Pure billing domain library. No framework dependency — no Yii2, no config-plugin.
@docs/overview.md @docs/domain-model.md @docs/price-types.md
Customer → Plan → Price → Action → Charge → Bill. Sale represents a subscription binding a Customer to a Target under a Plan.
No framework imports allowed — this is a pure domain library. Price types (RatePrice, SinglePrice, EnumPrice, ProgressivePrice) implement pricing strategies. Formula classes define calculation rules applied to prices. Money is a value object — never use floats for monetary values.