Which @angular/* package(s) are the source of the bug?

Don't known / other

Is this a regression?

No

Description

After reading this blog I wanted to try out a custom select in my Angular 19 project. But it doesn't work as it should. <selectedcontent> won't show the first/selected option on load. It should show ✓ On like in this codepen (check in Chrome beta or a Chromium 135 browser).

Please provide a link to a minimal reproduction of the bug

https://stackblitz.com/edit/angular-19-starter-bszk44yd?file=src%2Fmain.ts

Please provide the exception or error you saw

Please provide the environment you discovered this bug in (run ng version)

Browser: Chrome Beta (Chromium 135)
Angular CLI: 19.2.5
Node: Newest
Package Manager: pnpm newest
OS: macOS

Angular: 19.2.5
... animations, cli, common, compiler, compiler-cli, core, forms
... platform-browser, router

Package                         Version
---------------------------------------------------------
@angular/build                  19.2.5
@angular/cli                    19.2.5
rxjs                            7.8.2
typescript                      5.8.2

Anything else?

No response