diff --git a/backend/models.py b/backend/models.py
index 4d2a925..a625b73 100644
--- a/backend/models.py
+++ b/backend/models.py
@@ -1,4 +1,5 @@
-from sqlalchemy import Column, Integer, String, Boolean, DateTime
+from sqlalchemy import Column, Integer, String, Boolean, DateTime, ForeignKey, Text
+from sqlalchemy.orm import relationship
 from datetime import datetime, timezone
 from .database import Base
 
@@ -9,8 +10,35 @@ class User(Base):
     email = Column(String, unique=True, index=True, nullable=False)
     username = Column(String, unique=True, index=True, nullable=False)
     hashed_password = Column(String, nullable=False)
-    totp_secret = Column(String, nullable=True)  # Secret pour Keepassium/Authenticator
+    totp_secret = Column(String, nullable=False)
     is_admin = Column(Boolean, default=False)
-    is_active = Column(Boolean, default=True)
+    
+    # Relation : Un utilisateur peut avoir plusieurs projets
+    projects = relationship("Project", back_populates="owner", cascade="all, delete-orphan")
+
+
+class Project(Base):
+    __tablename__ = "projects"
+
+    id = Column(Integer, primary_key=True, index=True)
+    title = Column(String, nullable=False)
     created_at = Column(DateTime, default=lambda: datetime.now(timezone.utc))
-    last_activity = Column(DateTime, nullable=True)  # Servira pour la déconnexion après 60 min
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+    is_pinned = Column(Boolean, default=False)
+    user_id = Column(Integer, ForeignKey("users.id"), nullable=False)
+    
+    # Relations
+    owner = relationship("User", back_populates="projects")
+    messages = relationship("Message", back_populates="project", cascade="all, delete-orphan")
+
+
+class Message(Base):
+    __tablename__ = "messages"
+
+    id = Column(Integer, primary_key=True, index=True)
+    role = Column(String, nullable=False)  # Ex: 'user', 'assistant', 'worker_1', 'system'
+    content = Column(Text, nullable=False)
+    created_at = Column(DateTime, default=lambda: datetime.now(timezone.utc))
+    project_id = Column(Integer, ForeignKey("projects.id"), nullable=False)
+    
+    # Relation
+    project = relationship("Project", back_populates="messages")
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