Cannot override meta description with transformHead

[Zezombye]

Describe the bug

    transformHead(context) {
        let description = context.pageData?.frontmatter?.layout === "home" ? "Zezombye's Blog" : "Programming, self-improvement, and various stuff";
        return [
            ['meta', { name: 'description', content: description }],
        ]
    },

Although the <meta name="description"> tag is overridden, it doesn't take into account the description, putting instead the default description of "A VitePress site":

This does work if I put og:description, but Discord picks up the description tag.

Reproduction

It doesn't seem the build works properly at vitepress.new but by putting the transformHead hook and removing the default description field in the config, it should reproduce.

Expected behavior

The tag should be properly overridden

System Info

System:
    OS: Windows 10 10.0.17763
    CPU: (8) x64 AMD Ryzen 5 1500X Quad-Core Processor
    Memory: 12.95 GB / 31.95 GB
  Binaries:
    Node: 22.14.0 - C:\Program Files\nodejs\node.EXE
    npm: 10.9.2 - C:\Program Files\nodejs\npm.CMD
    pnpm: 10.7.0 - ~\AppData\Roaming\npm\pnpm.CMD
  Browsers:
    Chrome: 138.0.7204.49
    Internet Explorer: 11.0.17763.2989
  npmPackages:
    vitepress: ^1.6.3 => 1.6.3

Additional context

VitePress should by default put the description on the home page, but the title if on any other page as the meta description

Validations

• Check if you're on the latest VitePress version.
• Follow our Code of Conduct
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.

[brc-dd]

The title and description need to be overridden in the page data.

https://vitepress.dev/reference/site-config#transformpagedata

Something like this would've worked:

description: "Zezombye's Blog", // default

transformPageData(pageData) {
  if (pageData.frontmatter.layout !== 'home') {
    return {
      description: 'Programming, self-improvement, and various stuff'
    }
  }
}

It's kind of design limitation. We can't override the description in pageData from the overridden description in transformHead, because the JS chunks are already written by then. We also can't ignore the description present in the JS chunks because the html is only fetched once. There will be no way to sync description changes from page to page then.

[Zezombye]

It works, thanks! I had tried transformPageData but only setting the head tags, not setting the description directly.