Add allow_negative_stock toggle for sales, remissions, quotes, layaways and service orders

pos/services/service_order_engine.py

@@ -8,6 +8,16 @@ from datetime import datetime
 
 from services import inventory_engine
 
+
+def _tenant_allows_negative_stock(conn):
+    """Return True if the tenant explicitly allows selling below zero stock."""
+    cur = conn.cursor()
+    cur.execute("SELECT value FROM tenant_config WHERE key = 'allow_negative_stock'")
+    row = cur.fetchone()
+    cur.close()
+    return row is not None and str(row[0]).lower() in ('true', '1', 'yes')
+
+
 # Rached workshop statuses (applies to all tenants).
 ORDER_STATUSES = [
     'por_revisar',
@@ -612,10 +622,11 @@ def reserve_item(conn, so_item_id, branch_id, employee_id=None):
         raise ValueError("Item has no inventory linked")
 
     qty = int(quantity)
-    available = inventory_engine.get_stock(conn, inventory_id, branch_id)
-    if available < qty:
-        cur.close()
-        raise ValueError(f"Insufficient stock. Available: {available}, requested: {qty}")
+    if not _tenant_allows_negative_stock(conn):
+        available = inventory_engine.get_stock(conn, inventory_id, branch_id)
+        if available < qty:
+            cur.close()
+            raise ValueError(f"Sin stock suficiente. Disponible: {available}, solicitado: {qty}")
 
     inventory_engine.record_operation(
         conn,