fix: sync plan+tier after checkout, portal same-tab nav, cancel button always visible for paid plans, portal return URL to profile tab

frontend/src/app/dashboard/profile/page.tsx

@@ -71,7 +71,8 @@ export default function ProfilePage() {
   const [loadingPortal, setLoadingPortal] = useState(false);
   const [loadingCancel, setLoadingCancel] = useState(false);
   const [isClearing, setIsClearing] = useState(false);
-  const [activeTab, setActiveTab] = useState('account');
+  const searchParams = typeof window !== 'undefined' ? new URLSearchParams(window.location.search) : null;
+  const [activeTab, setActiveTab] = useState(searchParams?.get('tab') ?? 'account');
   const [defaultLanguage, setDefaultLanguage] = useState(settings.defaultTargetLanguage);
 
   const token = typeof window !== 'undefined' ? localStorage.getItem('token') : null;
@@ -98,7 +99,7 @@ export default function ProfilePage() {
       const res = await fetch(`${API_BASE}/api/v1/auth/billing-portal`, { headers: authHeaders });
       const j = await res.json();
       const url = j.data?.url ?? j.url;
-      if (url) window.open(url, '_blank');
+      if (url) window.location.href = url;  // same tab so return_url brings back to app
       else setStatusMsg({ type: 'err', text: t('profile.subscription.billingUnavailable') });
     } catch { setStatusMsg({ type: 'err', text: t('profile.subscription.billingError') }); }
     finally { setLoadingPortal(false); }
@@ -434,8 +435,8 @@ export default function ProfilePage() {
               </div>
             )}
 
-            {/* Danger zone */}
+            {/* Danger zone — show if user has a paid plan (even if sub ID not yet synced) */}
-            {!isFreePlan && !isCanceling && user?.stripe_subscription_id && (
+            {!isFreePlan && !isCanceling && (
               <div className="editorial-card p-10 lg:p-12 bg-white dark:bg-[#141414] border-none shadow-editorial border-l-4 border-l-red-500">
                 <div className="flex items-center gap-4 text-red-500 mb-8">
                   <ShieldAlert size={20} />

services/payment_service.py

@@ -288,22 +288,40 @@ async def handle_checkout_completed(session: Dict):
         subscription_ends_at = None
 
         if isinstance(subscription_raw, str):
-            subscription_id = subscription_raw
+            # Not expanded — fetch subscription to get period end
+            try:
+                sub = stripe.Subscription.retrieve(subscription_raw)
+                subscription_id = sub["id"]
+                if sub.get("current_period_end"):
+                    from datetime import timezone
+                    subscription_ends_at = datetime.fromtimestamp(
+                        sub["current_period_end"], tz=timezone.utc
+                    )
+            except Exception:
+                subscription_id = subscription_raw
         elif subscription_raw:
-            # Expanded subscription object (from sync path with expand=["subscription"])
+            # Expanded subscription object (from sync path)
             subscription_id = subscription_raw.get("id")
             period_end = subscription_raw.get("current_period_end")
             if period_end:
-                subscription_ends_at = datetime.fromtimestamp(period_end).isoformat()
+                from datetime import timezone
+                subscription_ends_at = datetime.fromtimestamp(period_end, tz=timezone.utc)
+
+        # Derive tier from plan (DB constraint: only 'free' or 'pro')
+        tier = "pro" if plan in ("pro", "business", "enterprise") else "free"
 
         update_user(user_id, {
             "plan": plan,
+            "tier": tier,
             "subscription_status": SubscriptionStatus.ACTIVE.value,
             "stripe_subscription_id": subscription_id,
+            "stripe_customer_id": session.get("customer") or None,
             "subscription_ends_at": subscription_ends_at,
+            "cancel_at_period_end": False,
             "docs_translated_this_month": 0,
             "pages_translated_this_month": 0,
         })
+        logger.info("Checkout synced: user %s → plan=%s tier=%s sub=%s", user_id, plan, tier, subscription_id)
 
 
 async def handle_subscription_updated(subscription: Dict):
@@ -420,16 +438,17 @@ async def get_billing_portal_url(user_id: str) -> Optional[str]:
     """Get Stripe billing portal URL for customer"""
     if not is_stripe_configured():
         return None
-    
+
     user = get_user_by_id(user_id)
     if not user or not user.stripe_customer_id:
         return None
-    
+
     try:
         session = stripe.billing_portal.Session.create(
             customer=user.stripe_customer_id,
-            return_url=f"{os.getenv('FRONTEND_URL', 'http://localhost:3000')}/dashboard"
+            return_url=f"{os.getenv('FRONTEND_URL', 'http://localhost:3000')}/dashboard/profile?tab=subscription"
         )
         return session.url
-    except:
+    except Exception as e:
+        logger.error("get_billing_portal_url error: %s", e)
         return None