sentrySvelteKit() deletes the adapter output directory (build/) on every serve-mode config load (vitest, vite dev) with @sveltejs/adapter-node 6 #25532

Outcome

@sentry/sveltekit's vite plugin deletes the adapter output directory (default build/) on every vite config load in serve mode — any vitest run and any vite dev server start — when the project uses @sveltejs/adapter-node@6.

Background

In a SvelteKit 3 project (vite 8 / rolldown-vite, vitest 5) whose vite.config.ts contains sentrySvelteKit() (default options) and sveltekit({ adapter: adapter() }) from @sveltejs/adapter-node@6.0.0:

1. sentrySvelteKit() always adds the sentry-sveltekit-global-values-injection-plugin (when autoUploadSourceMaps is the default true, regardless of command).
2. That plugin's configResolved hook eagerly resolves the adapter output dir (getAdapterOutputDir in packages/sveltekit/src/vite/svelteConfig.ts).
3. getNodeAdapterOutputDir() learns the directory by executing the real adapter's adapt() against a stub Builder: the stub's writeClient(dest) records dest and throws to short-circuit.
4. @sveltejs/adapter-node@6's adapt() begins with a direct filesystem call — fs.rmSync(out, { force: true, recursive: true }) (adapter-node/index.js, first statement) — which the stub Builder cannot intercept (adapter-node 5 routed this through builder.rimraf(), which the stub no-ops). The real build/ directory is deleted before the stub ever receives a call.

Because this happens in configResolved, it fires in serve mode too: every vitest run and every vite dev start wipes build/. In a vitest-then-e2e pipeline that serves the previously built output, the e2e web server dies with Cannot find module …/build.

Minimal reproduction

Any vitest run in such a project deletes build/. The call path can also be proven with no vite/vitest at all:

// repro.mjs — run from a SvelteKit app with @sentry/sveltekit and @sveltejs/adapter-node@6 installed
import { existsSync } from 'node:fs';
import { createRequire } from 'node:module';
import { dirname, join } from 'node:path';
import { pathToFileURL } from 'node:url';
import adapter from '@sveltejs/adapter-node';

const require = createRequire(import.meta.url);
const pkgDir = dirname(require.resolve('@sentry/sveltekit/package.json'));
const { getAdapterOutputDir } = await import(
	pathToFileURL(join(pkgDir, 'build/esm/vite/svelteConfig.js')).href // src/vite/svelteConfig.ts when built from source
);

console.log('build/ before:', existsSync('build')); // true (after `vite build`)
const out = await getAdapterOutputDir({ adapter: adapter() }, 'node');
console.log('detected output dir:', out); // "build"
console.log('build/ after:', existsSync('build')); // false — deleted

Output:

build/ before: true
detected output dir: build
build/ after: false

Why the stub Builder can't help

The stub in getNodeAdapterOutputDir implements writeClient, log, getBuildDirectory, rimraf, mkdirp and config. adapter-node 6 does its cleanup with a direct fs.rmSync before it calls any Builder method, so executing adapt() at all is destructive, no matter how defensive the stub is.

Suggested directions

• Resolve the adapter output dir lazily/only in build mode (the value feeds source-map upload and global-value injection that only matter at build time), so serve-mode config loads never execute adapt().
• Or stop executing the real adapter to learn the directory — e.g. read it from the adapter instance/config, or ask adapter authors to expose it.

Versions

• @sentry/sveltekit 11.6.0 (@sentry/bundler-plugins 11.6.0)
• @sveltejs/kit 3.0.1, @sveltejs/adapter-node 6.0.0
• vite 8.3.4, vitest 5.0.3, Node 24.20.0 (Windows; the fs.rmSync is platform-independent)