Jul 8 - Implement QR code per facility

app/models/facility.py

@@ -1,3 +1,4 @@
+import secrets
 from app import db
 from app.utils.time_utils import now_eastern
 
@@ -16,10 +17,28 @@ class Facility(db.Model):
     project_id = db.Column(db.Integer, db.ForeignKey('projects.id', ondelete='SET NULL'),
                            nullable=True, index=True)
 
+    # Phase 34: unguessable token encoded in the facility's public QR code.
+    # The QR points at /f/<public_token>, a login-free occupant summary page.
+    # Backfilled for existing rows by phase34; set at creation for new rows.
+    public_token = db.Column(db.String(48), nullable=True, unique=True, index=True)
+
     # Relationships
     areas = db.relationship('Area', backref='facility', lazy='dynamic')
     inspections = db.relationship('Inspection', backref='facility', lazy='dynamic')
 
+    @staticmethod
+    def generate_public_token() -> str:
+        """Return a fresh URL-safe token for the public QR link."""
+        return secrets.token_urlsafe(24)
+
+    def ensure_public_token(self) -> str:
+        """Return this facility's public_token, generating & persisting one
+        if it is missing (e.g. a row created before phase34 ran). The caller
+        is responsible for db.session.commit()."""
+        if not self.public_token:
+            self.public_token = self.generate_public_token()
+        return self.public_token
+
     def __repr__(self):
         return f'<Facility {self.name}>'