diff --git a/config/api_key_manager.php b/config/api_key_manager.php
new file mode 100644
index 0000000..831c7d8
--- /dev/null
+++ b/config/api_key_manager.php
@@ -0,0 +1,455 @@
+<?php
+/**
+ * Gestionnaire de clés API pour le chatbot
+ * Chiffrement AES-256-CBC des clés API
+ * 
+ * @author WebVal
+ * @date 2026-01-04
+ */
+
+class APIKeyManager {
+    
+    private static $encryption_key = null;
+    private static $db = null;
+    
+    /**
+     * Initialiser la connexion BDD
+     */
+    private static function init() {
+        if (self::$db === null) {
+            self::$db = Database::getInstance();
+        }
+    }
+    
+    /**
+     * Récupérer la clé de chiffrement
+     * Ordre de priorité : ENV > Fichier > Génération
+     */
+    private static function getEncryptionKey() {
+        if (self::$encryption_key !== null) {
+            return self::$encryption_key;
+        }
+        
+        // 1. Variable d'environnement
+        $key = getenv('WEBVAL_API_ENCRYPTION_KEY');
+        
+        // 2. Fichier externe (hors webroot)
+        if (!$key && file_exists('/etc/webval/encryption.key')) {
+            $key = file_get_contents('/etc/webval/encryption.key');
+        }
+        
+        // 3. Fichier dans config (fallback)
+        $keyFile = __DIR__ . '/../config/.encryption_key';
+        if (!$key && file_exists($keyFile)) {
+            $key = file_get_contents($keyFile);
+        }
+        
+        // 4. Générer une nouvelle clé si aucune n'existe
+        if (!$key) {
+            $key = bin2hex(random_bytes(32));
+            
+            // Essayer de sauvegarder
+            if (is_writable(__DIR__ . '/../config/')) {
+                file_put_contents($keyFile, $key);
+                chmod($keyFile, 0600);
+            }
+            
+            error_log("⚠️ Nouvelle clé de chiffrement générée. Sauvegarde recommandée.");
+        }
+        
+        self::$encryption_key = $key;
+        return $key;
+    }
+    
+    /**
+     * Chiffrer une clé API
+     * 
+     * @param string $plaintext Clé API en clair
+     * @return string Clé chiffrée (base64)
+     */
+    public static function encrypt($plaintext) {
+        if (empty($plaintext)) {
+            return null;
+        }
+        
+        $key = hash('sha256', self::getEncryptionKey(), true);
+        $iv = random_bytes(16);
+        
+        $ciphertext = openssl_encrypt(
+            $plaintext,
+            'AES-256-CBC',
+            $key,
+            OPENSSL_RAW_DATA,
+            $iv
+        );
+        
+        if ($ciphertext === false) {
+            throw new Exception("Erreur de chiffrement");
+        }
+        
+        // Format: IV (16 bytes) + Ciphertext
+        return base64_encode($iv . $ciphertext);
+    }
+    
+    /**
+     * Déchiffrer une clé API
+     * 
+     * @param string $encrypted Clé chiffrée (base64)
+     * @return string|null Clé API en clair
+     */
+    public static function decrypt($encrypted) {
+        if (empty($encrypted)) {
+            return null;
+        }
+        
+        $key = hash('sha256', self::getEncryptionKey(), true);
+        $data = base64_decode($encrypted);
+        
+        if ($data === false || strlen($data) < 16) {
+            throw new Exception("Données chiffrées invalides");
+        }
+        
+        $iv = substr($data, 0, 16);
+        $ciphertext = substr($data, 16);
+        
+        $plaintext = openssl_decrypt(
+            $ciphertext,
+            'AES-256-CBC',
+            $key,
+            OPENSSL_RAW_DATA,
+            $iv
+        );
+        
+        if ($plaintext === false) {
+            throw new Exception("Erreur de déchiffrement");
+        }
+        
+        return $plaintext;
+    }
+    
+    /**
+     * Sauvegarder une clé API
+     * 
+     * @param int $id_enseignant ID de l'enseignant
+     * @param string $provider Provider (gemini, mistral, etc.)
+     * @param string $api_key Clé API en clair
+     * @param string $model_default Modèle par défaut
+     * @return bool Succès
+     */
+    public static function saveKey($id_enseignant, $provider, $api_key, $model_default = null) {
+        self::init();
+        
+        // Chiffrer la clé
+        $encrypted = self::encrypt($api_key);
+        
+        // Upsert (INSERT ... ON DUPLICATE KEY UPDATE)
+        $query = "INSERT INTO api_keys 
+                  (id_enseignant, provider, api_key_encrypted, model_default, is_active, quota_reset_date)
+                  VALUES (?, ?, ?, ?, TRUE, DATE_ADD(CURDATE(), INTERVAL 1 MONTH))
+                  ON DUPLICATE KEY UPDATE
+                  api_key_encrypted = VALUES(api_key_encrypted),
+                  model_default = VALUES(model_default),
+                  is_active = TRUE,
+                  updated_at = CURRENT_TIMESTAMP";
+        
+        return self::$db->query($query, [
+            $id_enseignant,
+            $provider,
+            $encrypted,
+            $model_default
+        ]);
+    }
+    
+    /**
+     * Récupérer une clé API déchiffrée
+     * 
+     * @param int $id_enseignant ID de l'enseignant
+     * @param string $provider Provider
+     * @return array|null ['api_key' => '...', 'model_default' => '...']
+     */
+    public static function getKey($id_enseignant, $provider) {
+        self::init();
+        
+        $result = self::$db->fetchOne(
+            "SELECT api_key_encrypted, model_default, is_active 
+             FROM api_keys 
+             WHERE id_enseignant = ? AND provider = ?",
+            [$id_enseignant, $provider]
+        );
+        
+        if (!$result || !$result['is_active']) {
+            return null;
+        }
+        
+        return [
+            'api_key' => self::decrypt($result['api_key_encrypted']),
+            'model_default' => $result['model_default']
+        ];
+    }
+    
+    /**
+     * Supprimer une clé API
+     * 
+     * @param int $id_enseignant ID de l'enseignant
+     * @param string $provider Provider
+     * @return bool Succès
+     */
+    public static function deleteKey($id_enseignant, $provider) {
+        self::init();
+        
+        return self::$db->query(
+            "DELETE FROM api_keys WHERE id_enseignant = ? AND provider = ?",
+            [$id_enseignant, $provider]
+        );
+    }
+    
+    /**
+     * Lister toutes les clés d'un enseignant
+     * 
+     * @param int $id_enseignant ID de l'enseignant
+     * @return array Liste des clés (sans les clés déchiffrées)
+     */
+    public static function listKeys($id_enseignant) {
+        self::init();
+        
+        return self::$db->fetchAll(
+            "SELECT 
+                id,
+                provider,
+                model_default,
+                is_active,
+                quota_max,
+                quota_used,
+                quota_reset_date,
+                last_used,
+                created_at
+             FROM api_keys 
+             WHERE id_enseignant = ?
+             ORDER BY provider",
+            [$id_enseignant]
+        );
+    }
+    
+    /**
+     * Incrémenter le quota utilisé
+     * 
+     * @param int $id_enseignant ID de l'enseignant
+     * @param string $provider Provider
+     * @param int $tokens_used Nombre de tokens utilisés
+     */
+    public static function incrementQuota($id_enseignant, $provider, $tokens_used = 1) {
+        self::init();
+        
+        // Reset quota si date dépassée
+        self::$db->query(
+            "UPDATE api_keys 
+             SET quota_used = 0, quota_reset_date = DATE_ADD(CURDATE(), INTERVAL 1 MONTH)
+             WHERE id_enseignant = ? AND provider = ? AND quota_reset_date < CURDATE()",
+            [$id_enseignant, $provider]
+        );
+        
+        // Incrémenter
+        return self::$db->query(
+            "UPDATE api_keys 
+             SET quota_used = quota_used + ?, last_used = NOW()
+             WHERE id_enseignant = ? AND provider = ?",
+            [$tokens_used, $id_enseignant, $provider]
+        );
+    }
+    
+    /**
+     * Vérifier si le quota est dépassé
+     * 
+     * @param int $id_enseignant ID de l'enseignant
+     * @param string $provider Provider
+     * @return bool True si quota OK
+     */
+    public static function checkQuota($id_enseignant, $provider) {
+        self::init();
+        
+        $result = self::$db->fetchOne(
+            "SELECT quota_max, quota_used FROM api_keys 
+             WHERE id_enseignant = ? AND provider = ?",
+            [$id_enseignant, $provider]
+        );
+        
+        if (!$result || $result['quota_max'] === null) {
+            return true; // Pas de limite
+        }
+        
+        return $result['quota_used'] < $result['quota_max'];
+    }
+    
+    /**
+     * Tester une connexion API
+     * 
+     * @param string $provider Provider à tester
+     * @param string $api_key Clé API
+     * @param string $model Modèle à tester
+     * @return array ['success' => bool, 'message' => string, 'latency_ms' => int]
+     */
+    public static function testConnection($provider, $api_key, $model = null) {
+        $start = microtime(true);
+        
+        try {
+            switch ($provider) {
+                case 'gemini':
+                    $result = self::testGemini($api_key, $model ?? 'gemini-2.0-flash-exp');
+                    break;
+                
+                case 'mistral':
+                    $result = self::testMistral($api_key, $model ?? 'ministral-3b-latest');
+                    break;
+                
+                case 'openai':
+                    $result = self::testOpenAI($api_key, $model ?? 'gpt-4o-mini');
+                    break;
+                
+                case 'ollama':
+                    $result = self::testOllama($model ?? 'ministral-3:3b');
+                    break;
+                
+                default:
+                    return ['success' => false, 'message' => 'Provider inconnu'];
+            }
+            
+            $latency = round((microtime(true) - $start) * 1000);
+            $result['latency_ms'] = $latency;
+            
+            return $result;
+            
+        } catch (Exception $e) {
+            return [
+                'success' => false,
+                'message' => 'Erreur: ' . $e->getMessage(),
+                'latency_ms' => 0
+            ];
+        }
+    }
+    
+    /**
+     * Tester connexion Gemini
+     */
+    private static function testGemini($api_key, $model) {
+        $url = "https://generativelanguage.googleapis.com/v1beta/models/{$model}:generateContent?key={$api_key}";
+        
+        $ch = curl_init($url);
+        curl_setopt_array($ch, [
+            CURLOPT_POST => true,
+            CURLOPT_RETURNTRANSFER => true,
+            CURLOPT_HTTPHEADER => ['Content-Type: application/json'],
+            CURLOPT_TIMEOUT => 10,
+            CURLOPT_POSTFIELDS => json_encode([
+                'contents' => [['parts' => [['text' => 'Test']]]]
+            ])
+        ]);
+        
+        $response = curl_exec($ch);
+        $http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
+        curl_close($ch);
+        
+        if ($http_code === 200) {
+            return ['success' => true, 'message' => 'Connexion Gemini réussie'];
+        } elseif ($http_code === 400) {
+            return ['success' => false, 'message' => 'Clé API invalide'];
+        } elseif ($http_code === 429) {
+            return ['success' => false, 'message' => 'Quota dépassé'];
+        } else {
+            return ['success' => false, 'message' => "Erreur HTTP $http_code"];
+        }
+    }
+    
+    /**
+     * Tester connexion Mistral
+     */
+    private static function testMistral($api_key, $model) {
+        $ch = curl_init('https://api.mistral.ai/v1/chat/completions');
+        curl_setopt_array($ch, [
+            CURLOPT_POST => true,
+            CURLOPT_RETURNTRANSFER => true,
+            CURLOPT_HTTPHEADER => [
+                'Content-Type: application/json',
+                'Authorization: Bearer ' . $api_key
+            ],
+            CURLOPT_TIMEOUT => 10,
+            CURLOPT_POSTFIELDS => json_encode([
+                'model' => $model,
+                'messages' => [['role' => 'user', 'content' => 'Test']],
+                'max_tokens' => 10
+            ])
+        ]);
+        
+        $response = curl_exec($ch);
+        $http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
+        curl_close($ch);
+        
+        if ($http_code === 200) {
+            return ['success' => true, 'message' => 'Connexion Mistral réussie'];
+        } elseif ($http_code === 401) {
+            return ['success' => false, 'message' => 'Clé API invalide'];
+        } else {
+            return ['success' => false, 'message' => "Erreur HTTP $http_code"];
+        }
+    }
+    
+    /**
+     * Tester connexion OpenAI
+     */
+    private static function testOpenAI($api_key, $model) {
+        $ch = curl_init('https://api.openai.com/v1/chat/completions');
+        curl_setopt_array($ch, [
+            CURLOPT_POST => true,
+            CURLOPT_RETURNTRANSFER => true,
+            CURLOPT_HTTPHEADER => [
+                'Content-Type: application/json',
+                'Authorization: Bearer ' . $api_key
+            ],
+            CURLOPT_TIMEOUT => 10,
+            CURLOPT_POSTFIELDS => json_encode([
+                'model' => $model,
+                'messages' => [['role' => 'user', 'content' => 'Test']],
+                'max_tokens' => 10
+            ])
+        ]);
+        
+        $response = curl_exec($ch);
+        $http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
+        curl_close($ch);
+        
+        if ($http_code === 200) {
+            return ['success' => true, 'message' => 'Connexion OpenAI réussie'];
+        } elseif ($http_code === 401) {
+            return ['success' => false, 'message' => 'Clé API invalide'];
+        } else {
+            return ['success' => false, 'message' => "Erreur HTTP $http_code"];
+        }
+    }
+    
+    /**
+     * Tester connexion Ollama (local)
+     */
+    private static function testOllama($model) {
+        $ch = curl_init('http://localhost:11434/api/generate');
+        curl_setopt_array($ch, [
+            CURLOPT_POST => true,
+            CURLOPT_RETURNTRANSFER => true,
+            CURLOPT_HTTPHEADER => ['Content-Type: application/json'],
+            CURLOPT_TIMEOUT => 5,
+            CURLOPT_POSTFIELDS => json_encode([
+                'model' => $model,
+                'prompt' => 'Test',
+                'stream' => false
+            ])
+        ]);
+        
+        $response = curl_exec($ch);
+        $http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
+        curl_close($ch);
+        
+        if ($http_code === 200) {
+            return ['success' => true, 'message' => 'Connexion Ollama réussie'];
+        } else {
+            return ['success' => false, 'message' => 'Ollama non disponible'];
+        }
+    }
+}
diff --git a/sql/chatbot_api_management.sql b/sql/chatbot_api_management.sql
new file mode 100644
index 0000000..358ba5a
--- /dev/null
+++ b/sql/chatbot_api_management.sql
@@ -0,0 +1,136 @@
+-- ============================================
+-- WebVal - Gestion API Chatbot
+-- Tables pour la gestion des clés API et modèles
+-- Date: 2026-01-04
+-- ============================================
+
+-- Table des clés API des enseignants
+CREATE TABLE IF NOT EXISTS api_keys (
+    id INT AUTO_INCREMENT PRIMARY KEY,
+    id_enseignant INT NOT NULL,
+    provider ENUM('gemini', 'mistral', 'openai', 'anthropic', 'ollama') NOT NULL,
+    api_key_encrypted TEXT,  -- Clé chiffrée avec AES-256-CBC
+    model_default VARCHAR(100),  -- Modèle par défaut (ex: 'gemini-2.0-flash-exp')
+    is_active BOOLEAN DEFAULT TRUE,
+    quota_max INT DEFAULT NULL,  -- Limite mensuelle optionnelle
+    quota_used INT DEFAULT 0,
+    quota_reset_date DATE,  -- Date de reset du quota
+    last_used TIMESTAMP NULL,
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+    FOREIGN KEY (id_enseignant) REFERENCES utilisateurs(id_utilisateur) ON DELETE CASCADE,
+    UNIQUE KEY unique_provider (id_enseignant, provider),
+    INDEX idx_enseignant (id_enseignant),
+    INDEX idx_active (is_active)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
+-- Table des modèles disponibles (catalogue)
+CREATE TABLE IF NOT EXISTS available_models (
+    id INT AUTO_INCREMENT PRIMARY KEY,
+    provider VARCHAR(50) NOT NULL,
+    model_id VARCHAR(100) NOT NULL,  -- ID technique du modèle
+    display_name VARCHAR(150) NOT NULL,  -- Nom affiché
+    description TEXT,
+    context_length INT DEFAULT 4096,  -- Taille contexte en tokens
+    is_free BOOLEAN DEFAULT FALSE,
+    cost_per_1m_tokens DECIMAL(10,4) DEFAULT NULL,  -- Coût par million de tokens
+    recommended BOOLEAN DEFAULT FALSE,
+    speed_rating TINYINT DEFAULT 3,  -- 1=lent, 5=très rapide
+    quality_rating TINYINT DEFAULT 3,  -- 1=basique, 5=excellent
+    active BOOLEAN DEFAULT TRUE,
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    UNIQUE KEY unique_model (provider, model_id),
+    INDEX idx_provider (provider),
+    INDEX idx_recommended (recommended),
+    INDEX idx_active (active)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
+-- Table de configuration chatbot par évaluation
+CREATE TABLE IF NOT EXISTS chatbot_eval_config (
+    id INT AUTO_INCREMENT PRIMARY KEY,
+    id_evaluation INT NOT NULL,
+    id_enseignant INT NOT NULL,
+    provider_default VARCHAR(50) DEFAULT 'ollama',
+    model_default VARCHAR(100) DEFAULT 'ministral-3:3b',
+    allow_student_override BOOLEAN DEFAULT FALSE,  -- L'élève peut-il choisir ?
+    max_messages_per_question INT DEFAULT 3,
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+    FOREIGN KEY (id_evaluation) REFERENCES evaluations(id_evaluation) ON DELETE CASCADE,
+    FOREIGN KEY (id_enseignant) REFERENCES utilisateurs(id_utilisateur) ON DELETE CASCADE,
+    UNIQUE KEY unique_eval (id_evaluation),
+    INDEX idx_enseignant (id_enseignant)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
+-- Table de configuration par élève (override)
+CREATE TABLE IF NOT EXISTS chatbot_student_config (
+    id INT AUTO_INCREMENT PRIMARY KEY,
+    id_evaluation INT NOT NULL,
+    id_eleve INT NOT NULL,
+    provider_override VARCHAR(50),
+    model_override VARCHAR(100),
+    created_by INT NOT NULL,  -- ID enseignant qui a fait l'override
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+    FOREIGN KEY (id_evaluation) REFERENCES evaluations(id_evaluation) ON DELETE CASCADE,
+    FOREIGN KEY (id_eleve) REFERENCES utilisateurs(id_utilisateur) ON DELETE CASCADE,
+    FOREIGN KEY (created_by) REFERENCES utilisateurs(id_utilisateur) ON DELETE CASCADE,
+    UNIQUE KEY unique_student_eval (id_evaluation, id_eleve),
+    INDEX idx_evaluation (id_evaluation),
+    INDEX idx_eleve (id_eleve)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
+-- Pré-remplir les modèles disponibles
+INSERT INTO available_models 
+(provider, model_id, display_name, description, context_length, is_free, cost_per_1m_tokens, recommended, speed_rating, quality_rating) 
+VALUES
+-- Gemini (Google)
+('gemini', 'gemini-2.0-flash-exp', 'Gemini 2.0 Flash (Expérimental)', 'Modèle ultra-rapide de Google, gratuit avec quotas généreux', 1000000, TRUE, 0, TRUE, 5, 4),
+('gemini', 'gemini-1.5-flash', 'Gemini 1.5 Flash', 'Modèle rapide et équilibré', 1000000, TRUE, 0, FALSE, 4, 4),
+('gemini', 'gemini-1.5-pro', 'Gemini 1.5 Pro', 'Modèle le plus puissant de Google', 2000000, FALSE, 1.25, FALSE, 3, 5),
+
+-- Mistral
+('mistral', 'mistral-small-latest', 'Mistral Small', 'Modèle compact et rapide', 32000, FALSE, 0.20, FALSE, 5, 3),
+('mistral', 'ministral-3b-latest', 'Ministral 3B', 'Petit modèle efficace pour le raisonnement', 128000, FALSE, 0.04, TRUE, 5, 3),
+('mistral', 'ministral-8b-latest', 'Ministral 8B', 'Meilleur équilibre qualité/vitesse', 128000, FALSE, 0.10, TRUE, 4, 4),
+('mistral', 'mistral-large-latest', 'Mistral Large', 'Modèle le plus puissant de Mistral', 128000, FALSE, 2.00, FALSE, 3, 5),
+
+-- OpenAI
+('openai', 'gpt-4o-mini', 'GPT-4o Mini', 'Petit modèle rapide et économique', 128000, FALSE, 0.15, TRUE, 5, 4),
+('openai', 'gpt-4o', 'GPT-4o', 'Modèle multimodal puissant', 128000, FALSE, 2.50, FALSE, 4, 5),
+('openai', 'gpt-4-turbo', 'GPT-4 Turbo', 'Modèle GPT-4 optimisé', 128000, FALSE, 10.00, FALSE, 3, 5),
+
+-- Ollama (local)
+('ollama', 'ministral-3:3b', 'Ministral 3B (Local)', 'Modèle local rapide', 128000, TRUE, 0, TRUE, 4, 3),
+('ollama', 'qwen2-math:1.5b', 'Qwen2 Math 1.5B (Local)', 'Spécialisé en mathématiques', 32000, TRUE, 0, FALSE, 5, 3),
+('ollama', 'llama3.2:3b', 'Llama 3.2 3B (Local)', 'Modèle généraliste compact', 128000, TRUE, 0, FALSE, 3, 4);
+
+-- Ajouter colonne provider à la table chat_conversations pour tracking
+ALTER TABLE chat_conversations 
+ADD COLUMN IF NOT EXISTS provider VARCHAR(50) DEFAULT 'ollama',
+ADD COLUMN IF NOT EXISTS model_used VARCHAR(100) DEFAULT 'ministral-3:3b',
+ADD COLUMN IF NOT EXISTS api_response_time_ms INT DEFAULT NULL,
+ADD INDEX idx_provider (provider);
+
+-- Ajouter colonne provider à la table chat_messages pour analytics
+ALTER TABLE chat_messages 
+ADD COLUMN IF NOT EXISTS api_cost DECIMAL(10,6) DEFAULT 0.000000;
+
+-- Vue pour les stats d'utilisation enseignant
+CREATE OR REPLACE VIEW v_chatbot_usage_stats AS
+SELECT 
+    cc.id_enseignant,
+    cc.provider,
+    cc.model_used,
+    COUNT(DISTINCT cc.id_conversation) as total_conversations,
+    COUNT(cm.id) as total_messages,
+    AVG(cc.api_response_time_ms) as avg_response_time_ms,
+    SUM(cm.api_cost) as total_cost,
+    DATE_FORMAT(cc.date_debut, '%Y-%m') as month
+FROM chat_conversations cc
+LEFT JOIN chat_messages cm ON cc.id_conversation = cm.id_conversation
+GROUP BY cc.id_enseignant, cc.provider, cc.model_used, month;
+
+-- ============================================
+-- FIN DU SCRIPT
+-- ============================================
diff --git a/sql/update_chat_tables.sql b/sql/update_chat_tables.sql
new file mode 100644
index 0000000..2845b9c
--- /dev/null
+++ b/sql/update_chat_tables.sql
@@ -0,0 +1,109 @@
+-- ============================================
+-- WebVal - Mise à jour chat_conversations
+-- Ajout colonnes pour tracking API (sécurisé)
+-- ============================================
+
+-- Désactiver les erreurs temporairement
+SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0;
+
+-- Ajouter colonnes une par une (ignore si existe déjà)
+SET @s = (SELECT IF(
+    (SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS
+     WHERE table_schema = DATABASE()
+     AND table_name = 'chat_conversations'
+     AND column_name = 'provider') > 0,
+    'SELECT ''Column provider already exists''',
+    'ALTER TABLE chat_conversations ADD COLUMN provider VARCHAR(50) DEFAULT ''ollama'''
+));
+PREPARE stmt FROM @s;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+
+SET @s = (SELECT IF(
+    (SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS
+     WHERE table_schema = DATABASE()
+     AND table_name = 'chat_conversations'
+     AND column_name = 'model_used') > 0,
+    'SELECT ''Column model_used already exists''',
+    'ALTER TABLE chat_conversations ADD COLUMN model_used VARCHAR(100) DEFAULT ''ministral-3:3b'''
+));
+PREPARE stmt FROM @s;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+
+SET @s = (SELECT IF(
+    (SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS
+     WHERE table_schema = DATABASE()
+     AND table_name = 'chat_conversations'
+     AND column_name = 'api_response_time_ms') > 0,
+    'SELECT ''Column api_response_time_ms already exists''',
+    'ALTER TABLE chat_conversations ADD COLUMN api_response_time_ms INT DEFAULT NULL'
+));
+PREPARE stmt FROM @s;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+
+SET @s = (SELECT IF(
+    (SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS
+     WHERE table_schema = DATABASE()
+     AND table_name = 'chat_conversations'
+     AND column_name = 'id_enseignant') > 0,
+    'SELECT ''Column id_enseignant already exists''',
+    'ALTER TABLE chat_conversations ADD COLUMN id_enseignant INT DEFAULT NULL'
+));
+PREPARE stmt FROM @s;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+
+-- Index
+SET @s = (SELECT IF(
+    (SELECT COUNT(*) FROM INFORMATION_SCHEMA.STATISTICS
+     WHERE table_schema = DATABASE()
+     AND table_name = 'chat_conversations'
+     AND index_name = 'idx_provider') > 0,
+    'SELECT ''Index idx_provider already exists''',
+    'ALTER TABLE chat_conversations ADD INDEX idx_provider (provider)'
+));
+PREPARE stmt FROM @s;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+
+-- Foreign key (plus complexe, on teste avec SHOW CREATE TABLE)
+SET @fk_exists = (SELECT COUNT(*) FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
+                  WHERE table_schema = DATABASE()
+                  AND table_name = 'chat_conversations'
+                  AND referenced_table_name = 'utilisateurs'
+                  AND column_name = 'id_enseignant');
+
+SET @s = IF(@fk_exists > 0,
+    'SELECT ''Foreign key already exists''',
+    'ALTER TABLE chat_conversations ADD FOREIGN KEY (id_enseignant) REFERENCES utilisateurs(id_utilisateur) ON DELETE SET NULL'
+);
+PREPARE stmt FROM @s;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+
+-- Colonne api_cost dans chat_messages
+SET @s = (SELECT IF(
+    (SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS
+     WHERE table_schema = DATABASE()
+     AND table_name = 'chat_messages'
+     AND column_name = 'api_cost') > 0,
+    'SELECT ''Column api_cost already exists''',
+    'ALTER TABLE chat_messages ADD COLUMN api_cost DECIMAL(10,6) DEFAULT 0.000000'
+));
+PREPARE stmt FROM @s;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+
+-- Restaurer les notes SQL
+SET SQL_NOTES=@OLD_SQL_NOTES;
+
+-- Remplir id_enseignant rétroactivement
+UPDATE chat_conversations cc
+JOIN tentatives_eleves te ON cc.id_tentative = te.id_tentative
+JOIN evaluations e ON te.id_evaluation = e.id_evaluation
+SET cc.id_enseignant = e.id_enseignant
+WHERE cc.id_enseignant IS NULL;
+
+SELECT '✅ Colonnes ajoutées avec succès' as Status;