sequenceDiagram
    participant User
    participant Alert System
    participant ConditionExt
    participant Value Handler
    
    User->>Alert System: Trigger alert evaluation
    Alert System->>ConditionExt: evaluate(row)
    ConditionExt->>ConditionExt: Get column value from row
    
    alt Column not found
        ConditionExt-->>Alert System: return false
    else Column found
        ConditionExt->>Value Handler: Match on value type
        
        alt Value::String
            Value Handler->>Value Handler: trim_matches('"') on condition value
            Value Handler->>Value Handler: Compare strings with operator
            Value Handler-->>ConditionExt: Return comparison result
        else Value::Number
            Value Handler->>Value Handler: Parse and compare numbers
            Value Handler-->>ConditionExt: Return comparison result
        else Value::Bool
            Value Handler->>Value Handler: Parse and compare booleans
            Value Handler-->>ConditionExt: Return comparison result
        else Value::Null (NEW)
            Value Handler->>Value Handler: Check if operator is EqualTo
            Value Handler->>Value Handler: Check if condition value is "null" string
            Value Handler-->>ConditionExt: Return true if both match
        else Other types
            Value Handler-->>ConditionExt: return false
        end
        
        ConditionExt-->>Alert System: Return evaluation result
    end
    Alert System-->>User: Alert triggered or not