aria: nested accordion doesn't work

[imaksp]

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

Don't known / other

Is this a regression?

No

Description

Hi, I tried making an nested accordion using @angular/aria/accordion and Tailwind but only parent accordion is working, nothing happens on child trigger click, and if I keep it expanded by default it doesn't close on click. please check the demo for details.

Please provide a link to a minimal reproduction of the bug

https://github.com/imaksp/ng-nested-accordion-issue

Please provide the exception or error you saw

None

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

Angular CLI       : 21.2.7
Angular           : 21.2.8
Node.js           : 24.14.0
Package Manager   : pnpm 10.33.0
Operating System  : darwin arm64

┌───────────────────────────┬───────────────────┬───────────────────┐
│ Package                   │ Installed Version │ Requested Version │
├───────────────────────────┼───────────────────┼───────────────────┤
│ @angular/aria             │ 21.2.6            │ ^21.2.6           │
│ @angular/build            │ 21.2.7            │ ^21.2.7           │
│ @angular/cli              │ 21.2.7            │ ^21.2.7           │
│ @angular/common           │ 21.2.8            │ ^21.2.8           │
│ @angular/compiler         │ 21.2.8            │ ^21.2.8           │
│ @angular/compiler-cli     │ 21.2.8            │ ^21.2.8           │
│ @angular/core             │ 21.2.8            │ ^21.2.8           │
│ @angular/forms            │ 21.2.8            │ ^21.2.8           │
│ @angular/platform-browser │ 21.2.8            │ ^21.2.8           │
│ @angular/router           │ 21.2.8            │ ^21.2.8           │
│ rxjs                      │ 7.8.2             │ ~7.8.2            │
│ typescript                │ 5.9.3             │ ~5.9.3            │
│ vitest                    │ 4.1.4             │ ^4.1.4            │
└───────────────────────────┴───────────────────┴───────────────────┘

Anything else?

Official guide doesn't have a demo for nested case but I believe it should work.