Auto-create + publish default stall, republish stall on product publish

Two complementary fixes for the "Unknown Stall" bug, where a customer
sees a product on the relay but the parent stall is missing.

1. _auto_create_merchant() now creates a default "<username>'s Store"
   stall and publishes its kind 30017 event before returning. New users
   land with a fully-published merchant identity, so the very first
   product they create has a known parent stall on relays.

2. POST /api/v1/product (api_create_product) now republishes the parent
   stall before publishing the product. NIP-33 parameterized replaceable
   events make this idempotent, but it self-heals every existing case
   where the stall publish failed or never happened (transient relay
   issues, accounts that pre-date the auto-publish flow, manual stall
   creation that didn't reach all relays).

This complements the LNbits-side fix in core/services/users.py
(_create_default_merchant publishes the stall on signup) and the
webapp self-heal in useMarketStallSelfHeal.ts. With all three layers,
"Unknown Stall" should disappear from the customer view.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

views_api.py

@@ -101,6 +101,10 @@ async def _auto_create_merchant(
     """
     Provision a merchant record from the user's account keypair.
     Called automatically on first GET or explicitly via POST.
+
+    Also creates a default "Online" shipping zone and a default stall named
+    after the user, then publishes the stall to relays so that any product
+    the user creates references a stall the customer-facing client can find.
     """
     account = await get_account(wallet.wallet.user)
     assert account, "User account not found"
@@ -127,15 +131,36 @@ async def _auto_create_merchant(
 
     merchant = await create_merchant(wallet.wallet.user, partial_merchant)
 
-    await create_zone(
-        merchant.id,
-        Zone(
+    online_zone = Zone(
         id=f"online-{merchant.public_key}",
         name="Online",
         currency="sat",
         cost=0,
         countries=["Free (digital)"],
-        ),
+    )
+    await create_zone(merchant.id, online_zone)
+
+    # Create + publish a default stall so products created through the UI
+    # always have a published parent. Without this, a product publish lands
+    # on relays referencing a stall_id that no relay has seen, and the
+    # customer client renders "Unknown Stall".
+    display_name = account.username or "My"
+    default_stall = Stall(
+        wallet=wallet.wallet.id,
+        name=f"{display_name}'s Store",
+        currency="sat",
+        shipping_zones=[online_zone],
+    )
+    default_stall = await create_stall(merchant.id, default_stall)
+    try:
+        stall_event = await sign_and_send_to_nostr(merchant, default_stall)
+        default_stall.event_id = stall_event.id
+        await update_stall(merchant.id, default_stall)
+    except Exception as ex:
+        # Non-fatal: merchant is usable; a product publish (or self-heal)
+        # will republish the stall later.
+        logger.warning(
+            f"[NOSTRMARKET] Failed to publish default stall for {merchant.id}: {ex}"
         )
 
     await resubscribe_to_all_merchants()
@@ -767,6 +792,21 @@ async def api_create_product(
         assert stall, "Stall missing for product"
         data.config.currency = stall.currency
 
+        # Re-publish the parent stall before publishing the product. NIP-33
+        # parameterized replaceable events make this idempotent on relays.
+        # This guarantees the customer client never sees a product whose
+        # parent stall isn't on the relay (e.g., when the original stall
+        # publish failed transiently or never ran).
+        try:
+            stall_event = await sign_and_send_to_nostr(merchant, stall)
+            stall.event_id = stall_event.id
+            await update_stall(merchant.id, stall)
+        except Exception as ex:
+            logger.warning(
+                f"[NOSTRMARKET] Failed to refresh stall {stall.id} "
+                f"before product publish: {ex}"
+            )
+
         product = await create_product(merchant.id, data=data)
 
         event = await sign_and_send_to_nostr(merchant, product)