Fix pattern matching for @ encoded routes

.changeset/rich-walls-doubt.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+Fix pattern matching for routes starting with an encoded `@` symbol

packages/kit/src/utils/routing.js

@@ -16,11 +16,12 @@ export function parse_route_id(id) {
 		id === ''
 			? /^\/$/
 			: new RegExp(
-					`^${decodeURIComponent(id)
+					`^${id
 						.split(/(?:@[a-zA-Z0-9_-]+)?(?:\/|$)/)
 						.map((segment, i, segments) => {
+							const decoded_segment = decodeURIComponent(segment);
 							// special case — /[...rest]/ could contain zero segments
-							const match = /^\[\.\.\.(\w+)(?:=(\w+))?\]$/.exec(segment);
+							const match = /^\[\.\.\.(\w+)(?:=(\w+))?\]$/.exec(decoded_segment);
 							if (match) {
 								names.push(match[1]);
 								types.push(match[2]);
@@ -30,9 +31,9 @@ export function parse_route_id(id) {
 							const is_last = i === segments.length - 1;
 
 							return (
-								segment &&
+								decoded_segment &&
 								'/' +
-									segment
+									decoded_segment
 										.split(/\[(.+?)\]/)
 										.map((content, i) => {
 											if (i % 2) {

packages/kit/src/utils/routing.spec.js

@@ -42,6 +42,16 @@ const tests = {
 		pattern: /^\/matched\/([^/]+?)\/?$/,
 		names: ['id'],
 		types: ['uuid']
+	},
+	'%23hash-encoded': {
+		pattern: /^\/%23hash-encoded\/?$/,
+		names: [],
+		types: []
+	},
+	'%40at-encoded/[id]': {
+		pattern: /^\/@at-encoded\/([^/]+?)\/?$/,
+		names: ['id'],
+		types: [undefined]
 	}
 };