Field Types That Break Contracts

An API sends a price as 19.99. One client uses decimal arithmetic, while another uses binary floating-point arithmetic. When they apply discounts, taxes, or repeated calculations, differences in precision and rounding rules can produce different totals.

The API looked simple. The field type made the disagreement possible.

Changing a published field type is difficult because clients may store its values in databases, spreadsheets, caches, and generated models. A safer correction often requires a new field and a migration, rather than changing the old field in place.

This lesson collects the