feat(core): cascade or document product soft-delete → seller offer soft-delete #1575

Environment

• Mercur 2.3.5: @mercurjs/core@2.3.5, @mercurjs/admin@2.3.5, @mercurjs/vendor@2.3.5
• Medusa 2.20.1 (@medusajs/core-flows)
• Confirmed from published npm .medusa/server (not a downstream fork of core workflows)

Problem / current behavior

Mercur models Product ≠ Offer. Soft-deleting a catalog product does not soft-delete or deactivate seller offers that point at it:

• Admin DELETE /admin/products/:id soft-deletes the product (and variants) immediately.
• Vendor DELETE /vendor/products/:id only stages PRODUCT_DELETE; after operator confirm the product is soft-deleted the same way.
• Neither path cleans offers. Admin Offers (/dashboard/offers) then shows blank orphan rows (offer still live, product gone).
• Discovery already listens to product.deleted / product.product.deleted for re-index, but core does not clean offers on those events.
• Offer events include offer.deleted with { id, product_id } — useful after cleanup, not a substitute for product→offer cascade.

Marketplaces must invent a subscriber themselves or live with orphan Admin Offers UI.

Proposed solution / API

Pick one (or both) of:

1. Cascade / built-in side effect: When a product is soft-deleted (admin direct or confirmed vendor PRODUCT_DELETE), soft-delete (or officially deactivate) seller offers for that product_id via the same path as deleteOffersWorkflow (@mercurjs/core/workflows), emitting offer.deleted.
2. Documented extension hook: Export/document a recommended subscriber or workflow hook (event names, payload shape, “resolve offer ids by product_id → deleteOffersWorkflow”) so marketplaces do not rediscover orphan Offers rows. Vendor confirm path must be covered the same as admin delete.

Empty offer list should be a no-op. Batching for many offers is fine. Failures should not leave the product delete half-applied without logging.

Why it matters

Operators soft-delete catalog products expecting listings to disappear. Orphan offers break Admin Offers, confuse moderation, and leave storefront/discovery edges inconsistent until someone hand-deletes each offer.

Affected apps

• Core / API product delete workflows (admin + vendor PRODUCT_DELETE confirm)
• Admin Offers list / product delete UX
• Vendor product delete → operator confirm path (same end state)

Suggested implementation notes

Related existing GitHub issues

None known that ask for product soft-delete → offer cascade or an official cleanup hook. Re-scan before filing.

Acceptance criteria

• Soft-deleting a product that has seller offers removes/deactivates those offers (Admin Offers no longer shows blank orphans)
• Same behavior for admin direct delete and confirmed vendor PRODUCT_DELETE
• Zero offers → no-op; many offers → batched / resilient
• Docs describe cascade or the recommended subscriber/workflow hook (event names + deleteOffersWorkflow)
• offer.deleted still fires so discovery / integrations can react