fix: allow asset(...) to be used with imported assets

.changeset/little-impalas-warn.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: allow `asset(...)` to be used with imported assets

documentation/docs/98-reference/20-$app-types.md

@@ -15,12 +15,12 @@ import type { RouteId, RouteParams, LayoutParams } from '$app/types';
 
 ## Asset
 
-A union of all the filenames of assets contained in your `static` directory.
+A union of all the filenames of assets contained in your `static` directory, plus a `string` wildcard for asset paths generated from `import` declarations.
 
 <div class="ts-block">
 
 ```dts
-type Asset = '/favicon.png' | '/robots.txt';
+type Asset = '/favicon.png' | '/robots.txt' | (string & {});
 ```
 
 </div>

packages/kit/src/core/sync/write_non_ambient.js

@@ -91,6 +91,8 @@ function generate_app_types(manifest_data) {
 		layouts.push(layout_type);
 	}
 
+	const assets = manifest_data.assets.map((asset) => s('/' + asset.file));
+
 	return [
 		'declare module "$app/types" {',
 		'\texport interface AppTypes {',
@@ -99,7 +101,7 @@ function generate_app_types(manifest_data) {
 		`\t\tLayoutParams(): {\n\t\t\t${layouts.join(';\n\t\t\t')}\n\t\t};`,
 		`\t\tPathname(): ${Array.from(pathnames).join(' | ')};`,
 		'\t\tResolvedPathname(): `${"" | `/${string}`}${ReturnType<AppTypes[\'Pathname\']>}`;',
-		`\t\tAsset(): ${manifest_data.assets.map((asset) => s('/' + asset.file)).join(' | ') || 'never'};`,
+		`\t\tAsset(): ${assets.concat('string & {}').join(' | ')};`,
 		'\t}',
 		'}'
 	].join('\n');

packages/kit/src/core/sync/write_types/index.spec.js

@@ -46,7 +46,7 @@ test('Creates correct $types', { timeout: 60000 }, () => {
 			execSync('pnpm testtypes', { cwd: path.join(cwd, dir) });
 		} catch (e) {
 			console.error(/** @type {any} */ (e).stdout.toString());
-			throw new Error('Type tests failed');
+			throw new Error(`${dir} type tests failed`);
 		}
 	}
 });

packages/kit/src/runtime/app/paths/types.d.ts

@@ -56,7 +56,7 @@ export function resolve<T extends RouteId | Pathname>(...args: ResolveArgs<T>):
  * 	import { asset } from '$app/paths';
  * </script>
  *
- * <img alt="a potato" src={asset('potato.jpg')} />
+ * <img alt="a potato" src={asset('/potato.jpg')} />
  * ```
  * @since 2.26
  */

packages/kit/types/index.d.ts

@@ -2770,7 +2770,7 @@ declare module '$app/paths' {
 	 * 	import { asset } from '$app/paths';
 	 * </script>
 	 *
-	 * <img alt="a potato" src={asset('potato.jpg')} />
+	 * <img alt="a potato" src={asset('/potato.jpg')} />
 	 * ```
 	 * @since 2.26
 	 */