>;
+
+export type UnionNotificationBody =
+  | MentionNotificationBody
+  | InvitationNotificationBody;
+
+// #endregion
+
+// #region output
+
+export type MentionNotification = Notification &
+  z.infer<typeof MentionNotificationCreateSchema>;
+
+export type InvitationNotification = Notification &
+  z.infer<typeof InvitationNotificationCreateSchema>;
+
+export type UnionNotification = MentionNotification | InvitationNotification;
+
+// #endregion
+
+@Injectable()
+export class NotificationModel extends BaseModel {
+  // #region mention
+
+  async createMention(input: MentionNotificationCreate) {
+    const data = MentionNotificationCreateSchema.parse(input);
+    const row = await this.create({
+      userId: data.userId,
+      level: data.level,
+      type: NotificationType.Mention,
+      body: data.body,
+    });
+    this.logger.log(
+      `Created mention notification:${row.id} for user:${data.userId} in workspace:${data.body.workspaceId}`
+    );
+    return row as MentionNotification;
+  }
+
+  // #endregion
+
+  // #region invitation
+
+  async createInvitation(
+    input: InvitationNotificationCreate,
+    type: NotificationType = NotificationType.Invitation
+  ) {
+    const data = InvitationNotificationCreateSchema.parse(input);
+    const row = await this.create({
+      userId: data.userId,
+      level: data.level,
+      type,
+      body: data.body,
+    });
+    this.logger.log(
+      `Created ${type} notification ${row.id} to user ${data.userId} in workspace ${data.body.workspaceId}`
+    );
+    return row as InvitationNotification;
+  }
+
+  // #endregion
+
+  // #region common
+
+  private async create(data: Prisma.NotificationUncheckedCreateInput) {
+    return await this.db.notification.create({
+      data,
+    });
+  }
+
+  async markAsRead(notificationId: string, userId: string) {
+    await this.db.notification.update({
+      where: { id: notificationId, userId },
+      data: {
+        read: true,
+      },
+    });
+  }
+
+  /**
+   * Find many notifications by user id, exclude read notifications by default
+   */
+  async findManyByUserId(
+    userId: string,
+    options?: {
+      includeRead?: boolean;
+    } & PaginationInput
+  ) {
+    const rows = await this.db.notification.findMany({
+      where: {
+        userId,
+        ...(options?.includeRead ? {} : { read: false }),
+        ...(options?.after ? { createdAt: { gt: options.after } } : {}),
+      },
+      orderBy: { createdAt: 'desc' },
+      skip: options?.offset,
+      take: options?.first,
+    });
+    return rows as UnionNotification[];
+  }
+
+  async countByUserId(userId: string, options: { includeRead?: boolean } = {}) {
+    return this.db.notification.count({
+      where: {
+        userId,
+        ...(options.includeRead ? {} : { read: false }),
+      },
+    });
+  }
+
+  async get(notificationId: string) {
+    const row = await this.db.notification.findUnique({
+      where: { id: notificationId },
+    });
+    return row as UnionNotification;
+  }
+
+  async cleanExpiredNotifications() {
+    const { count } = await this.db.notification.deleteMany({
+      // delete notifications that are older than one year
+      where: { createdAt: { lte: new Date(Date.now() - ONE_YEAR) } },
+    });
+    this.logger.log(`Deleted ${count} expired notifications`);
+    return count;
+  }
+
+  // #endregion
+}
--- a/packages/backend/server/src/schema.gql
+++ b/packages/backend/server/src/schema.gql
@@ -330,7 +330,7 @@ type EditorType {
  name: String!
 }

-union ErrorDataUnion = AlreadyInSpaceDataType | BlobNotFoundDataType | CopilotContextFileNotSupportedDataType | CopilotDocNotFoundDataType | CopilotFailedToMatchContextDataType | CopilotFailedToModifyContextDataType | CopilotInvalidContextDataType | CopilotMessageNotFoundDataType | CopilotPromptNotFoundDataType | CopilotProviderSideErrorDataType | DocActionDeniedDataType | DocHistoryNotFoundDataType | DocNotFoundDataType | DocUpdateBlockedDataType | ExpectToGrantDocUserRolesDataType | ExpectToRevokeDocUserRolesDataType | ExpectToUpdateDocUserRoleDataType | GraphqlBadRequestDataType | InvalidEmailDataType | InvalidHistoryTimestampDataType | InvalidLicenseUpdateParamsDataType | InvalidOauthCallbackCodeDataType | InvalidPasswordLengthDataType | InvalidRuntimeConfigTypeDataType | MemberNotFoundInSpaceDataType | MissingOauthQueryParameterDataType | NotInSpaceDataType | QueryTooLongDataType | RuntimeConfigNotFoundDataType | SameSubscriptionRecurringDataType | SpaceAccessDeniedDataType | SpaceNotFoundDataType | SpaceOwnerNotFoundDataType | SpaceShouldHaveOnlyOneOwnerDataType | SubscriptionAlreadyExistsDataType | SubscriptionNotExistsDataType | SubscriptionPlanNotFoundDataType | UnknownOauthProviderDataType | UnsupportedClientVersionDataType | UnsupportedSubscriptionPlanDataType | ValidationErrorDataType | VersionRejectedDataType | WorkspaceMembersExceedLimitToDowngradeDataType | WorkspacePermissionNotFoundDataType | WrongSignInCredentialsDataType
+union ErrorDataUnion = AlreadyInSpaceDataType | BlobNotFoundDataType | CopilotContextFileNotSupportedDataType | CopilotDocNotFoundDataType | CopilotFailedToMatchContextDataType | CopilotFailedToModifyContextDataType | CopilotInvalidContextDataType | CopilotMessageNotFoundDataType | CopilotPromptNotFoundDataType | CopilotProviderSideErrorDataType | DocActionDeniedDataType | DocHistoryNotFoundDataType | DocNotFoundDataType | DocUpdateBlockedDataType | ExpectToGrantDocUserRolesDataType | ExpectToRevokeDocUserRolesDataType | ExpectToUpdateDocUserRoleDataType | GraphqlBadRequestDataType | InvalidEmailDataType | InvalidHistoryTimestampDataType | InvalidLicenseUpdateParamsDataType | InvalidOauthCallbackCodeDataType | InvalidPasswordLengthDataType | InvalidRuntimeConfigTypeDataType | MemberNotFoundInSpaceDataType | MentionUserDocAccessDeniedDataType | MissingOauthQueryParameterDataType | NotInSpaceDataType | QueryTooLongDataType | RuntimeConfigNotFoundDataType | SameSubscriptionRecurringDataType | SpaceAccessDeniedDataType | SpaceNotFoundDataType | SpaceOwnerNotFoundDataType | SpaceShouldHaveOnlyOneOwnerDataType | SubscriptionAlreadyExistsDataType | SubscriptionNotExistsDataType | SubscriptionPlanNotFoundDataType | UnknownOauthProviderDataType | UnsupportedClientVersionDataType | UnsupportedSubscriptionPlanDataType | ValidationErrorDataType | VersionRejectedDataType | WorkspaceMembersExceedLimitToDowngradeDataType | WorkspacePermissionNotFoundDataType | WrongSignInCredentialsDataType

 enum ErrorNames {
  ACCESS_DENIED
@@ -401,8 +401,11 @@ enum ErrorNames {
  MAILER_SERVICE_IS_NOT_CONFIGURED
  MEMBER_NOT_FOUND_IN_SPACE
  MEMBER_QUOTA_EXCEEDED
+  MENTION_USER_DOC_ACCESS_DENIED
+  MENTION_USER_ONESELF_DENIED
  MISSING_OAUTH_QUERY_PARAMETER
  NETWORK_ERROR
+  NOTIFICATION_NOT_FOUND
  NOT_FOUND
  NOT_IN_SPACE
  NO_COPILOT_PROVIDER_AVAILABLE
@@ -531,6 +534,42 @@ type InvalidRuntimeConfigTypeDataType {
  want: String!
 }

+type InvitationAcceptedNotificationBodyType {
+  """
+  The user who created the notification, maybe null when user is deleted or sent by system
+  """
+  createdByUser: PublicUserType
+  inviteId: String!
+
+  """The type of the notification"""
+  type: NotificationType!
+  workspace: NotificationWorkspaceType
+}
+
+type InvitationBlockedNotificationBodyType {
+  """
+  The user who created the notification, maybe null when user is deleted or sent by system
+  """
+  createdByUser: PublicUserType
+  inviteId: String!
+
+  """The type of the notification"""
+  type: NotificationType!
+  workspace: NotificationWorkspaceType
+}
+
+type InvitationNotificationBodyType {
+  """
+  The user who created the notification, maybe null when user is deleted or sent by system
+  """
+  createdByUser: PublicUserType
+  inviteId: ID!
+
+  """The type of the notification"""
+  type: NotificationType!
+  workspace: NotificationWorkspaceType
+}
+
 type InvitationType {
  """Invitee information"""
  invitee: UserType!
@@ -677,6 +716,45 @@ type MemberNotFoundInSpaceDataType {
  spaceId: String!
 }

+input MentionDocInput {
+  """The block id in the doc"""
+  blockId: String
+
+  """The element id in the doc"""
+  elementId: String
+  id: String!
+  title: String!
+}
+
+type MentionDocType {
+  blockId: String
+  elementId: String
+  id: String!
+  title: String!
+}
+
+input MentionInput {
+  doc: MentionDocInput!
+  userId: String!
+  workspaceId: String!
+}
+
+type MentionNotificationBodyType {
+  """
+  The user who created the notification, maybe null when user is deleted or sent by system
+  """
+  createdByUser: PublicUserType
+  doc: MentionDocType!
+
+  """The type of the notification"""
+  type: NotificationType!
+  workspace: NotificationWorkspaceType
+}
+
+type MentionUserDocAccessDeniedDataType {
+  docId: String!
+}
+
 type MissingOauthQueryParameterDataType {
  name: String!
 }
@@ -740,8 +818,14 @@ type Mutation {
  invite(email: String!, permission: Permission @deprecated(reason: "never used"), sendInviteMail: Boolean, workspaceId: String!): String!
  inviteBatch(emails: [String!]!, sendInviteMail: Boolean, workspaceId: String!): [InviteResult!]!
  leaveWorkspace(sendLeaveMail: Boolean, workspaceId: String!, workspaceName: String @deprecated(reason: "no longer used")): Boolean!
+
+  """mention user in a doc"""
+  mentionUser(input: MentionInput!): ID!
  publishDoc(docId: String!, mode: PublicDocMode = Page, workspaceId: String!): DocType!
  publishPage(mode: PublicDocMode = Page, pageId: String!, workspaceId: String!): DocType! @deprecated(reason: "use publishDoc instead")
+
+  """mark notification as read"""
+  readNotification(id: String!): Boolean!
  recoverDoc(guid: String!, timestamp: DateTime!, workspaceId: String!): DateTime!
  releaseDeletedBlobs(workspaceId: String!): Boolean!

@@ -798,6 +882,64 @@ type NotInSpaceDataType {
  spaceId: String!
 }

+"""Notification level"""
+enum NotificationLevel {
+  Default
+  High
+  Low
+  Min
+  None
+}
+
+type NotificationObjectType {
+  """Just a placeholder to export UnionNotificationBodyType, don't use it"""
+  _placeholderForUnionNotificationBodyType: UnionNotificationBodyType!
+
+  """
+  The body of the notification, different types have different fields, see UnionNotificationBodyType
+  """
+  body: JSONObject!
+
+  """The created at time of the notification"""
+  createdAt: DateTime!
+  id: ID!
+
+  """The level of the notification"""
+  level: NotificationLevel!
+
+  """Whether the notification has been read"""
+  read: Boolean!
+
+  """The type of the notification"""
+  type: NotificationType!
+
+  """The updated at time of the notification"""
+  updatedAt: DateTime!
+}
+
+type NotificationObjectTypeEdge {
+  cursor: String!
+  node: NotificationObjectType!
+}
+
+"""Notification type"""
+enum NotificationType {
+  Invitation
+  InvitationAccepted
+  InvitationBlocked
+  InvitationRejected
+  Mention
+}
+
+type NotificationWorkspaceType {
+  """Workspace avatar url"""
+  avatarUrl: String
+  id: ID!
+
+  """Workspace name"""
+  name: String!
+}
+
 enum OAuthProviderType {
  GitHub
  Google
@@ -817,6 +959,12 @@ type PaginatedGrantedDocUserType {
  totalCount: Int!
 }

+type PaginatedNotificationObjectType {
+  edges: [NotificationObjectTypeEdge!]!
+  pageInfo: PageInfo!
+  totalCount: Int!
+}
+
 input PaginationInput {
  """returns the elements in the list that come after the specified cursor."""
  after: String
@@ -1120,6 +1268,8 @@ enum SubscriptionVariant {
  Onetime
 }

+union UnionNotificationBodyType = InvitationAcceptedNotificationBodyType | InvitationBlockedNotificationBodyType | InvitationNotificationBodyType | MentionNotificationBodyType
+
 type UnknownOauthProviderDataType {
  name: String!
 }
@@ -1226,6 +1376,12 @@ type UserType {

  """User name"""
  name: String!
+
+  """Get user notification count"""
+  notificationCount: Int!
+
+  """Get current user notifications"""
+  notifications(pagination: PaginationInput!): PaginatedNotificationObjectType!
  quota: UserQuotaType!
  quotaUsage: UserQuotaUsageType!
  subscriptions: [SubscriptionType!]!