@sentry/sveltekit: loading the Vite config deletes the adapter-node 6 output directory (build/) #25186

Is there an existing issue for this?

• I have checked for existing issues https://github.com/getsentry/sentry-javascript/issues
• I have reviewed the documentation https://docs.sentry.io/
• I am using the latest SDK release https://github.com/getsentry/sentry-javascript/releases

How do you use Sentry?

Sentry Saas (sentry.io)

Which SDK are you using?

@sentry/sveltekit

SDK Version

10.76.1

Framework Version

SvelteKit 3.0.1, @sveltejs/adapter-node 6.0.0, Vite 8.2.2, Svelte 5.57.2

Link to Sentry event

Not applicable (build-time behaviour).

Reproduction Example/SDK Setup

vite.config.ts:

import adapter from '@sveltejs/adapter-node';
import { sentrySvelteKit } from '@sentry/sveltekit';
import { sveltekit } from '@sveltejs/kit/vite';
import { defineConfig } from 'vite';

export default defineConfig({
	plugins: [
		sentrySvelteKit({ org: 'my-org', project: 'my-project', authToken: process.env.SENTRY_AUTH_TOKEN }),
		sveltekit({ adapter: adapter() })
	]
});

Minimal script that calls the SDK's adapter probe the way sentrySvelteKit() does on every config load:

// probe.cjs
const fs = require('node:fs');
const { getAdapterOutputDir } = require('@sentry/sveltekit/build/cjs/vite/svelteConfig.js');

(async () => {
	const { default: adapter } = await import('@sveltejs/adapter-node');
	fs.mkdirSync('build', { recursive: true });
	fs.writeFileSync('build/probe', 'x');
	console.log('before:', fs.existsSync('build/probe'));
	console.log('probe returned:', await getAdapterOutputDir({ adapter: adapter() }, 'node'));
	console.log('after :', fs.existsSync('build/probe'), fs.existsSync('build'));
})();

Output:

before: true
probe returned: build
after : false false

Steps to Reproduce

1. SvelteKit 3 project with @sveltejs/adapter-node 6 and sentrySvelteKit() in the Vite plugins.
2. vite build (output lands in build/).
3. Load the Vite config again in any way, for example svelte-kit sync (which svelte-check setups run first), vite dev, or vite build of another project in the same cwd.
4. ls build – the directory is gone.

Same project, same steps with sentrySvelteKit() removed from the plugins: build/ survives svelte-kit sync.

Expected Result

Detecting the adapter's output directory has no side effects on disk. The build output only disappears when the adapter is actually run by vite build.

Actual Result

getAdapterOutputDir (packages/sveltekit/src/vite/svelteConfig.ts) discovers the output directory by calling the real adapter's adapt() with a stub builder whose rimraf is a no-op and whose writeClient throws to escape early:

const adapterBuilder = {
	writeClient(dest) {
		outputDir = dest.replace(/\/client.*/, '');
		throw new Error('We got what we came for, throwing to exit the adapter');
	},
	rimraf: () => {},
	mkdirp: () => {},
	...
};
await nodeAdapter.adapt(adapterBuilder);

That relies on the adapter clearing its output through builder.rimraf. adapter-node 5 did (builder.rimraf(out)); adapter-node 6 clears it directly before anything else:

// @sveltejs/adapter-node 6.0.0, index.js
async adapt(builder) {
	fs.rmSync(out, { force: true, recursive: true });
	...
	builder.writeClient(client_dir);

So the probe deletes the real build/ directory every time the Vite config is loaded, which with SvelteKit 3 happens on svelte-kit sync, svelte-check, vite dev and vite build. The probe still returns the right directory, so nothing in the build log hints at it.

Additional Context

• The probe's adapt() call is the only @sentry/sveltekit code path involved; the sourcemaps deletion globs are not reached (no upload is configured in the minimal repro).
• In a CI image that builds and copies in one step this goes unnoticed. Locally, running svelte-check after a build silently removes the build, which is how we found it.
• A probe that does not execute adapter code (a static table of default output dirs per adapter name, or an explicit adapter/outputDir option taking precedence) would avoid the coupling to how adapters clean up. Alternatively, run the adapter inside a temporary cwd.
• Related: @sentry/sveltekit: source maps are never uploaded with SvelteKit 3 #25096 / fix(sveltekit): Upload source maps with SvelteKit 3 #25139 (reading the Kit 3 config from the Vite plugin) touch the same file.

Priority

P2 (Medium)