Feature: Guard against published products being silently invisible on the storefront (opt-in default-channel auto-link / dashboard validation)

[dishanagalawatta]

Originally opened as issue #17801 — closed by the triage bot with a pointer here.

Context

A published product with no sales-channel links is silently invisible on the storefront: GET /store/products is scoped by the publishable API key to its linked sales channels and only returns products that are both status = published and linked to one of those channels. The admin dashboard lets an operator flip draft → published without assigning a channel, and the result is a 200 with an empty list — no error, no signal, anywhere.

This was reported as #14374 ("Successfully created product is not shown in the storefront") and closed as a docs issue. We hit it in production anyway (new operator publishes a product; storefront shows nothing; everyone assumes a caching bug) — the docs describe the rule, but nothing guards against the trap.

Reproduction

1. Create a product via Admin (draft).
2. Set status = published (dashboard toggle or API) without touching sales channels.
3. GET /store/products?publishable_key=<key> → 200 { count: 0 }.
4. Admin shows the product as published. No diagnostic exists.

Why this matters

• The failure mode is silent and looks exactly like a caching bug — this pattern generates recurring support confusion for new merchants.
• The behavior itself is correct (multi-channel scoping is deliberate), so the fix should be guardrails, not a behavior change that breaks marketplaces.

Proposed solution (respecting the multi-channel doctrine)

Any of these, ordered by impact:

Option A — opt-in auto-link setting. A store-level setting (e.g. auto_link_published_products_to_default_channel, default off) consulted by the product create/update core-flows: when a product transitions to published with zero channel links, link it to the store's default_sales_channel_id. Opt-in, so multi-channel merchants are unaffected.

Option B — dashboard validation. In the admin product form, when an operator sets the product to published while no sales channel is selected, show a warning (or configurable block): "This product will not appear on any storefront until it is assigned to a sales channel."

Option C — detectability minimum. Expose a cheap signal for storefronts/integrations to detect the condition (e.g. include sales_channels in standard product admin responses when requested, and document the check).

Reference implementation (running in production on Medusa 2.22.6)

We implemented Option A as a fire-and-forget subscriber, precisely to keep it opt-in and non-invasive:

// Pure decision function
export function needsDefaultChannelLink(row: { status?: string; sales_channels?: unknown[] }): boolean {
  if (row.status !== "published") return false
  return (row.sales_channels ?? []).length === 0
}

// Subscriber on product.created / product.updated:
//   query product status + sales_channels.id
//   if needsDefaultChannelLink -> resolve default channel
//     (store.default_sales_channel_id, falling back to channel named "Default Sales Channel")
//   link.create({ [Modules.PRODUCT]: { product_id }, [Modules.SALES_CHANNEL]: { sales_channel_id } })
//   drafts are left alone; products already in any channel are left alone

Happy to open a PR for Option A behind a flag, or contribute the dashboard warning if the maintainers prefer Option B.