Fix splitting of concatenated Set-Cookie headers in edge-runtime package

.changeset/old-houses-film.md

@@ -0,0 +1,7 @@
+---
+'@edge-runtime/cookies': minor
+'edge-runtime': path
+---
+
+feat(cookies): expose splitCookiesString function
+fix: splitting cookies when concatenated

packages/cookies/src/index.ts

@@ -1,4 +1,9 @@
 export type { CookieListItem, RequestCookie, ResponseCookie } from './types'
 export { RequestCookies } from './request-cookies'
 export { ResponseCookies } from './response-cookies'
-export { stringifyCookie, parseCookie, parseSetCookie } from './serialize'
+export {
+  stringifyCookie,
+  parseCookie,
+  parseSetCookie,
+  splitCookiesString,
+} from './serialize'

packages/runtime/package.json

@@ -24,6 +24,7 @@
     "web"
   ],
   "dependencies": {
+    "@edge-runtime/cookies": "workspace:*",
     "@edge-runtime/format": "workspace:*",
     "@edge-runtime/ponyfill": "workspace:*",
     "@edge-runtime/vm": "workspace:*",

packages/runtime/src/server/create-handler.ts

@@ -2,6 +2,7 @@ import type { EdgeRuntime } from '../edge-runtime'
 import type { IncomingMessage, ServerResponse } from 'http'
 import type { Logger, NodeHeaders } from '../types'
 import type { EdgeContext } from '@edge-runtime/vm'
+import { splitCookiesString } from '@edge-runtime/cookies'
 import { getClonableBodyStream, pipeBodyStreamToResponse } from './body-streams'
 import prettyMs from 'pretty-ms'
 import timeSpan from 'time-span'
@@ -112,13 +113,15 @@ function toRequestInitHeaders(req: IncomingMessage): RequestInit['headers'] {
 
 /**
  * Transforms WHATWG Headers into a Node Headers shape. Copies all items but
- * does a special case for Set-Cookie using the [`getSetCookie`](https://developer.mozilla.org/en-US/docs/Web/API/Headers/getSetCookie) method.
+ * does a special case for Set-Cookie header field-values are sometimes comma joined in one string. This splits them without choking on commas
+ * that are within a single set-cookie field-value, such as in the Expires portion.
  */
 function toNodeHeaders(headers?: Headers): NodeHeaders {
   const result: NodeHeaders = {}
   if (headers) {
     for (const [key, value] of headers.entries()) {
-      result[key] = key === 'set-cookie' ? headers.getSetCookie() : value
+      result[key] =
+        key?.toLowerCase() === 'set-cookie' ? splitCookiesString(value) : value
     }
   }
   return result