From 24f64a56e1bc62a623e758da69e2cfefa5c61ba1 Mon Sep 17 00:00:00 2001
From: Manzoor Wani <manzoorwani.jk@gmail.com>
Date: Tue, 16 Jun 2026 23:28:39 +0530
Subject: [PATCH] chore: add web-login proxy doneUrl regression for #8875

---
 mock-registry/lib/index.js |  9 ++++++---
 test/lib/commands/login.js | 13 +++++++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/mock-registry/lib/index.js b/mock-registry/lib/index.js
index 6f3b022467f35..a0efca8c697ca 100644
--- a/mock-registry/lib/index.js
+++ b/mock-registry/lib/index.js
@@ -261,15 +261,18 @@ class MockRegistry {
       .reply(200, { token })
   }
 
-  weblogin ({ token = 'npm_default-test-token' }) {
-    const doneUrl = new URL('/npm-cli-test/done', this.origin).href
+  weblogin ({ token = 'npm_default-test-token', doneRegistry } = {}) {
+    const donePath = '/npm-cli-test/done'
+    // doneRegistry emulates a proxy/mirror that advertises a doneUrl on a different origin than the configured registry.
+    // The poll itself is always mocked on this registry, since that is where the session lives.
+    const doneUrl = new URL(donePath, doneRegistry ?? this.origin).href
     const loginUrl = new URL('/npm-cli-test/login/cli/00000000-0000-0000-0000-000000000000', this.origin).href
     this.nock = this.nock
       .post(this.fullPath('/-/v1/login'), () => {
         return true
       })
       .reply(200, { doneUrl, loginUrl })
-      .get('/npm-cli-test/done')
+      .get(donePath)
       .reply(200, { token })
   }
 
diff --git a/test/lib/commands/login.js b/test/lib/commands/login.js
index f855fe683bd9f..623bc5845708f 100644
--- a/test/lib/commands/login.js
+++ b/test/lib/commands/login.js
@@ -129,6 +129,19 @@ t.test('web', t => {
     })
     t.match(outputs[0], '/npm-cli-test/login/cli/00000000-0000-0000-0000-000000000000')
   })
+  t.test('proxy registry whose doneUrl points at the canonical registry', async t => {
+    // Regression for npm/cli#8875: a proxy/mirror returns a doneUrl on registry.npmjs.org.
+    // npm must poll the configured proxy where the session lives, not the canonical registry.
+    const proxy = 'https://proxy.registry.example/'
+    const { npm, registry, login, rc } = await mockLogin(t, {
+      registry: proxy,
+      config: { 'auth-type': 'web', registry: proxy },
+    })
+    registry.weblogin({ token: 'npm_proxy-token', doneRegistry: 'https://registry.npmjs.org' })
+    await login.exec([])
+    t.same(npm.config.get('//proxy.registry.example/:_authToken'), 'npm_proxy-token')
+    t.match(rc(), { '//proxy.registry.example/:_authToken': 'npm_proxy-token' })
+  })
   t.test('server error', async t => {
     const { registry, login } = await mockLogin(t, {
       config: { 'auth-type': 'web' },