Default Stock as a regular stock

In upstream MSI, inventory_stock_1 is a MySQL view over cataloginventory_stock_status. In msi-core it is a real index table built by the MSI indexer, and stock 1 is indexed, read, edited and deleted like any stock you create yourself.

Caution

This is the breaking change of msi-core. Upgrade from Magento MSI describes what it breaks and how to migrate.

Upstream MSI runs stock 1 through the legacy indexer and a view, and branches around it everywhere. msi-core indexes every stock the same way and stops reading or writing the legacy tables.

One code path for every stock

• The MSI stock indexer no longer skips stock 1, and the flag that forced it through the exception path is gone.
• InventoryConfigurableProductIndexer, InventoryBundleProductIndexer and InventoryGroupedProductIndexer cover stock 1, so composite salability comes from MSI instead of the legacy CatalogInventory indexer. The plugins that used to patch the gap by driving the legacy indexer are removed.
• The if ($stockId === $defaultStockId) branch is gone from the salability readers, the product collections and filters, the price index, search, catalog rules and visual merchandiser: around fifty branches across twenty modules.
• The read fallback to cataloginventory_stock_item is removed. It only existed because the view held no rows for disabled products; the real table does, because the index is built from inventory_source_item rather than from the enabled catalog.
• Stock 1 is editable and deletable, and its sources can be assigned and unassigned. The admin website still resolves to stock 1, and fails with a clear error rather than a raw NoSuchEntityException when someone deletes it.

Stock item configuration lives in MSI

manage_stock, backorders, min_qty, qty_increments and the rest lived in cataloginventory_stock_item for every stock, not just the default, so no stock was ever independent of the legacy system.

• The configuration lives in inventory_stock_item_configuration, keyed by sku. A data patch migrates the rows upstream actually wrote (stock 1, scope 0).
• The indexer joins the new table, which removes the hidden stock_id = 1 condition its joins carried.
• The configuration of a deleted product is dropped with it.

Per-stock or per-source configuration overrides would be the natural next step and are deliberately out of scope: they change the data model rather than its storage. A configuration read for stock 5 answers the same as one for stock 1, exactly as upstream.

The legacy tables are frozen

MSI no longer writes cataloginventory_stock_item or cataloginventory_stock_status. The whole synchronisation layer is deleted, and the legacy cataloginventory_stock indexer is inert. The tables are kept, because Magento_CatalogInventory is required by 42 core modules and cannot be uninstalled. Writes that still reach them are counted by legacy write detection.

The legacy read contracts are unaffected. StockRegistryInterface, StockStateInterface, StockItemRepositoryInterface, StockStatusRepositoryInterface and StockManagementInterface are served from MSI, so code going through them needs no change.

Core readers redirected to MSI

Every reader of the legacy tables inside Magento reads the MSI index, including those that reach the table through $stockItemResource->getMainTable() and are invisible to a grep:

• the qty and stock status columns and filters of the admin product grid;
• the Quantity column of the widget grids (review, url rewrite, bundle option and downloadable product pickers);
• the bundle selection filter behind dynamic bundle prices;
• the stock columns of the product export;
• the bundle and configurable price indexers;
• the low stock report.

Defects fixed along the way

• A configuration-only save of a legacy stock item did not rebuild the stock index, so a manage_stock change did not reach salability.
• A full stock reindex left catalog pages stale in the full page cache.
• The composite stock status settled before the source items were reindexed, so a parent could report the previous state.
• An import carrying no stock column rewrote the configuration; one carrying no quantity zeroed the default source item.
• A products filter arriving grouped had only its first id read.
• A sku the index does not carry is reported out of stock instead of raising.
• The stock registry snapshot was not dropped when source items were saved or deleted.
• A required bundle option with nothing to sell was ignored when pricing the bundle.
• A product page outside the stock broke instead of hiding the quantity message.

Performance

• A list of stock items is answered from MSI without loading the legacy rows it replaces, and the product type lookup is skipped when every sku already carries a quantity.
• Saving the inventory configuration section no longer rewrites every cataloginventory_stock_item row: measured at 2464 discarded writes on a 2.5k product catalog, a full pass over the table for nothing.
• A legacy stock item save triggers a reindex only when it moved something the index reads.