feat: account migration (#10507)

* add Move activity

* add endpoint to move from local to remote

* follow move activity coming to inbox

* fix move endpoint

* add known-as endpoint to create account alias

* add migration page

* add route to migration page

* add move and known-as endpoints

* fix dependnecies error

* fix new endpoints

* fix move activity id

* fix refollow

* add movedToUri and alsoKnownAs to api

* fix moveToUri indicator

* fix missing context

* add chengelog

* rename MkMoved to MkAccountMoved

* add missing semicolon

* fix targetUri

* fix followings query

* remove redundant null check

CHANGELOG.md

@@ -21,6 +21,7 @@
 ### General
 - チャンネルをお気に入りに登録できるように
 - チャンネルにノートをピン留めできるように
+- アカウントの引っ越し（フォロワー引き継ぎ）に対応
 
 ### Client
 - 検索ページでURLを入力した際に照会したときと同等の挙動をするように

locales/en-US.yml

@@ -988,6 +988,16 @@ enableChartsForFederatedInstances: "Generate remote instance data charts"
 showClipButtonInNoteFooter: "Add \"Clip\" to note action menu"
 largeNoteReactions: "Enlargen displayed reactions"
 noteIdOrUrl: "Note ID or URL"
+migration: "Migration"
+moveTo: "Move current account to new account"
+moveToLabel: "Account you're moving to:"
+moveAccountDescription: "This process is irreversible. Make sure you've set up an alias for this account on your new account before moving. Please enter the tag of the account formatted like @person@instance.com"
+moveFrom: "Move to this account from an older account"
+moveFromLabel: "Account you're moving from:"
+moveFromDescription: "This will set an alias of your old account so that you can move from that account to this current one. Do this BEFORE moving from your older account. Please enter the tag of the account formatted like @person@instance.com"
+migrationConfirm: "Are you absolutely sure you want to migrate your acccount to {account}? Once you do this, you won't be able to reverse it, and you won't be able to use your account normally again.\nAlso, please ensure that you've set this current account as the account you're moving from."
+accountMoved: "User has moved to a new account:"
+
 _achievements:
   earnedAt: "Unlocked at"
   _types:
@@ -1898,4 +1908,3 @@ _webhookSettings:
     renote: "When renoted"
     reaction: "When receiving a reaction"
     mention: "When being mentioned"
-

locales/ja-JP.yml

@@ -989,6 +989,15 @@ enableChartsForFederatedInstances: "リモートサーバーのチャートを
 showClipButtonInNoteFooter: "ノートのアクションにクリップを追加"
 largeNoteReactions: "ノートのリアクションを大きく表示"
 noteIdOrUrl: "ノートIDまたはURL"
+migration: "アカウントの引っ越し"
+moveTo: "このアカウントを新しいアカウントに引っ越す"
+moveToLabel: "引っ越し先のアカウント："
+moveAccountDescription: "この操作は取り消せません。まずは引っ越し先のアカウントでこのアカウントに対しエイリアスを作成したことを確認してください。エイリアス作成後、引っ越し先のアカウントをこのように入力してください：@person@instance.com"
+moveFrom: "別のアカウントからこのアカウントに引っ越す"
+moveFromLabel: "引っ越し元のアカウント："
+moveFromDescription: "別のアカウントからこのアカウントにフォロワーを引き継いで引っ越したい場合、ここでエイリアスを作成しておく必要があります。必ず引っ越しを実行する前に作成してください！引っ越し元のアカウントをこのように入力してください：@person@instance.com"
+migrationConfirm: "本当にこのアカウントを {account} に引っ越しますか？一度引っ越しを行うと取り消せず、二度とこのアカウントを元の状態で使用できなくなります。\nまた、引っ越し先のアカウントでエイリアスを作成したことを確認してください。"
+accountMoved: "このユーザーは新しいアカウントに引っ越しました："
 
 _achievements:
   earnedAt: "獲得日時"
@@ -1955,4 +1964,3 @@ _webhookSettings:
     renote: "Renoteされたとき"
     reaction: "リアクションがあったとき"
     mention: "メンションされたとき"
-

packages/backend/src/core/AccountMoveService.ts

@@ -0,0 +1,114 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { IsNull } from 'typeorm';
+
+import { bindThis } from '@/decorators.js';
+import { DI } from '@/di-symbols.js';
+import type { LocalUser } from '@/models/entities/User.js';
+import { User } from '@/models/entities/User.js';
+import type { FollowingsRepository, UsersRepository } from '@/models/index.js';
+
+import { GlobalEventService } from '@/core/GlobalEventService.js';
+import { UserFollowingService } from '@/core/UserFollowingService.js';
+import { ApDeliverManagerService } from '@/core/activitypub/ApDeliverManagerService.js';
+import { ApRendererService } from '@/core/activitypub/ApRendererService.js';
+import { UserEntityService } from '@/core/entities/UserEntityService.js';
+import { AccountUpdateService } from '@/core/AccountUpdateService.js';
+import { RelayService } from '@/core/RelayService.js';
+
+@Injectable()
+export class AccountMoveService {
+	constructor(
+		@Inject(DI.usersRepository)
+		private usersRepository: UsersRepository,
+
+		@Inject(DI.followingsRepository)
+		private followingsRepository: FollowingsRepository,
+
+		private userEntityService: UserEntityService,
+		private apRendererService: ApRendererService,
+		private apDeliverManagerService: ApDeliverManagerService,
+		private globalEventService: GlobalEventService,
+		private userFollowingService: UserFollowingService,
+		private accountUpdateService: AccountUpdateService,
+		private relayService: RelayService,
+	) {
+	}
+
+	/**
+	 * Move a local account to a remote account.
+	 *
+	 * After delivering Move activity, its local followers unfollow the old account and then follow the new one.
+	 */
+	@bindThis
+	public async moveToRemote(src: LocalUser, dst: User): Promise<unknown> {
+		// Make sure that the destination is a remote account.
+		if (this.userEntityService.isLocalUser(dst)) throw new Error('move destiantion is not remote');
+		if (!dst.uri) throw new Error('destination uri is empty');
+
+		// add movedToUri to indicate that the user has moved
+		const update = {} as Partial<User>;
+		update.alsoKnownAs = src.alsoKnownAs?.concat([dst.uri]) ?? [dst.uri];
+		update.movedToUri = dst.uri;
+		await this.usersRepository.update(src.id, update);
+
+		const srcPerson = await this.apRendererService.renderPerson(src);
+		const updateAct = this.apRendererService.addContext(this.apRendererService.renderUpdate(srcPerson, src));
+		await this.apDeliverManagerService.deliverToFollowers(src, updateAct);
+		this.relayService.deliverToRelays(src, updateAct);
+
+		// Deliver Move activity to the followers of the old account
+		const moveAct = this.apRendererService.addContext(this.apRendererService.renderMove(src, dst));
+		await this.apDeliverManagerService.deliverToFollowers(src, moveAct);
+
+		// Publish meUpdated event
+		const iObj = await this.userEntityService.pack<true, true>(src.id, src, { detail: true, includeSecrets: true });
+		this.globalEventService.publishMainStream(src.id, 'meUpdated', iObj);
+
+		// follow the new account and unfollow the old one
+		const followings = await this.followingsRepository.find({
+			relations: {
+				follower: true,
+			},
+			where: {
+				followeeId: src.id,
+				followerHost: IsNull(), // follower is local
+			}
+		});
+		followings.forEach(async (following) => {
+			if (!following.follower) return;
+			try {
+				await this.userFollowingService.follow(following.follower, dst);
+				await this.userFollowingService.unfollow(following.follower, src);
+			} catch {
+				/* empty */
+			}
+		});
+
+		return iObj;
+	}
+
+	/**
+	 * Create an alias of an old remote account.
+	 *
+	 * The user's new profile will be published to the followers.
+	 */
+	@bindThis
+	public async createAlias(me: LocalUser, updates: Partial<User>): Promise<unknown> {
+		await this.usersRepository.update(me.id, updates);
+
+		// Publish meUpdated event
+		const iObj = await this.userEntityService.pack<true, true>(me.id, me, {
+			detail: true,
+			includeSecrets: true,
+		});
+		this.globalEventService.publishMainStream(me.id, 'meUpdated', iObj);
+
+		if (me.isLocked === false) {
+			await this.userFollowingService.acceptAllFollowRequests(me);
+		}
+
+		this.accountUpdateService.publishToFollowers(me.id);
+
+		return iObj;
+	}
+}

packages/backend/src/core/CoreModule.ts

@@ -1,4 +1,5 @@
 import { Module } from '@nestjs/common';
+import { AccountMoveService } from './AccountMoveService.js';
 import { AccountUpdateService } from './AccountUpdateService.js';
 import { AiService } from './AiService.js';
 import { AntennaService } from './AntennaService.js';
@@ -119,6 +120,7 @@ import type { Provider } from '@nestjs/common';
 
 //#region 文字列ベースでのinjection用(循環参照対応のため)
 const $LoggerService: Provider = { provide: 'LoggerService', useExisting: LoggerService };
+const $AccountMoveService: Provider = { provide: 'AccountMoveService', useExisting: AccountMoveService };
 const $AccountUpdateService: Provider = { provide: 'AccountUpdateService', useExisting: AccountUpdateService };
 const $AiService: Provider = { provide: 'AiService', useExisting: AiService };
 const $AntennaService: Provider = { provide: 'AntennaService', useExisting: AntennaService };
@@ -242,6 +244,7 @@ const $ApQuestionService: Provider = { provide: 'ApQuestionService', useExisting
 	],
 	providers: [
 		LoggerService,
+		AccountMoveService,
 		AccountUpdateService,
 		AiService,
 		AntennaService,
@@ -359,6 +362,7 @@ const $ApQuestionService: Provider = { provide: 'ApQuestionService', useExisting
 
 		//#region 文字列ベースでのinjection用(循環参照対応のため)
 		$LoggerService,
+		$AccountMoveService,
 		$AccountUpdateService,
 		$AiService,
 		$AntennaService,
@@ -477,6 +481,7 @@ const $ApQuestionService: Provider = { provide: 'ApQuestionService', useExisting
 	exports: [
 		QueueModule,
 		LoggerService,
+		AccountMoveService,
 		AccountUpdateService,
 		AiService,
 		AntennaService,
@@ -593,6 +598,7 @@ const $ApQuestionService: Provider = { provide: 'ApQuestionService', useExisting
 
 		//#region 文字列ベースでのinjection用(循環参照対応のため)
 		$LoggerService,
+		$AccountMoveService,
 		$AccountUpdateService,
 		$AiService,
 		$AntennaService,

packages/backend/src/core/activitypub/ApInboxService.ts

@@ -1,5 +1,5 @@
 import { Inject, Injectable } from '@nestjs/common';
-import { In } from 'typeorm';
+import { In, IsNull } from 'typeorm';
 import { DI } from '@/di-symbols.js';
 import type { Config } from '@/config.js';
 import { UserFollowingService } from '@/core/UserFollowingService.js';
@@ -22,7 +22,7 @@ import { QueueService } from '@/core/QueueService.js';
 import type { UsersRepository, NotesRepository, FollowingsRepository, AbuseUserReportsRepository, FollowRequestsRepository } from '@/models/index.js';
 import { bindThis } from '@/decorators.js';
 import type { RemoteUser } from '@/models/entities/User.js';
-import { getApId, getApIds, getApType, isAccept, isActor, isAdd, isAnnounce, isBlock, isCollection, isCollectionOrOrderedCollection, isCreate, isDelete, isFlag, isFollow, isLike, isPost, isReject, isRemove, isTombstone, isUndo, isUpdate, validActor, validPost } from './type.js';
+import { getApHrefNullable, getApId, getApIds, getApType, getOneApHrefNullable, isAccept, isActor, isAdd, isAnnounce, isBlock, isCollection, isCollectionOrOrderedCollection, isCreate, isDelete, isFlag, isFollow, isLike, isMove, isPost, isReject, isRemove, isTombstone, isUndo, isUpdate, validActor, validPost } from './type.js';
 import { ApNoteService } from './models/ApNoteService.js';
 import { ApLoggerService } from './ApLoggerService.js';
 import { ApDbResolverService } from './ApDbResolverService.js';
@@ -31,7 +31,7 @@ import { ApAudienceService } from './ApAudienceService.js';
 import { ApPersonService } from './models/ApPersonService.js';
 import { ApQuestionService } from './models/ApQuestionService.js';
 import type { Resolver } from './ApResolverService.js';
-import type { IAccept, IAdd, IAnnounce, IBlock, ICreate, IDelete, IFlag, IFollow, ILike, IObject, IReject, IRemove, IUndo, IUpdate } from './type.js';
+import type { IAccept, IAdd, IAnnounce, IBlock, ICreate, IDelete, IFlag, IFollow, ILike, IObject, IReject, IRemove, IUndo, IUpdate, IMove } from './type.js';
 
 @Injectable()
 export class ApInboxService {
@@ -139,6 +139,8 @@ export class ApInboxService {
 			await this.block(actor, activity);
 		} else if (isFlag(activity)) {
 			await this.flag(actor, activity);
+		} else if (isMove(activity)) {
+			await this.move(actor, activity);
 		} else {
 			this.logger.warn(`unrecognized activity type: ${activity.type}`);
 		}
@@ -728,4 +730,55 @@ export class ApInboxService {
 			return `skip: Unknown type: ${getApType(object)}`;
 		}
 	}
+
+	@bindThis
+	private async move(actor: RemoteUser, activity: IMove): Promise<string> {
+		// fetch the new and old accounts
+		const targetUri = getApHrefNullable(activity.target);
+		if (!targetUri) return 'skip: invalid activity target';
+		const new_acc = await this.apPersonService.resolvePerson(targetUri);
+		const old_acc = await this.apPersonService.resolvePerson(actor.uri);
+
+		// update them if they're remote
+		if (new_acc.uri) await this.apPersonService.updatePerson(new_acc.uri);
+		if (old_acc.uri) await this.apPersonService.updatePerson(old_acc.uri);
+
+		// check if alsoKnownAs of the new account is valid
+		let isValidMove = true;
+		if (old_acc.uri) {
+			if (!new_acc.alsoKnownAs?.includes(old_acc.uri)) {
+				isValidMove = false;
+			}
+		} else if (!new_acc.alsoKnownAs?.includes(old_acc.id)) {
+			isValidMove = false;
+		}
+		if (!isValidMove) {
+			return 'skip: accounts invalid';
+		}
+
+		// add target uri to movedToUri in order to indicate that the user has moved
+		await this.usersRepository.update(old_acc.id, { movedToUri: targetUri });
+
+		// follow the new account and unfollow the old one
+		const followings = await this.followingsRepository.find({
+			relations: {
+				follower: true,
+			},
+			where: {
+				followeeId: old_acc.id,
+				followerHost: IsNull(), // follower is local
+			}
+		});
+		followings.forEach(async (following) => {
+			if (!following.follower) return;
+			try {
+				await this.userFollowingService.follow(following.follower, new_acc);
+				await this.userFollowingService.unfollow(following.follower, old_acc);
+			} catch {
+				/* empty */
+			}
+		});
+
+		return 'ok';
+	}
 }

packages/backend/src/core/activitypub/ApRendererService.ts

@@ -25,7 +25,7 @@ import { CustomEmojiService } from '@/core/CustomEmojiService.js';
 import { isNotNull } from '@/misc/is-not-null.js';
 import { LdSignatureService } from './LdSignatureService.js';
 import { ApMfmService } from './ApMfmService.js';
-import type { IAccept, IActivity, IAdd, IAnnounce, IApDocument, IApEmoji, IApHashtag, IApImage, IApMention, IBlock, ICreate, IDelete, IFlag, IFollow, IKey, ILike, IObject, IPost, IQuestion, IReject, IRemove, ITombstone, IUndo, IUpdate } from './type.js';
+import type { IAccept, IActivity, IAdd, IAnnounce, IApDocument, IApEmoji, IApHashtag, IApImage, IApMention, IBlock, ICreate, IDelete, IFlag, IFollow, IKey, ILike, IMove, IObject, IPost, IQuestion, IReject, IRemove, ITombstone, IUndo, IUpdate } from './type.js';
 import type { IIdentifier } from './models/identifier.js';
 
 @Injectable()
@@ -292,6 +292,22 @@ export class ApRendererService {
 		};
 	}
 
+	@bindThis
+	public renderMove(
+		src: { id: User['id']; host: User['host']; uri: User['host'] },
+		dst: { id: User['id']; host: User['host']; uri: User['host'] },
+	): IMove {
+		const actor = this.userEntityService.isLocalUser(src) ? `${this.config.url}/users/${src.id}` : src.uri!;
+		const target = this.userEntityService.isLocalUser(dst) ? `${this.config.url}/users/${dst.id}` : dst.uri!;
+		return {
+			id: `${this.config.url}/moves/${src.id}/${dst.id}`,
+			actor,
+			type: 'Move',
+			object: actor,
+			target,
+		};
+	}
+
 	@bindThis
 	public async renderNote(note: Note, dive = true): Promise<IPost> {
 		const getPromisedFiles = async (ids: string[]) => {
@@ -498,6 +514,14 @@ export class ApRendererService {
 			attachment: attachment.length ? attachment : undefined,
 		} as any;
 
+		if (user.movedToUri) {
+			person.movedTo = user.movedToUri;
+		}
+
+		if (user.alsoKnownAs) {
+			person.alsoKnownAs = user.alsoKnownAs;
+		}
+
 		if (profile.birthday) {
 			person['vcard:bday'] = profile.birthday;
 		}

packages/backend/src/core/activitypub/models/ApPersonService.ts

@@ -281,6 +281,8 @@ export class ApPersonService implements OnModuleInit {
 					lastFetchedAt: new Date(),
 					name: truncate(person.name, nameLength),
 					isLocked: !!person.manuallyApprovesFollowers,
+					movedToUri: person.movedTo,
+					alsoKnownAs: person.alsoKnownAs,
 					isExplorable: !!person.discoverable,
 					username: person.preferredUsername,
 					usernameLower: person.preferredUsername!.toLowerCase(),
@@ -473,6 +475,8 @@ export class ApPersonService implements OnModuleInit {
 			isBot: getApType(object) === 'Service',
 			isCat: (person as any).isCat === true,
 			isLocked: !!person.manuallyApprovesFollowers,
+			movedToUri: person.movedTo ?? null,
+			alsoKnownAs: person.alsoKnownAs ?? null,
 			isExplorable: !!person.discoverable,
 		} as Partial<User>;
 

packages/backend/src/core/activitypub/type.ts

@@ -157,6 +157,8 @@ export interface IActor extends IObject {
 	name?: string;
 	preferredUsername?: string;
 	manuallyApprovesFollowers?: boolean;
+	movedTo?: string;
+	alsoKnownAs?: string[];
 	discoverable?: boolean;
 	inbox: string;
 	sharedInbox?: string;	// 後方互換性のため
@@ -300,6 +302,11 @@ export interface IFlag extends IActivity {
 	type: 'Flag';
 }
 
+export interface IMove extends IActivity {
+	type: 'Move';
+	target: IObject | string;
+}
+
 export const isCreate = (object: IObject): object is ICreate => getApType(object) === 'Create';
 export const isDelete = (object: IObject): object is IDelete => getApType(object) === 'Delete';
 export const isUpdate = (object: IObject): object is IUpdate => getApType(object) === 'Update';
@@ -314,3 +321,4 @@ export const isLike = (object: IObject): object is ILike => getApType(object) ==
 export const isAnnounce = (object: IObject): object is IAnnounce => getApType(object) === 'Announce';
 export const isBlock = (object: IObject): object is IBlock => getApType(object) === 'Block';
 export const isFlag = (object: IObject): object is IFlag => getApType(object) === 'Flag';
+export const isMove = (object: IObject): object is IMove => getApType(object) === 'Move';

packages/backend/src/core/entities/UserEntityService.ts

@@ -15,6 +15,7 @@ import { birthdaySchema, descriptionSchema, localUsernameSchema, locationSchema,
 import type { UsersRepository, UserSecurityKeysRepository, FollowingsRepository, FollowRequestsRepository, BlockingsRepository, MutingsRepository, DriveFilesRepository, NoteUnreadsRepository, ChannelFollowingsRepository, UserNotePiningsRepository, UserProfilesRepository, InstancesRepository, AnnouncementReadsRepository, AnnouncementsRepository, PagesRepository, UserProfile, RenoteMutingsRepository } from '@/models/index.js';
 import { bindThis } from '@/decorators.js';
 import { RoleService } from '@/core/RoleService.js';
+import { ApPersonService } from '@/core/activitypub/models/ApPersonService.js';
 import { FederatedInstanceService } from '@/core/FederatedInstanceService.js';
 import type { OnModuleInit } from '@nestjs/common';
 import type { AntennaService } from '../AntennaService.js';
@@ -47,6 +48,7 @@ function isRemoteUser(user: User | { host: User['host'] }): boolean {
 
 @Injectable()
 export class UserEntityService implements OnModuleInit {
+	private apPersonService: ApPersonService;
 	private noteEntityService: NoteEntityService;
 	private driveFileEntityService: DriveFileEntityService;
 	private pageEntityService: PageEntityService;
@@ -122,6 +124,7 @@ export class UserEntityService implements OnModuleInit {
 	}
 
 	onModuleInit() {
+		this.apPersonService = this.moduleRef.get('ApPersonService');
 		this.noteEntityService = this.moduleRef.get('NoteEntityService');
 		this.driveFileEntityService = this.moduleRef.get('DriveFileEntityService');
 		this.pageEntityService = this.moduleRef.get('PageEntityService');
@@ -363,6 +366,8 @@ export class UserEntityService implements OnModuleInit {
 			...(opts.detail ? {
 				url: profile!.url,
 				uri: user.uri,
+				movedToUri: user.movedToUri ? await this.apPersonService.resolvePerson(user.movedToUri) : null,
+				alsoKnownAs: user.alsoKnownAs,
 				createdAt: user.createdAt.toISOString(),
 				updatedAt: user.updatedAt ? user.updatedAt.toISOString() : null,
 				lastFetchedAt: user.lastFetchedAt ? user.lastFetchedAt.toISOString() : null,

packages/backend/src/models/entities/User.ts

@@ -68,6 +68,19 @@ export class User {
 	})
 	public followingCount: number;
 
+	@Column('varchar', {
+		length: 512,
+		nullable: true,
+		comment: 'The URI of the new account of the User',
+	})
+	public movedToUri: string | null;
+
+	@Column('simple-array', {
+		nullable: true,
+		comment: 'URIs the user is known as too',
+	})
+	public alsoKnownAs: string[] | null;
+
 	@Column('integer', {
 		default: 0,
 		comment: 'The count of notes.',

packages/backend/src/models/json-schema/user.ts

@@ -72,6 +72,18 @@ export const packedUserDetailedNotMeOnlySchema = {
 			format: 'uri',
 			nullable: true, optional: false,
 		},
+		movedToUri: {
+			type: 'string',
+			format: 'uri',
+			nullable: true,
+			optional: false,
+		},
+		alsoKnownAs: {
+			type: 'array',
+			format: 'uri',
+			nullable: true,
+			optional: false,
+		},
 		createdAt: {
 			type: 'string',
 			nullable: false, optional: false,

packages/backend/src/server/api/EndpointsModule.ts

@@ -220,6 +220,8 @@ import * as ep___i_signinHistory from './endpoints/i/signin-history.js';
 import * as ep___i_unpin from './endpoints/i/unpin.js';
 import * as ep___i_updateEmail from './endpoints/i/update-email.js';
 import * as ep___i_update from './endpoints/i/update.js';
+import * as ep___i_move from './endpoints/i/move.js';
+import * as ep___i_knownAs from './endpoints/i/known-as.js';
 import * as ep___i_webhooks_create from './endpoints/i/webhooks/create.js';
 import * as ep___i_webhooks_show from './endpoints/i/webhooks/show.js';
 import * as ep___i_webhooks_list from './endpoints/i/webhooks/list.js';
@@ -551,6 +553,8 @@ const $i_signinHistory: Provider = { provide: 'ep:i/signin-history', useClass: e
 const $i_unpin: Provider = { provide: 'ep:i/unpin', useClass: ep___i_unpin.default };
 const $i_updateEmail: Provider = { provide: 'ep:i/update-email', useClass: ep___i_updateEmail.default };
 const $i_update: Provider = { provide: 'ep:i/update', useClass: ep___i_update.default };
+const $i_move: Provider = { provide: 'ep:i/move', useClass: ep___i_move.default };
+const $i_knownAs: Provider = { provide: 'ep:i/known-as', useClass: ep___i_knownAs.default };
 const $i_webhooks_create: Provider = { provide: 'ep:i/webhooks/create', useClass: ep___i_webhooks_create.default };
 const $i_webhooks_list: Provider = { provide: 'ep:i/webhooks/list', useClass: ep___i_webhooks_list.default };
 const $i_webhooks_show: Provider = { provide: 'ep:i/webhooks/show', useClass: ep___i_webhooks_show.default };
@@ -886,6 +890,8 @@ const $retention: Provider = { provide: 'ep:retention', useClass: ep___retention
 		$i_unpin,
 		$i_updateEmail,
 		$i_update,
+		$i_move,
+		$i_knownAs,
 		$i_webhooks_create,
 		$i_webhooks_list,
 		$i_webhooks_show,
@@ -1215,6 +1221,8 @@ const $retention: Provider = { provide: 'ep:retention', useClass: ep___retention
 		$i_unpin,
 		$i_updateEmail,
 		$i_update,
+		$i_move,
+		$i_knownAs,
 		$i_webhooks_create,
 		$i_webhooks_list,
 		$i_webhooks_show,

packages/backend/src/server/api/endpoints.ts

@@ -220,6 +220,8 @@ import * as ep___i_signinHistory from './endpoints/i/signin-history.js';
 import * as ep___i_unpin from './endpoints/i/unpin.js';
 import * as ep___i_updateEmail from './endpoints/i/update-email.js';
 import * as ep___i_update from './endpoints/i/update.js';
+import * as ep___i_move from './endpoints/i/move.js';
+import * as ep___i_knownAs from './endpoints/i/known-as.js';
 import * as ep___i_webhooks_create from './endpoints/i/webhooks/create.js';
 import * as ep___i_webhooks_show from './endpoints/i/webhooks/show.js';
 import * as ep___i_webhooks_list from './endpoints/i/webhooks/list.js';
@@ -549,6 +551,8 @@ const eps = [
 	['i/unpin', ep___i_unpin],
 	['i/update-email', ep___i_updateEmail],
 	['i/update', ep___i_update],
+	['i/move', ep___i_move],
+	['i/known-as', ep___i_knownAs],
 	['i/webhooks/create', ep___i_webhooks_create],
 	['i/webhooks/list', ep___i_webhooks_list],
 	['i/webhooks/show', ep___i_webhooks_show],

packages/backend/src/server/api/endpoints/i/known-as.ts

@@ -0,0 +1,92 @@
+import { Injectable } from '@nestjs/common';
+import ms from 'ms';
+
+import { User } from '@/models/entities/User.js';
+import { Endpoint } from '@/server/api/endpoint-base.js';
+import { ApiError } from '@/server/api/error.js';
+
+import { AccountMoveService } from '@/core/AccountMoveService.js';
+import { RemoteUserResolveService } from '@/core/RemoteUserResolveService.js';
+import { UserEntityService } from '@/core/entities/UserEntityService.js';
+import { ApiLoggerService } from '@/server/api/ApiLoggerService.js';
+
+export const meta = {
+	tags: ['users'],
+
+	secure: true,
+	requireCredential: true,
+
+	limit: {
+		duration: ms('1day'),
+		max: 30,
+	},
+
+	errors: {
+		noSuchUser: {
+			message: 'No such user.',
+			code: 'NO_SUCH_USER',
+			id: 'fcd2eef9-a9b2-4c4f-8624-038099e90aa5',
+		},
+		notRemote: {
+			message: 'User is not remote. You can only migrate from other instances.',
+			code: 'NOT_REMOTE',
+			id: '4362f8dc-731f-4ad8-a694-be2a88922a24',
+		},
+		uriNull: {
+			message: 'User ActivityPup URI is null.',
+			code: 'URI_NULL',
+			id: 'bf326f31-d430-4f97-9933-5d61e4d48a23',
+		},
+	},
+} as const;
+
+export const paramDef = {
+	type: 'object',
+	properties: {
+		alsoKnownAs: { type: 'string' },
+	},
+	required: ['alsoKnownAs'],
+} as const;
+
+@Injectable()
+export default class extends Endpoint<typeof meta, typeof paramDef> {
+	constructor(
+		private userEntityService: UserEntityService,
+		private remoteUserResolveService: RemoteUserResolveService,
+		private apiLoggerService: ApiLoggerService,
+		private accountMoveService: AccountMoveService,
+	) {
+		super(meta, paramDef, async (ps, me) => {
+			// Check parameter
+			if (!ps.alsoKnownAs) throw new ApiError(meta.errors.noSuchUser);
+
+			let unfiltered = ps.alsoKnownAs;
+			const updates = {} as Partial<User>;
+
+			if (!unfiltered) {
+				updates.alsoKnownAs = null;
+			} else {
+				// Parse user's input into the old account
+				if (unfiltered.startsWith('acct:')) unfiltered = unfiltered.substring(5);
+				if (unfiltered.startsWith('@')) unfiltered = unfiltered.substring(1);
+				if (!unfiltered.includes('@')) throw new ApiError(meta.errors.notRemote);
+
+				const userAddress = unfiltered.split('@');
+				// Retrieve the old account
+				const knownAs = await this.remoteUserResolveService.resolveUser(userAddress[0], userAddress[1]).catch((e) => {
+					this.apiLoggerService.logger.warn(`failed to resolve remote user: ${e}`);
+					throw new ApiError(meta.errors.noSuchUser);
+				});
+
+				const toUrl: string | null = knownAs.uri;
+				if (!toUrl) throw new ApiError(meta.errors.uriNull);
+				// Only allow moving from a remote account
+				if (this.userEntityService.isLocalUser(knownAs)) throw new ApiError(meta.errors.notRemote);
+
+				updates.alsoKnownAs = updates.alsoKnownAs?.concat([toUrl]) ?? [toUrl];
+			}
+
+			return await this.accountMoveService.createAlias(me, updates);
+		});
+	}
+}

packages/backend/src/server/api/endpoints/i/move.ts

@@ -0,0 +1,136 @@
+import { Inject, Injectable } from '@nestjs/common';
+import ms from 'ms';
+
+import type { Config } from '@/config.js';
+import { DI } from '@/di-symbols.js';
+
+import { Endpoint } from '@/server/api/endpoint-base.js';
+import { ApiError } from '@/server/api/error.js';
+
+import { AccountMoveService } from '@/core/AccountMoveService.js';
+import { RemoteUserResolveService } from '@/core/RemoteUserResolveService.js';
+import { UserEntityService } from '@/core/entities/UserEntityService.js';
+import { ApiLoggerService } from '@/server/api/ApiLoggerService.js';
+import { GetterService } from '@/server/api/GetterService.js';
+import { ApPersonService } from '@/core/activitypub/models/ApPersonService.js';
+
+export const meta = {
+	tags: ['users'],
+
+	secure: true,
+	requireCredential: true,
+	limit: {
+		duration: ms('1day'),
+		max: 5,
+	},
+
+	errors: {
+		noSuchMoveTarget: {
+			message: 'No such move target.',
+			code: 'NO_SUCH_MOVE_TARGET',
+			id: 'b5c90186-4ab0-49c8-9bba-a1f76c202ba4',
+		},
+		remoteAccountForbids: {
+			message:
+				'Remote account doesn\'t have proper \'Known As\' alias. Did you remember to set it?',
+			code: 'REMOTE_ACCOUNT_FORBIDS',
+			id: 'b5c90186-4ab0-49c8-9bba-a1f766282ba4',
+		},
+		notRemote: {
+			message: 'User is not remote. You can only migrate to other instances.',
+			code: 'NOT_REMOTE',
+			id: '4362f8dc-731f-4ad8-a694-be2a88922a24',
+		},
+		rootForbidden: {
+			message: 'The root cant migrate.',
+			code: 'NOT_ROOT_FORBIDDEN',
+			id: '4362e8dc-731f-4ad8-a694-be2a88922a24',
+		},
+		noSuchUser: {
+			message: 'No such user.',
+			code: 'NO_SUCH_USER',
+			id: 'fcd2eef9-a9b2-4c4f-8624-038099e90aa5',
+		},
+		uriNull: {
+			message: 'User ActivityPup URI is null.',
+			code: 'URI_NULL',
+			id: 'bf326f31-d430-4f97-9933-5d61e4d48a23',
+		},
+		localUriNull: {
+			message: 'Local User ActivityPup URI is null.',
+			code: 'URI_NULL',
+			id: '95ba11b9-90e8-43a5-ba16-7acc1ab32e71',
+		},
+		alreadyMoved: {
+			message: 'Account was already moved to another account.',
+			code: 'ALREADY_MOVED',
+			id: 'b234a14e-9ebe-4581-8000-074b3c215962',
+		},
+	},
+} as const;
+
+export const paramDef = {
+	type: 'object',
+	properties: {
+		moveToAccount: { type: 'string' },
+	},
+	required: ['moveToAccount'],
+} as const;
+
+// eslint-disable-next-line import/no-default-export
+@Injectable()
+export default class extends Endpoint<typeof meta, typeof paramDef> {
+	constructor(
+		@Inject(DI.config)
+		private config: Config,
+
+		private userEntityService: UserEntityService,
+		private remoteUserResolveService: RemoteUserResolveService,
+		private apiLoggerService: ApiLoggerService,
+		private accountMoveService: AccountMoveService,
+		private getterService: GetterService,
+		private apPersonService: ApPersonService,
+	) {
+		super(meta, paramDef, async (ps, me) => {
+			// Check parameter
+			if (!ps.moveToAccount) throw new ApiError(meta.errors.noSuchMoveTarget);
+			// Abort if user is the root
+			if (me.isRoot) throw new ApiError(meta.errors.rootForbidden);
+			// Abort if user has already moved
+			if (me.movedToUri) throw new ApiError(meta.errors.alreadyMoved);
+
+			let unfiltered = ps.moveToAccount;
+			if (!unfiltered) throw new ApiError(meta.errors.noSuchMoveTarget);
+
+			// Parse user's input into the destination account
+			if (unfiltered.startsWith('acct:')) unfiltered = unfiltered.substring(5);
+			if (unfiltered.startsWith('@')) unfiltered = unfiltered.substring(1);
+			if (!unfiltered.includes('@')) throw new ApiError(meta.errors.notRemote);
+
+			const userAddress = unfiltered.split('@');
+			// Retrieve the destination account
+			const remoteMoveTo = await this.remoteUserResolveService.resolveUser(userAddress[0], userAddress[1]).catch((e) => {
+				this.apiLoggerService.logger.warn(`failed to resolve remote user: ${e}`);
+				throw new ApiError(meta.errors.noSuchMoveTarget);
+			});
+			const moveTo = await this.getterService.getRemoteUser(remoteMoveTo.id);
+			if (!moveTo.uri) throw new ApiError(meta.errors.uriNull);
+			await this.apPersonService.updatePerson(moveTo.uri);
+			// Only allow moving to a remote account
+			if (this.userEntityService.isLocalUser(moveTo)) throw new ApiError(meta.errors.notRemote);
+
+			let allowed = false;
+
+			const fromUrl = `${this.config.url}/users/${me.id}`;
+			// Make sure that the user has indicated the old account as an alias
+			moveTo.alsoKnownAs?.forEach((elem) => {
+				if (fromUrl.includes(elem)) allowed = true;
+			});
+
+			// Abort if unintended
+			if (!(allowed && moveTo.uri && fromUrl)) throw new ApiError(meta.errors.remoteAccountForbids);
+
+			return await this.accountMoveService.moveToRemote(me, moveTo);
+		});
+	}
+}

packages/frontend/src/components/MkAccountMoved.vue

@@ -0,0 +1,33 @@
+<template>
+<div class="msjugskd _block">
+	<i class="ti ti-plane-departure" style="margin-right: 8px;"></i>
+	{{ i18n.ts.accountMoved }}
+	<MkMention class="link" :username="acct" :host="host ?? localHost"/>
+</div>
+</template>
+
+<script lang="ts" setup>
+import MkMention from './MkMention.vue';
+import { i18n } from '@/i18n';
+import { host as localHost } from '@/config';
+
+defineProps<{
+	acct: string;
+	host: string;
+}>();
+</script>
+
+<style lang="scss" scoped>
+.msjugskd {
+	padding: 16px;
+	font-size: 90%;
+	background: var(--infoWarnBg);
+	color: var(--error);
+	border-radius: var(--radius);
+
+	> .link {
+		margin-left: 4px;
+		color: var(--accent);
+	}
+}
+</style>

packages/frontend/src/pages/settings/index.vue

@@ -130,6 +130,11 @@ const menuDef = computed(() => [{
 }, {
 	title: i18n.ts.otherSettings,
 	items: [{
+		icon: 'ti ti-plane',
+		text: i18n.ts.migration,
+		to: '/settings/migration',
+		active: currentPage?.route.name === 'migration',
+	}, {
 		icon: 'ti ti-package',
 		text: i18n.ts.importAndExport,
 		to: '/settings/import-export',

packages/frontend/src/pages/settings/migration.vue

@@ -0,0 +1,73 @@
+<template>
+<div class="_gaps_m">
+	<FormSection>
+		<template #label>{{ i18n.ts.moveTo }}</template>
+		<MkInput v-model="moveToAccount" manual-save>
+			<template #prefix><i class="ti ti-plane-departure"></i></template>
+			<template #label>{{ i18n.ts.moveToLabel }}</template>
+		</MkInput>
+	</FormSection>
+	<FormInfo warn>{{ i18n.ts.moveAccountDescription }}</FormInfo>
+
+	<FormSection>
+		<template #label>{{ i18n.ts.moveFrom }}</template>
+		<MkInput v-model="accountAlias" manual-save>
+			<template #prefix><i class="ti ti-plane-arrival"></i></template>
+			<template #label>{{ i18n.ts.moveFromLabel }}</template>
+		</MkInput>
+	</FormSection>
+	<FormInfo warn>{{ i18n.ts.moveFromDescription }}</FormInfo>
+</div>
+</template>
+
+<script lang="ts" setup>
+import { ref, watch } from 'vue';
+import FormSection from '@/components/form/section.vue';
+import FormInfo from '@/components/MkInfo.vue';
+import MkInput from '@/components/MkInput.vue';
+import * as os from '@/os';
+import { i18n } from '@/i18n';
+import { definePageMetadata } from '@/scripts/page-metadata';
+
+const moveToAccount = ref('');
+const accountAlias = ref('');
+
+async function move(): Promise<void> {
+	const account = moveToAccount.value;
+	const confirm = await os.confirm({
+		type: 'warning',
+		text: i18n.t('migrationConfirm', { account: account.toString() }),
+	});
+	if (confirm.canceled) return;
+	os.apiWithDialog('i/move', {
+		moveToAccount: account,
+	});
+}
+
+async function save(): Promise<void> {
+	const account = accountAlias.value;
+	os.apiWithDialog('i/known-as', {
+		alsoKnownAs: account,
+	});
+}
+
+watch(accountAlias, async () => {
+	await save();
+});
+
+watch(moveToAccount, async () => {
+	await move();
+});
+
+definePageMetadata({
+	title: i18n.ts.migration,
+	icon: 'ti ti-plane',
+});
+</script>
+
+<style lang="scss">
+.description {
+	font-size: .85em;
+	padding: 1rem;
+}
+</style>

packages/frontend/src/pages/user/home.vue

@@ -7,6 +7,7 @@
 			<!-- <div class="punished" v-if="user.isSilenced"><i class="ti ti-alert-triangle" style="margin-right: 8px;"></i> {{ i18n.ts.userSilenced }}</div> -->
 
 			<div class="profile _gaps">
+				<MkAccountMoved v-if="user.movedToUri" :host="user.movedToUri.host" :acct="user.movedToUri.username"/>
 				<MkRemoteCaution v-if="user.host != null" :href="user.url ?? user.uri!" class="warn"/>
 
 				<div :key="user.id" class="main _panel">
@@ -117,6 +118,7 @@ import calcAge from 's-age';
 import * as misskey from 'misskey-js';
 import MkNote from '@/components/MkNote.vue';
 import MkFollowButton from '@/components/MkFollowButton.vue';
+import MkAccountMoved from '@/components/MkAccountMoved.vue';
 import MkRemoteCaution from '@/components/MkRemoteCaution.vue';
 import MkOmit from '@/components/MkOmit.vue';
 import MkInfo from '@/components/MkInfo.vue';

packages/frontend/src/router.ts

@@ -161,6 +161,10 @@ export const routes = [{
 		path: '/preferences-backups',
 		name: 'preferences-backups',
 		component: page(() => import('./pages/settings/preferences-backups.vue')),
+	}, {
+		path: '/migration',
+		name: 'migration',
+		component: page(() => import('./pages/settings/migration.vue'))
 	}, {
 		path: '/custom-css',
 		name: 'general',

packages/misskey-js/src/api.types.ts

@@ -362,6 +362,8 @@ export type Endpoints = {
 	'i/get-word-muted-notes-count': { req: TODO; res: TODO; };
 	'i/import-following': { req: TODO; res: TODO; };
 	'i/import-user-lists': { req: TODO; res: TODO; };
+	'i/move': { req: TODO; res: TODO; };
+	'i/known-as': { req: TODO; res: TODO; };
 	'i/notifications': { req: {
 		limit?: number;
 		sinceId?: Notification['id'];

packages/misskey-js/src/entities.ts

@@ -14,6 +14,8 @@ export type UserLite = {
 	onlineStatus: 'online' | 'active' | 'offline' | 'unknown';
 	avatarUrl: string;
 	avatarBlurhash: string;
+	alsoKnownAs: string[];
+	movedToUri: any;
 	emojis: {
 		name: string;
 		url: string;