View Transitions Name broken in Astro 5.9.0

[radishzzz]

Astro Info

Astro                    v5.8.2
Node                     v23.11.0
System                   macOS (arm64)
Package Manager          pnpm
Output                   static
Adapter                  none
Integrations             unocss
                         @astrojs/mdx
                         @astrojs/partytown
                         @astrojs/sitemap
                         astro-robots-txt
                         astro-compress

If this issue only occurs in one browser, which browser is a problem?

No response

Describe the Bug

Currently my Astro version is 5.8.2, and View Transitions Name work normally. Once I upgrade to 5.9.0, View Transitions functionality has issues.

My View Transition configuration is specifically as follows:

    <div
      class="box-content inline-block pr-1"
      transition:name={`site-title-${currentLang}`}
      data-disable-theme-transition
    >

or like this:

      <div
        class="py-0.8 text-3.5 font-time lg:hidden"
        transition:name={`time-${post.data.abbrlink || post.id}${lang ? `-${lang}` : ''}`}
        data-disable-theme-transition
      >

In Astro version 5.8.2, the build result is as follows:

<a href="/en/posts/theme-guide/" class="cjk:tracking-0.02em" data-astro-transition-scope="astro-5tzck4eb-1" data-disable-theme-transition="" lg="font-medium text-4.5">Theme Guide </a>

In Astro version 5.9.0, the build result is as follows:

<a href="/en/posts/theme-guide/" class="cjk:tracking-0.02em" data-astro-transition-scope="[object Promise]" data-disable-theme-transition="" lg="font-medium text-4.5">Theme Guide </a>

The difference is astro-5tzck4eb-1 and [object Promise].

This is the repository astro-theme-retypeset where the above problem occurs.

What's the expected result?

data-astro-transition-scope generates characters normally, instead of generating [object Promise].

Link to Minimal Reproducible Example

https://stackblitz.com/edit/github-zulo7woo?file=src%2Fpages%2Findex.astro

Participation

• I am willing to submit a pull request for this issue.

[martrapp]

Seems to happen with any view transitions scope, even for simpler forms like transition:name="foo".

[martrapp]

Here we "go". Since renderTransition() is now async, we have to await its result.

[martrapp]

That bug caught me so off guard, I forgot my manners. Huge thanks to @radishzzz 👋🏼 for filing the issue and dropping a repro! Really appreciate you taking the time to do that.