From 7c5f3b02972b1ce53e39f0dd04f6fce4e5511c43 Mon Sep 17 00:00:00 2001
From: Camila Belo <camilaibs@gmail.com>
Date: Fri, 12 Jul 2024 11:22:31 +0200
Subject: [PATCH] refactor: use string types for service instance occurrences

Signed-off-by: Camila Belo <camilaibs@gmail.com>
---
 .changeset/mighty-apricots-taste.md           |   5 +
 .changeset/purple-carrots-crash.md            |   5 +
 .changeset/shy-waves-share.md                 |   5 +
 .changeset/small-bottles-cough.md             |  58 ++++++++
 .changeset/thirty-adults-grab.md              |   6 +
 packages/backend-app-api/api-report-alpha.md  |   2 +-
 packages/backend-app-api/api-report.md        |  38 +++---
 .../src/wiring/ServiceRegistry.ts             |  38 +++---
 packages/backend-defaults/api-report-auth.md  |   2 +-
 packages/backend-defaults/api-report-cache.md |   2 +-
 .../backend-defaults/api-report-database.md   |   2 +-
 .../backend-defaults/api-report-discovery.md  |   2 +-
 .../backend-defaults/api-report-httpAuth.md   |   2 +-
 .../backend-defaults/api-report-httpRouter.md |   2 +-
 .../backend-defaults/api-report-lifecycle.md  |   2 +-
 .../backend-defaults/api-report-logger.md     |   2 +-
 .../api-report-permissions.md                 |   2 +-
 .../backend-defaults/api-report-rootConfig.md |   4 +-
 .../backend-defaults/api-report-rootHealth.md |   2 +-
 .../api-report-rootHttpRouter.md              |   4 +-
 .../api-report-rootLifecycle.md               |   2 +-
 .../backend-defaults/api-report-rootLogger.md |   2 +-
 .../backend-defaults/api-report-scheduler.md  |   2 +-
 .../backend-defaults/api-report-urlReader.md  |   2 +-
 .../backend-defaults/api-report-userInfo.md   |   2 +-
 .../urlReader/urlReaderServiceFactory.ts      |   2 +-
 .../api-report.md                             |  10 +-
 .../backend-plugin-api/api-report-alpha.md    |   2 +-
 packages/backend-plugin-api/api-report.md     | 124 +++++++++---------
 packages/backend-plugin-api/src/deprecated.ts |  12 +-
 .../src/services/system/types.ts              | 116 ++++++++--------
 packages/backend-test-utils/api-report.md     | 109 ++++++++++-----
 .../src/next/wiring/ServiceFactoryTester.ts   |  22 ++--
 plugins/catalog-node/api-report-alpha.md      |   2 +-
 plugins/events-node/api-report.md             |   4 +-
 plugins/notifications-node/api-report.md      |   2 +-
 .../search-backend-node/api-report-alpha.md   |   2 +-
 plugins/signals-node/api-report.md            |   8 +-
 38 files changed, 374 insertions(+), 236 deletions(-)
 create mode 100644 .changeset/mighty-apricots-taste.md
 create mode 100644 .changeset/purple-carrots-crash.md
 create mode 100644 .changeset/shy-waves-share.md
 create mode 100644 .changeset/small-bottles-cough.md
 create mode 100644 .changeset/thirty-adults-grab.md

diff --git a/.changeset/mighty-apricots-taste.md b/.changeset/mighty-apricots-taste.md
new file mode 100644
index 0000000000..80b70020cb
--- /dev/null
+++ b/.changeset/mighty-apricots-taste.md
@@ -0,0 +1,5 @@
+---
+'@backstage/backend-app-api': patch
+---
+
+Update the `ServiceRegister` implementation to enable registering multiple service implementations for a given service ref.
diff --git a/.changeset/purple-carrots-crash.md b/.changeset/purple-carrots-crash.md
new file mode 100644
index 0000000000..62f90677b8
--- /dev/null
+++ b/.changeset/purple-carrots-crash.md
@@ -0,0 +1,5 @@
+---
+'@backstage/backend-test-utils': patch
+---
+
+Update the `ServiceFactoryTester` to be able to test services that enables multi implementation installation.
diff --git a/.changeset/shy-waves-share.md b/.changeset/shy-waves-share.md
new file mode 100644
index 0000000000..861590fd01
--- /dev/null
+++ b/.changeset/shy-waves-share.md
@@ -0,0 +1,5 @@
+---
+'@backstage/backend-defaults': patch
+---
+
+Update the `UrlReader` service to depends on multiple instances of `UrlReaderFactoryProvider` service.
diff --git a/.changeset/small-bottles-cough.md b/.changeset/small-bottles-cough.md
new file mode 100644
index 0000000000..40098a84c7
--- /dev/null
+++ b/.changeset/small-bottles-cough.md
@@ -0,0 +1,58 @@
+---
+'@backstage/backend-plugin-api': minor
+---
+
+The `createServiceRef` function now accepts a new boolean `multiple` option. The `multiple` option defaults to `false` and when set to `true`, it enables that multiple implementation are installed for the created service ref.
+
+We're looking for ways to make it possible to augment services without the need to replace the entire service.
+
+Typical example of that being the ability to install support for additional targets for the `UrlReader` service without replacing the service itself. This achieves that by allowing us to define services that can have multiple simultaneous implementation, allowing the `UrlReader` implementation to depend on such a service to collect all possible implementation of support for external targets:
+
+```diff
+// @backstage/backend-defaults
+
++ export const urlReaderFactoriesServiceRef = createServiceRef<ReaderFactory>({
++   id: 'core.urlReader.factories',
++   scope: 'plugin',
++   multiton: true,
++ });
+
+...
+
+export const urlReaderServiceFactory = createServiceFactory({
+  service: coreServices.urlReader,
+  deps: {
+    config: coreServices.rootConfig,
+    logger: coreServices.logger,
++   factories: urlReaderFactoriesServiceRef,
+  },
+-  async factory({ config, logger }) {
++  async factory({ config, logger, factories }) {
+    return UrlReaders.default({
+      config,
+      logger,
++     factories,
+    });
+  },
+});
+```
+
+With that, you can then add more custom `UrlReader` factories by installing more implementations of the `urlReaderFactoriesServiceRef` in your backend instance. Something like:
+
+```ts
+// packages/backend/index.ts
+import { createServiceFactory } from '@backstage/backend-plugin-api';
+import { urlReaderFactoriesServiceRef } from '@backstage/backend-defaults';
+...
+
+backend.add(createServiceFactory({
+  service: urlReaderFactoriesServiceRef,
+  deps: {},
+  async factory() {
+    return CustomUrlReader.factory;
+  },
+}));
+
+...
+
+```
diff --git a/.changeset/thirty-adults-grab.md b/.changeset/thirty-adults-grab.md
new file mode 100644
index 0000000000..391e7a39bb
--- /dev/null
+++ b/.changeset/thirty-adults-grab.md
@@ -0,0 +1,6 @@
+---
+'@backstage/plugin-search-backend-node': patch
+'@backstage/plugin-catalog-node': patch
+---
+
+Explicit declare if the service ref accepts `single` ou `multiple` implementations.
diff --git a/packages/backend-app-api/api-report-alpha.md b/packages/backend-app-api/api-report-alpha.md
index b811208845..8616eec29a 100644
--- a/packages/backend-app-api/api-report-alpha.md
+++ b/packages/backend-app-api/api-report-alpha.md
@@ -10,7 +10,7 @@ import { ServiceFactoryCompat } from '@backstage/backend-plugin-api';
 export const featureDiscoveryServiceFactory: ServiceFactoryCompat<
   FeatureDiscoveryService,
   'root',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-app-api/api-report.md b/packages/backend-app-api/api-report.md
index 4019ad3086..dea309ebb0 100644
--- a/packages/backend-app-api/api-report.md
+++ b/packages/backend-app-api/api-report.md
@@ -49,7 +49,7 @@ import { UserInfoService } from '@backstage/backend-plugin-api';
 export const authServiceFactory: ServiceFactoryCompat<
   AuthService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -81,7 +81,7 @@ export interface Backend {
 export const cacheServiceFactory: ServiceFactoryCompat<
   CacheService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -115,7 +115,7 @@ export interface CreateSpecializedBackendOptions {
 export const databaseServiceFactory: ServiceFactoryCompat<
   DatabaseService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -138,7 +138,7 @@ export type DefaultRootHttpRouterOptions = DefaultRootHttpRouterOptions_2;
 export const discoveryServiceFactory: ServiceFactoryCompat<
   DiscoveryService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -165,7 +165,7 @@ export class HostDiscovery implements DiscoveryService {
 export const httpAuthServiceFactory: ServiceFactoryCompat<
   HttpAuthService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -173,7 +173,7 @@ export const httpAuthServiceFactory: ServiceFactoryCompat<
 export const httpRouterServiceFactory: ServiceFactoryCompat<
   HttpRouterService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -197,7 +197,7 @@ export type IdentityFactoryOptions = {
 export const identityServiceFactory: ServiceFactoryCompat<
   IdentityService,
   'plugin',
-  true,
+  'singleton',
   IdentityFactoryOptions
 >;
 
@@ -210,7 +210,7 @@ export type LifecycleMiddlewareOptions = LifecycleMiddlewareOptions_2;
 export const lifecycleServiceFactory: ServiceFactoryCompat<
   LifecycleService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -228,7 +228,7 @@ export function loadBackendConfig(options: {
 export const loggerServiceFactory: ServiceFactoryCompat<
   LoggerService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -257,7 +257,7 @@ export type MiddlewareFactoryOptions = MiddlewareFactoryOptions_2;
 export const permissionsServiceFactory: ServiceFactoryCompat<
   PermissionsService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -288,7 +288,7 @@ export interface RootConfigFactoryOptions {
 export const rootConfigServiceFactory: ServiceFactoryCompat<
   RootConfigService,
   'root',
-  true,
+  'singleton',
   RootConfigFactoryOptions
 >;
 
@@ -305,14 +305,14 @@ export type RootHttpRouterFactoryOptions = RootHttpRouterFactoryOptions_2;
 // @public @deprecated (undocumented)
 export const rootHttpRouterServiceFactory: ((
   options?: RootHttpRouterFactoryOptions_2 | undefined,
-) => ServiceFactory<RootHttpRouterService, 'root', true>) &
-  ServiceFactory<RootHttpRouterService, 'root', true>;
+) => ServiceFactory<RootHttpRouterService, 'root', 'singleton'>) &
+  ServiceFactory<RootHttpRouterService, 'root', 'singleton'>;
 
 // @public @deprecated
 export const rootLifecycleServiceFactory: ServiceFactoryCompat<
   RootLifecycleService,
   'root',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -320,7 +320,7 @@ export const rootLifecycleServiceFactory: ServiceFactoryCompat<
 export const rootLoggerServiceFactory: ServiceFactoryCompat<
   RootLoggerService,
   'root',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -328,7 +328,7 @@ export const rootLoggerServiceFactory: ServiceFactoryCompat<
 export const schedulerServiceFactory: ServiceFactoryCompat<
   SchedulerService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -336,7 +336,7 @@ export const schedulerServiceFactory: ServiceFactoryCompat<
 export const tokenManagerServiceFactory: ServiceFactoryCompat<
   TokenManagerService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -344,7 +344,7 @@ export const tokenManagerServiceFactory: ServiceFactoryCompat<
 export const urlReaderServiceFactory: ServiceFactoryCompat<
   UrlReaderService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -352,7 +352,7 @@ export const urlReaderServiceFactory: ServiceFactoryCompat<
 export const userInfoServiceFactory: ServiceFactoryCompat<
   UserInfoService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-app-api/src/wiring/ServiceRegistry.ts b/packages/backend-app-api/src/wiring/ServiceRegistry.ts
index e1644dad89..0abd5605ae 100644
--- a/packages/backend-app-api/src/wiring/ServiceRegistry.ts
+++ b/packages/backend-app-api/src/wiring/ServiceRegistry.ts
@@ -60,14 +60,14 @@ export class ServiceRegistry {
   static create(factories: Array<ServiceFactory>): ServiceRegistry {
     const factoryMap = new Map<string, InternalServiceFactory[]>();
     for (const factory of factories) {
-      if (factory.service.singleton) {
-        factoryMap.set(factory.service.id, [toInternalServiceFactory(factory)]);
-      } else {
+      if (factory.service.multiton) {
         const existing = factoryMap.get(factory.service.id) ?? [];
         factoryMap.set(
           factory.service.id,
           existing.concat(toInternalServiceFactory(factory)),
         );
+      } else {
+        factoryMap.set(factory.service.id, [toInternalServiceFactory(factory)]);
       }
     }
     const registry = new ServiceRegistry(factoryMap);
@@ -155,7 +155,7 @@ export class ServiceRegistry {
       if (this.#providedFactories.get(ref.id)) {
         return false;
       }
-      if (!ref.singleton) {
+      if (ref.multiton) {
         return false;
       }
 
@@ -205,7 +205,12 @@ export class ServiceRegistry {
       );
     }
 
-    if (factory.service.singleton) {
+    if (factory.service.multiton) {
+      const newFactories = (
+        this.#providedFactories.get(factoryId) ?? []
+      ).concat(toInternalServiceFactory(factory));
+      this.#providedFactories.set(factoryId, newFactories);
+    } else {
       if (this.#addedFactoryIds.has(factoryId)) {
         throw new Error(
           `Duplicate service implementations provided for ${factoryId}`,
@@ -216,11 +221,6 @@ export class ServiceRegistry {
       this.#providedFactories.set(factoryId, [
         toInternalServiceFactory(factory),
       ]);
-    } else {
-      const newFactories = (
-        this.#providedFactories.get(factoryId) ?? []
-      ).concat(toInternalServiceFactory(factory));
-      this.#providedFactories.set(factoryId, newFactories);
     }
   }
 
@@ -240,20 +240,20 @@ export class ServiceRegistry {
     }
   }
 
-  get<T, TSingleton extends boolean>(
-    ref: ServiceRef<T, 'plugin' | 'root', TSingleton>,
+  get<T, TInstances extends 'singleton' | 'multiton'>(
+    ref: ServiceRef<T, 'plugin' | 'root', TInstances>,
     pluginId: string,
-  ): Promise<TSingleton extends true ? T : T[]> | undefined {
+  ): Promise<TInstances extends 'multiton' ? T[] : T> | undefined {
     this.#instantiatedFactories.add(ref.id);
 
     const resolvedFactory = this.#resolveFactory(ref, pluginId);
 
     if (!resolvedFactory) {
-      return ref.singleton
-        ? undefined
-        : (Promise.resolve([]) as
-            | Promise<TSingleton extends true ? T : T[]>
-            | undefined);
+      return ref.multiton
+        ? (Promise.resolve([]) as
+            | Promise<TInstances extends 'multiton' ? T[] : T>
+            | undefined)
+        : undefined;
     }
 
     return resolvedFactory
@@ -346,6 +346,6 @@ export class ServiceRegistry {
           }),
         );
       })
-      .then(results => (ref.singleton ? results[0] : results));
+      .then(results => (ref.multiton ? results : results[0]));
   }
 }
diff --git a/packages/backend-defaults/api-report-auth.md b/packages/backend-defaults/api-report-auth.md
index 85287c524e..5ceca7f72e 100644
--- a/packages/backend-defaults/api-report-auth.md
+++ b/packages/backend-defaults/api-report-auth.md
@@ -10,7 +10,7 @@ import { ServiceFactoryCompat } from '@backstage/backend-plugin-api';
 export const authServiceFactory: ServiceFactoryCompat<
   AuthService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-defaults/api-report-cache.md b/packages/backend-defaults/api-report-cache.md
index c6debd6a2b..e8b6f075ab 100644
--- a/packages/backend-defaults/api-report-cache.md
+++ b/packages/backend-defaults/api-report-cache.md
@@ -28,7 +28,7 @@ export type CacheManagerOptions = {
 export const cacheServiceFactory: ServiceFactoryCompat<
   CacheService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-defaults/api-report-database.md b/packages/backend-defaults/api-report-database.md
index d7585cc791..8d204db025 100644
--- a/packages/backend-defaults/api-report-database.md
+++ b/packages/backend-defaults/api-report-database.md
@@ -35,7 +35,7 @@ export type DatabaseManagerOptions = {
 export const databaseServiceFactory: ServiceFactoryCompat<
   DatabaseService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-defaults/api-report-discovery.md b/packages/backend-defaults/api-report-discovery.md
index dc0d9b2bbe..1b19a42aa5 100644
--- a/packages/backend-defaults/api-report-discovery.md
+++ b/packages/backend-defaults/api-report-discovery.md
@@ -11,7 +11,7 @@ import { ServiceFactoryCompat } from '@backstage/backend-plugin-api';
 export const discoveryServiceFactory: ServiceFactoryCompat<
   DiscoveryService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-defaults/api-report-httpAuth.md b/packages/backend-defaults/api-report-httpAuth.md
index d8d283c01e..a65a6e157d 100644
--- a/packages/backend-defaults/api-report-httpAuth.md
+++ b/packages/backend-defaults/api-report-httpAuth.md
@@ -10,7 +10,7 @@ import { ServiceFactoryCompat } from '@backstage/backend-plugin-api';
 export const httpAuthServiceFactory: ServiceFactoryCompat<
   HttpAuthService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-defaults/api-report-httpRouter.md b/packages/backend-defaults/api-report-httpRouter.md
index 7673367f18..300e75a44d 100644
--- a/packages/backend-defaults/api-report-httpRouter.md
+++ b/packages/backend-defaults/api-report-httpRouter.md
@@ -18,7 +18,7 @@ export function createLifecycleMiddleware(
 export const httpRouterServiceFactory: ServiceFactoryCompat<
   HttpRouterService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-defaults/api-report-lifecycle.md b/packages/backend-defaults/api-report-lifecycle.md
index ad41fd4fcb..54ffb77fed 100644
--- a/packages/backend-defaults/api-report-lifecycle.md
+++ b/packages/backend-defaults/api-report-lifecycle.md
@@ -10,7 +10,7 @@ import { ServiceFactoryCompat } from '@backstage/backend-plugin-api';
 export const lifecycleServiceFactory: ServiceFactoryCompat<
   LifecycleService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-defaults/api-report-logger.md b/packages/backend-defaults/api-report-logger.md
index c881d20344..40ca4e21b4 100644
--- a/packages/backend-defaults/api-report-logger.md
+++ b/packages/backend-defaults/api-report-logger.md
@@ -10,7 +10,7 @@ import { ServiceFactoryCompat } from '@backstage/backend-plugin-api';
 export const loggerServiceFactory: ServiceFactoryCompat<
   LoggerService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-defaults/api-report-permissions.md b/packages/backend-defaults/api-report-permissions.md
index 92e3feaeaf..eea11ed7c9 100644
--- a/packages/backend-defaults/api-report-permissions.md
+++ b/packages/backend-defaults/api-report-permissions.md
@@ -10,7 +10,7 @@ import { ServiceFactoryCompat } from '@backstage/backend-plugin-api';
 export const permissionsServiceFactory: ServiceFactoryCompat<
   PermissionsService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-defaults/api-report-rootConfig.md b/packages/backend-defaults/api-report-rootConfig.md
index 60fed5734b..2935ad1128 100644
--- a/packages/backend-defaults/api-report-rootConfig.md
+++ b/packages/backend-defaults/api-report-rootConfig.md
@@ -28,8 +28,8 @@ export interface RootConfigFactoryOptions {
 // @public (undocumented)
 export const rootConfigServiceFactory: ((
   options?: RootConfigFactoryOptions,
-) => ServiceFactory<RootConfigService, 'root', true>) &
-  ServiceFactory<RootConfigService, 'root', true>;
+) => ServiceFactory<RootConfigService, 'root', 'singleton'>) &
+  ServiceFactory<RootConfigService, 'root', 'singleton'>;
 
 // (No @packageDocumentation comment for this package)
 ```
diff --git a/packages/backend-defaults/api-report-rootHealth.md b/packages/backend-defaults/api-report-rootHealth.md
index ca104ecf37..c7580cacd6 100644
--- a/packages/backend-defaults/api-report-rootHealth.md
+++ b/packages/backend-defaults/api-report-rootHealth.md
@@ -10,7 +10,7 @@ import { ServiceFactoryCompat } from '@backstage/backend-plugin-api';
 export const rootHealthServiceFactory: ServiceFactoryCompat<
   RootHealthService,
   'root',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-defaults/api-report-rootHttpRouter.md b/packages/backend-defaults/api-report-rootHttpRouter.md
index a6e5a31428..94c22960ef 100644
--- a/packages/backend-defaults/api-report-rootHttpRouter.md
+++ b/packages/backend-defaults/api-report-rootHttpRouter.md
@@ -143,8 +143,8 @@ export type RootHttpRouterFactoryOptions = {
 // @public (undocumented)
 export const rootHttpRouterServiceFactory: ((
   options?: RootHttpRouterFactoryOptions,
-) => ServiceFactory<RootHttpRouterService, 'root', true>) &
-  ServiceFactory<RootHttpRouterService, 'root', true>;
+) => ServiceFactory<RootHttpRouterService, 'root', 'singleton'>) &
+  ServiceFactory<RootHttpRouterService, 'root', 'singleton'>;
 
 // (No @packageDocumentation comment for this package)
 ```
diff --git a/packages/backend-defaults/api-report-rootLifecycle.md b/packages/backend-defaults/api-report-rootLifecycle.md
index 52eaa3fe0e..e522471d04 100644
--- a/packages/backend-defaults/api-report-rootLifecycle.md
+++ b/packages/backend-defaults/api-report-rootLifecycle.md
@@ -10,7 +10,7 @@ import { ServiceFactoryCompat } from '@backstage/backend-plugin-api';
 export const rootLifecycleServiceFactory: ServiceFactoryCompat<
   RootLifecycleService,
   'root',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-defaults/api-report-rootLogger.md b/packages/backend-defaults/api-report-rootLogger.md
index d91aaf0ae8..3878420192 100644
--- a/packages/backend-defaults/api-report-rootLogger.md
+++ b/packages/backend-defaults/api-report-rootLogger.md
@@ -14,7 +14,7 @@ import { transport } from 'winston';
 export const rootLoggerServiceFactory: ServiceFactoryCompat<
   RootLoggerService,
   'root',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-defaults/api-report-scheduler.md b/packages/backend-defaults/api-report-scheduler.md
index 7d8706def2..9953518e09 100644
--- a/packages/backend-defaults/api-report-scheduler.md
+++ b/packages/backend-defaults/api-report-scheduler.md
@@ -21,7 +21,7 @@ export class DefaultSchedulerService {
 export const schedulerServiceFactory: ServiceFactoryCompat<
   SchedulerService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-defaults/api-report-urlReader.md b/packages/backend-defaults/api-report-urlReader.md
index 431e2af701..ad732101dd 100644
--- a/packages/backend-defaults/api-report-urlReader.md
+++ b/packages/backend-defaults/api-report-urlReader.md
@@ -429,7 +429,7 @@ export class UrlReaders {
 export const urlReaderServiceFactory: ServiceFactoryCompat<
   UrlReaderService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-defaults/api-report-userInfo.md b/packages/backend-defaults/api-report-userInfo.md
index 31ae1dd8bb..27f73d06e1 100644
--- a/packages/backend-defaults/api-report-userInfo.md
+++ b/packages/backend-defaults/api-report-userInfo.md
@@ -10,7 +10,7 @@ import { UserInfoService } from '@backstage/backend-plugin-api';
 export const userInfoServiceFactory: ServiceFactoryCompat<
   UserInfoService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
diff --git a/packages/backend-defaults/src/entrypoints/urlReader/urlReaderServiceFactory.ts b/packages/backend-defaults/src/entrypoints/urlReader/urlReaderServiceFactory.ts
index 9859166ba0..b5c22402ff 100644
--- a/packages/backend-defaults/src/entrypoints/urlReader/urlReaderServiceFactory.ts
+++ b/packages/backend-defaults/src/entrypoints/urlReader/urlReaderServiceFactory.ts
@@ -42,7 +42,7 @@ export const urlReaderProviderFactoriesServiceRef =
   createServiceRef<ReaderFactory>({
     id: 'core.urlReader.factories',
     scope: 'plugin',
-    singleton: false,
+    multiton: true,
   });
 
 /**
diff --git a/packages/backend-dynamic-feature-service/api-report.md b/packages/backend-dynamic-feature-service/api-report.md
index b74bbcdc95..97dea60170 100644
--- a/packages/backend-dynamic-feature-service/api-report.md
+++ b/packages/backend-dynamic-feature-service/api-report.md
@@ -117,7 +117,7 @@ export interface DynamicPluginsFactoryOptions {
 export const dynamicPluginsFeatureDiscoveryServiceFactory: ServiceFactoryCompat<
   FeatureDiscoveryService,
   'root',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -128,7 +128,7 @@ export const dynamicPluginsFrontendSchemas: BackendFeatureCompat;
 export const dynamicPluginsRootLoggerServiceFactory: ServiceFactoryCompat<
   RootLoggerService,
   'root',
-  true,
+  'singleton',
   undefined
 >;
 
@@ -149,7 +149,7 @@ export interface DynamicPluginsSchemasService {
 export const dynamicPluginsSchemasServiceFactory: ServiceFactoryCompat<
   DynamicPluginsSchemasService,
   'root',
-  true,
+  'singleton',
   DynamicPluginsSchemasOptions
 >;
 
@@ -157,7 +157,7 @@ export const dynamicPluginsSchemasServiceFactory: ServiceFactoryCompat<
 export const dynamicPluginsServiceFactory: ServiceFactoryCompat<
   DynamicPluginProvider,
   'root',
-  true,
+  'singleton',
   DynamicPluginsFactoryOptions
 >;
 
@@ -165,7 +165,7 @@ export const dynamicPluginsServiceFactory: ServiceFactoryCompat<
 export const dynamicPluginsServiceRef: ServiceRef<
   DynamicPluginProvider,
   'root',
-  true
+  'singleton'
 >;
 
 // @public (undocumented)
diff --git a/packages/backend-plugin-api/api-report-alpha.md b/packages/backend-plugin-api/api-report-alpha.md
index 9a82d3adbe..0f4348336a 100644
--- a/packages/backend-plugin-api/api-report-alpha.md
+++ b/packages/backend-plugin-api/api-report-alpha.md
@@ -18,7 +18,7 @@ export interface FeatureDiscoveryService {
 export const featureDiscoveryServiceRef: ServiceRef<
   FeatureDiscoveryService,
   'root',
-  true
+  'singleton'
 >;
 
 // (No @packageDocumentation comment for this package)
diff --git a/packages/backend-plugin-api/api-report.md b/packages/backend-plugin-api/api-report.md
index 3925d3b2f4..99c7b1b9fc 100644
--- a/packages/backend-plugin-api/api-report.md
+++ b/packages/backend-plugin-api/api-report.md
@@ -189,28 +189,32 @@ export type CacheServiceSetOptions = {
 
 // @public
 export namespace coreServices {
-  const auth: ServiceRef<AuthService, 'plugin', true>;
-  const userInfo: ServiceRef<UserInfoService, 'plugin', true>;
-  const cache: ServiceRef<CacheService, 'plugin', true>;
-  const rootConfig: ServiceRef<RootConfigService, 'root', true>;
-  const database: ServiceRef<DatabaseService, 'plugin', true>;
-  const discovery: ServiceRef<DiscoveryService, 'plugin', true>;
-  const rootHealth: ServiceRef<RootHealthService, 'root', true>;
-  const httpAuth: ServiceRef<HttpAuthService, 'plugin', true>;
-  const httpRouter: ServiceRef<HttpRouterService, 'plugin', true>;
-  const lifecycle: ServiceRef<LifecycleService, 'plugin', true>;
-  const logger: ServiceRef<LoggerService, 'plugin', true>;
-  const permissions: ServiceRef<PermissionsService, 'plugin', true>;
-  const pluginMetadata: ServiceRef<PluginMetadataService, 'plugin', true>;
-  const rootHttpRouter: ServiceRef<RootHttpRouterService, 'root', true>;
-  const rootLifecycle: ServiceRef<RootLifecycleService, 'root', true>;
-  const rootLogger: ServiceRef<RootLoggerService, 'root', true>;
-  const scheduler: ServiceRef<SchedulerService, 'plugin', true>;
+  const auth: ServiceRef<AuthService, 'plugin', 'singleton'>;
+  const userInfo: ServiceRef<UserInfoService, 'plugin', 'singleton'>;
+  const cache: ServiceRef<CacheService, 'plugin', 'singleton'>;
+  const rootConfig: ServiceRef<RootConfigService, 'root', 'singleton'>;
+  const database: ServiceRef<DatabaseService, 'plugin', 'singleton'>;
+  const discovery: ServiceRef<DiscoveryService, 'plugin', 'singleton'>;
+  const rootHealth: ServiceRef<RootHealthService, 'root', 'singleton'>;
+  const httpAuth: ServiceRef<HttpAuthService, 'plugin', 'singleton'>;
+  const httpRouter: ServiceRef<HttpRouterService, 'plugin', 'singleton'>;
+  const lifecycle: ServiceRef<LifecycleService, 'plugin', 'singleton'>;
+  const logger: ServiceRef<LoggerService, 'plugin', 'singleton'>;
+  const permissions: ServiceRef<PermissionsService, 'plugin', 'singleton'>;
+  const pluginMetadata: ServiceRef<
+    PluginMetadataService,
+    'plugin',
+    'singleton'
+  >;
+  const rootHttpRouter: ServiceRef<RootHttpRouterService, 'root', 'singleton'>;
+  const rootLifecycle: ServiceRef<RootLifecycleService, 'root', 'singleton'>;
+  const rootLogger: ServiceRef<RootLoggerService, 'root', 'singleton'>;
+  const scheduler: ServiceRef<SchedulerService, 'plugin', 'singleton'>;
   const // @deprecated
-    tokenManager: ServiceRef<TokenManagerService, 'plugin', true>;
-  const urlReader: ServiceRef<UrlReaderService, 'plugin', true>;
+    tokenManager: ServiceRef<TokenManagerService, 'plugin', 'singleton'>;
+  const urlReader: ServiceRef<UrlReaderService, 'plugin', 'singleton'>;
   const // @deprecated
-    identity: ServiceRef<IdentityService, 'plugin', true>;
+    identity: ServiceRef<IdentityService, 'plugin', 'singleton'>;
 }
 
 // @public
@@ -251,20 +255,20 @@ export interface CreateExtensionPointOptions {
 // @public
 export function createServiceFactory<
   TService,
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TImpl extends TService,
   TDeps extends {
     [name in string]: ServiceRef<unknown, 'root'>;
   },
   TOpts extends object | undefined = undefined,
 >(
-  options: RootServiceFactoryOptions<TService, TSingleton, TImpl, TDeps>,
-): ServiceFactoryCompat<TService, 'root', TSingleton>;
+  options: RootServiceFactoryOptions<TService, TInstances, TImpl, TDeps>,
+): ServiceFactoryCompat<TService, 'root', TInstances>;
 
 // @public @deprecated
 export function createServiceFactory<
   TService,
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TImpl extends TService,
   TDeps extends {
     [name in string]: ServiceRef<unknown, 'root'>;
@@ -273,13 +277,13 @@ export function createServiceFactory<
 >(
   options: (
     options?: TOpts,
-  ) => RootServiceFactoryOptions<TService, TSingleton, TImpl, TDeps>,
-): ServiceFactoryCompat<TService, 'root', TSingleton, TOpts>;
+  ) => RootServiceFactoryOptions<TService, TInstances, TImpl, TDeps>,
+): ServiceFactoryCompat<TService, 'root', TInstances, TOpts>;
 
 // @public
 export function createServiceFactory<
   TService,
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TImpl extends TService,
   TDeps extends {
     [name in string]: ServiceRef<unknown>;
@@ -289,17 +293,17 @@ export function createServiceFactory<
 >(
   options: PluginServiceFactoryOptions<
     TService,
-    TSingleton,
+    TInstances,
     TContext,
     TImpl,
     TDeps
   >,
-): ServiceFactoryCompat<TService, 'plugin', TSingleton>;
+): ServiceFactoryCompat<TService, 'plugin', TInstances>;
 
 // @public @deprecated
 export function createServiceFactory<
   TService,
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TImpl extends TService,
   TDeps extends {
     [name in string]: ServiceRef<unknown>;
@@ -311,32 +315,32 @@ export function createServiceFactory<
     options?: TOpts,
   ) => PluginServiceFactoryOptions<
     TService,
-    TSingleton,
+    TInstances,
     TContext,
     TImpl,
     TDeps
   >,
-): ServiceFactoryCompat<TService, 'plugin', TSingleton, TOpts>;
+): ServiceFactoryCompat<TService, 'plugin', TInstances, TOpts>;
 
 // @public
 export function createServiceRef<TService>(
-  options: ServiceRefOptions<TService, 'plugin', true>,
-): ServiceRef<TService, 'plugin', true>;
+  options: ServiceRefOptions<TService, 'plugin', 'singleton'>,
+): ServiceRef<TService, 'plugin', 'singleton'>;
 
 // @public
 export function createServiceRef<TService>(
-  options: ServiceRefOptions<TService, 'root', true>,
-): ServiceRef<TService, 'root', true>;
+  options: ServiceRefOptions<TService, 'root', 'singleton'>,
+): ServiceRef<TService, 'root', 'singleton'>;
 
 // @public
 export function createServiceRef<TService>(
-  options: ServiceRefOptions<TService, 'plugin', false>,
-): ServiceRef<TService, 'plugin', false>;
+  options: ServiceRefOptions<TService, 'plugin', 'multiton'>,
+): ServiceRef<TService, 'plugin', 'multiton'>;
 
 // @public
 export function createServiceRef<TService>(
-  options: ServiceRefOptions<TService, 'root', false>,
-): ServiceRef<TService, 'root', false>;
+  options: ServiceRefOptions<TService, 'root', 'multiton'>,
+): ServiceRef<TService, 'root', 'multiton'>;
 
 // @public
 export interface DatabaseService {
@@ -473,18 +477,18 @@ export interface PluginMetadataService {
 // @public @deprecated (undocumented)
 export type PluginServiceFactoryConfig<
   TService,
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TContext,
   TImpl extends TService,
   TDeps extends {
     [name in string]: ServiceRef<unknown>;
   },
-> = PluginServiceFactoryOptions<TService, TSingleton, TContext, TImpl, TDeps>;
+> = PluginServiceFactoryOptions<TService, TInstances, TContext, TImpl, TDeps>;
 
 // @public (undocumented)
 export interface PluginServiceFactoryOptions<
   TService,
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TContext,
   TImpl extends TService,
   TDeps extends {
@@ -504,7 +508,7 @@ export interface PluginServiceFactoryOptions<
   ): TImpl | Promise<TImpl>;
   initialization?: 'always' | 'lazy';
   // (undocumented)
-  service: ServiceRef<TService, 'plugin', TSingleton>;
+  service: ServiceRef<TService, 'plugin', TInstances>;
 }
 
 // @public
@@ -566,17 +570,17 @@ export interface RootLoggerService extends LoggerService {}
 // @public @deprecated (undocumented)
 export type RootServiceFactoryConfig<
   TService,
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TImpl extends TService,
   TDeps extends {
     [name in string]: ServiceRef<unknown>;
   },
-> = RootServiceFactoryOptions<TService, TSingleton, TImpl, TDeps>;
+> = RootServiceFactoryOptions<TService, TInstances, TImpl, TDeps>;
 
 // @public (undocumented)
 export interface RootServiceFactoryOptions<
   TService, // TODO(Rugvip): Can we forward the entire service ref type here instead of forwarding each type arg once the callback form is gone?
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TImpl extends TService,
   TDeps extends {
     [name in string]: ServiceRef<unknown>;
@@ -588,7 +592,7 @@ export interface RootServiceFactoryOptions<
   factory(deps: ServiceRefsToInstances<TDeps, 'root'>): TImpl | Promise<TImpl>;
   initialization?: 'always' | 'lazy';
   // (undocumented)
-  service: ServiceRef<TService, 'root', TSingleton>;
+  service: ServiceRef<TService, 'root', TInstances>;
 }
 
 // @public
@@ -669,23 +673,23 @@ export type SearchResponseFile = UrlReaderServiceSearchResponseFile;
 export interface ServiceFactory<
   TService = unknown,
   TScope extends 'plugin' | 'root' = 'plugin' | 'root',
-  TSingleton extends boolean = boolean,
+  TInstances extends 'singleton' | 'multiton' = 'singleton' | 'multiton',
 > extends BackendFeature {
   // (undocumented)
-  service: ServiceRef<TService, TScope, TSingleton>;
+  service: ServiceRef<TService, TScope, TInstances>;
 }
 
 // @public @deprecated (undocumented)
 export interface ServiceFactoryCompat<
   TService = unknown,
   TScope extends 'plugin' | 'root' = 'plugin' | 'root',
-  TSingleton extends boolean = boolean,
+  TInstances extends 'singleton' | 'multiton' = 'singleton' | 'multiton',
   TOpts extends object | undefined = undefined,
-> extends ServiceFactory<TService, TScope, TSingleton> {
+> extends ServiceFactory<TService, TScope, TInstances> {
   // @deprecated (undocumented)
   (
     ...options: undefined extends TOpts ? [] : [options?: TOpts]
-  ): ServiceFactory<TService, TScope, TSingleton>;
+  ): ServiceFactory<TService, TScope, TInstances>;
 }
 
 // @public @deprecated
@@ -695,11 +699,11 @@ export type ServiceFactoryOrFunction = ServiceFactory | (() => ServiceFactory);
 export type ServiceRef<
   TService,
   TScope extends 'root' | 'plugin' = 'root' | 'plugin',
-  TSingleton extends boolean = boolean,
+  TInstances extends 'singleton' | 'multiton' = 'singleton' | 'multiton',
 > = {
   id: string;
   scope: TScope;
-  singleton: TSingleton;
+  multiton: TInstances extends 'multiton' ? true : false;
   T: TService;
   $$type: '@backstage/ServiceRef';
 };
@@ -708,14 +712,14 @@ export type ServiceRef<
 export type ServiceRefConfig<
   TService,
   TScope extends 'root' | 'plugin',
-  TSingleton extends boolean,
-> = ServiceRefOptions<TService, TScope, TSingleton>;
+  TInstances extends 'singleton' | 'multiton',
+> = ServiceRefOptions<TService, TScope, TInstances>;
 
 // @public (undocumented)
 export interface ServiceRefOptions<
   TService,
   TScope extends 'root' | 'plugin',
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
 > {
   // (undocumented)
   defaultFactory?(
@@ -728,9 +732,9 @@ export interface ServiceRefOptions<
   // (undocumented)
   id: string;
   // (undocumented)
-  scope?: TScope;
+  multiton?: TInstances extends 'multiton' ? true : false;
   // (undocumented)
-  singleton?: TSingleton;
+  scope?: TScope;
 }
 
 // @public @deprecated
diff --git a/packages/backend-plugin-api/src/deprecated.ts b/packages/backend-plugin-api/src/deprecated.ts
index e68affa0fa..0d02f9ed7e 100644
--- a/packages/backend-plugin-api/src/deprecated.ts
+++ b/packages/backend-plugin-api/src/deprecated.ts
@@ -28,8 +28,8 @@ import {
 export type ServiceRefConfig<
   TService,
   TScope extends 'root' | 'plugin',
-  TSingleton extends boolean,
-> = ServiceRefOptions<TService, TScope, TSingleton>;
+  TInstances extends 'singleton' | 'multiton',
+> = ServiceRefOptions<TService, TScope, TInstances>;
 
 /**
  * @public
@@ -37,10 +37,10 @@ export type ServiceRefConfig<
  */
 export type RootServiceFactoryConfig<
   TService,
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TImpl extends TService,
   TDeps extends { [name in string]: ServiceRef<unknown> },
-> = RootServiceFactoryOptions<TService, TSingleton, TImpl, TDeps>;
+> = RootServiceFactoryOptions<TService, TInstances, TImpl, TDeps>;
 
 /**
  * @public
@@ -48,8 +48,8 @@ export type RootServiceFactoryConfig<
  */
 export type PluginServiceFactoryConfig<
   TService,
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TContext,
   TImpl extends TService,
   TDeps extends { [name in string]: ServiceRef<unknown> },
-> = PluginServiceFactoryOptions<TService, TSingleton, TContext, TImpl, TDeps>;
+> = PluginServiceFactoryOptions<TService, TInstances, TContext, TImpl, TDeps>;
diff --git a/packages/backend-plugin-api/src/services/system/types.ts b/packages/backend-plugin-api/src/services/system/types.ts
index e856136ddc..7cd18da4d2 100644
--- a/packages/backend-plugin-api/src/services/system/types.ts
+++ b/packages/backend-plugin-api/src/services/system/types.ts
@@ -24,7 +24,7 @@ import { BackendFeature } from '../../types';
 export type ServiceRef<
   TService,
   TScope extends 'root' | 'plugin' = 'root' | 'plugin',
-  TSingleton extends boolean = boolean,
+  TInstances extends 'singleton' | 'multiton' = 'singleton' | 'multiton',
 > = {
   id: string;
 
@@ -39,7 +39,7 @@ export type ServiceRef<
    */
   scope: TScope;
 
-  singleton: TSingleton;
+  multiton: TInstances extends 'multiton' ? true : false;
 
   /**
    * Utility for getting the type of the service, using `typeof serviceRef.T`.
@@ -54,9 +54,9 @@ export type ServiceRef<
 export interface ServiceFactory<
   TService = unknown,
   TScope extends 'plugin' | 'root' = 'plugin' | 'root',
-  TSingleton extends boolean = boolean,
+  TInstances extends 'singleton' | 'multiton' = 'singleton' | 'multiton',
 > extends BackendFeature {
-  service: ServiceRef<TService, TScope, TSingleton>;
+  service: ServiceRef<TService, TScope, TInstances>;
 }
 
 /**
@@ -66,23 +66,23 @@ export interface ServiceFactory<
 export interface ServiceFactoryCompat<
   TService = unknown,
   TScope extends 'plugin' | 'root' = 'plugin' | 'root',
-  TSingleton extends boolean = boolean,
+  TInstances extends 'singleton' | 'multiton' = 'singleton' | 'multiton',
   TOpts extends object | undefined = undefined,
-> extends ServiceFactory<TService, TScope, TSingleton> {
+> extends ServiceFactory<TService, TScope, TInstances> {
   /**
    * @deprecated Callable service factories will be removed in a future release, please re-implement the service factory using the available APIs instead. If no options are being passed, you can simply remove the trailing `()`.
    */
   (
     ...options: undefined extends TOpts ? [] : [options?: TOpts]
-  ): ServiceFactory<TService, TScope, TSingleton>;
+  ): ServiceFactory<TService, TScope, TInstances>;
 }
 
 /** @internal */
 export interface InternalServiceFactory<
   TService = unknown,
   TScope extends 'plugin' | 'root' = 'plugin' | 'root',
-  TSingleton extends boolean = boolean,
-> extends ServiceFactory<TService, TScope, TSingleton> {
+  TInstances extends 'singleton' | 'multiton' = 'singleton' | 'multiton',
+> extends ServiceFactory<TService, TScope, TInstances> {
   version: 'v1';
   initialization?: 'always' | 'lazy';
   deps: { [key in string]: ServiceRef<unknown> };
@@ -105,11 +105,11 @@ export type ServiceFactoryOrFunction = ServiceFactory | (() => ServiceFactory);
 export interface ServiceRefOptions<
   TService,
   TScope extends 'root' | 'plugin',
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
 > {
   id: string;
   scope?: TScope;
-  singleton?: TSingleton;
+  multiton?: TInstances extends 'multiton' ? true : false;
   defaultFactory?(
     service: ServiceRef<TService, TScope>,
   ): Promise<ServiceFactory>;
@@ -127,8 +127,8 @@ export interface ServiceRefOptions<
  * @public
  */
 export function createServiceRef<TService>(
-  options: ServiceRefOptions<TService, 'plugin', true>,
-): ServiceRef<TService, 'plugin', true>;
+  options: ServiceRefOptions<TService, 'plugin', 'singleton'>,
+): ServiceRef<TService, 'plugin', 'singleton'>;
 
 /**
  * Creates a new service definition. This overload is used to create root scoped services.
@@ -136,8 +136,8 @@ export function createServiceRef<TService>(
  * @public
  */
 export function createServiceRef<TService>(
-  options: ServiceRefOptions<TService, 'root', true>,
-): ServiceRef<TService, 'root', true>;
+  options: ServiceRefOptions<TService, 'root', 'singleton'>,
+): ServiceRef<TService, 'root', 'singleton'>;
 
 /**
  * Creates a new service definition. This overload is used to create plugin scoped services.
@@ -145,8 +145,8 @@ export function createServiceRef<TService>(
  * @public
  */
 export function createServiceRef<TService>(
-  options: ServiceRefOptions<TService, 'plugin', false>,
-): ServiceRef<TService, 'plugin', false>;
+  options: ServiceRefOptions<TService, 'plugin', 'multiton'>,
+): ServiceRef<TService, 'plugin', 'multiton'>;
 
 /**
  * Creates a new service definition. This overload is used to create root scoped services.
@@ -154,16 +154,19 @@ export function createServiceRef<TService>(
  * @public
  */
 export function createServiceRef<TService>(
-  options: ServiceRefOptions<TService, 'root', false>,
-): ServiceRef<TService, 'root', false>;
-export function createServiceRef<TService, TSingleton extends boolean>(
-  options: ServiceRefOptions<TService, any, TSingleton>,
-): ServiceRef<TService, any, TSingleton> {
-  const { id, scope = 'plugin', singleton = true, defaultFactory } = options;
+  options: ServiceRefOptions<TService, 'root', 'multiton'>,
+): ServiceRef<TService, 'root', 'multiton'>;
+export function createServiceRef<
+  TService,
+  TInstances extends 'singleton' | 'multiton',
+>(
+  options: ServiceRefOptions<TService, any, TInstances>,
+): ServiceRef<TService, any, TInstances> {
+  const { id, scope = 'plugin', multiton = false, defaultFactory } = options;
   return {
     id,
     scope,
-    singleton,
+    multiton,
     get T(): TService {
       throw new Error(`tried to read ServiceRef.T of ${this}`);
     },
@@ -172,7 +175,7 @@ export function createServiceRef<TService, TSingleton extends boolean>(
     },
     $$type: '@backstage/ServiceRef',
     __defaultFactory: defaultFactory,
-  } as ServiceRef<TService, typeof scope, TSingleton> & {
+  } as ServiceRef<TService, typeof scope, TInstances> & {
     __defaultFactory?: (
       service: ServiceRef<TService>,
     ) => Promise<ServiceFactory<TService> | (() => ServiceFactory<TService>)>;
@@ -186,15 +189,15 @@ type ServiceRefsToInstances<
 > = {
   [key in keyof T as T[key]['scope'] extends TScope
     ? key
-    : never]: T[key]['singleton'] extends true
-    ? T[key]['T']
-    : Array<T[key]['T']>;
+    : never]: T[key]['multiton'] extends true
+    ? Array<T[key]['T']>
+    : T[key]['T'];
 };
 
 /** @public */
 export interface RootServiceFactoryOptions<
   TService, // TODO(Rugvip): Can we forward the entire service ref type here instead of forwarding each type arg once the callback form is gone?
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TImpl extends TService,
   TDeps extends { [name in string]: ServiceRef<unknown> },
 > {
@@ -209,7 +212,7 @@ export interface RootServiceFactoryOptions<
    * Service factories for root scoped services use `always` as the default, while plugin scoped services use `lazy`.
    */
   initialization?: 'always' | 'lazy';
-  service: ServiceRef<TService, 'root', TSingleton>;
+  service: ServiceRef<TService, 'root', TInstances>;
   deps: TDeps;
   factory(deps: ServiceRefsToInstances<TDeps, 'root'>): TImpl | Promise<TImpl>;
 }
@@ -217,7 +220,7 @@ export interface RootServiceFactoryOptions<
 /** @public */
 export interface PluginServiceFactoryOptions<
   TService,
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TContext,
   TImpl extends TService,
   TDeps extends { [name in string]: ServiceRef<unknown> },
@@ -233,7 +236,7 @@ export interface PluginServiceFactoryOptions<
    * Service factories for root scoped services use `always` as the default, while plugin scoped services use `lazy`.
    */
   initialization?: 'always' | 'lazy';
-  service: ServiceRef<TService, 'plugin', TSingleton>;
+  service: ServiceRef<TService, 'plugin', TInstances>;
   deps: TDeps;
   createRootContext?(
     deps: ServiceRefsToInstances<TDeps, 'root'>,
@@ -252,13 +255,13 @@ export interface PluginServiceFactoryOptions<
  */
 export function createServiceFactory<
   TService,
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TImpl extends TService,
   TDeps extends { [name in string]: ServiceRef<unknown, 'root'> },
   TOpts extends object | undefined = undefined,
 >(
-  options: RootServiceFactoryOptions<TService, TSingleton, TImpl, TDeps>,
-): ServiceFactoryCompat<TService, 'root', TSingleton>;
+  options: RootServiceFactoryOptions<TService, TInstances, TImpl, TDeps>,
+): ServiceFactoryCompat<TService, 'root', TInstances>;
 /**
  * Creates a root scoped service factory with optional options.
  *
@@ -271,15 +274,15 @@ export function createServiceFactory<
  */
 export function createServiceFactory<
   TService,
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TImpl extends TService,
   TDeps extends { [name in string]: ServiceRef<unknown, 'root'> },
   TOpts extends object | undefined = undefined,
 >(
   options: (
     options?: TOpts,
-  ) => RootServiceFactoryOptions<TService, TSingleton, TImpl, TDeps>,
-): ServiceFactoryCompat<TService, 'root', TSingleton, TOpts>;
+  ) => RootServiceFactoryOptions<TService, TInstances, TImpl, TDeps>,
+): ServiceFactoryCompat<TService, 'root', TInstances, TOpts>;
 /**
  * Creates a plugin scoped service factory without options.
  *
@@ -288,7 +291,7 @@ export function createServiceFactory<
  */
 export function createServiceFactory<
   TService,
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TImpl extends TService,
   TDeps extends { [name in string]: ServiceRef<unknown> },
   TContext = undefined,
@@ -296,12 +299,12 @@ export function createServiceFactory<
 >(
   options: PluginServiceFactoryOptions<
     TService,
-    TSingleton,
+    TInstances,
     TContext,
     TImpl,
     TDeps
   >,
-): ServiceFactoryCompat<TService, 'plugin', TSingleton>;
+): ServiceFactoryCompat<TService, 'plugin', TInstances>;
 /**
  * Creates a plugin scoped service factory with optional options.
  *
@@ -314,7 +317,7 @@ export function createServiceFactory<
  */
 export function createServiceFactory<
   TService,
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TImpl extends TService,
   TDeps extends { [name in string]: ServiceRef<unknown> },
   TContext = undefined,
@@ -324,44 +327,49 @@ export function createServiceFactory<
     options?: TOpts,
   ) => PluginServiceFactoryOptions<
     TService,
-    TSingleton,
+    TInstances,
     TContext,
     TImpl,
     TDeps
   >,
-): ServiceFactoryCompat<TService, 'plugin', TSingleton, TOpts>;
+): ServiceFactoryCompat<TService, 'plugin', TInstances, TOpts>;
 export function createServiceFactory<
   TService,
-  TSingleton extends boolean,
+  TInstances extends 'singleton' | 'multiton',
   TImpl extends TService,
   TDeps extends { [name in string]: ServiceRef<unknown> },
   TContext,
   TOpts extends object | undefined = undefined,
 >(
   options:
-    | RootServiceFactoryOptions<TService, TSingleton, TImpl, TDeps>
-    | PluginServiceFactoryOptions<TService, TSingleton, TContext, TImpl, TDeps>
+    | RootServiceFactoryOptions<TService, TInstances, TImpl, TDeps>
+    | PluginServiceFactoryOptions<TService, TInstances, TContext, TImpl, TDeps>
     | ((
         options: TOpts,
-      ) => RootServiceFactoryOptions<TService, TSingleton, TImpl, TDeps>)
+      ) => RootServiceFactoryOptions<TService, TInstances, TImpl, TDeps>)
     | ((
         options: TOpts,
       ) => PluginServiceFactoryOptions<
         TService,
-        TSingleton,
+        TInstances,
         TContext,
         TImpl,
         TDeps
       >)
-    | (() => RootServiceFactoryOptions<TService, TSingleton, TImpl, TDeps>)
+    | (() => RootServiceFactoryOptions<TService, TInstances, TImpl, TDeps>)
     | (() => PluginServiceFactoryOptions<
         TService,
-        TSingleton,
+        TInstances,
         TContext,
         TImpl,
         TDeps
       >),
-): ServiceFactoryCompat<TService, 'root' | 'plugin', boolean, TOpts> {
+): ServiceFactoryCompat<
+  TService,
+  'root' | 'plugin',
+  'singleton' | 'multiton',
+  TOpts
+> {
   const configCallback =
     typeof options === 'function' ? options : () => options;
   const factory = (
@@ -371,7 +379,7 @@ export function createServiceFactory<
     if (anyConf.service.scope === 'root') {
       const c = anyConf as RootServiceFactoryOptions<
         TService,
-        TSingleton,
+        TInstances,
         TImpl,
         TDeps
       >;
@@ -387,7 +395,7 @@ export function createServiceFactory<
     }
     const c = anyConf as PluginServiceFactoryOptions<
       TService,
-      TSingleton,
+      TInstances,
       TContext,
       TImpl,
       TDeps
diff --git a/packages/backend-test-utils/api-report.md b/packages/backend-test-utils/api-report.md
index 5a9e016dcd..584fedb1f5 100644
--- a/packages/backend-test-utils/api-report.md
+++ b/packages/backend-test-utils/api-report.md
@@ -156,7 +156,12 @@ export namespace mockServices {
   // (undocumented)
   export namespace auth {
     const // (undocumented)
-      factory: ServiceFactoryCompat<AuthService, 'plugin', true, undefined>;
+      factory: ServiceFactoryCompat<
+        AuthService,
+        'plugin',
+        'singleton',
+        undefined
+      >;
     const // (undocumented)
       mock: (
         partialImpl?: Partial<AuthService> | undefined,
@@ -165,7 +170,12 @@ export namespace mockServices {
   // (undocumented)
   export namespace cache {
     const // (undocumented)
-      factory: ServiceFactoryCompat<CacheService, 'plugin', true, undefined>;
+      factory: ServiceFactoryCompat<
+        CacheService,
+        'plugin',
+        'singleton',
+        undefined
+      >;
     const // (undocumented)
       mock: (
         partialImpl?: Partial<CacheService> | undefined,
@@ -174,7 +184,12 @@ export namespace mockServices {
   // (undocumented)
   export namespace database {
     const // (undocumented)
-      factory: ServiceFactoryCompat<DatabaseService, 'plugin', true, undefined>;
+      factory: ServiceFactoryCompat<
+        DatabaseService,
+        'plugin',
+        'singleton',
+        undefined
+      >;
     const // (undocumented)
       mock: (
         partialImpl?: Partial<DatabaseService> | undefined,
@@ -188,7 +203,7 @@ export namespace mockServices {
       factory: ServiceFactoryCompat<
         DiscoveryService,
         'plugin',
-        true,
+        'singleton',
         undefined
       >;
     const // (undocumented)
@@ -199,7 +214,12 @@ export namespace mockServices {
   // (undocumented)
   export namespace events {
     const // (undocumented)
-      factory: ServiceFactoryCompat<EventsService, 'plugin', true, undefined>;
+      factory: ServiceFactoryCompat<
+        EventsService,
+        'plugin',
+        'singleton',
+        undefined
+      >;
     const // (undocumented)
       mock: (
         partialImpl?: Partial<EventsService> | undefined,
@@ -213,8 +233,8 @@ export namespace mockServices {
   export namespace httpAuth {
     const factory: ((options?: {
       defaultCredentials?: BackstageCredentials;
-    }) => ServiceFactory<HttpAuthService, 'plugin', true>) &
-      ServiceFactory<HttpAuthService, 'plugin', true>;
+    }) => ServiceFactory<HttpAuthService, 'plugin', 'singleton'>) &
+      ServiceFactory<HttpAuthService, 'plugin', 'singleton'>;
     const // (undocumented)
       mock: (
         partialImpl?: Partial<HttpAuthService> | undefined,
@@ -226,7 +246,7 @@ export namespace mockServices {
       factory: ServiceFactoryCompat<
         HttpRouterService,
         'plugin',
-        true,
+        'singleton',
         undefined
       >;
     const // (undocumented)
@@ -239,7 +259,12 @@ export namespace mockServices {
   // (undocumented)
   export namespace identity {
     const // (undocumented)
-      factory: ServiceFactoryCompat<IdentityService, 'plugin', true, undefined>;
+      factory: ServiceFactoryCompat<
+        IdentityService,
+        'plugin',
+        'singleton',
+        undefined
+      >;
     const // (undocumented)
       mock: (
         partialImpl?: Partial<IdentityService> | undefined,
@@ -251,7 +276,7 @@ export namespace mockServices {
       factory: ServiceFactoryCompat<
         LifecycleService,
         'plugin',
-        true,
+        'singleton',
         undefined
       >;
     const // (undocumented)
@@ -262,7 +287,12 @@ export namespace mockServices {
   // (undocumented)
   export namespace logger {
     const // (undocumented)
-      factory: ServiceFactoryCompat<LoggerService, 'plugin', true, undefined>;
+      factory: ServiceFactoryCompat<
+        LoggerService,
+        'plugin',
+        'singleton',
+        undefined
+      >;
     const // (undocumented)
       mock: (
         partialImpl?: Partial<LoggerService> | undefined,
@@ -274,7 +304,7 @@ export namespace mockServices {
       factory: ServiceFactoryCompat<
         PermissionsService,
         'plugin',
-        true,
+        'singleton',
         undefined
       >;
     const // (undocumented)
@@ -291,15 +321,28 @@ export namespace mockServices {
       data?: JsonObject;
     };
     const // (undocumented)
-      factory: ServiceFactory<RootConfigService, 'root', boolean> &
+      factory: ServiceFactory<
+        RootConfigService,
+        'root',
+        'singleton' | 'multiton'
+      > &
         ((
           options?: Options | undefined,
-        ) => ServiceFactory<RootConfigService, 'root', boolean>);
+        ) => ServiceFactory<
+          RootConfigService,
+          'root',
+          'singleton' | 'multiton'
+        >);
   }
   // (undocumented)
   export namespace rootHealth {
     const // (undocumented)
-      factory: ServiceFactoryCompat<RootHealthService, 'root', true, undefined>;
+      factory: ServiceFactoryCompat<
+        RootHealthService,
+        'root',
+        'singleton',
+        undefined
+      >;
     const // (undocumented)
       mock: (
         partialImpl?: Partial<RootHealthService> | undefined,
@@ -310,8 +353,8 @@ export namespace mockServices {
     const // (undocumented)
       factory: ((
         options?: RootHttpRouterFactoryOptions | undefined,
-      ) => ServiceFactory<RootHttpRouterService, 'root', true>) &
-        ServiceFactory<RootHttpRouterService, 'root', true>;
+      ) => ServiceFactory<RootHttpRouterService, 'root', 'singleton'>) &
+        ServiceFactory<RootHttpRouterService, 'root', 'singleton'>;
     const // (undocumented)
       mock: (
         partialImpl?: Partial<RootHttpRouterService> | undefined,
@@ -323,7 +366,7 @@ export namespace mockServices {
       factory: ServiceFactoryCompat<
         RootLifecycleService,
         'root',
-        true,
+        'singleton',
         undefined
       >;
     const // (undocumented)
@@ -340,10 +383,10 @@ export namespace mockServices {
       level?: 'none' | 'error' | 'warn' | 'info' | 'debug';
     };
     const // (undocumented)
-      factory: ServiceFactory<LoggerService, 'root', boolean> &
+      factory: ServiceFactory<LoggerService, 'root', 'singleton' | 'multiton'> &
         ((
           options?: Options | undefined,
-        ) => ServiceFactory<LoggerService, 'root', boolean>);
+        ) => ServiceFactory<LoggerService, 'root', 'singleton' | 'multiton'>);
     const // (undocumented)
       mock: (
         partialImpl?: Partial<RootLoggerService> | undefined,
@@ -355,7 +398,7 @@ export namespace mockServices {
       factory: ServiceFactoryCompat<
         SchedulerService,
         'plugin',
-        true,
+        'singleton',
         undefined
       >;
     const // (undocumented)
@@ -371,7 +414,7 @@ export namespace mockServices {
       factory: ServiceFactoryCompat<
         TokenManagerService,
         'plugin',
-        true,
+        'singleton',
         undefined
       >;
     const // (undocumented)
@@ -385,7 +428,7 @@ export namespace mockServices {
       factory: ServiceFactoryCompat<
         UrlReaderService,
         'plugin',
-        true,
+        'singleton',
         undefined
       >;
     const // (undocumented)
@@ -401,7 +444,7 @@ export namespace mockServices {
     const factory: ServiceFactoryCompat<
       UserInfoService,
       'plugin',
-      true,
+      'singleton',
       undefined
     >;
     const // (undocumented)
@@ -422,31 +465,31 @@ export function registerMswTestHooks(worker: {
 export class ServiceFactoryTester<
   TService,
   TScope extends 'root' | 'plugin',
-  TSingleton extends boolean = true,
+  TInstances extends 'singleton' | 'multiton' = 'singleton',
 > {
   static from<
     TService,
     TScope extends 'root' | 'plugin',
-    TSingleton extends boolean = true,
+    TInstances extends 'singleton' | 'multiton' = 'singleton',
   >(
-    subject: ServiceFactory<TService, TScope, TSingleton>,
+    subject: ServiceFactory<TService, TScope, TInstances>,
     options?: ServiceFactoryTesterOptions,
-  ): ServiceFactoryTester<TService, TScope, TSingleton>;
+  ): ServiceFactoryTester<TService, TScope, TInstances>;
   // @deprecated
   get(
     ...args: 'root' extends TScope ? [] : [pluginId?: string]
-  ): Promise<TSingleton extends true ? TService : TService[]>;
+  ): Promise<TInstances extends 'multiton' ? TService[] : TService>;
   getService<
     TGetService,
     TGetScope extends 'root' | 'plugin',
-    TGetSingleton extends boolean,
+    TGetInstances extends 'singleton' | 'multiton' = 'singleton',
   >(
-    service: ServiceRef<TGetService, TGetScope, TGetSingleton>,
+    service: ServiceRef<TGetService, TGetScope, TGetInstances>,
     ...args: 'root' extends TGetScope ? [] : [pluginId?: string]
-  ): Promise<TGetSingleton extends true ? TGetService : TGetService[]>;
+  ): Promise<TGetInstances extends 'multiton' ? TGetService[] : TGetService>;
   getSubject(
     ...args: 'root' extends TScope ? [] : [pluginId?: string]
-  ): Promise<TSingleton extends true ? TService : TService[]>;
+  ): Promise<TInstances extends 'multiton' ? TService[] : TService>;
 }
 
 // @public
diff --git a/packages/backend-test-utils/src/next/wiring/ServiceFactoryTester.ts b/packages/backend-test-utils/src/next/wiring/ServiceFactoryTester.ts
index 94092aff68..e8530f89bf 100644
--- a/packages/backend-test-utils/src/next/wiring/ServiceFactoryTester.ts
+++ b/packages/backend-test-utils/src/next/wiring/ServiceFactoryTester.ts
@@ -46,9 +46,9 @@ export interface ServiceFactoryTesterOptions {
 export class ServiceFactoryTester<
   TService,
   TScope extends 'root' | 'plugin',
-  TSingleton extends boolean = true,
+  TInstances extends 'singleton' | 'multiton' = 'singleton',
 > {
-  readonly #subject: ServiceRef<TService, TScope, TSingleton>;
+  readonly #subject: ServiceRef<TService, TScope, TInstances>;
   readonly #registry: ServiceRegistry;
 
   /**
@@ -61,11 +61,11 @@ export class ServiceFactoryTester<
   static from<
     TService,
     TScope extends 'root' | 'plugin',
-    TSingleton extends boolean = true,
+    TInstances extends 'singleton' | 'multiton' = 'singleton',
   >(
-    subject: ServiceFactory<TService, TScope, TSingleton>,
+    subject: ServiceFactory<TService, TScope, TInstances>,
     options?: ServiceFactoryTesterOptions,
-  ): ServiceFactoryTester<TService, TScope, TSingleton> {
+  ): ServiceFactoryTester<TService, TScope, TInstances> {
     const registry = ServiceRegistry.create([
       ...defaultServiceFactories,
       ...(options?.dependencies ?? []),
@@ -75,7 +75,7 @@ export class ServiceFactoryTester<
   }
 
   private constructor(
-    subject: ServiceRef<TService, TScope, TSingleton>,
+    subject: ServiceRef<TService, TScope, TInstances>,
     registry: ServiceRegistry,
   ) {
     this.#subject = subject;
@@ -89,7 +89,7 @@ export class ServiceFactoryTester<
    */
   async get(
     ...args: 'root' extends TScope ? [] : [pluginId?: string]
-  ): Promise<TSingleton extends true ? TService : TService[]> {
+  ): Promise<TInstances extends 'multiton' ? TService[] : TService> {
     return this.getSubject(...args);
   }
 
@@ -105,7 +105,7 @@ export class ServiceFactoryTester<
    */
   async getSubject(
     ...args: 'root' extends TScope ? [] : [pluginId?: string]
-  ): Promise<TSingleton extends true ? TService : TService[]> {
+  ): Promise<TInstances extends 'multiton' ? TService[] : TService> {
     const [pluginId] = args;
     const instance = this.#registry.get(this.#subject, pluginId ?? 'test')!;
     return instance;
@@ -121,11 +121,11 @@ export class ServiceFactoryTester<
   async getService<
     TGetService,
     TGetScope extends 'root' | 'plugin',
-    TGetSingleton extends boolean,
+    TGetInstances extends 'singleton' | 'multiton' = 'singleton',
   >(
-    service: ServiceRef<TGetService, TGetScope, TGetSingleton>,
+    service: ServiceRef<TGetService, TGetScope, TGetInstances>,
     ...args: 'root' extends TGetScope ? [] : [pluginId?: string]
-  ): Promise<TGetSingleton extends true ? TGetService : TGetService[]> {
+  ): Promise<TGetInstances extends 'multiton' ? TGetService[] : TGetService> {
     const [pluginId] = args;
     const instance = await this.#registry.get(service, pluginId ?? 'test');
     if (instance === undefined) {
diff --git a/plugins/catalog-node/api-report-alpha.md b/plugins/catalog-node/api-report-alpha.md
index a2579e29f4..daa388d5e3 100644
--- a/plugins/catalog-node/api-report-alpha.md
+++ b/plugins/catalog-node/api-report-alpha.md
@@ -88,7 +88,7 @@ export interface CatalogProcessingExtensionPoint {
 export const catalogProcessingExtensionPoint: ExtensionPoint<CatalogProcessingExtensionPoint>;
 
 // @alpha
-export const catalogServiceRef: ServiceRef<CatalogApi, 'plugin', true>;
+export const catalogServiceRef: ServiceRef<CatalogApi, 'plugin', 'singleton'>;
 
 // (No @packageDocumentation comment for this package)
 ```
diff --git a/plugins/events-node/api-report.md b/plugins/events-node/api-report.md
index e159446103..729f526dee 100644
--- a/plugins/events-node/api-report.md
+++ b/plugins/events-node/api-report.md
@@ -66,12 +66,12 @@ export type EventsServiceEventHandler = (params: EventParams) => Promise<void>;
 export const eventsServiceFactory: ServiceFactoryCompat<
   EventsService,
   'plugin',
-  true,
+  'singleton',
   undefined
 >;
 
 // @public
-export const eventsServiceRef: ServiceRef<EventsService, 'plugin', true>;
+export const eventsServiceRef: ServiceRef<EventsService, 'plugin', 'singleton'>;
 
 // @public (undocumented)
 export type EventsServiceSubscribeOptions = {
diff --git a/plugins/notifications-node/api-report.md b/plugins/notifications-node/api-report.md
index fd356131ee..995b98bc21 100644
--- a/plugins/notifications-node/api-report.md
+++ b/plugins/notifications-node/api-report.md
@@ -68,7 +68,7 @@ export interface NotificationService {
 export const notificationService: ServiceRef<
   NotificationService,
   'plugin',
-  true
+  'singleton'
 >;
 
 // @public (undocumented)
diff --git a/plugins/search-backend-node/api-report-alpha.md b/plugins/search-backend-node/api-report-alpha.md
index dc41fa6400..e1d5bd024d 100644
--- a/plugins/search-backend-node/api-report-alpha.md
+++ b/plugins/search-backend-node/api-report-alpha.md
@@ -49,7 +49,7 @@ export type SearchIndexServiceInitOptions = {
 export const searchIndexServiceRef: ServiceRef<
   SearchIndexService,
   'plugin',
-  true
+  'singleton'
 >;
 
 // (No @packageDocumentation comment for this package)
diff --git a/plugins/signals-node/api-report.md b/plugins/signals-node/api-report.md
index b2d5a2b210..a368dd2ece 100644
--- a/plugins/signals-node/api-report.md
+++ b/plugins/signals-node/api-report.md
@@ -37,7 +37,7 @@ export type SignalPayload<TMessage extends JsonObject = JsonObject> = {
 export interface SignalService extends SignalsService {}
 
 // @public @deprecated (undocumented)
-export const signalService: ServiceRef<SignalsService, 'plugin', true>;
+export const signalService: ServiceRef<SignalsService, 'plugin', 'singleton'>;
 
 // @public (undocumented)
 export interface SignalsService {
@@ -52,7 +52,11 @@ export type SignalsServiceOptions = {
 };
 
 // @public (undocumented)
-export const signalsServiceRef: ServiceRef<SignalsService, 'plugin', true>;
+export const signalsServiceRef: ServiceRef<
+  SignalsService,
+  'plugin',
+  'singleton'
+>;
 
 // (No @packageDocumentation comment for this package)
 ```