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:

kit/packages/kit/src/runtime/client/client.js

Line 1617 in acec5e6

[PAGE_URL_KEY]: page.url.href

kit/packages/kit/src/runtime/client/client.js

Line 1642 in acec5e6

[PAGE_URL_KEY]: page.url.href

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 :)

[teemingc]

This has the same issue as #11503 where we are trying to avoid updating the page store with the URL passed to pushState and instead keep the page store URL and load URL the same as the original page we were on. However, we should be updating the load URL.

[Nic-Polumeyv]

dummdidumm closed #16307 with the rationale that returning to a pushState/replaceState entry should preserve the shallow navigation state, while the comment above suggests updating the URL that subsequent loads run with. If preserving the shallow state is the intended behavior, this should probably close as working as designed. I can PR a short note in the shallow routing docs that page.url and load keep the original URL when returning to a shallow entry.