data.stored_decimal_scale: Update by id adds a decimal with more places than its field keeps

Update by id adds a decimal with more places than its field keeps.

Area 6, Reads and writes; not declinable; the next step is usually the agent's.

The database rounds a sum its own way, so a decimal added to a stored field keeps no more places than the field does:

example

type Balance = Decimal {    scale: 2}entity Wallet {    id: Uuid    balance: Balance}action add_interest(wallet_id: Wallet.id) fails WalletNotFound -> Wallet {    return attempt Wallet.update(wallet_id) {        set: {            balance: Balance(Wallet.balance + 0.005)        }    }}

jadpo checkcheck failed: 1 error, 1 file

error Wallet.update adds a decimal with more places than Wallet.balance keeps

--> main.jadpo:13:47

   |13 |             balance: Balance(Wallet.balance + 0.005)   |                                               ^^^^^ 3 decimal places

reason: The database works Wallet.balance out in one step, and keeps it at scale: 2; 0.005 has 3, and PostgreSQL would round the result half away from zero where Jadpo rounds half to even, so the stored value could differ from Jadpo's.
next: Give the value at most 2 decimal places, or a type with scale: 2 or fewer (agent)
rule: data.stored_decimal_scale
help: https://jadpo.dev/docs/errors/data.stored_decimal_scale