Changed link redirects from middleware to router

ref https://linear.app/ghost/issue/BER-3095

Extracted the link redirects code from the middleware to the router.
This avoids route comparison on every requests Ghost receives.

Author: rmgpinto

ghost/core/core/frontend/web/routers/link-redirects.js

@@ -0,0 +1,5 @@
+const linkRedirects = require('../../../server/services/link-redirection');
+
+module.exports = function handleRedirects(siteApp) {
+    siteApp.get(linkRedirects.service.redirectPrefix() + '*', linkRedirects.service.handleRequest);
+};

ghost/core/core/frontend/web/site.js

@@ -15,7 +15,7 @@ const themeMiddleware = themeEngine.middleware;
 const membersService = require('../../server/services/members');
 const offersService = require('../../server/services/offers');
 const customRedirects = require('../../server/services/custom-redirects');
-const linkRedirects = require('../../server/services/link-redirection');
+const linkRedirectsHandler = require('./routers/link-redirects');
 const {cardAssets} = require('../services/assets-minification');
 const siteRoutes = require('./routes');
 const shared = require('../../server/web/shared');
@@ -51,7 +51,7 @@ module.exports = function setupSiteApp(routerConfig) {
 
     siteApp.use(offersService.middleware);
 
-    siteApp.use(linkRedirects.service.handleRequest);
+    linkRedirectsHandler(siteApp);
 
     // you can extend Ghost with a custom redirects file
     // see https://github.com/TryGhost/Ghost/issues/7707

ghost/core/core/server/services/link-redirection/LinkRedirectsService.js

@@ -77,6 +77,25 @@ class LinkRedirectsService {
         return link;
     }
 
+    /**
+     * Returns the full path prefix including subdirectory (e.g., /blog/r/)
+     * Used for building full URLs
+     * @return {string}
+     **/
+    redirectPrefix() {
+        const fullURLWithRedirectPrefix = `${this.#baseURL.pathname}${this.#redirectURLPrefix}`;
+        return fullURLWithRedirectPrefix;
+    }
+
+    /**
+     * Returns the route path for Express routing (always /r/)
+     * Express routing uses req.path which excludes subdirectory
+     * @return {string}
+     **/
+    routePath() {
+        return `/${this.#redirectURLPrefix}`;
+    }
+
     /**
      * @param {import('express').Request} req
      * @param {import('express').Response} res
@@ -86,18 +105,6 @@ class LinkRedirectsService {
      */
     async handleRequest(req, res, next) {
         try {
-            // skip handling if original url doesn't match the prefix
-            const fullURLWithRedirectPrefix = `${this.#baseURL.pathname}${this.#redirectURLPrefix}`;
-            // @NOTE: below is equivalent to doing:
-            //          router.get('/r/'), (req, res) ...
-            //        To make it cleaner we should rework it to:
-            //          linkRedirects.service.handleRequest(router);
-            //        and mount routes on top like for example sitemapHandler does
-            //        Cleanup issue: https://github.com/TryGhost/Toolbox/issues/516
-            if (!req.originalUrl.startsWith(fullURLWithRedirectPrefix)) {
-                return next();
-            }
-
             const url = new URL(req.originalUrl, this.#baseURL);
             const link = await this.#linkRedirectRepository.getByURL(url);
 

ghost/core/test/unit/server/services/link-redirection/LinkRedirectsService.test.js

@@ -65,6 +65,28 @@ describe('LinkRedirectsService', function () {
         });
     });
 
+    describe('redirectPrefix', function () {
+        it('returns the full path including subdirectory', function () {
+            const instance = new LinkRedirectsService({
+                linkRedirectRepository: {},
+                config: {
+                    baseURL: new URL('https://localhost:2368/blog/')
+                }
+            });
+            assert.equal(instance.redirectPrefix(), '/blog/r/');
+        });
+
+        it('returns path without subdirectory when none configured', function () {
+            const instance = new LinkRedirectsService({
+                linkRedirectRepository: {},
+                config: {
+                    baseURL: new URL('https://localhost:2368/')
+                }
+            });
+            assert.equal(instance.redirectPrefix(), '/r/');
+        });
+    });
+
     describe('handleRequest', function () {
         it('redirects if found', async function () {
             const linkRedirectRepository = {