Unable to use only valibot adapter due to unnecessary imports causing build failure

[Deyvan]

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Description
When importing

import { valibotClient } from "sveltekit-superforms/adapters"

the build fails with the error:
Could not resolve "effect" imported by "sveltekit-superforms". Is it installed?

My project only uses valibot, but the package imports other validator dependencies (like effect) that are not installed and not needed.

It would be great to be able to import only the required validator adapter directly, for example:

import { valibotClient } from "sveltekit-superforms/adapters/valibot"

[ciscoheat]

Other adapters are automatically tree shaken when the project builds, there must be something your build setup does that prevents that. Can you try to reproduce it in a MRE, as simple as possible with no extra build tools?

[arnolicious]

Fascinatingly, I have the same problem, but only on the latest version (2.29.1). I've tried switching back and forth multiple times, and it seems to be consistently working on 2.28.1 and not working on 2.29.1.

For me, I'm using the zod adapter, and the error thrown is
Failed to resolve import "valibot" from "node_modules/.vite/deps/sveltekit-superforms_adapters.js?v=53738640". Does the file exist?

Since we are using the vite-rolldown preview version, I also tried switching to the stable vite@7.3.0 version, which has the same problem, however maybe a more helpful error?

✘ [ERROR] Could not resolve "valibot"

    node_modules/@valibot/to-json-schema/dist/index.mjs:1:19:
      1 │ import * as v from "valibot";
        ╵                    ~~~~~~~~~

  You can mark the path "valibot" as external to exclude it from the bundle, which will remove this
  error and leave the unresolved path in the bundle.

/home/arno/crewbrain/workspace/gigplaner.ap/gigplaner.act/frontend/node_modules/esbuild/lib/main.js:1467
  let error = new Error(text);
              ^

Error: Error during dependency optimization:

✘ [ERROR] Could not resolve "valibot"

    node_modules/@valibot/to-json-schema/dist/index.mjs:1:19:
      1 │ import * as v from "valibot";
        ╵                    ~~~~~~~~~

  You can mark the path "valibot" as external to exclude it from the bundle, which will remove this error and leave the unresolved path in the bundle.

[ciscoheat]

If you can make a simple as possible MRE, I'm very grateful.

[Alex-E-Clove]

The good old deleting node_modules and your lock file before running your install command again solved it for me.

[Nono-04]

Interesting im running in the same exact thing, in on 2.29.1 as well. But im using Zod and its complaining that I need Volibot.

✗ Build failed in 13.03s
error during build:
node_modules/sveltekit-superforms/dist/adapters/valibot.js (2:9): "safeParseAsync" is not exported by "__vite-optional-peer-dep:valibot:sveltekit-superforms:false", imported by "node_modules/sveltekit-superforms/dist/adapters/valibot.js".
file: /azp/_work/4/s/X/node_modules/sveltekit-superforms/dist/adapters/valibot.js:2:9

1: import { createAdapter } from './adapters.js';
2: import { safeParseAsync } from 'valibot';
            ^

Weirdly it only fails on my CI (Ubuntu), on my Machine (Windows) the build works.

[ensko]

I'm reproducing this (also wanting to use zod instead of valibot) like this:

npx sv create my-app
# (answer all questions with defaults)
cd my-app
npm i -D sveltekit-superforms zod

According to package-lock.json, I now have

{
	"@sveltejs/adapter-auto": "^7.0.0",
	"@sveltejs/kit": "^2.49.1",
	"@sveltejs/vite-plugin-svelte": "^6.2.1",
	"svelte": "^5.45.6",
	"svelte-check": "^4.3.4",
	"sveltekit-superforms": "^2.29.1",
	"typescript": "^5.9.3",
	"vite": "^7.2.6",
	"zod": "^4.2.1"
}

then, in src/routes/#page.svelte, add

<script lang="ts">
	import { zod4 } from 'sveltekit-superforms/adapters';
</script>

Then, running npm run dev (and opening the page if the error doesn't appear instantly) I get

[ERROR] Could not resolve "valibot"

    node_modules/@valibot/to-json-schema/dist/index.mjs:1:19:
      1 │ import * as v from "valibot";

I guess the problem is that importing sveltekit-superforms/adapters tries to pull in all referenced libraries (or should tree shaking avoid this?). I tried sveltekit-superforms/adapters/zod4.js instead, but that doesn't work. The import line is copied/taken from here: https://superforms.rocks/migration-v2#supervalidate

[ciscoheat]

I can't reproduce it (tried both npm and pnpm), and there would be loads of bug reports if that simple import broke the library, so I wonder what the difference is. What's your setup?

[leroytromp]

I am getting something similar after upgrading to 2.29.1. Running on Ubuntu through WSL2 on a Windows machine. The funny thing is that I am not even using valibot (I am using zod4). Downgrading back to 2.28.1 for now.

See screenshot below for error message:

[ciscoheat]

It could be that the library @valibot/to-json-schema is doing import * as v from "valibot"; which prevents it from being tree-shaken. As the JSON Schema conversion is synchronous, it cannot be dynamically imported either, so it's a bit of a problem, and I'm not sure why it happens on Linux but not Windows.

[ciscoheat]

Opened a PR to hopefully fix it. open-circle/valibot#1382

[ensko]

What's your setup?

Linux (Kubuntu 24.04), Node 24.12.0 & npm 11.6.2 installed via nvm. I did some more experimentation; the exact same process works when switching to node 22.22.1, npm 10.9.4 by running nvm use 22.

Node 22/NPM 10 works; superforms 2.28.1 works; Node 24/NPM11+superforms 2.29.1 doesn't work.

There are some interesting differences when comparing the package-lock.json files:

Node 24, superforms 2.28 vs 2.29:

• 2.28: contains @gcornut/valibot-json-schema:0.42.0 (optional), valibot:1.2.0 (optional)
• 2.29: contains @valibot/to-json-schema:1.5.0 (optional)

(other unrelated differences skipped) @valibot/to-json-schema:1.5.0 has a peer dependency on valibot:^1.2.0, @gcornut/valibot-json-schema:0.42.0 has a regular dependency on valibot:~0.42.0. I guess together with superform's peer dependency on valibot:^1.0.0 this was resolved to valibot:1.2.0

superforms 2.29, Node 22 vs 24:

• 22: contains valibot:1.2.0 (optional) (and class-validator:0.14.3, optional)
• 24: marks more packages as peer dependencies, including @sveltejs/kit, zod

no other package differences in the lock files—here I'm not sure why valibot ends up installed in one but not the other.

Here are the package-lock.json files attached in case it's helpful:

node-22-superforms-2.29-package-lock.json
node-24-superforms-2.28-package-lock.json
node-24-superforms-2.29-package-lock.json

[jeannemas]

I don't know if any of you have noticed this, but in the meantime to "bypasss" the lack of effect (imported by sveltekit-superforms), I tried manually adding it as a dev dependency to my project so that it can build, but now I have the same issue where it requires another peer/optionnal-dependency, this time it's typebox. Could this be related to how our package manager incorrectly resolves the peer/optionnal-dependencies-meta?

Prior to adding effect as a dev-dependency:

After adding effect as dev-dependency:

Only after adding typebox as a dev-dependency can my project build.