Attachment in Async / Await Component not working

[jere2101]

Describe the bug

In my App (in Dev Mode) i experienced that my attachement didn't trigger when the node was added to the DOM. Only after the component refreshed ( from HMR i guess ) the attachment triggered and in my case rendered a map.

I have a small repl where it doesn't work either but i don't know if async is activated on the Svelte Playground. Maybe this is the expected output and i'm doing something wrong in the repl.

Thanks for your help ♥️

Reproduction

https://svelte.dev/playground/8fe0eb6dbe8943b5ba057de9b6259ecb?version=latest

System Info

svelte: 5.38.1

Severity

blocking all usage of svelte

[paoloricciuti]

Async is active in the playground by default (but regardless in your repro you are still wrapping it with a boundary), let me check

[irishburlybear]

I just came across this and made another repl:
https://svelte.dev/playground/a94fa5d58eb94263bb812e61441d4774?version=5.38.6

[dummdidumm]

This happens because schedule_effect is run for the attachment, which marks the root effect and its tree as dirty, but there's nothing that then flushes it, since the flush already happened earlier. Not sure what's the best way to fix it yet.