RFC : Emit an event when products are added to a category

[adevinwild]

Summary

We should emit an event whenever products are added or removed from a product category. This will allow developers to subscribe to changes in product-category associations.

Current implementation

Currently, no events are emitted when products are linked to or unlinked from a product category.

Proposed implementation

We will emit a ProductCategoryWorkflowEvents.UPDATED event upon the completion of the batchLinkProductsToCategoryWorkflow

export const batchLinkProductsToCategoryWorkflow = createWorkflow(
  batchLinkProductsToCategoryWorkflowId,
   (input: WorkflowData<ProductCategoryWorkflow.BatchUpdateProductsOnCategoryWorkflowInput>): WorkflowData<void> => {

    batchLinkProductsToCategoryStep(input)
     
    // ℹ️ This allows us to listen for any membership changes on a product category
    emitEventStep({
      eventName: ProductCategoryWorkflowEvents.UPDATED,
      data: [{ id: input.id }],
    })
    
  }
)

This enables developers to trigger downstream logic based on category updates, such as invalidating storefront cache for a specific category 👍

Link to PR : #14222