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backend/internal/modules/pricing/model.go

@@ -0,0 +1,26 @@
+// Package pricing implements quantity-based pricing for products (spec
+// section 16): a product can have several price tiers, each pairing a
+// quantity with a unit (from the units module) and a price. Pricing logic
+// (computing an order line's total from a chosen tier) is centralized here
+// in the backend -- the frontend only ever displays tiers and sends back a
+// tier ID + multiplier; it never sends a price the backend has to trust.
+package pricing
+
+import (
+	"time"
+
+	"github.com/google/uuid"
+)
+
+type PriceTier struct {
+	ID         uuid.UUID `gorm:"type:uuid;primaryKey"`
+	ProductID  uuid.UUID `gorm:"type:uuid;not null;index"`
+	UnitID     uuid.UUID `gorm:"type:uuid;not null"`
+	Quantity   float64   `gorm:"not null"`
+	PriceCents int64     `gorm:"not null"`
+	Position   int       `gorm:"not null;default:0"`
+	CreatedAt  time.Time
+	UpdatedAt  time.Time
+}
+
+func (PriceTier) TableName() string { return "price_tiers" }