fix(users): handle active discounts on delete

Ensure active_discounts cascades on user/promo removal, clean orphan rows during migration, and rely on DB cascade for user deletion.

db/migrator.py

@@ -168,6 +168,48 @@ def _migration_0004_add_discount_promo_codes(connection: Connection) -> None:
         )
     )
 
+
+def _migration_0005_fix_active_discounts_fk_cascade(connection: Connection) -> None:
+    inspector = inspect(connection)
+    if not inspector.has_table("active_discounts"):
+        return
+
+    connection.execute(
+        text(
+            "DELETE FROM active_discounts ad "
+            "WHERE NOT EXISTS (SELECT 1 FROM users u WHERE u.user_id = ad.user_id) "
+            "OR NOT EXISTS (SELECT 1 FROM promo_codes p WHERE p.promo_code_id = ad.promo_code_id)"
+        )
+    )
+
+    connection.execute(
+        text("ALTER TABLE active_discounts DROP CONSTRAINT IF EXISTS active_discounts_user_id_fkey")
+    )
+    connection.execute(
+        text("ALTER TABLE active_discounts DROP CONSTRAINT IF EXISTS fk_active_discounts_user")
+    )
+    connection.execute(
+        text("ALTER TABLE active_discounts DROP CONSTRAINT IF EXISTS active_discounts_promo_code_id_fkey")
+    )
+    connection.execute(
+        text("ALTER TABLE active_discounts DROP CONSTRAINT IF EXISTS fk_active_discounts_promo_code")
+    )
+
+    connection.execute(
+        text(
+            "ALTER TABLE active_discounts "
+            "ADD CONSTRAINT fk_active_discounts_user "
+            "FOREIGN KEY (user_id) REFERENCES users (user_id) ON DELETE CASCADE"
+        )
+    )
+    connection.execute(
+        text(
+            "ALTER TABLE active_discounts "
+            "ADD CONSTRAINT fk_active_discounts_promo_code "
+            "FOREIGN KEY (promo_code_id) REFERENCES promo_codes (promo_code_id) ON DELETE CASCADE"
+        )
+    )
+
 MIGRATIONS: List[Migration] = [
     Migration(
         id="0001_add_channel_subscription_fields",
@@ -189,6 +231,11 @@ MIGRATIONS: List[Migration] = [
         description="Add support for percentage discount promo codes",
         upgrade=_migration_0004_add_discount_promo_codes,
     ),
+    Migration(
+        id="0005_fix_active_discounts_fk_cascade",
+        description="Ensure active_discounts FKs cascade on user/promo delete",
+        upgrade=_migration_0005_fix_active_discounts_fk_cascade,
+    ),
 ]
 
 

db/models.py

@@ -210,8 +210,16 @@ class ActiveDiscount(Base):
     """Tracks pending discount promo codes awaiting payment (permanent until used)"""
     __tablename__ = "active_discounts"
 
-    user_id = Column(BigInteger, ForeignKey("users.user_id"), primary_key=True)
-    promo_code_id = Column(Integer, ForeignKey("promo_codes.promo_code_id"), nullable=False)
+    user_id = Column(
+        BigInteger,
+        ForeignKey("users.user_id", ondelete="CASCADE"),
+        primary_key=True,
+    )
+    promo_code_id = Column(
+        Integer,
+        ForeignKey("promo_codes.promo_code_id", ondelete="CASCADE"),
+        nullable=False,
+    )
     discount_percentage = Column(Integer, nullable=False)
     activated_at = Column(DateTime(timezone=True), server_default=func.now())