all kinds of frontend sec. adaptations

src/pages/AuthCallbackPage.tsx

@@ -1,15 +1,29 @@
-import { useEffect } from 'react'
+// src/pages/AuthCallbackPage.tsx
+import { useEffect, useRef } from 'react'
 import { useNavigate } from 'react-router-dom'
 import { userManager } from 'auth/oidc'
 
-
 export default function AuthCallbackPage() {
-const navigate = useNavigate()
-useEffect(() => {
-userManager.signinRedirectCallback().then((res) => {
-const target = (res?.state as any)?.returnTo || '/'
-navigate(target, { replace: true })
-})
-}, [navigate])
-return <p>Completing sign-in…</p>
-}
+  const navigate = useNavigate()
+  const handled = useRef(false)
+
+  useEffect(() => {
+    if (handled.current) return         // 👈 skydd mot StrictMode dubbelkörning
+    handled.current = true
+
+    ;(async () => {
+      try {
+        const res = await userManager.signinRedirectCallback()
+        const target = (res?.state as any)?.returnTo || '/'
+        // Städa bort ?code&state ur URL:en:
+        window.history.replaceState({}, '', target)
+        navigate(target, { replace: true })
+      } catch (err) {
+        console.error('signinRedirectCallback failed:', err)
+        navigate('/', { replace: true })
+      }
+    })()
+  }, [navigate])
+
+  return <p>Completing sign-in…</p>
+}