fix(signals): only warn about memory leak when source injector is root

modules/signals/rxjs-interop/spec/rx-method.spec.ts

@@ -402,7 +402,7 @@ describe('rxMethod', () => {
       [of(1), 'Observable'],
     ] as const) {
       describe(`${name}`, () => {
-        it('warns when source injector is used', () => {
+        it('warns when source injector is root', () => {
           let a = 1;
           const adder = createAdder((value) => (a += value));
           adder(reactiveValue);
@@ -414,6 +414,20 @@ describe('rxMethod', () => {
           );
         });
 
+        it('does not warn when source injector is not root', () => {
+          let a = 1;
+          const childInjector = createEnvironmentInjector(
+            [],
+            TestBed.inject(EnvironmentInjector)
+          );
+          const adder = runInInjectionContext(childInjector, () =>
+            rxMethod<number>(tap((value) => (a += value)))
+          );
+          adder(reactiveValue);
+
+          expect(warnSpy).not.toHaveBeenCalled();
+        });
+
         it('does not warn on manual injector', () => {
           let a = 1;
           const adder = createAdder((value) => (a += value));

modules/signals/rxjs-interop/src/rx-method.ts

@@ -80,11 +80,15 @@ export function rxMethod<Input>(
     }
 
     const callerInjector = getCallerInjector();
+    const instanceInjector =
+      config?.injector ?? callerInjector ?? sourceInjector;
+
     if (
       typeof ngDevMode !== 'undefined' &&
       ngDevMode &&
       config?.injector === undefined &&
-      callerInjector === undefined
+      callerInjector === undefined &&
+      isRootInjector(sourceInjector)
     ) {
       console.warn(
         '@ngrx/signals/rxjs-interop: The reactive method was called outside',
@@ -96,9 +100,6 @@ export function rxMethod<Input>(
       );
     }
 
-    const instanceInjector =
-      config?.injector ?? callerInjector ?? sourceInjector;
-
     if (typeof input === 'function') {
       const watcher = effect(
         () => {
@@ -139,3 +140,15 @@ function getCallerInjector(): Injector | undefined {
     return undefined;
   }
 }
+
+/**
+ * Checks whether the given injector is a root or platform injector.
+ *
+ * Uses the `scopes` property from Angular's `R3Injector` (the concrete
+ * `EnvironmentInjector` implementation) via duck typing. This is an
+ * internal Angular API that may change in future versions.
+ */
+function isRootInjector(injector: Injector): boolean {
+  const scopes: Set<string> | undefined = (injector as any)['scopes'];
+  return scopes?.has('root') === true || scopes?.has('platform') === true;
+}

modules/signals/spec/signal-method.spec.ts

@@ -248,7 +248,7 @@ describe('signalMethod', () => {
       warnSpy.mockClear();
     });
 
-    it('warns when source injector is used for a signal', () => {
+    it('warns when source injector is root', () => {
       let a = 1;
       const adder = createAdder((value) => (a += value));
       adder(n);
@@ -260,6 +260,20 @@ describe('signalMethod', () => {
       );
     });
 
+    it('does not warn when source injector is not root', () => {
+      let a = 1;
+      const childInjector = createEnvironmentInjector(
+        [],
+        TestBed.inject(EnvironmentInjector)
+      );
+      const adder = runInInjectionContext(childInjector, () =>
+        signalMethod<number>((value) => (a += value))
+      );
+      adder(n);
+
+      expect(warnSpy).not.toHaveBeenCalled();
+    });
+
     it('does not warn on non-reactive value and source injector', () => {
       let a = 1;
       const adder = createAdder((value) => (a += value));

modules/signals/src/signal-method.ts

@@ -59,11 +59,15 @@ export function signalMethod<Input>(
   ): EffectRef => {
     if (isReactiveComputation(input)) {
       const callerInjector = getCallerInjector();
+      const instanceInjector =
+        config?.injector ?? callerInjector ?? sourceInjector;
+
       if (
         typeof ngDevMode !== 'undefined' &&
         ngDevMode &&
         config?.injector === undefined &&
-        callerInjector === undefined
+        callerInjector === undefined &&
+        isRootInjector(sourceInjector)
       ) {
         console.warn(
           '@ngrx/signals: The function returned by signalMethod was called',
@@ -75,9 +79,6 @@ export function signalMethod<Input>(
         );
       }
 
-      const instanceInjector =
-        config?.injector ?? callerInjector ?? sourceInjector;
-
       const watcher = effect(
         () => {
           const value = input();
@@ -118,3 +119,15 @@ function getCallerInjector(): Injector | undefined {
 function isReactiveComputation<T>(value: T | (() => T)): value is () => T {
   return typeof value === 'function';
 }
+
+/**
+ * Checks whether the given injector is a root or platform injector.
+ *
+ * Uses the `scopes` property from Angular's `R3Injector` (the concrete
+ * `EnvironmentInjector` implementation) via duck typing. This is an
+ * internal Angular API that may change in future versions.
+ */
+function isRootInjector(injector: Injector): boolean {
+  const scopes: Set<string> | undefined = (injector as any)['scopes'];
+  return scopes?.has('root') === true || scopes?.has('platform') === true;
+}

projects/www/src/app/pages/guide/signals/rxjs-integration.md

@@ -299,7 +299,7 @@ export class Numbers implements OnInit {
 
 <ngrx-docs-alert type="inform">
 
-If the injector is not provided when calling the reactive method with a signal, a computation function, or an observable outside the injection context, a warning message about a potential memory leak is displayed in development mode.
+If the reactive method is initialized in a root-scoped injector (e.g. a service with `providedIn: 'root'`) and called with a signal, a computation function, or an observable outside the injection context without providing an injector, a warning message about a potential memory leak is displayed in development mode. This warning does not apply when the reactive method is initialized in a non-root injector (e.g. a component or a service provided at the component level), since cleanup is handled by the source injector's lifecycle.
 
 </ngrx-docs-alert>
 

projects/www/src/app/pages/guide/signals/signal-method.md

@@ -128,7 +128,7 @@ Here, the `effect` used internally by `signalMethod` outlives the component, whi
 
 <ngrx-docs-alert type="inform">
 
-If an injector is not provided when a method generated by `signalMethod` is called with a signal outside the injection context, a warning message about a potential memory leak is displayed in development mode.
+If `signalMethod` is initialized in a root-scoped injector (e.g. a service with `providedIn: 'root'`) and called with a signal outside the injection context without providing an injector, a warning message about a potential memory leak is displayed in development mode. This warning does not apply when `signalMethod` is initialized in a non-root injector (e.g. a component or a service provided at the component level), since cleanup is handled by the source injector's lifecycle.
 
 </ngrx-docs-alert>