Jul 9 - Chat - save chat sessions

app/models/support.py

@@ -39,3 +39,54 @@ class SupportTicketReply(db.Model):
 
     def __repr__(self):
         return f'<SupportTicketReply {self.id} ticket={self.ticket_id}>'
+
+
+# ── AI support-chat persistence (phase37) ─────────────────────────────────────
+
+class SupportChatSession(db.Model):
+    """One saved AI-chat conversation for a customer. Persisted so both the
+    customer and staff can reference past conversations and maintain continuity
+    (prior messages are reloaded into the chat window on return)."""
+    __tablename__ = 'support_chat_sessions'
+
+    id          = db.Column(db.Integer, primary_key=True)
+    customer_id = db.Column(db.Integer, db.ForeignKey('users.id', ondelete='CASCADE'),
+                            nullable=False, index=True)
+    created_at  = db.Column(db.DateTime, default=now_eastern, nullable=False)
+    updated_at  = db.Column(db.DateTime, default=now_eastern, nullable=False, index=True)
+
+    customer = db.relationship('User', foreign_keys=[customer_id])
+    messages = db.relationship(
+        'SupportChatMessage', backref='session',
+        cascade='all, delete-orphan',
+        order_by='SupportChatMessage.created_at',
+        lazy='dynamic',
+    )
+
+    @property
+    def message_count(self):
+        return self.messages.count()
+
+    @property
+    def preview(self):
+        """First user message, for list views."""
+        first = self.messages.filter_by(role='user').first()
+        return first.content if first else '(no messages)'
+
+    def __repr__(self):
+        return f'<SupportChatSession {self.id} customer={self.customer_id}>'
+
+
+class SupportChatMessage(db.Model):
+    """A single turn in a SupportChatSession. role = 'user' | 'assistant'."""
+    __tablename__ = 'support_chat_messages'
+
+    id         = db.Column(db.Integer, primary_key=True)
+    session_id = db.Column(db.Integer, db.ForeignKey('support_chat_sessions.id', ondelete='CASCADE'),
+                           nullable=False, index=True)
+    role       = db.Column(db.String(16), nullable=False)   # 'user' | 'assistant'
+    content    = db.Column(db.Text, nullable=False)
+    created_at = db.Column(db.DateTime, default=now_eastern, nullable=False)
+
+    def __repr__(self):
+        return f'<SupportChatMessage {self.id} session={self.session_id} role={self.role}>'