fix: refetch queries after a refreshAll navigation when the cached query survives it

[Nic-Polumeyv]

Replaces #16453 now that main is winding down; fixes #16444.

#promise ??= this.#run() compiles to an unconditional $.set (sveltejs/svelte#18592), so a render that evaluates while the resetting batch from a refreshAll navigation is still pending reads the pre-reset promise through the batch overlay and writes it straight back, erasing the reset. The deferred restart in client.js then sees a non-null promise and never refetches. Whether the cached query survives the navigation at all is GC timing, which is why this mostly shows up in Firefox.

This affects any refreshAll navigation: remote form redirects, applyAction, goto(url, { refreshAll: true }). Verified against the reproduction in #16444 on version-3 in Firefox: 10/10 stale before, 0/10 after, with the ??= line being the only difference. The spec fails without the runtime change.

[pkg-svelte-dev]

Install the latest version of @sveltejs/kit from 993601d:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/993601d23b8b9ffbc84c72f17c78dfc3a2371400

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/16546

Note

This PR is from a fork. A maintainer must approve approve each commit before it can be built and installed.

[changeset-bot]

🦋 Changeset detected

Latest commit: 993601d

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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@sveltejs/kit	Patch

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[Rich-Harris]

I think we should probably close this in favour of sveltejs/svelte#18594 (just waiting for CI to run on that and we can cut a release)

[Nic-Polumeyv]

I'm going to put this in draft to test if #16444 is fully fixed at a later date. Unless you've already tested this and want to close it.