fix: generate route types only once during svelte-kit sync

.changeset/tidy-single-sync.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: avoid generating route types twice during svelte-kit sync

packages/kit/src/cli.js

@@ -103,7 +103,11 @@ if (command === 'sync') {
 		const sveltekit_config = extract_svelte_config(vite_config);
 
 		const sync = await import('./core/sync/sync.js');
-		sync.all_types(sveltekit_config, vite_config.root);
+		// Resolving a build config already syncs via the compile plugin. Plugin-free configs
+		// (for example, component libraries) still need the types-only fallback.
+		if (!vite_config.plugins.some((plugin) => plugin.name === 'vite-plugin-sveltekit-compile')) {
+			sync.all_types(sveltekit_config, vite_config.root);
+		}
 
 		const entry = resolve_env_entry(sveltekit_config, vite_config.root);
 		await sync.env(sveltekit_config, entry, vite_config.root, values.mode);

packages/kit/test/apps/options/test/test.js

@@ -1,11 +1,46 @@
 import process from 'node:process';
+import path from 'node:path';
+import { spawnSync } from 'node:child_process';
 import { expect } from '@playwright/test';
 import { test } from '../../../utils.js';
 
 test.describe.configure({ mode: 'parallel' });
 
 test.skip(!!process.env.PATHS_ASSETS || process.env.PATHS_RELATIVE === 'false');
 
+test('sync generates route types once', ({ javaScriptEnabled }) => {
+	test.skip(!javaScriptEnabled);
+
+	// Every write_all_types invocation writes route_meta_data.json, even when the types are current.
+	const preload = `
+		import fs from 'node:fs';
+		const write = fs.writeFileSync;
+		fs.writeFileSync = function(file, ...args) {
+			if (String(file).endsWith('route_meta_data.json')) {
+				console.log('route types generated');
+			}
+			return write.call(this, file, ...args);
+		};
+	`;
+
+	const result = spawnSync(
+		process.execPath,
+		[
+			'--import',
+			`data:text/javascript,${encodeURIComponent(preload)}`,
+			'node_modules/@sveltejs/kit/svelte-kit.js',
+			'sync',
+			'--config',
+			'vite.custom.config.js'
+		],
+		{ cwd: path.resolve(import.meta.dirname, '..'), encoding: 'utf-8', timeout: 30_000 }
+	);
+
+	expect(result.error).toBeUndefined();
+	expect(result.status, result.stderr).toBe(0);
+	expect(result.stdout.match(/route types generated/g)).toHaveLength(1);
+});
+
 test.describe('CSP', () => {
 	test('blocks script from external site', async ({ page, start_server }) => {
 		const { port } = await start_server((req, res) => {

packages/kit/test/apps/options/unit-test/vite.spec.js

@@ -1,6 +1,7 @@
 import { test, expect } from 'vitest';
 import { spawnSync } from 'node:child_process';
 import path from 'node:path';
+import fs from 'node:fs';
 import { createFilter, resolveConfig } from 'vite';
 import { bullet_list } from '../../../../src/utils/format.js';
 
@@ -78,3 +79,110 @@ test('transformIndexHtml warning for app plugins', { timeout }, () => {
 		contains: [bullet_list(['app-html-transform'])]
 	});
 });
+
+test('sync generates types without the SvelteKit plugin', { timeout }, () => {
+	const temp = path.join(cwd, '.test-tmp');
+	fs.mkdirSync(temp, { recursive: true });
+	const root = fs.mkdtempSync(path.join(temp, 'sync-'));
+
+	try {
+		fs.writeFileSync(
+			path.join(root, 'vite.config.js'),
+			'export default { root: import.meta.dirname };'
+		);
+		fs.mkdirSync(path.join(root, 'src/routes'), { recursive: true });
+		fs.writeFileSync(
+			path.join(root, 'src/routes/+page.server.js'),
+			'export const load = () => ({ message: "hello" });'
+		);
+
+		const result = spawnSync(
+			process.execPath,
+			[
+				'node_modules/@sveltejs/kit/svelte-kit.js',
+				'sync',
+				'--config',
+				path.join(root, 'vite.config.js')
+			],
+			{ cwd, encoding: 'utf-8', timeout }
+		);
+
+		expect(result.error).toBeUndefined();
+		expect(result.status, result.stderr).toBe(0);
+		expect(fs.existsSync(path.join(root, 'node_modules/$app/tsconfig.json'))).toBe(true);
+		expect(
+			fs.readFileSync(path.join(root, '.svelte-kit/types/src/routes/$types.d.ts'), 'utf-8')
+		).toContain('PageServerLoad');
+		expect(fs.existsSync(path.join(root, 'node_modules/$app/types/index.d.ts'))).toBe(true);
+		expect(fs.existsSync(path.join(root, 'node_modules/$app/types/env.d.ts'))).toBe(true);
+	} finally {
+		fs.rmSync(root, { recursive: true, force: true });
+	}
+});
+
+test.each(['build', 'serve'])(
+	'sync generates fresh types with compile plugin apply: %s',
+	{ timeout },
+	(apply) => {
+		const temp = path.join(cwd, '.test-tmp');
+		fs.mkdirSync(temp, { recursive: true });
+		const root = fs.mkdtempSync(path.join(temp, 'sync-'));
+
+		try {
+			fs.writeFileSync(
+				path.join(root, 'vite.config.js'),
+				`
+					import { sveltekit } from '@sveltejs/kit/vite';
+					const plugins = await sveltekit({ files: { src: 'source' }, outDir: '.custom-output' });
+					plugins.find((plugin) => plugin.name === 'vite-plugin-sveltekit-compile').apply = '${apply}';
+					export default { root: import.meta.dirname, plugins };
+				`
+			);
+			fs.mkdirSync(path.join(root, 'source/routes'), { recursive: true });
+			fs.writeFileSync(
+				path.join(root, 'source/app.html'),
+				'<html><head>%sveltekit.head%</head><body>%sveltekit.body%</body></html>'
+			);
+			fs.writeFileSync(
+				path.join(root, 'source/routes/+page.server.js'),
+				'export const load = () => ({ message: "hello" });'
+			);
+			fs.writeFileSync(
+				path.join(root, 'source/env.js'),
+				'export const variables = import.meta.env.MODE === "custom" ? { CUSTOM_MODE: {} } : { OTHER_MODE: {} };'
+			);
+
+			const result = spawnSync(
+				process.execPath,
+				[
+					'node_modules/@sveltejs/kit/svelte-kit.js',
+					'sync',
+					'--config',
+					path.join(root, 'vite.config.js'),
+					'--mode',
+					'custom'
+				],
+				{ cwd, encoding: 'utf-8', timeout }
+			);
+
+			expect(result.error).toBeUndefined();
+			expect(result.status, result.stderr).toBe(0);
+			expect(fs.existsSync(path.join(root, 'node_modules/$app/tsconfig.json'))).toBe(true);
+			expect(
+				fs.readFileSync(path.join(root, '.custom-output/types/source/routes/$types.d.ts'), 'utf-8')
+			).toContain('PageServerLoad');
+			expect(fs.existsSync(path.join(root, 'node_modules/$app/types/index.d.ts'))).toBe(true);
+			const env_types = fs.readFileSync(
+				path.join(root, 'node_modules/$app/types/env.d.ts'),
+				'utf-8'
+			);
+			expect(env_types).toContain('CUSTOM_MODE');
+			expect(env_types).not.toContain('OTHER_MODE');
+			expect(fs.existsSync(path.join(root, '.custom-output/generated/build/server.js'))).toBe(
+				apply === 'build'
+			);
+		} finally {
+			fs.rmSync(root, { recursive: true, force: true });
+		}
+	}
+);

scripts/sync-all.js

@@ -25,6 +25,11 @@ for (const directories of [
 		chdir(cwd);
 
 		const vite_config = await load_vite_config();
+		// The compile plugin has already synced these files while resolving the config.
+		if (vite_config.plugins.some((plugin) => plugin.name === 'vite-plugin-sveltekit-compile')) {
+			continue;
+		}
+
 		const sveltekit_config = extract_svelte_config(vite_config);
 
 		const manifest_data = create_manifest_data(sveltekit_config, cwd);