fix: preserve page context via cookie after Bluesky redirect (#930)

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
Co-authored-by: Daniel Roe <daniel@roe.dev>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

Author: 4 people

app/components/Header/AuthModal.client.vue

@@ -3,15 +3,15 @@ import { useAtproto } from '~/composables/atproto/useAtproto'
 import { authRedirect } from '~/utils/atproto/helpers'
 
 const handleInput = shallowRef('')
-
+const route = useRoute()
 const { user, logout } = useAtproto()
 
 async function handleBlueskySignIn() {
-  await authRedirect('https://bsky.social')
+  await authRedirect('https://bsky.social', { redirectTo: route.fullPath })
 }
 
 async function handleCreateAccount() {
-  await authRedirect('https://npmx.social', true)
+  await authRedirect('https://npmx.social', { create: true, redirectTo: route.fullPath })
 }
 
 async function handleLogin() {

app/utils/atproto/helpers.ts

@@ -1,14 +1,22 @@
 import type { FetchError } from 'ofetch'
 import type { LocationQueryRaw } from 'vue-router'
 
+interface AuthRedirectOptions {
+  create?: boolean
+  redirectTo?: string
+}
+
 /**
  * Redirect user to ATProto authentication
  */
-export async function authRedirect(identifier: string, create: boolean = false) {
+export async function authRedirect(identifier: string, options: AuthRedirectOptions = {}) {
   let query: LocationQueryRaw = { handle: identifier }
-  if (create) {
+  if (options.create) {
     query = { ...query, create: 'true' }
   }
+  if (options.redirectTo) {
+    query = { ...query, returnTo: options.redirectTo }
+  }
   await navigateTo(
     {
       path: '/api/auth/atproto',

server/api/auth/atproto.get.ts

@@ -10,6 +10,8 @@ import { handleResolver } from '#server/utils/atproto/oauth'
 import { Client } from '@atproto/lex'
 import * as app from '#shared/types/lexicons/app'
 import { ensureValidAtIdentifier } from '@atproto/syntax'
+// @ts-expect-error virtual file from oauth module
+import { clientUri } from '#oauth/config'
 
 /**
  * Fetch the user's profile record to get their avatar blob reference
@@ -66,6 +68,25 @@ export default defineEventHandler(async event => {
   })
 
   if (!query.code) {
+    // Validate returnTo is a safe relative path (prevent open redirect)
+    // Only set cookie on initial auth request, not the callback
+    let redirectPath = '/'
+    try {
+      const clientOrigin = new URL(clientUri).origin
+      const returnToUrl = new URL(query.returnTo?.toString() || '/', clientUri)
+      if (returnToUrl.origin === clientOrigin) {
+        redirectPath = returnToUrl.pathname + returnToUrl.search + returnToUrl.hash
+      }
+    } catch {
+      // Invalid URL, fall back to root
+    }
+
+    setCookie(event, 'auth_return_to', redirectPath, {
+      maxAge: 60 * 5,
+      httpOnly: true,
+      // secure only if NOT in dev mode
+      secure: !import.meta.dev,
+    })
     try {
       const handle = query.handle?.toString()
       const create = query.create?.toString()
@@ -126,5 +147,9 @@ export default defineEventHandler(async event => {
       },
     })
   }
-  return sendRedirect(event, '/')
+
+  const returnToURL = getCookie(event, 'auth_return_to') || '/'
+  deleteCookie(event, 'auth_return_to')
+
+  return sendRedirect(event, returnToURL)
 })