Undocumented edge case - early return of non-trailing `validate` calls on complex remote form

Describe the bug

When calling .validate programmatically on a "complex-enough" remote form, only the trailing edge will actually execute the necessary logic, all prior calls return early - a kind of debouncing I assume. This claim is based on my understanding of the relevant source code at current HEAD:

https://github.com/sveltejs/kit/blob/25371d17d2236f7b62841cd5545670fbfab4fee0/packages/kit/src/runtime/client/remote-functions/form.svelte.js#L525-L527

This may lead to some unexpected behavior. The reproduction shows such case when validate is called twice shortly after one another, falsely masking validation issue in one of the two logic flows. This mimics an occurrence in a project of mine when user tries to click on a button while the focus is still on the input containing invalid data - both button onclick and form onchange call validate.

Ideally, I'd expect all debounced calls to also return the same Promise the trailing edge does. But if this is not negotiable, perhaps a note in the documentation should help others avoid the same rabbit hole I went down.

Reproduction

Please see https://github.com/vnphanquang/remote-form-repeat-validate for details.

Essentially, the repro tries to simulate a large form so that the init of FormData is slowed down enough for multiple calls of validate to be debounced. I presume similar issue may also be observed when there is some complex state derivation/dependency. issues is not populated after cancelled calls, hence the problem.

System Info

System:
    OS: Linux 6.18 Arch Linux
    CPU: (12) x64 AMD Ryzen 5 7500F 6-Core Processor
    Memory: 21.53 GB / 30.93 GB
    Container: Yes
    Shell: 4.3.3 - /usr/bin/fish
  Binaries:
    Node: 24.12.0 - $HOME/.volta/tools/image/node/24.12.0/bin/node
    npm: 11.6.2 - $HOME/.volta/tools/image/node/24.12.0/bin/npm
    pnpm: 10.26.0 - $HOME/.volta/bin/pnpm
  Browsers:
    Firefox: 147.0.1
    Firefox Developer Edition: 147.0.1
  npmPackages:
    @sveltejs/adapter-node: ^5.5.4 => 5.5.4
    @sveltejs/kit: ^2.55.0 => 2.55.0
    @sveltejs/vite-plugin-svelte: ^7.0.0 => 7.0.0
    svelte: ^5.53.11 => 5.53.11
    vite: ^8.0.0 => 8.0.0

Severity

annoyance

Additional Information

No response

Start with packages/kit/src/runtime/client/remote-functions/form.svelte.js at lines 525-527, then run the remote-form-repeat-validate reproduction to observe repeated validate calls on a complex form. Determine the expected behavior for cancelled calls and their Promises; done when the behavior is resolved or clearly documented.