Saleor Core

Backend behavior reference derived from the Saleor core source code. Covers internal mechanics that aren't fully documented in the public API reference — discount precedence, stock availability modes, denormalized fields, and known Dashboard gotchas.

When to Apply

• Building or debugging discount/promotion UI in the Dashboard
• Investigating why a voucher or promotion isn't applying
• Understanding order-level vs line-level discount precedence
• Working with OrderDiscount / OrderLineDiscount objects
• Debugging unit_discount_value on OrderLine
• Deciding whether discounts stack or suppress each other
• Building price-explanation / waterfall tooling on confirmed orders
• Reconstructing how an order-level discount distributed across lines
• Handling free-gift order lines (OrderLine.isGift = true)
• Working on stock availability, shipping zones, warehouses, or Shop.useLegacyShippingZoneStockAvailability
• Debugging why PRODUCT_VARIANT_*_IN_CHANNEL webhooks aren't firing
• Building diagnostic / "doctor" tooling that explains availability problems
• Auditing Dashboard copy that uses "available" / "in stock" / "purchasable"

Rule Categories

Quick Reference

1. Discounts (CRITICAL)

• discount-precedence — Full precedence hierarchy, stacking rules, manual vs voucher vs promotion interactions, denormalized field semantics, known Dashboard bug
• order-discount-allocation — Two-pass calculation of order-level discounts (Pass A collapses records into a single subtotal_discount; Pass B distributes proportionally across lines with last-line absorbing rounding), what the API exposes (per-line totals, per-record-at-order amounts) and what it doesn't (per-record-per-line decomposition), gift-line shape gotcha (ORDER_PROMOTION on OrderLine.discounts[] when isGift = true), reconstruction guidance for consumers

2. Stock (CRITICAL)

• stock-availability-modes — Shop.useLegacyShippingZoneStockAvailability (3.23+), purchasability vs shippability, server queryset dispatch, mode-conditional webhooks, Dashboard UI / copy / severity rules, migration footguns, test fixtures

How to Use

Read individual rule files for detailed explanations and source-level evidence:

rules/discount-precedence.md
rules/order-discount-allocation.md
rules/stock-availability-modes.md

Each rule file contains:

• Precedence hierarchy or computation rules
• Source code references from saleor/ with function names and file paths
• Anti-patterns and known bugs