bug: `page.url` updates on link preload when `compilerOptions.experimental.async` is true

[ieedan]

Describe the bug

This one is really ugly cause it's really not what you'd expect. I'm not really sure what's going on here but as you can see the value updates inside script tags breaking things in unexpected ways. Weirdly enough it doesn't actually update the value in the template.

In the video I remove both the experimental.remoteFunctions and experimental.async options but it's isolated to experimental.async.

(P.S. Leaving this as an annoyance cause this is experimental but I def couldn't ship with this bug)

Reproduction

CleanShot.2025-11-21.at.07.08.20.mp4

https://github.com/ieedan/svelte-repro

Logs

System Info

System:
    OS: macOS 15.6.1
    CPU: (12) arm64 Apple M4 Pro
    Memory: 196.77 MB / 24.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.19.0 - /Users/ieedan/.nvm/versions/node/v22.19.0/bin/node
    npm: 10.9.3 - /Users/ieedan/.nvm/versions/node/v22.19.0/bin/npm
    pnpm: 10.17.1 - /Users/ieedan/Library/pnpm/pnpm
    bun: 1.2.13 - /Users/ieedan/.bun/bin/bun
    Deno: 2.4.0 - /Users/ieedan/.deno/bin/deno
  Browsers:
    Chrome: 142.0.7444.176
    Safari: 18.6
  npmPackages:
    svelte: ^5.43.8 => 5.43.14

Severity

annoyance

[dummdidumm]

$inspect logs eagerly whatever a value is, and when hovering over the link it will preload and therefore have that value for a short time, so it's correct. The important bit is that the UI doesn't update and that effects don't run until the preload is actually turning into the real current page.

There's a few related bugs but $inspect firing is expected. If there's something else please provide a reproduction showing that.

[ieedan]

Yeah let me update the reproduction because it will also effect things like trying to render something conditionally based on the URL.