pushState and replaceState causing inconsistencies with different url

[AlexisGado]

Describe the bug

When calling pushState or replaceState with a first argument that is not the current page's url, subsequent navigations (typically "go back") will lead to unexpected behaviors. In particular, the url in the browser's history will be different from the one used in the load function of a page.

See for example this SO question which explains the bug that led me here: https://stackoverflow.com/questions/77703203/url-is-incorrect-in-load-after-pushstate-and-navigation

I'm not a svelteKit contributor, and am not ready yet to be one, but I think the bug is caused by these lines: https://github.com/sveltejs/kit/blob/acec5e6a2c6325ee226594664e8ba723d1b81e17/packages/kit/src/runtime/client/client.js#L1617 https://github.com/sveltejs/kit/blob/acec5e6a2c6325ee226594664e8ba723d1b81e17/packages/kit/src/runtime/client/client.js#L1642

PAGE_URL_KEY is set to the current page's url while the original history API is called with the new url provided by the user. Changing page.url.href to resolve_url(url).href solved my issue.

Reproduction

https://github.com/AlexisGado/bug-nav-svelte

• go to /page1
• click the button that will push a new state /page1?a=1 and navigate to /page2?a=1
• go back using the browser's button
• browser shows the correct url /page1?a=1 (meaning that the browser history was updated)
• The load function of page1 runs but the url (logged) is incorrect: /page1

Logs

No response

System Info

System:
    OS: macOS 14.0
    CPU: (8) arm64 Apple M1
    Memory: 59.53 MB / 8.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 21.4.0 - /opt/homebrew/bin/node
    npm: 10.2.4 - /opt/homebrew/bin/npm
  Browsers:
    Chrome: 119.0.6045.123
    Safari: 17.0

Severity

serious, but I can work around it

Additional Information

If you know a better way of doing what I was trying to achieve, please feel free to answer the SO question :)