Improve the frontend modals

services/inventory/app/schemas/inventory.py

@@ -43,10 +43,10 @@ class IngredientCreate(InventoryBaseSchema):
     brand: Optional[str] = Field(None, max_length=100, description="Brand name")
     unit_of_measure: UnitOfMeasure = Field(..., description="Unit of measure")
     package_size: Optional[float] = Field(None, gt=0, description="Package size")
-    
+
     # Pricing
-    average_cost: Optional[Decimal] = Field(None, ge=0, description="Average cost per unit")
-    standard_cost: Optional[Decimal] = Field(None, ge=0, description="Standard cost per unit")
+    # Note: average_cost is calculated automatically from purchases (not set on create)
+    standard_cost: Optional[Decimal] = Field(None, ge=0, description="Standard/target cost per unit for budgeting")
     
     # Stock management
     low_stock_threshold: float = Field(10.0, ge=0, description="Low stock alert threshold")
@@ -187,6 +187,13 @@ class StockCreate(InventoryBaseSchema):
     shelf_life_days: Optional[int] = Field(None, gt=0, description="Batch-specific shelf life in days")
     storage_instructions: Optional[str] = Field(None, description="Batch-specific storage instructions")
 
+    @validator('supplier_id', pre=True)
+    def validate_supplier_id(cls, v):
+        """Convert empty string to None for optional UUID field"""
+        if v == '' or (isinstance(v, str) and v.strip() == ''):
+            return None
+        return v
+
     @validator('storage_temperature_max')
     def validate_temperature_range(cls, v, values):
         min_temp = values.get('storage_temperature_min')
@@ -233,6 +240,13 @@ class StockUpdate(InventoryBaseSchema):
     shelf_life_days: Optional[int] = Field(None, gt=0, description="Batch-specific shelf life in days")
     storage_instructions: Optional[str] = Field(None, description="Batch-specific storage instructions")
 
+    @validator('supplier_id', pre=True)
+    def validate_supplier_id(cls, v):
+        """Convert empty string to None for optional UUID field"""
+        if v == '' or (isinstance(v, str) and v.strip() == ''):
+            return None
+        return v
+
 
 class StockResponse(InventoryBaseSchema):
     """Schema for stock API responses"""