diff --git a/attached_assets/Pasted--PRODUCTION-Looking-for-user-with-username-admin-PRODUCTION-Looking-for--1762258084615_1762258084615.txt b/attached_assets/Pasted--PRODUCTION-Looking-for-user-with-username-admin-PRODUCTION-Looking-for--1762258084615_1762258084615.txt
new file mode 100644
index 0000000..08590bd
--- /dev/null
+++ b/attached_assets/Pasted--PRODUCTION-Looking-for-user-with-username-admin-PRODUCTION-Looking-for--1762258084615_1762258084615.txt
@@ -0,0 +1,201 @@
+
+      
+]
+
+🔍 [PRODUCTION] Looking for user with username: admin
+
+🔍 [PRODUCTION] Looking for user with username: admin
+
+🔍 [PRODUCTION] Looking for user with username: admin
+
+🔍 [PRODUCTION] Looking for user with username: admin_local
+
+🔍 [PRODUCTION] User search result: Found
+
+🔍 [PRODUCTION] User search result: Found
+
+🔍 [PRODUCTION] User search result: Found
+
+❌ [PRODUCTION] User not found with username: admin_local
+
+🔍 [PRODUCTION] User search result: Not found
+
+🎯 [PRODUCTION] Found announcements: 4
+
+GET /api/announcements 304 in 9ms
+
+GET /api/user 304 in 4ms
+
+📢 [SERVER] Fetching announcements for user: _1754936203292 environment: production
+
+📢 [SERVER] User found: { username: 'ff292', role: 'employee' }
+
+🎯 [PRODUCTION] Using PostgreSQL DASHBOARD_MESSAGES table
+
+🔍 [PRODUCTION] Raw messages from DB: 4 items: [
+
+  {
+
+    id: 20,
+
+    title: 'DLC',
+
+    content: 'Attention des DLC sont en expiré bientôt ou expiré, il faut s en occuper',
+
+    type: 'success',
+
+    storeId: 2,
+
+    createdBy: 'admin',
+
+    createdAt: 2025-09-24T11:26:13.521Z
+
+  },
+
+  {
+
+    id: 17,
+
+    title: 'Module Avoir',
+
+    content: "Le module d'avoir est en place",
+
+    type: 'error',
+
+    storeId: 1,
+
+    createdBy: 'admin',
+
+    createdAt: 2025-09-09T07:47:47.650Z
+
+  },
+
+  {
+
+    id: 16,
+
+    title: 'Mise à jour Prix',
+
+    content: 'Merci de mettre vos prix a jour tous les matins, certain magasin ne le font pas.',
+
+    type: 'success',
+
+    storeId: null,
+
+    createdBy: 'admin',
+
+    createdAt: 2025-08-18T10:45:08.585Z
+
+  },
+
+  {
+
+    id: 8,
+
+    title: 'Bon de Livraison',
+
+    content: 'Lorsque vous rentrez un numéro de bon de livraison, faite le a l identique, même les majuscules. Pour My candy Shop, prendre le numéro de commande.',
+
+    type: 'info',
+
+    storeId: null,
+
+    createdBy: 'admin_local',
+
+    createdAt: 2025-08-07T11:04:38.123Z
+
+  }
+
+]
+
+🔍 [PRODUCTION] Looking for user with username: admin
+
+🔍 [PRODUCTION] Looking for user with username: admin
+
+🔍 [PRODUCTION] Looking for user with username: admin
+
+🔍 [PRODUCTION] Looking for user with username: admin_local
+
+❌ [PRODUCTION] User not found with username: admin_local
+
+🔍 [PRODUCTION] User search result: Found
+
+🔍 [PRODUCTION] User search result: Found
+
+🔍 [PRODUCTION] User search result: Found
+
+🔍 [PRODUCTION] User search result: Not found
+
+🎯 [PRODUCTION] Found announcements: 4
+
+GET /api/announcements 304 in 24ms
+
+GET /api/groups 304 in 5ms
+
+GET /api/user 304 in 4ms
+
+GET /api/suppliers 200 in 4ms
+
+GET /api/dlc-products 200 in 53ms
+
+📊 [EXPORT] Début de l'export Excel
+
+🔍 [EXPORT] Utilisateur: admin (admin)
+
+📋 [EXPORT] Paramètres: {
+
+  groupId: 1,
+
+  month: '2025-12',
+
+  paymentMethods: [ 'Traite Magnétique' ],
+
+  includeHT: true,
+
+  includeTTC: true
+
+}
+
+❌ PRODUCTION: Delivery #127 (store 2) linked to order #81 (store 1) - STORE MISMATCH DETECTED!
+
+🔗 PRODUCTION: getDeliveries() récupéré 357 livraisons avec relations
+
+📦 [EXPORT] Import du module xlsx...
+
+❌ [EXPORT] Erreur export Excel: Error: Dynamic require of "stream" is not supported
+
+    at file:///app/dist/index.js:11:9
+
+    at make_xlsx_lib (file:///app/dist/index.js:44815:22)
+
+    at node_modules/xlsx/xlsx.js (file:///app/dist/index.js:44819:41)
+
+    at __require2 (file:///app/dist/index.js:17:50)
+
+    at file:///app/dist/index.js:47198:63
+
+    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
+
+    at async file:///app/dist/index.js:47198:20
+
+❌ [EXPORT] Message: Dynamic require of "stream" is not supported
+
+❌ [EXPORT] Stack: Error: Dynamic require of "stream" is not supported
+
+    at file:///app/dist/index.js:11:9
+
+    at make_xlsx_lib (file:///app/dist/index.js:44815:22)
+
+    at node_modules/xlsx/xlsx.js (file:///app/dist/index.js:44819:41)
+
+    at __require2 (file:///app/dist/index.js:17:50)
+
+    at file:///app/dist/index.js:47198:63
+
+    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
+
+    at async file:///app/dist/index.js:47198:20
+
+POST /api/payment-schedule/export 500 in 910ms
+
+HEAD /api/health 200 in 1ms
\ No newline at end of file
diff --git a/attached_assets/Pasted-Actions-hoursRemaining-438287-CACHE-R-sultat-cache-found--1762258677960_1762258677960.txt b/attached_assets/Pasted-Actions-hoursRemaining-438287-CACHE-R-sultat-cache-found--1762258677960_1762258677960.txt
new file mode 100644
index 0000000..5fab322
--- /dev/null
+++ b/attached_assets/Pasted-Actions-hoursRemaining-438287-CACHE-R-sultat-cache-found--1762258677960_1762258677960.txt
@@ -0,0 +1,205 @@
+Actions
+ 
+ 
+ 
+      
+  hoursRemaining: 438287
+
+}
+
+🔍 [CACHE] Résultat cache: {
+
+  found: true,
+
+  isReconciled: true,
+
+  expired: false,
+
+  expiresAt: 2075-11-04T10:58:49.338Z,
+
+  currentTime: '2025-11-04T12:17:35.661Z'
+
+}
+
+🛡️ [CACHE] PERMANENT - Facture validée avec coche verte, AUCUNE vérification: {
+
+  invoiceReference: '22529151',
+
+  groupId: 1,
+
+  exists: true,
+
+  invoiceAmount: '2653.75',
+
+  dueDate: null
+
+}
+
+✅ [INVOICE] Résultat depuis cache: {
+
+  exists: true,
+
+  matchType: 'invoice_reference',
+
+  errorMessage: null,
+
+  invoiceReference: '22529151',
+
+  supplierName: 'Sovacom',
+
+  invoiceAmount: 2653.75,
+
+  invoiceAmountTTC: 3184.5,
+
+  dueDate: null,
+
+  fromCache: true,
+
+  permanent: true
+
+}
+
+🔍 [INVOICE] Début vérification facture: { invoiceReference: 'FCLT035833', groupId: 1, forceRefresh: false }
+
+🔍 [INVOICE] Vérification cache...
+
+🔍 [CACHE] Recherche cache pour: {
+
+  invoiceReference: 'FCLT035833',
+
+  groupId: 1,
+
+  cacheKey: '1_fclt035833'
+
+}
+
+✅ [DATABASE-CACHE] Cache hit pour: {
+
+  cacheKey: '1_fclt035833',
+
+  expires: 2075-11-04T10:58:49.353Z,
+
+  hoursRemaining: 438287
+
+}
+
+🔍 [CACHE] Résultat cache: {
+
+  found: true,
+
+  isReconciled: true,
+
+  expired: false,
+
+  expiresAt: 2075-11-04T10:58:49.353Z,
+
+  currentTime: '2025-11-04T12:17:35.662Z'
+
+}
+
+🛡️ [CACHE] PERMANENT - Facture validée avec coche verte, AUCUNE vérification: {
+
+  invoiceReference: 'FCLT035833',
+
+  groupId: 1,
+
+  exists: true,
+
+  invoiceAmount: '1307.26',
+
+  dueDate: null
+
+}
+
+✅ [INVOICE] Résultat depuis cache: {
+
+  exists: true,
+
+  matchType: 'invoice_reference',
+
+  errorMessage: null,
+
+  invoiceReference: 'FCLT035833',
+
+  supplierName: 'Idvpc',
+
+  invoiceAmount: 1307.26,
+
+  invoiceAmountTTC: 1568.71,
+
+  dueDate: null,
+
+  fromCache: true,
+
+  permanent: true
+
+}
+
+💰 Livraisons nécessitant récupération TTC: 0
+
+📅 Total échéances retournées: 34
+
+GET /api/payment-schedule 304 in 892ms
+
+📊 [EXPORT] Début de l'export Excel
+
+🔍 [EXPORT] Utilisateur: admin (admin)
+
+📋 [EXPORT] Paramètres: {
+
+  groupId: 1,
+
+  month: '2025-11',
+
+  paymentMethods: [ 'Non défini' ],
+
+  includeHT: true,
+
+  includeTTC: true
+
+}
+
+❌ PRODUCTION: Delivery #127 (store 2) linked to order #81 (store 1) - STORE MISMATCH DETECTED!
+
+🔗 PRODUCTION: getDeliveries() récupéré 357 livraisons avec relations
+
+📦 [EXPORT] Import du module xlsx...
+
+❌ [EXPORT] Erreur export Excel: Error: Dynamic require of "stream" is not supported
+
+    at file:///app/dist/index.js:11:9
+
+    at make_xlsx_lib (file:///app/dist/index.js:44815:22)
+
+    at node_modules/xlsx/xlsx.js (file:///app/dist/index.js:44819:41)
+
+    at __require2 (file:///app/dist/index.js:17:50)
+
+    at file:///app/dist/index.js:47198:63
+
+    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
+
+    at async file:///app/dist/index.js:47198:20
+
+❌ [EXPORT] Message: Dynamic require of "stream" is not supported
+
+❌ [EXPORT] Stack: Error: Dynamic require of "stream" is not supported
+
+    at file:///app/dist/index.js:11:9
+
+    at make_xlsx_lib (file:///app/dist/index.js:44815:22)
+
+    at node_modules/xlsx/xlsx.js (file:///app/dist/index.js:44819:41)
+
+    at __require2 (file:///app/dist/index.js:17:50)
+
+    at file:///app/dist/index.js:47198:63
+
+    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
+
+    at async file:///app/dist/index.js:47198:20
+
+POST /api/payment-schedule/export 500 in 936ms
+
+HEAD /api/health 200 in 1ms
+
diff --git a/attached_assets/Pasted-Actions-isReconciled-true-expired-false-expiresAt-2075-11-04T10-5-1762258554084_1762258554084.txt b/attached_assets/Pasted-Actions-isReconciled-true-expired-false-expiresAt-2075-11-04T10-5-1762258554084_1762258554084.txt
new file mode 100644
index 0000000..052d21e
--- /dev/null
+++ b/attached_assets/Pasted-Actions-isReconciled-true-expired-false-expiresAt-2075-11-04T10-5-1762258554084_1762258554084.txt
@@ -0,0 +1,205 @@
+Actions
+ 
+ 
+ 
+      
+  isReconciled: true,
+
+  expired: false,
+
+  expiresAt: 2075-11-04T10:58:49.326Z,
+
+  currentTime: '2025-11-04T12:15:03.672Z'
+
+}
+
+🛡️ [CACHE] PERMANENT - Facture validée avec coche verte, AUCUNE vérification: {
+
+  invoiceReference: '000752796',
+
+  groupId: 1,
+
+  exists: true,
+
+  invoiceAmount: '1203.12',
+
+  dueDate: null
+
+}
+
+✅ [INVOICE] Résultat depuis cache: {
+
+  exists: true,
+
+  matchType: 'invoice_reference',
+
+  errorMessage: null,
+
+  invoiceReference: '000752796',
+
+  supplierName: 'CMP',
+
+  invoiceAmount: 1203.12,
+
+  invoiceAmountTTC: 1443.74,
+
+  dueDate: null,
+
+  fromCache: true,
+
+  permanent: true
+
+}
+
+🔍 [INVOICE] Début vérification facture: { invoiceReference: '22529151', groupId: 1, forceRefresh: false }
+
+🔍 [INVOICE] Vérification cache...
+
+🔍 [CACHE] Recherche cache pour: { invoiceReference: '22529151', groupId: 1, cacheKey: '1_22529151' }
+
+✅ [DATABASE-CACHE] Cache hit pour: {
+
+  cacheKey: '1_22529151',
+
+  expires: 2075-11-04T10:58:49.338Z,
+
+  hoursRemaining: 438287
+
+}
+
+🔍 [CACHE] Résultat cache: {
+
+  found: true,
+
+  isReconciled: true,
+
+  expired: false,
+
+  expiresAt: 2075-11-04T10:58:49.338Z,
+
+  currentTime: '2025-11-04T12:15:03.675Z'
+
+}
+
+🛡️ [CACHE] PERMANENT - Facture validée avec coche verte, AUCUNE vérification: {
+
+  invoiceReference: '22529151',
+
+  groupId: 1,
+
+  exists: true,
+
+  invoiceAmount: '2653.75',
+
+  dueDate: null
+
+}
+
+✅ [INVOICE] Résultat depuis cache: {
+
+  exists: true,
+
+  matchType: 'invoice_reference',
+
+  errorMessage: null,
+
+  invoiceReference: '22529151',
+
+  supplierName: 'Sovacom',
+
+  invoiceAmount: 2653.75,
+
+  invoiceAmountTTC: 3184.5,
+
+  dueDate: null,
+
+  fromCache: true,
+
+  permanent: true
+
+}
+
+🔍 [INVOICE] Début vérification facture: { invoiceReference: 'FCLT035833', groupId: 1, forceRefresh: false }
+
+🔍 [INVOICE] Vérification cache...
+
+🔍 [CACHE] Recherche cache pour: {
+
+  invoiceReference: 'FCLT035833',
+
+  groupId: 1,
+
+  cacheKey: '1_fclt035833'
+
+}
+
+✅ [DATABASE-CACHE] Cache hit pour: {
+
+  cacheKey: '1_fclt035833',
+
+  expires: 2075-11-04T10:58:49.353Z,
+
+  hoursRemaining: 438287
+
+}
+
+🔍 [CACHE] Résultat cache: {
+
+  found: true,
+
+  isReconciled: true,
+
+  expired: false,
+
+  expiresAt: 2075-11-04T10:58:49.353Z,
+
+  currentTime: '2025-11-04T12:15:03.677Z'
+
+}
+
+🛡️ [CACHE] PERMANENT - Facture validée avec coche verte, AUCUNE vérification: {
+
+  invoiceReference: 'FCLT035833',
+
+  groupId: 1,
+
+  exists: true,
+
+  invoiceAmount: '1307.26',
+
+  dueDate: null
+
+}
+
+✅ [INVOICE] Résultat depuis cache: {
+
+  exists: true,
+
+  matchType: 'invoice_reference',
+
+  errorMessage: null,
+
+  invoiceReference: 'FCLT035833',
+
+  supplierName: 'Idvpc',
+
+  invoiceAmount: 1307.26,
+
+  invoiceAmountTTC: 1568.71,
+
+  dueDate: null,
+
+  fromCache: true,
+
+  permanent: true
+
+}
+
+💰 Livraisons nécessitant récupération TTC: 0
+
+📅 Total échéances retournées: 34
+
+GET /api/payment-schedule 304 in 17159ms
+
+HEAD /api/health 200 in 1ms
+
diff --git a/attached_assets/{20C84D95-5589-4A3B-A3E8-FF26B0DE30B9}_1762258671191.png b/attached_assets/{20C84D95-5589-4A3B-A3E8-FF26B0DE30B9}_1762258671191.png
new file mode 100644
index 0000000..440210a
Binary files /dev/null and b/attached_assets/{20C84D95-5589-4A3B-A3E8-FF26B0DE30B9}_1762258671191.png differ
diff --git a/attached_assets/{243F4726-3549-4C96-80EB-0FD9A84A36ED}_1762259049954.png b/attached_assets/{243F4726-3549-4C96-80EB-0FD9A84A36ED}_1762259049954.png
new file mode 100644
index 0000000..c5ab841
Binary files /dev/null and b/attached_assets/{243F4726-3549-4C96-80EB-0FD9A84A36ED}_1762259049954.png differ
diff --git a/attached_assets/{58EC7866-65BC-47E0-8411-6F41026061E8}_1762258865336.png b/attached_assets/{58EC7866-65BC-47E0-8411-6F41026061E8}_1762258865336.png
new file mode 100644
index 0000000..d9ab6d1
Binary files /dev/null and b/attached_assets/{58EC7866-65BC-47E0-8411-6F41026061E8}_1762258865336.png differ
diff --git a/attached_assets/{773F1FF1-B583-448A-8998-E60750EFCEB7}_1762258496115.png b/attached_assets/{773F1FF1-B583-448A-8998-E60750EFCEB7}_1762258496115.png
new file mode 100644
index 0000000..6a3895d
Binary files /dev/null and b/attached_assets/{773F1FF1-B583-448A-8998-E60750EFCEB7}_1762258496115.png differ
diff --git a/attached_assets/{A4AE40BA-CB21-4BC1-B78E-3D15E088357E}_1762258064762.png b/attached_assets/{A4AE40BA-CB21-4BC1-B78E-3D15E088357E}_1762258064762.png
new file mode 100644
index 0000000..db917d6
Binary files /dev/null and b/attached_assets/{A4AE40BA-CB21-4BC1-B78E-3D15E088357E}_1762258064762.png differ
diff --git a/client/src/pages/PaymentSchedulePage.tsx b/client/src/pages/PaymentSchedulePage.tsx
index 042fa8b..886aa1b 100644
--- a/client/src/pages/PaymentSchedulePage.tsx
+++ b/client/src/pages/PaymentSchedulePage.tsx
@@ -212,7 +212,7 @@ export default function PaymentSchedulePage() {
       const url = window.URL.createObjectURL(blob);
       const a = document.createElement('a');
       a.href = url;
-      a.download = `echeancier_${selectedMonth}.xlsx`;
+      a.download = `echeancier_${selectedMonth}.csv`;
       document.body.appendChild(a);
       a.click();
       window.URL.revokeObjectURL(url);
@@ -221,7 +221,7 @@ export default function PaymentSchedulePage() {
       setShowExportModal(false);
       toast({
         title: "Export réussi",
-        description: "Le fichier Excel a été téléchargé avec succès.",
+        description: "Le fichier CSV a été téléchargé avec succès. Ouvrez-le dans Excel.",
       });
     } catch (error) {
       console.error('Erreur export:', error);
@@ -303,10 +303,10 @@ export default function PaymentSchedulePage() {
             variant="outline"
             className="gap-2"
             disabled={filteredSchedules.length === 0}
-            data-testid="button-export-excel"
+            data-testid="button-export-csv"
           >
             <FileSpreadsheet className="h-4 w-4" />
-            Exporter Excel
+            Exporter CSV
           </Button>
           <div className="w-64">
             <Select value={selectedMonth} onValueChange={setSelectedMonth}>
@@ -459,16 +459,16 @@ export default function PaymentSchedulePage() {
         </CardContent>
       </Card>
 
-      {/* Modale d'export Excel */}
+      {/* Modale d'export CSV */}
       <Dialog open={showExportModal} onOpenChange={setShowExportModal}>
         <DialogContent className="sm:max-w-md">
           <DialogHeader>
             <DialogTitle className="flex items-center gap-2">
               <FileSpreadsheet className="h-5 w-5 text-green-600" />
-              Exporter vers Excel
+              Exporter vers CSV
             </DialogTitle>
             <DialogDescription>
-              Sélectionnez les modes de paiement et les colonnes à inclure dans l'export
+              Sélectionnez les modes de paiement et les colonnes à inclure dans l'export (ouvrez le fichier dans Excel)
             </DialogDescription>
           </DialogHeader>
 
diff --git a/server/routes.ts b/server/routes.ts
index f0d38a7..814a8ff 100644
--- a/server/routes.ts
+++ b/server/routes.ts
@@ -589,28 +589,31 @@ export async function registerRoutes(app: Express): Promise<Server> {
         .filter((schedule: any) => validatedPaymentMethods.includes(schedule.paymentMethod))
         .sort((a: any, b: any) => a.dueDate.getTime() - b.dueDate.getTime());
 
-      // Générer le fichier Excel
-      console.log('📦 [EXPORT] Import du module xlsx...');
-      const XLSX = await import('xlsx');
-      console.log('✅ [EXPORT] Module xlsx importé avec succès');
-      const workbook = XLSX.utils.book_new();
-      console.log('📄 [EXPORT] Workbook créé');
+      // Générer le fichier CSV avec tabulations
+      console.log('📄 [EXPORT] Génération du fichier CSV avec tabulations...');
 
-      // Préparer les données pour Excel
+      // Préparer les en-têtes
       const headers = ['Date d\'échéance', 'Fournisseur', 'Facture', 'Mode de paiement'];
       if (includeHT) headers.push('Montant HT');
       if (includeTTC) headers.push('Montant TTC');
 
-      const data = schedules.map((schedule: any) => {
-        const row: any = {
-          'Date d\'échéance': format(schedule.dueDate, 'dd/MM/yyyy', { locale: fr }),
-          'Fournisseur': schedule.supplierName,
-          'Facture': schedule.invoiceReference,
-          'Mode de paiement': schedule.paymentMethod,
-        };
-        if (includeHT) row['Montant HT'] = schedule.amountHT;
-        if (includeTTC) row['Montant TTC'] = schedule.amountTTC;
-        return row;
+      // Créer les lignes de données
+      const csvLines: string[] = [];
+      
+      // Ajouter la ligne d'en-tête
+      csvLines.push(headers.join('\t'));
+
+      // Ajouter les données
+      schedules.forEach((schedule: any) => {
+        const row: string[] = [
+          format(schedule.dueDate, 'dd/MM/yyyy', { locale: fr }),
+          schedule.supplierName,
+          schedule.invoiceReference,
+          schedule.paymentMethod,
+        ];
+        if (includeHT) row.push(schedule.amountHT.toFixed(2));
+        if (includeTTC) row.push(schedule.amountTTC.toFixed(2));
+        csvLines.push(row.join('\t'));
       });
 
       // Calculer les totaux
@@ -618,40 +621,21 @@ export async function registerRoutes(app: Express): Promise<Server> {
       const totalTTC = schedules.reduce((sum: number, s: any) => sum + s.amountTTC, 0);
 
       // Ajouter une ligne de total
-      const totalRow: any = {
-        'Date d\'échéance': '',
-        'Fournisseur': '',
-        'Facture': '',
-        'Mode de paiement': 'TOTAL',
-      };
-      if (includeHT) totalRow['Montant HT'] = totalHT;
-      if (includeTTC) totalRow['Montant TTC'] = totalTTC;
-      data.push(totalRow);
+      const totalRow: string[] = ['', '', '', 'TOTAL'];
+      if (includeHT) totalRow.push(totalHT.toFixed(2));
+      if (includeTTC) totalRow.push(totalTTC.toFixed(2));
+      csvLines.push(totalRow.join('\t'));
 
-      // Créer la feuille Excel
-      const worksheet = XLSX.utils.json_to_sheet(data, { header: headers });
-
-      // Définir la largeur des colonnes
-      worksheet['!cols'] = [
-        { wch: 15 },  // Date
-        { wch: 25 },  // Fournisseur
-        { wch: 15 },  // Facture
-        { wch: 18 },  // Mode de paiement
-        { wch: 12 },  // Montant HT
-        { wch: 12 },  // Montant TTC
-      ];
-
-      XLSX.utils.book_append_sheet(workbook, worksheet, 'Échéancier');
-
-      // Générer le buffer Excel
-      const excelBuffer = XLSX.write(workbook, { type: 'buffer', bookType: 'xlsx' });
+      // Générer le contenu CSV avec BOM UTF-8 pour Excel
+      const BOM = '\uFEFF';
+      const csvContent = BOM + csvLines.join('\n');
 
       // Envoyer le fichier
-      res.setHeader('Content-Disposition', `attachment; filename="echeancier_${validatedMonth}.xlsx"`);
-      res.setHeader('Content-Type', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
-      res.send(excelBuffer);
+      res.setHeader('Content-Disposition', `attachment; filename="echeancier_${validatedMonth}.csv"`);
+      res.setHeader('Content-Type', 'text/csv; charset=utf-8');
+      res.send(csvContent);
 
-      console.log(`📊 Export Excel généré: ${schedules.length} échéances pour ${group.name}`);
+      console.log(`📊 [EXPORT] CSV généré: ${schedules.length} échéances pour ${group.name}`);
 
     } catch (error: any) {
       console.error('❌ [EXPORT] Erreur export Excel:', error);
diff --git a/tsconfig.server.json b/tsconfig.server.json
new file mode 100644
index 0000000..0126094
--- /dev/null
+++ b/tsconfig.server.json
@@ -0,0 +1,18 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "target": "ES2022",
+    "outDir": "./dist/server",
+    "rootDir": "./server",
+    "skipLibCheck": true,
+    "esModuleInterop": true,
+    "allowSyntheticDefaultImports": true,
+    "strict": false,
+    "forceConsistentCasingInFileNames": true,
+    "resolveJsonModule": true
+  },
+  "include": ["server/**/*"],
+  "exclude": ["node_modules", "dist"]
+}