fix: correctly return asset list when building (#9095)

* pass array of assets into the buider.writeClient Set

* add asset path prefix to server assets

* copy test from #9102

* tweak changeset

* one of the things needs to be posixified and i do not know which

* try this

---------

Co-authored-by: Rich Harris <[email protected]>

Author: eltigerchino

.changeset/late-rings-warn.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: return correct asset list from `builder.writeClient()`

packages/kit/src/core/adapt/builder.js

@@ -185,9 +185,9 @@ export function create_builder({
 			const server_assets = copy(
 				`${config.kit.outDir}/output/server/${config.kit.appDir}/immutable/assets`,
 				join(dest, config.kit.appDir, 'immutable/assets')
-			);
+			).map((filename) => join(config.kit.appDir, 'immutable/assets', filename));
 			const client_assets = copy(`${config.kit.outDir}/output/client`, dest);
-			return Array.from(new Set(...server_assets, ...client_assets));
+			return Array.from(new Set([...server_assets, ...client_assets]));
 		},
 
 		// @ts-expect-error

packages/kit/src/core/adapt/builder.spec.js

@@ -5,6 +5,7 @@ import { test } from 'uvu';
 import * as assert from 'uvu/assert';
 import glob from 'tiny-glob/sync.js';
 import { create_builder } from './builder.js';
+import { posixify } from '../../utils/filesystem.js';
 
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = join(__filename, '..');
@@ -45,15 +46,23 @@ test('copy files', () => {
 	const dest = join(__dirname, 'output');
 
 	rmSync(dest, { recursive: true, force: true });
-	builder.writeClient(dest);
+
+	assert.equal(
+		builder.writeClient(dest),
+		glob('**', { cwd: dest, dot: true, filesOnly: true }).map(posixify)
+	);
 
 	assert.equal(
 		glob('**', { cwd: `${outDir}/output/client`, dot: true }),
 		glob('**', { cwd: dest, dot: true })
 	);
 
 	rmSync(dest, { recursive: true, force: true });
-	builder.writeServer(dest);
+
+	assert.equal(
+		builder.writeServer(dest),
+		glob('**', { cwd: dest, dot: true, filesOnly: true }).map(posixify)
+	);
 
 	assert.equal(
 		glob('**', { cwd: `${outDir}/output/server`, dot: true }),