## ADDED Requirements

### Requirement: Formula Field Cycle Prevention
The system SHALL detect and prevent circular references in custom field formulas to avoid infinite calculation loops.

#### Scenario: Formula self-reference rejected
- **WHEN** user creates a formula field that references itself
- **THEN** system rejects with 400 Bad Request
- **THEN** error message indicates self-reference is not allowed

#### Scenario: Formula circular reference chain rejected
- **WHEN** user creates formula where Field A references Field B and Field B references Field A
- **THEN** system rejects with 400 Bad Request
- **THEN** error message includes the reference cycle path

#### Scenario: Valid formula references accepted
- **WHEN** user creates formula referencing other fields without cycles
- **THEN** system saves the formula and calculates values correctly