update trailing slash logic

packages/next/src/lib/metadata/resolvers/resolve-url.test.ts

@@ -111,7 +111,7 @@ describe('resolveAbsoluteUrlWithPathname', () => {
       )
     })
 
-    it('should not add trailing slash to relative url that ends with a file extension', () => {
+    it('should not add trailing slash to relative url that matches file pattern', () => {
       expect(resolver('/foo.html')).toBe('https://example.com/foo.html')
       expect(resolver(new URL('/foo.html', metadataBase))).toBe(
         'https://example.com/foo.html'

packages/next/src/lib/metadata/resolvers/resolve-url.ts

@@ -86,6 +86,13 @@ function resolveRelativeUrl(url: string | URL, pathname: string): string | URL {
   return url
 }
 
+// The regex is matching logic from packages/next/src/lib/load-custom-routes.ts
+const FILE_REGEX =
+  /^(?:\/((?!\.well-known(?:\/.*)?)(?:[^/]+\/)*[^/]+\.\w+))\/[/#?]?$/i
+function isFilePattern(pathname: string): boolean {
+  return FILE_REGEX.test(pathname)
+}
+
 // Resolve `pathname` if `url` is a relative path the compose with `metadataBase`.
 function resolveAbsoluteUrlWithPathname(
   url: string | URL,
@@ -112,7 +119,8 @@ function resolveAbsoluteUrlWithPathname(
     let isRelative = resolvedUrl.startsWith('/')
     let isExternal = false
     let hasQuery = resolvedUrl.includes('?')
-    let hasFileExtension = /\.[0-9a-z]+$/i.test(resolvedUrl)
+    // Do not apply trailing slash for file like urls, aligning with the behavior with `trailingSlash`
+    let isFileUrl = isFilePattern(resolvedUrl)
 
     if (!isRelative) {
       try {
@@ -123,8 +131,7 @@ function resolveAbsoluteUrlWithPathname(
         // If it's not a valid URL, treat it as external
         isExternal = true
       }
-      if (!hasFileExtension && !isExternal && !hasQuery)
-        return `${resolvedUrl}/`
+      if (!isFileUrl && !isExternal && !hasQuery) return `${resolvedUrl}/`
     }
   }