To implement custom logic for selecting an inventory source, the correct Adobe Commerce development pattern is to create a new Source Selection Algorithm (SSA). This involves creating a new module that implements the Magento\InventorySourceSelectionApi\Api\SourceSelectionInterface. The custom logic, which in this case would calculate the best source based on shipping address and delivery cost, is placed within the execute() method of this implementation. The new algorithm must then be registered with the system using dependency injection by adding it to the sourceSelectionAlgorithms list in a di.xml file.

B: The Distance Priority Algorithm only considers geographic distance, not delivery cost. The PlaceReservationsForSalesEventInterface is used for creating inventory reservations after a source has been selected, not for the selection logic itself.

C: The Source Priority Algorithm uses a pre-configured, static priority of sources and does not dynamically evaluate criteria like shipping address or cost. GetSourceSelectionAlgorithmList is a method to retrieve existing algorithms, not implement a new one.

1. Adobe Commerce Developer Documentation

"Create a custom algorithm": "To create a custom source selection algorithm

you must create a module that implements the SourceSelectionInterface and register it in the di.xml file." This directly supports option A as the correct procedure.

Source: Adobe Commerce Developer Documentation > Inventory Management > Source selection > Create a custom algorithm.

2. Adobe Commerce Developer Documentation

"Source Selection Interface": The documentation for the Magento\InventorySourceSelectionApi\Api\SourceSelectionInterface specifies that it is the contract for Source Selection Algorithms. Any custom algorithm must implement this interface.

Source: Adobe Commerce Developer Documentation > Technical resources > Magento\InventorySourceSelectionApi\Api\SourceSelectionInterface.

3. Adobe Commerce Developer Documentation

"Distance Priority Algorithm": This document explains that the algorithm "calculates the distance between the shipping destination address and source locations" to determine the closest source. It makes no mention of incorporating delivery cost

confirming it does not meet the full requirement.

Source: Adobe Commerce Developer Documentation > Inventory Management > Distance Priority Algorithm.