Decisions

Odd rules have reasons. Without the reason, the next agent tidies the rule away and brings back the bug that caused it. A decision keeps the reason next to the rule.

# One voucher per order

Decided: 12 March 2026, Cedric May
Applies to: feature/cart C2, feature/product-page C2

## Why
Stacked discounts were abused: codes from newsletter,
partner and loyalty programmes combined to more than
40 % off. Support spent two days a month on refunds.

## Rejected
- A limit per customer: needs accounts; most orders are guests.
- A maximum discount: customers found it confusing.

## Check
→ cart.spec#one-voucher

When to write one

• A fixed statement would look wrong to a newcomer.
• You rejected an obvious alternative.
• A bug or an incident led to the rule. These are the scars worth keeping; each gets a regression check.
• A guided proposal from a model is accepted. The decision records the measured gain.

Changing a fixed statement

Fixed statements change only together with a decision: a new file, or a new dated entry in the existing one, that names the reason and what it replaces. The statement keeps its id if the rule is the same rule, refined; it gets a new id if it is a different rule.