fix(cart): enforce Stripe $0.50 minimum; add public sales stats

Stripe rejects charges under $0.50 — a $0.33 item was silently freed
because requires_payment threshold (64¢) skipped all card processing.

Changes:
- Cart + Invoice: add requires_stripe_payment (>= 50¢)
- cart_checkout GET + cart_complete_checkout POST: block Stripe when
  total < $0.50 and only Stripe is available; message points to DOGE/XMR
- Invoice Stripe charge loop: guard on requires_stripe_payment (safety net)
- Shop model: add public_sales_stats boolean (default False)
- shop_settings: toggle for public_sales_stats
- shop() view: include sales_count + sales_revenue when flag is on
- shop.j2: conditional stats section (sales count + revenue)
- Migration: 1a2b3c4d5e6f add_public_sales_stats_to_shop

make_post_sell/models/cart.py

@@ -412,6 +412,14 @@ class Cart(RBase, Base):
             return True
         return False
 
+    @property
+    def requires_stripe_payment(self):
+        """Return True if Stripe can legally process this cart, else False.
+        Stripe enforces a hard floor of $0.50 USD — below that, Stripe rejects the charge.
+        Use DOGE or XMR for purchases under $0.50.
+        """
+        return self.total_in_cents >= 50
+
     @property
     def is_not_public(self):
         return not self.public

make_post_sell/models/invoice.py

@@ -260,6 +260,14 @@ class Invoice(RBase, Base):
             return True
         return False
 
+    @property
+    def requires_stripe_payment(self):
+        """Return True if Stripe can legally process this invoice, else False.
+        Stripe enforces a hard floor of $0.50 USD — below that, Stripe rejects the charge.
+        Use DOGE or XMR for purchases under $0.50.
+        """
+        return self.total_in_cents >= 50
+
     @property
     def human_created_timestamp(self):
         """Return the created timestamp in a human-readable format."""

make_post_sell/models/shop.py

@@ -151,6 +151,9 @@ class Shop(RBase, Base):
     # Grayscale mode: render entire site in black and white
     grayscale_mode = Column(Boolean, default=False)
 
+    # Public sales stats: show sales counts and revenue on the shop page (off by default)
+    public_sales_stats = Column(Boolean, default=False)
+
     # Color filter: 0=off, 1=grayscale, 2=red, 3=green, 4=blue,
     #               5=red+green, 6=red+blue, 7=green+blue
     color_filter = Column(BigInteger, default=0)

make_post_sell/scripts/alembic/versions/1a2b3c4d5e6f_add_public_sales_stats_to_shop.py

@@ -0,0 +1,37 @@
+"""add public_sales_stats to shop
+
+Revision ID: 1a2b3c4d5e6f
+Revises: 0ee5654cfe7d
+Create Date: 2026-04-10 00:00:00.000000
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '1a2b3c4d5e6f'
+down_revision = '0ee5654cfe7d'
+branch_labels = None
+depends_on = None
+
+
+def _column_exists(table, column):
+    from alembic import op as _op
+    from sqlalchemy import inspect
+    bind = _op.get_bind()
+    insp = inspect(bind)
+    return column in [c["name"] for c in insp.get_columns(table)]
+
+
+def upgrade():
+    if not _column_exists('mps_shop', 'public_sales_stats'):
+        op.add_column(
+            'mps_shop',
+            sa.Column('public_sales_stats', sa.Boolean(), nullable=False, server_default='0'),
+        )
+
+
+def downgrade():
+    if _column_exists('mps_shop', 'public_sales_stats'):
+        op.drop_column('mps_shop', 'public_sales_stats')

make_post_sell/templates/shop.j2

@@ -2,6 +2,14 @@
 
 {% block content -%}
 
+{% if sales_count is defined %}
+<section class="shop-stats">
+  <span>{{ sales_count }} sale{{ 's' if sales_count != 1 else '' }}</span>
+  &nbsp;&middot;&nbsp;
+  <span>${{ '%.2f'|format(sales_revenue) }} earned</span>
+</section>
+{% endif %}
+
 <section class="serp{% if request.shop.grid_lanes_enabled %} grid-lanes-enabled{% endif %}">
 {% if products %}
 {% for product in products %}

make_post_sell/views/cart.py

@@ -591,6 +591,16 @@ def cart_checkout(request):
             and not request.monero_enabled
             and not request.dogecoin_enabled
         )
+
+        # Stripe has a hard $0.50 minimum — block carts below that when only Stripe is available
+        if cart.total_in_cents > 0 and not cart.requires_stripe_payment and only_stripe_enabled:
+            msg = (
+                "Stripe requires a minimum of $0.50. Use DOGE or XMR for purchases under $0.50.",
+                "error",
+            )
+            request.session.flash(msg)
+            return HTTPFound("/cart")
+
         if cart.requires_payment and only_stripe_enabled and stripe_user_shop is None:
             msg = ("Please enter your payment information.", "info")
             request.session.flash(msg)
@@ -709,6 +719,21 @@ def cart_complete_checkout(request):
         request.session.flash(msg)
         return HTTPFound("/cart")
 
+    # Block Stripe for carts under Stripe's $0.50 minimum when only Stripe is available
+    _only_stripe_at_checkout = (
+        request.stripe_enabled
+        and not request.paypal_enabled
+        and not request.monero_enabled
+        and not request.dogecoin_enabled
+    )
+    if cart.total_in_cents > 0 and not cart.requires_stripe_payment and _only_stripe_at_checkout:
+        msg = (
+            "Stripe requires a minimum of $0.50. Use DOGE or XMR for purchases under $0.50.",
+            "error",
+        )
+        request.session.flash(msg)
+        return HTTPFound("/cart")
+
     # If Stripe is enabled and payment is required, ensure a Stripe customer exists
     if (
         cart.requires_payment
@@ -754,7 +779,7 @@ def cart_complete_checkout(request):
             for invoice in invoices:
                 shop = invoice.shop
 
-                if invoice.requires_payment:
+                if invoice.requires_stripe_payment:
                     stripe_user_shop = shop.stripe_user_shop(request.user)
                     if stripe_user_shop is None:
                         msg = (

make_post_sell/views/shop.py

@@ -230,9 +230,19 @@ def shop(request):
     if "slug" not in request.matchdict:
         return HTTPFound(f"/s/{shop.id}/{shop.slug}")
 
-    return {
-        "products": get_products_from_a_shop(shop),
-    }
+    ctx = {"products": get_products_from_a_shop(shop)}
+
+    if shop.public_sales_stats:
+        from ..models.invoice import Invoice
+        from sqlalchemy import func as sa_func
+
+        invoices = shop.invoices
+        ctx["sales_count"] = invoices.count()
+        ctx["sales_revenue"] = invoices.with_entities(
+            sa_func.coalesce(sa_func.sum(Invoice.total_in_cents), 0)
+        ).scalar() / 100.0
+
+    return ctx
 
 
 @view_config(route_name="shop_products", renderer="shop_products.j2")
@@ -832,6 +842,20 @@ def shop_settings(request):
                         )
                     )
 
+            # Handle public sales stats setting
+            public_sales_stats_value = request.params.get("public_sales_stats")
+            if public_sales_stats_value is not None:
+                public_sales_stats = int(public_sales_stats_value) == 1
+                if shop.public_sales_stats != public_sales_stats:
+                    shop.public_sales_stats = public_sales_stats
+                    status = "enabled" if public_sales_stats else "disabled"
+                    request.session.flash(
+                        (
+                            f"Public sales stats are now {status}",
+                            "success",
+                        )
+                    )
+
         # Handle stripe settings form
         if form_section == "stripe-settings":
             # Handle disable action