Merge commit from fork

* fix: 404 for immutable assets that don't match static files

* how did i not see this

* woot

Author: elliott-with-the-longest-name-on-github

.changeset/eighty-rabbits-sit.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-vercel': patch
+---
+
+fix: 404 for immutable assets that don't match static files

packages/adapter-vercel/index.js

@@ -616,6 +616,19 @@ function static_vercel_config(builder, config, dir) {
 	}
 
 	const routes = [
+		// Strip any user-supplied __pathname query parameter; SvelteKit reserves
+		// this for ISR handlers
+		{
+			src: '.*',
+			continue: true,
+			transforms: [
+				{
+					type: 'request.query',
+					op: 'delete',
+					target: { key: '__pathname' }
+				}
+			]
+		},
 		...prerendered_redirects,
 		{
 			src: `/${builder.getAppPath()}/immutable/.+`,
@@ -666,6 +679,16 @@ function static_vercel_config(builder, config, dir) {
 		handle: 'filesystem'
 	});
 
+	// Prevent incorrect caching: if a request to /_app/immutable/* doesn't match
+	// a static file, return 404 instead of falling through to dynamic routes.
+	// Otherwise, we could accidentally immutably cache dynamic content served
+	// by the fallback function.
+	routes.push({
+		src: `/${builder.getAppPath()}/immutable/.+`,
+		status: 404,
+		continue: false
+	});
+
 	return {
 		version: 3,
 		routes,