[fix] redirects from actions don't honor the provided status code (#8210)

fixes #8209

Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>

Author: coryvirok

.changeset/tidy-pandas-report.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+Fix form action redirect status code

packages/kit/src/runtime/server/page/index.js

@@ -62,7 +62,7 @@ export async function render_page(event, route, page, options, state, resolve_op
 			// (this also determines status code)
 			action_result = await handle_action_request(event, leaf_node.server);
 			if (action_result?.type === 'redirect') {
-				return redirect_response(303, action_result.location);
+				return redirect_response(action_result.status, action_result.location);
 			}
 			if (action_result?.type === 'error') {
 				const error = action_result.error;

packages/kit/test/apps/basics/test/test.js

@@ -2010,12 +2010,25 @@ test.describe('Actions', () => {
 		);
 	});
 
-	test('redirect', async ({ page }) => {
+	test('redirect', async ({ page, javaScriptEnabled }) => {
 		await page.goto('/actions/redirect');
 
 		page.click('button');
 
-		await Promise.all([page.waitForResponse('/actions/redirect'), page.waitForNavigation()]);
+		const [redirect] = await Promise.all([
+			page.waitForResponse('/actions/redirect'),
+			page.waitForNavigation()
+		]);
+		if (javaScriptEnabled) {
+			expect(await redirect.json()).toEqual({
+				type: 'redirect',
+				location: '/actions/enhance',
+				status: 303
+			});
+		} else {
+			expect(redirect.status()).toBe(303);
+			expect(redirect.headers()['location']).toBe('/actions/enhance');
+		}
 
 		expect(page.url()).toContain('/actions/enhance');
 	});