fix: Ensure response headers are set for extra target network requests (#28322)

cli/CHANGELOG.md

@@ -5,6 +5,7 @@ _Released 11/21/2023 (PENDING)_
 
 **Bugfixes:**
 
+- Fixed an issue where pages opened in a new tab were missing response headers, causing them not to load properly. Fixes [#28293](https://github.com/cypress-io/cypress/issues/28293) and [#28303](https://github.com/cypress-io/cypress/issues/28303).
 - We now pass a flag to Chromium browsers to disable default component extensions. This is a common flag passed during browser automation. Fixed in [#28294](https://github.com/cypress-io/cypress/pull/28294).
 
 ## 13.5.0

packages/proxy/lib/http/response-middleware.ts

@@ -174,6 +174,10 @@ const FilterNonProxiedResponse: ResponseMiddleware = function () {
   if (this.req.isFromExtraTarget) {
     this.debug('response for [%s %s] is from extra target', this.req.method, this.req.proxiedUrl)
 
+    // this is normally done in the OmitProblematicHeaders middleware, but we
+    // don't want to omit any headers in this case
+    this.res.set(this.incomingRes.headers)
+
     this.onlyRunMiddleware([
       'AttachPlainTextStreamFn',
       'PatchExpressSetHeader',

packages/proxy/test/unit/http/response-middleware.spec.ts

@@ -103,22 +103,28 @@ describe('http/response-middleware', function () {
   describe('FilterNonProxiedResponse', () => {
     const { FilterNonProxiedResponse } = ResponseMiddleware
     let ctx
+    let headers
 
     beforeEach(() => {
+      headers = { 'header-name': 'header-value' }
       ctx = {
         onlyRunMiddleware: sinon.stub(),
+        incomingRes: { headers },
         req: {},
         res: {
+          set: sinon.stub(),
           off: (event, listener) => {},
         },
       }
     })
 
-    it('runs minimal subsequent middleware if request is from an extra target', () => {
+    it('sets headers on response and runs minimal subsequent middleware if request is from an extra target', () => {
       ctx.req.isFromExtraTarget = true
 
       return testMiddleware([FilterNonProxiedResponse], ctx)
       .then(() => {
+        expect(ctx.res.set).to.be.calledWith(headers)
+
         expect(ctx.onlyRunMiddleware).to.be.calledWith([
           'AttachPlainTextStreamFn',
           'PatchExpressSetHeader',