sveltejs · SobolievOleksii · Jul 10, 2026 · Jul 10, 2026 · Jul 10, 2026 · Jul 16, 2026
diff --git a/packages/adapter-node/package.json b/packages/adapter-node/package.json
@@ -35,11 +35,13 @@
 	"scripts": {
 		"dev": "rolldown -cw",
 		"build": "rolldown -c",
-		"test": "vitest run",
+		"test": "pnpm test:unit && pnpm test:apps",
 		"check": "tsc",
 		"lint": "prettier --check .",
 		"format": "pnpm lint --write",
-		"prepublishOnly": "pnpm build"
+		"prepublishOnly": "pnpm build",
+		"test:unit": "vitest run",
+		"test:apps": "pnpm build && pnpm -r --workspace-concurrency 1 --filter=\"./test/**\" test"
 	},
 	"devDependencies": {
 		"@polka/url": "catalog:",

diff --git a/packages/adapter-node/test/apps/instrumentation/.gitignore b/packages/adapter-node/test/apps/instrumentation/.gitignore
@@ -0,0 +1,4 @@
+.DS_Store
+node_modules
+/.svelte-kit
+/build
diff --git a/packages/adapter-node/test/apps/instrumentation/package.json b/packages/adapter-node/test/apps/instrumentation/package.json
@@ -0,0 +1,21 @@
+{
+	"name": "test-adapter-node-instrumentation",
+	"version": "0.0.1",
+	"private": true,
+	"type": "module",
+	"imports": {
+		"#lib/*": "./src/lib/*"
+	},
+	"scripts": {
+		"dev": "vite dev",
+		"build": "vite build",
+		"prepare": "svelte-kit sync || echo ''",
+		"test": "MY_BASE_URL=https://api.example pnpm build && node test/boot.js"
+	},
+	"devDependencies": {
+		"@sveltejs/kit": "workspace:^",
+		"@sveltejs/vite-plugin-svelte": "catalog:",
+		"svelte": "catalog:",
+		"vite": "catalog:"
+	}
+}
diff --git a/packages/adapter-node/test/apps/instrumentation/src/app.html b/packages/adapter-node/test/apps/instrumentation/src/app.html
@@ -0,0 +1,12 @@
+<!doctype html>
+<html lang="en">
+	<head>
+		<meta charset="utf-8" />
+		<meta name="viewport" content="width=device-width, initial-scale=1" />
+		%sveltekit.head%
+	</head>
+
+	<body>
+		<div>%sveltekit.body%</div>
+	</body>
+</html>
diff --git a/packages/adapter-node/test/apps/instrumentation/src/env.js b/packages/adapter-node/test/apps/instrumentation/src/env.js
@@ -0,0 +1,5 @@
+import { defineEnvVars } from '@sveltejs/kit/env';
+
+export const variables = defineEnvVars({
+	MY_BASE_URL: { public: false, static: false }
+});
diff --git a/packages/adapter-node/test/apps/instrumentation/src/instrumentation.server.js b/packages/adapter-node/test/apps/instrumentation/src/instrumentation.server.js
@@ -0,0 +1,4 @@
+// The mere presence of this file makes adapter-node call `builder.instrument()`
+// (with `env: 'process.env'` on the eager-env branch), generating the env-init
+// facade — the code path under test.
+console.log('[instrumentation] evaluated');
diff --git a/packages/adapter-node/test/apps/instrumentation/src/lib/server/api-client.js b/packages/adapter-node/test/apps/instrumentation/src/lib/server/api-client.js
@@ -0,0 +1,5 @@
+import { MY_BASE_URL } from '$app/env/private';
+
+// Module-scope read — mirrors configuring an API client with `baseUrl` from dynamic
+// env. Correct only if env is populated before this module evaluates.
+export const CAPTURED_AT_MODULE_SCOPE = MY_BASE_URL;
diff --git a/packages/adapter-node/test/apps/instrumentation/src/routes/+page.svelte b/packages/adapter-node/test/apps/instrumentation/src/routes/+page.svelte
@@ -0,0 +1 @@
+<h1>adapter-node instrumentation test app</h1>
diff --git a/packages/adapter-node/test/apps/instrumentation/src/routes/env/+server.js b/packages/adapter-node/test/apps/instrumentation/src/routes/env/+server.js
@@ -0,0 +1,10 @@
+import process from 'node:process';
+import { json } from '@sveltejs/kit';
+import { CAPTURED_AT_MODULE_SCOPE } from '#lib/server/api-client.js';
+
+export function GET() {
+	return json({
+		captured: CAPTURED_AT_MODULE_SCOPE ?? null,
+		live: process.env.MY_BASE_URL ?? null
+	});
+}
diff --git a/packages/adapter-node/test/apps/instrumentation/test/boot.js b/packages/adapter-node/test/apps/instrumentation/test/boot.js
@@ -0,0 +1,66 @@
+// Boots the adapter-node build output with an instrumentation file present and
+// asserts that (1) the server starts at all — regression for the env-init facade
+// resolving `set_env` from the adapter's own `env.js` (sveltejs/kit#16303),
+// and (2) a module-scope `$app/env/private` read observes the runtime value —
+// regression for sveltejs/kit#16288.
+import { spawn } from 'node:child_process';
+import process from 'node:process';
+
+const PORT = 3399;
+const EXPECTED = 'https://api.example';
+
+const server = spawn(process.execPath, ['build/index.js'], {
+	env: {
+		...process.env,
+		MY_BASE_URL: EXPECTED,
+		PORT: String(PORT),
+		HOST: '127.0.0.1'
+	},
+	stdio: ['ignore', 'pipe', 'pipe']
+});
+
+let output = '';
+server.stdout.on('data', (chunk) => (output += chunk));
+server.stderr.on('data', (chunk) => (output += chunk));
+
+let exited = false;
+server.on('exit', () => (exited = true));
+
+function fail(message) {
+	console.error(`FAIL: ${message}`);
+	console.error('--- server output ---');
+	console.error(output || '(none)');
+	server.kill();
+	process.exit(1);
+}
+
+try {
+	let response;
+	for (let attempt = 0; attempt < 40; attempt++) {
+		if (exited) fail('server exited before responding (startup crash)');
+		await new Promise((resolve) => setTimeout(resolve, 250));
+		try {
+			response = await fetch(`http://127.0.0.1:${PORT}/env`);
+			break;
+		} catch {
+			// not up yet
+		}
+	}
+	if (!response) fail('server never came up');
+
+	const { captured, live } = await response.json();
+	if (live !== EXPECTED)
+		fail(`live env read is ${JSON.stringify(live)}, expected ${JSON.stringify(EXPECTED)}`);
+	if (captured !== EXPECTED) {
+		fail(
+			`module-scope $app/env/private read captured ${JSON.stringify(captured)} — evaluated before env was set`
+		);
+	}
+	console.log(
+		'PASS: server booted with instrumentation and module-scope env read observed the runtime value'
+	);
+	server.kill();
+	process.exit(0);
+} catch (error) {
+	fail(error.message);
+}
diff --git a/packages/adapter-node/test/apps/instrumentation/tsconfig.json b/packages/adapter-node/test/apps/instrumentation/tsconfig.json
@@ -0,0 +1,13 @@
+{
+	"compilerOptions": {
+		"allowJs": true,
+		"checkJs": true,
+		"esModuleInterop": true,
+		"forceConsistentCasingInFileNames": true,
+		"resolveJsonModule": true,
+		"skipLibCheck": true,
+		"sourceMap": true,
+		"moduleResolution": "bundler"
+	},
+	"extends": "./.svelte-kit/tsconfig.json"
+}
diff --git a/packages/adapter-node/test/apps/instrumentation/vite.config.js b/packages/adapter-node/test/apps/instrumentation/vite.config.js
@@ -0,0 +1,14 @@
+import { sveltekit } from '@sveltejs/kit/vite';
+import adapter from '../../../index.js';
+
+/** @type {import('vite').UserConfig} */
+export default {
+	build: {
+		minify: false
+	},
+	plugins: [
+		sveltekit({
+			adapter: adapter()
+		})
+	]
+};
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml