Setting/updating a signal must be done in NgZone(?)

[csisy-bt4w]

Describe the problem that you experienced

We've just started using signals and OnPush change detection and found out that setting/updating a signal must be done in NgZone, otherwise the component will not be updated (until something else forces a change detection).

The documentation writes about signals and OnPush components, but it does not mention anything about the zone.

Enter the URL of the topic with the problem

https://angular.io/guide/signals#reading-signals-in-onpush-components

Describe what you were looking for in the documentation

Clarification, or more in-depth description about the connection between the zone and signals.

Describe the actions that led you to experience the problem

We are using a ResizeObserver to detect if an element is resized. The following Stackblitz example is simplified, but the root problem is the same: https://stackblitz.com/edit/stackblitz-starters-fbyzdi?file=src%2Fmain.ts

All you have to do is to resize the viewport and check if the is small? value turns to true (the value is logged into the console as well).

Currently, the OutsideZoneComponent is used and as you can see, the component is not updated. More importantly, the component will not be updated even if the OnPush strategy is not used.

If you uncomment the <app-inside-zone/> tag in the App's template, everything works as expected.

Describe what you want to experience that would fix the problem

No response

Add a screenshot if that helps illustrate the problem

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If this problem caused an exception or error, please paste it here

No response

If the problem is browser-specific, please specify the device, OS, browser, and version

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Provide any additional information here in as much as detail as you can

No response

[JeanMeche]

Hi, this is a dupe of essentially #31695.
ResizeObserver isn't patched by zone.js so the callback is run outside the angular zone.

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