feat(marketplace): moderation endpoints and age gate enforcement

backend/app/services/purchase.py

@@ -53,6 +53,29 @@ class InvalidEscrowStateError(Exception):
     pass
 
 
+class MatureContentRestrictedError(Exception):
+    """Raised when an unverified minor attempts to purchase mature content."""
+    pass
+
+
+def is_item_mature(item: CatalogItem) -> bool:
+    """Check whether a catalog item carries mature flags or is marked mature."""
+    if not item.metadata_json or not isinstance(item.metadata_json, dict):
+        return False
+    if item.metadata_json.get("is_mature") or item.metadata_json.get("mature"):
+        return True
+    flags = item.metadata_json.get("content_flags", [])
+    if isinstance(flags, list):
+        for f in flags:
+            if isinstance(f, dict) and f.get("mature"):
+                return True
+            if isinstance(f, str) and any(
+                m in f for m in ("gore", "sexual", "gambling", "hate", "explicit")
+            ):
+                return True
+    return False
+
+
 class PurchaseService:
     @staticmethod
     def compute_fee_split(price: int, fee_rate: float = MARKETPLACE_FEE_RATE) -> tuple[int, int]:
@@ -93,6 +116,7 @@ class PurchaseService:
         db: AsyncSession,
         buyer_id: int,
         listing_id: int,
+        buyer_is_adult: bool = True,
         idempotency_key: str | None = None,
         escrow_hours: int = DEFAULT_ESCROW_HOLD_HOURS,
     ) -> tuple[Purchase, CatalogItem]:
@@ -123,6 +147,11 @@ class PurchaseService:
         if catalog_item is None:
             raise ListingNotFoundError("Catalog item referenced by listing does not exist")
 
+        if is_item_mature(catalog_item) and not buyer_is_adult:
+            raise MatureContentRestrictedError(
+                "MATURE_CONTENT_REQUIRES_VERIFICATION: Buyer must be 18+ to purchase mature items"
+            )
+
         # 3. Calculate fee split
         price = listing.price
         platform_fee, seller_net = cls.compute_fee_split(price)
@@ -247,5 +276,48 @@ class PurchaseService:
         await db.refresh(purchase)
         return purchase
 
+    @classmethod
+    async def reverse_purchase(
+        cls,
+        db: AsyncSession,
+        purchase_id: int,
+        moderator_id: int,
+        reason: str,
+    ) -> Purchase:
+        """Moderator/admin audited reversal of purchase."""
+        stmt = select(Purchase).where(Purchase.id == purchase_id).with_for_update()
+        res = await db.execute(stmt)
+        purchase = res.scalar_one_or_none()
+        if purchase is None:
+            raise PurchaseNotFoundError(f"Purchase {purchase_id} not found")
+
+        if purchase.status in (PurchaseStatus.reversed, PurchaseStatus.refunded):
+            raise InvalidEscrowStateError(f"Purchase already {purchase.status.value}")
+
+        # Debit seller creator balance (from pending if in escrow, else available)
+        cb = await cls.get_or_create_creator_balance(db, purchase.seller_id, for_update=True)
+        if purchase.status == PurchaseStatus.pending_escrow:
+            cb.pending = max(0, cb.pending - purchase.seller_net)
+        else:
+            cb.available = max(0, cb.available - purchase.seller_net)
+        cb.updated_at = datetime.now(timezone.utc)
+
+        # Refund buyer wallet
+        await WalletService.credit(
+            db=db,
+            user_id=purchase.buyer_id,
+            amount=purchase.price,
+            tx_type=TransactionType.refund,
+            reference_type="purchase_reversal",
+            reference_id=str(purchase.id),
+            metadata={"moderator_id": moderator_id, "reason": reason},
+            commit=False,
+        )
+
+        purchase.status = PurchaseStatus.reversed
+        await db.commit()
+        await db.refresh(purchase)
+        return purchase
+
 
 purchase_service = PurchaseService()