enhance(backend): refine system account (#15530)

* wip

* wip

* wip

* Update SystemAccountService.ts

* Update 1740121393164-system-accounts.js

* Update DeleteAccountService.ts

* wip

* wip

* wip

* wip

* Update 1740121393164-system-accounts.js

* Update RepositoryModule.ts

* wip

* wip

* wip

* Update ApRendererService.ts

* wip

* wip

* Update SystemAccountService.ts

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* add print logs

* ログが長すぎて出てないかもしれない

* fix migration

* refactor

* fix fed-tests

* Update RelayService.ts

* merge

* Update user.test.ts

* chore: emit log

* fix: tweak sleep duration

* fix: exit 1

* fix: wait for misskey processes to become healthy

* fix: longer sleep for user deletion

* fix: make sleep longer again

* デッドロック解消の試み

https://github.com/misskey-dev/misskey/issues/15005

* Revert "デッドロック解消の試み"

This reverts commit 266141f66f.

* wip

* Update SystemAccountService.ts

---------

Co-authored-by: おさむのひと <46447427+samunohito@users.noreply.github.com>
Co-authored-by: zyoshoka <107108195+zyoshoka@users.noreply.github.com>

packages/backend/src/core/SignupService.ts

@@ -16,11 +16,12 @@ import { MiUserKeypair } from '@/models/UserKeypair.js';
 import { MiUsedUsername } from '@/models/UsedUsername.js';
 import { generateNativeUserToken } from '@/misc/token.js';
 import { UserEntityService } from '@/core/entities/UserEntityService.js';
-import { InstanceActorService } from '@/core/InstanceActorService.js';
 import { bindThis } from '@/decorators.js';
 import UsersChart from '@/core/chart/charts/users.js';
 import { UtilityService } from '@/core/UtilityService.js';
 import { UserService } from '@/core/UserService.js';
+import { SystemAccountService } from '@/core/SystemAccountService.js';
+import { MetaService } from '@/core/MetaService.js';
 
 @Injectable()
 export class SignupService {
@@ -41,7 +42,8 @@ export class SignupService {
 		private userService: UserService,
 		private userEntityService: UserEntityService,
 		private idService: IdService,
-		private instanceActorService: InstanceActorService,
+		private systemAccountService: SystemAccountService,
+		private metaService: MetaService,
 		private usersChart: UsersChart,
 	) {
 	}
@@ -86,9 +88,7 @@ export class SignupService {
 			throw new Error('USED_USERNAME');
 		}
 
-		const isTheFirstUser = !await this.instanceActorService.realLocalUsersPresent();
-
-		if (!opts.ignorePreservedUsernames && !isTheFirstUser) {
+		if (!opts.ignorePreservedUsernames && this.meta.rootUserId != null) {
 			const isPreserved = this.meta.preservedUsernames.map(x => x.toLowerCase()).includes(username.toLowerCase());
 			if (isPreserved) {
 				throw new Error('USED_USERNAME');
@@ -129,7 +129,6 @@ export class SignupService {
 				usernameLower: username.toLowerCase(),
 				host: this.utilityService.toPunyNullable(host),
 				token: secret,
-				isRoot: isTheFirstUser,
 			}));
 
 			await transactionalEntityManager.save(new MiUserKeypair({
@@ -153,6 +152,10 @@ export class SignupService {
 		this.usersChart.update(account, true);
 		this.userService.notifySystemWebhook(account, 'userCreated');
 
+		if (this.meta.rootUserId == null) {
+			await this.metaService.update({ rootUserId: account.id });
+		}
+
 		return { account, secret };
 	}
 }