fix: show target-language-specific translations in preview + rename migration

Two issues found in screenshot review:
1. Glossary preview always showed English 'target' field (foie → liver)
   instead of the language-specific translation. Now looks up
   term.translations[targetLang] first, falls back to term.target.
   When target is Persian, preview shows 'foie → کبد' (Persian).

2. Previous migration b7c8d9e0f1a2 was already applied on server before
   the rename was added. New migration c8d9e0f1a2b3 handles the rename
   separately: glossaries with target_language='multi' get their name
   changed from 'Anglais' to 'Multilingue'.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

services/email_service.py

@@ -117,3 +117,211 @@ async def send_email_async(to: str, subject: str, body: str) -> bool:
     except Exception as e:
         logger.error(f"Failed to send email (async) to {to}: {e}")
         return False
+
+
+async def send_subscription_email_async(
+    to_email: str,
+    user_name: str,
+    event_type: str,
+    details: dict
+) -> bool:
+    """
+    Send subscription transactional email in French.
+    event_type can be: 'activated', 'cancelled', 'ended', 'payment_failed', 'credits_purchased'
+    """
+    display_name = user_name or to_email.split("@")[0]
+    
+    frontend_url = os.getenv("FRONTEND_URL", "http://localhost:3000")
+    dashboard_url = f"{frontend_url}/dashboard"
+    profile_url = f"{frontend_url}/dashboard/profile?tab=subscription"
+    pricing_url = f"{frontend_url}/pricing"
+    
+    subject = "Notification Office Translator"
+    header_title = "Office Translator"
+    content_html = ""
+    
+    if event_type == "activated":
+        plan_name = details.get("plan_name", "Premium").capitalize()
+        ends_at = details.get("ends_at", "")
+        subject = "Votre abonnement Office Translator est activé ! 🚀"
+        header_title = "Bienvenue chez Office Translator"
+        content_html = f"""
+        <p>Bonjour {display_name},</p>
+        <p>Nous sommes ravis de vous compter parmi nos membres Premium ! Votre abonnement au forfait <strong>{plan_name}</strong> est désormais actif.</p>
+        <div class="info-box">
+            <div class="info-title">Détails de votre abonnement :</div>
+            <p style="margin: 4px 0;"><strong>Forfait :</strong> {plan_name}</p>
+            {"<p style='margin: 4px 0;'><strong>Date de renouvellement :</strong> " + ends_at + "</p>" if ends_at else ""}
+        </div>
+        <p>Vous pouvez dès à présent profiter de toutes les fonctionnalités premium, y compris la traduction illimitée de documents et l'accès à nos meilleurs modèles d'IA.</p>
+        <div class="button-container">
+            <a href="{dashboard_url}" class="button">Accéder à mon tableau de bord</a>
+        </div>
+        """
+    elif event_type == "cancelled":
+        ends_at = details.get("ends_at", "")
+        subject = "Confirmation d'annulation de votre abonnement - Office Translator"
+        header_title = "Abonnement annulé"
+        content_html = f"""
+        <p>Bonjour {display_name},</p>
+        <p>Nous vous confirmons que l'annulation de votre abonnement a bien été prise en compte à votre demande.</p>
+        <div class="info-box">
+            <div class="info-title">Informations importantes :</div>
+            {"<p style='margin: 4px 0;'><strong>Accès actif jusqu'au :</strong> " + ends_at + "</p>" if ends_at else ""}
+            <p style="margin: 4px 0;">Aucun autre prélèvement ne sera effectué.</p>
+        </div>
+        <p>Vous conservez un accès complet à toutes les fonctionnalités premium de votre forfait jusqu'à la fin de la période de facturation en cours.</p>
+        <p>Si vous changez d'avis, vous pouvez réactiver votre abonnement à tout moment depuis votre profil.</p>
+        <div class="button-container">
+            <a href="{profile_url}" class="button">Gérer mon compte</a>
+        </div>
+        """
+    elif event_type == "ended":
+        subject = "Votre accès premium a expiré - Office Translator"
+        header_title = "Accès premium terminé"
+        content_html = f"""
+        <p>Bonjour {display_name},</p>
+        <p>Votre abonnement Office Translator a pris fin et votre compte a été basculé vers le forfait <strong>Gratuit</strong>.</p>
+        <p>Vous pouvez toujours traduire des documents dans la limite de votre quota gratuit. Vos documents et votre historique restent disponibles.</p>
+        <p>Pour retrouver l'accès à la traduction rapide, sans limites et à nos modèles IA avancés, vous pouvez vous réabonner en un clic.</p>
+        <div class="button-container">
+            <a href="{pricing_url}" class="button">Voir nos forfaits</a>
+        </div>
+        """
+    elif event_type == "payment_failed":
+        subject = "Échec de paiement - Action requise - Office Translator ⚠️"
+        header_title = "Problème de paiement"
+        content_html = f"""
+        <p>Bonjour {display_name},</p>
+        <p>Nous n'avons pas pu prélever le règlement de votre abonnement Office Translator. Notre tentative de paiement a échoué.</p>
+        <p>Pour éviter toute interruption de votre service premium, nous vous invitons à mettre à jour vos coordonnées de paiement dès que possible.</p>
+        <div class="button-container">
+            <a href="{profile_url}" class="button">Mettre à jour mon moyen de paiement</a>
+        </div>
+        <p>Si vous avez des questions, n'hésitez pas à répondre à cet e-mail.</p>
+        """
+    elif event_type == "credits_purchased":
+        credits = details.get("credits", 0)
+        subject = "Achat de crédits réussi - Office Translator 💳"
+        header_title = "Crédits ajoutés"
+        content_html = f"""
+        <p>Bonjour {display_name},</p>
+        <p>Nous vous remercions pour votre achat ! Vos crédits supplémentaires ont bien été crédités sur votre compte.</p>
+        <div class="info-box">
+            <div class="info-title">Détails de l'achat :</div>
+            <p style="margin: 4px 0;"><strong>Crédits achetés :</strong> +{credits}</p>
+            <p style="margin: 4px 0;">Chaque crédit vous permet de traduire une page de document supplémentaire.</p>
+        </div>
+        <p>Vous pouvez suivre votre solde de crédits et l'historique de vos traductions depuis votre tableau de bord.</p>
+        <div class="button-container">
+            <a href="{dashboard_url}" class="button">Traduire un document</a>
+        </div>
+        """
+    else:
+        return False
+        
+    full_html = f"""<!DOCTYPE html>
+<html>
+<head>
+  <meta charset="utf-8">
+  <style>
+    body {{
+      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
+      background-color: #f8fafc;
+      color: #334155;
+      margin: 0;
+      padding: 0;
+    }}
+    .wrapper {{
+      width: 100%;
+      background-color: #f8fafc;
+      padding: 40px 0;
+    }}
+    .container {{
+      max-width: 600px;
+      margin: 0 auto;
+      background: #ffffff;
+      border-radius: 16px;
+      overflow: hidden;
+      box-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
+      border: 1px solid #e2e8f0;
+    }}
+    .header {{
+      background: linear-gradient(135deg, #4f46e5, #06b6d4);
+      padding: 32px;
+      text-align: center;
+      color: #ffffff;
+    }}
+    .header h1 {{
+      margin: 0;
+      font-size: 24px;
+      font-weight: 700;
+      letter-spacing: -0.025em;
+    }}
+    .content {{
+      padding: 32px;
+      line-height: 1.6;
+    }}
+    .content p {{
+      margin-top: 0;
+      margin-bottom: 16px;
+    }}
+    .button-container {{
+      text-align: center;
+      margin: 32px 0;
+    }}
+    .button {{
+      background-color: #4f46e5;
+      color: #ffffff !important;
+      padding: 12px 32px;
+      text-decoration: none;
+      font-weight: 600;
+      border-radius: 8px;
+      display: inline-block;
+      box-shadow: 0 4px 6px -1px rgba(79, 70, 229, 0.2);
+    }}
+    .footer {{
+      background-color: #f1f5f9;
+      padding: 24px;
+      text-align: center;
+      font-size: 12px;
+      color: #64748b;
+      border-top: 1px solid #e2e8f0;
+    }}
+    .footer p {{
+      margin: 4px 0;
+    }}
+    .info-box {{
+      background-color: #f8fafc;
+      border: 1px solid #e2e8f0;
+      border-radius: 8px;
+      padding: 16px;
+      margin-bottom: 24px;
+    }}
+    .info-title {{
+      font-weight: 600;
+      color: #1e293b;
+      margin-bottom: 8px;
+    }}
+  </style>
+</head>
+<body>
+  <div class="wrapper">
+    <div class="container">
+      <div class="header">
+        <h1>{header_title}</h1>
+      </div>
+      <div class="content">
+        {content_html}
+      </div>
+      <div class="footer">
+        <p>Cet e-mail automatique a été envoyé par <strong>Office Translator</strong>.</p>
+        <p>&copy; {datetime.now().year} Office Translator. Tous droits réservés.</p>
+      </div>
+    </div>
+  </div>
+</body>
+</html>
+"""
+    return await send_email_async(to_email, subject, full_html)
+

services/payment_service.py

@@ -268,16 +268,74 @@ async def handle_webhook(payload: bytes, sig_header: str) -> Dict[str, Any]:
 
 async def handle_checkout_completed(session: Dict):
     """Handle successful checkout"""
-    metadata = session.get("metadata", {})
+    metadata = session.get("metadata", {}) or {}
     user_id = metadata.get("user_id")
     
     if not user_id:
         return
+        
+    session_id = session.get("id")
     
+    # Check for duplicate session processing using PaymentHistory
+    db_available = False
+    try:
+        from database.connection import get_sync_session
+        from database.models import PaymentHistory as DBPaymentHistory
+        db_available = True
+    except ImportError:
+        pass
+
+    if db_available and session_id:
+        try:
+            with get_sync_session() as db_session:
+                existing = db_session.query(DBPaymentHistory).filter(
+                    DBPaymentHistory.stripe_payment_intent_id == session_id
+                ).first()
+                if existing:
+                    logger.info("Checkout session %s already processed. Skipping.", session_id)
+                    return
+        except Exception as e:
+            logger.error("Error checking PaymentHistory duplication: %s", e)
+
+    user = get_user_by_id(user_id)
+    if not user:
+        return
+
     # Check if it's a credit purchase
     if metadata.get("type") == "credits":
         credits = int(metadata.get("credits", 0))
         add_credits(user_id, credits)
+        
+        # Log to PaymentHistory
+        if db_available and session_id:
+            try:
+                with get_sync_session() as db_session:
+                    payment = DBPaymentHistory(
+                        user_id=user_id,
+                        stripe_payment_intent_id=session_id,
+                        stripe_invoice_id=session.get("invoice") or session.get("subscription"),
+                        amount_cents=session.get("amount_total") or 0,
+                        currency=session.get("currency") or "usd",
+                        payment_type="credits",
+                        status="succeeded",
+                        description=f"Achat de {credits} crédits",
+                    )
+                    db_session.add(payment)
+                    db_session.commit()
+            except Exception as e:
+                logger.error("Failed to write credits payment to history: %s", e)
+
+        # Send Email
+        try:
+            from services.email_service import send_subscription_email_async
+            await send_subscription_email_async(
+                to_email=user.email,
+                user_name=user.name,
+                event_type="credits_purchased",
+                details={"credits": credits}
+            )
+        except Exception as e:
+            logger.error("Failed to send credit purchase email: %s", e)
         return
     
     # It's a subscription
@@ -310,6 +368,12 @@ async def handle_checkout_completed(session: Dict):
         # Derive tier from plan (DB constraint: only 'free' or 'pro')
         tier = "pro" if plan in ("pro", "business", "enterprise") else "free"
 
+        is_new_sub = (
+            user.stripe_subscription_id != subscription_id
+            or user.subscription_status != SubscriptionStatus.ACTIVE.value
+            or user.plan != plan
+        )
+
         update_user(user_id, {
             "plan": plan,
             "tier": tier,
@@ -323,14 +387,51 @@ async def handle_checkout_completed(session: Dict):
         })
         logger.info("Checkout synced: user %s → plan=%s tier=%s sub=%s", user_id, plan, tier, subscription_id)
 
+        # Log to PaymentHistory
+        if db_available and session_id:
+            try:
+                with get_sync_session() as db_session:
+                    payment = DBPaymentHistory(
+                        user_id=user_id,
+                        stripe_payment_intent_id=session_id,
+                        stripe_invoice_id=subscription_id or session.get("invoice"),
+                        amount_cents=session.get("amount_total") or 0,
+                        currency=session.get("currency") or "usd",
+                        payment_type="subscription",
+                        status="succeeded",
+                        description=f"Abonnement au forfait {plan}",
+                    )
+                    db_session.add(payment)
+                    db_session.commit()
+            except Exception as e:
+                logger.error("Failed to write subscription payment to history: %s", e)
+
+        # Send activation email
+        if is_new_sub:
+            try:
+                from services.email_service import send_subscription_email_async
+                ends_str = subscription_ends_at.strftime("%d/%m/%Y") if subscription_ends_at else ""
+                await send_subscription_email_async(
+                    to_email=user.email,
+                    user_name=user.name,
+                    event_type="activated",
+                    details={"plan_name": plan, "ends_at": ends_str}
+                )
+            except Exception as e:
+                logger.error("Failed to send activation email: %s", e)
+
 
 async def handle_subscription_updated(subscription: Dict):
     """Handle subscription updates"""
-    metadata = subscription.get("metadata", {})
+    metadata = subscription.get("metadata", {}) or {}
     user_id = metadata.get("user_id")
     
     if not user_id:
         return
+        
+    user = get_user_by_id(user_id)
+    if not user:
+        return
     
     status_map = {
         "active": SubscriptionStatus.ACTIVE,
@@ -343,38 +444,79 @@ async def handle_subscription_updated(subscription: Dict):
     stripe_status = subscription.get("status", "active")
     status = status_map.get(stripe_status, SubscriptionStatus.ACTIVE)
     
+    stripe_cancel_at_period_end = subscription.get("cancel_at_period_end", False)
+    is_newly_cancelling = stripe_cancel_at_period_end and not user.cancel_at_period_end
+
+    period_end = subscription.get("current_period_end")
+    ends_str = ""
+    if period_end:
+        from datetime import timezone
+        ends_str = datetime.fromtimestamp(period_end, tz=timezone.utc).strftime("%d/%m/%Y")
+
     update_user(user_id, {
         "subscription_status": status.value,
-        "cancel_at_period_end": subscription.get("cancel_at_period_end", False),
+        "cancel_at_period_end": stripe_cancel_at_period_end,
         "subscription_ends_at": datetime.fromtimestamp(
             subscription.get("current_period_end", 0)
         ).isoformat() if subscription.get("current_period_end") else None
     })
 
+    # Send cancellation email if they just selected to cancel
+    if is_newly_cancelling:
+        try:
+            from services.email_service import send_subscription_email_async
+            await send_subscription_email_async(
+                to_email=user.email,
+                user_name=user.name,
+                event_type="cancelled",
+                details={"ends_at": ends_str}
+            )
+        except Exception as e:
+            logger.error("Failed to send cancellation email in handle_subscription_updated: %s", e)
+
 
 async def handle_subscription_deleted(subscription: Dict):
-    """Handle subscription cancellation"""
-    metadata = subscription.get("metadata", {})
+    """Handle subscription cancellation (actually ended)"""
+    metadata = subscription.get("metadata", {}) or {}
     user_id = metadata.get("user_id")
     
     if not user_id:
         return
-    
+        
+    user = get_user_by_id(user_id)
+    if not user:
+        return
+
+    had_active_sub = user.plan != PlanType.FREE.value or user.tier != "free"
+
     update_user(user_id, {
         "plan": PlanType.FREE.value,
+        "tier": "free",
         "subscription_status": SubscriptionStatus.CANCELED.value,
         "stripe_subscription_id": None,
     })
 
+    # Send ended email
+    if had_active_sub:
+        try:
+            from services.email_service import send_subscription_email_async
+            await send_subscription_email_async(
+                to_email=user.email,
+                user_name=user.name,
+                event_type="ended",
+                details={}
+            )
+        except Exception as e:
+            logger.error("Failed to send subscription ended email: %s", e)
+
 
 async def handle_payment_failed(invoice: Dict):
-    """Handle failed payment — set subscription status to PAST_DUE"""
+    """Handle failed payment — set subscription status to PAST_DUE and send email"""
     customer_id = invoice.get("customer")
     if not customer_id:
         return
 
     # Find user by stripe_customer_id
-    user = None
     try:
         from database.connection import get_sync_session
         from database.models import User as DBUser
@@ -393,6 +535,18 @@ async def handle_payment_failed(invoice: Dict):
                     "Payment failed for customer %s (user %s) — status set to past_due",
                     customer_id, user_id,
                 )
+
+                # Send email
+                try:
+                    from services.email_service import send_subscription_email_async
+                    await send_subscription_email_async(
+                        to_email=db_user.email,
+                        user_name=db_user.name,
+                        event_type="payment_failed",
+                        details={}
+                    )
+                except Exception as e:
+                    logger.error("Failed to send payment failed email: %s", e)
     except Exception as exc:
         logger.error("handle_payment_failed DB error: %s", exc)
 
@@ -417,14 +571,31 @@ async def cancel_subscription(user_id: str) -> Dict[str, Any]:
             cancel_at = datetime.fromtimestamp(subscription.cancel_at).isoformat()
 
         subscription_ends_at = None
+        ends_str = ""
         if subscription.current_period_end:
             subscription_ends_at = datetime.fromtimestamp(subscription.current_period_end).isoformat()
+            ends_str = datetime.fromtimestamp(subscription.current_period_end).strftime("%d/%m/%Y")
+
+        is_new_cancel = not user.cancel_at_period_end
 
         update_user(user_id, {
             "cancel_at_period_end": True,
             "subscription_ends_at": subscription_ends_at,
         })
 
+        # Send cancellation confirmation email
+        if is_new_cancel:
+            try:
+                from services.email_service import send_subscription_email_async
+                await send_subscription_email_async(
+                    to_email=user.email,
+                    user_name=user.name,
+                    event_type="cancelled",
+                    details={"ends_at": ends_str}
+                )
+            except Exception as e:
+                logger.error("Failed to send cancellation email in cancel_subscription: %s", e)
+
         return {
             "status": "canceling",
             "cancel_at": cancel_at,