Add API-level validation for budget_amount to catch corrupted data early and provide clear error messages

app/models.py

@@ -1,4 +1,4 @@
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, validator
 from typing import Optional, List
 from datetime import datetime
 from enum import Enum
@@ -44,7 +44,16 @@ class CategoryExpense(BaseModel):
 class RecommendationRequest(BaseModel):
     user_id: str = Field(..., description="User identifier")
     category_id: str = Field(..., description="Category ID to check for previous data")
-    budget_amount: Optional[float] = Field(None, description="Current budget amount for this category (optional)")
+    budget_amount: Optional[float] = Field(None, gt=0, le=1e12, description="Current budget amount for this category (optional, max 1 trillion)")
+    
+    @validator('budget_amount')
+    def validate_budget_amount(cls, v):
+        if v is not None:
+            if v <= 0:
+                raise ValueError('budget_amount must be greater than 0')
+            if v > 1e12:  # More than 1 trillion is likely corrupted data
+                raise ValueError(f'budget_amount ({v:,.0f}) is unreasonably large. Maximum allowed is 1,000,000,000,000 (1 trillion). Please check your input.')
+        return v
 
 class RecommendationResponse(BaseModel):
     has_previous_data: bool

app/smart_recommendation.py

@@ -293,7 +293,14 @@ class SmartBudgetRecommender:
         # If budget_amount is provided, use it
         using_budget_amount_only = False
         if budget_amount and budget_amount > 0:
-            print(f"🔍 get_recommendation_for_category: Using provided budget_amount: {budget_amount}")
+            # Check for data corruption in budget_amount
+            if budget_amount > 1e15:  # Unreasonably large number
+                print(f"🚨 DATA CORRUPTION: budget_amount is {budget_amount:,.2e} - too large, using safe fallback")
+                # Use a reasonable default based on category or cap at 1 billion
+                budget_amount = 1e9  # 1 billion as safe maximum
+                print(f"   Capped budget_amount to {budget_amount:,.0f}")
+            
+            print(f"🔍 get_recommendation_for_category: Using provided budget_amount: {budget_amount:,.0f}")
             # First, get category name
             category_name = self._get_category_name(category_id)
             avg_expense = budget_amount