diff --git a/bp/product/routes.py b/bp/product/routes.py
index ca230c8..4ea209a 100644
--- a/bp/product/routes.py
+++ b/bp/product/routes.py
@@ -252,19 +252,23 @@ def register():
 
         # no explicit commit; your session middleware should handle it
 
-        # htmx support (optional)
+        # htmx response: OOB-swap mini cart + product buttons
         if request.headers.get("HX-Request") == "true":
-            # You can return a small fragment or mini-cart here
+            from shared.infrastructure.fragments import fetch_fragment
+            from shared.infrastructure.cart_identity import current_cart_identity as _ci
+            frag_ident = _ci()
+            cart_params = {}
+            if frag_ident["user_id"] is not None:
+                cart_params["user_id"] = frag_ident["user_id"]
+            if frag_ident["session_id"] is not None:
+                cart_params["session_id"] = frag_ident["session_id"]
+            cart_mini_html = await fetch_fragment("cart", "cart-mini", params=cart_params)
 
             return await render_template(
                 "_types/product/_added.html",
+                cart_mini_html=cart_mini_html,
                 cart=g.cart,
                 item=ci,
-                total=total,
-                cart_count=sum(i.quantity for i in g.cart),
-                cart_total=total(g.cart),
-                calendar_total=lambda entries: 0,
-                calendar_cart_entries=[],
             )
 
         # normal POST: go to cart page
diff --git a/templates/_types/product/_added.html b/templates/_types/product/_added.html
new file mode 100644
index 0000000..ad44b9d
--- /dev/null
+++ b/templates/_types/product/_added.html
@@ -0,0 +1,16 @@
+{# HTMX response after add-to-cart: OOB-swap the mini cart + product buttons #}
+{% import '_types/product/_cart.html' as _cart %}
+
+{# 1. Update mini cart via cart-mini fragment #}
+{{ cart_mini_html | safe }}
+
+{# 2. Update add/remove buttons on the product #}
+{{ _cart.add(d.slug, cart, oob='true') }}
+
+{# 3. Update cart item row if visible #}
+{% from '_types/product/_cart.html' import cart_item with context %}
+{% if item and item.quantity > 0 %}
+  {{ cart_item(oob='true') }}
+{% elif item %}
+  {{ cart_item(oob='delete') }}
+{% endif %}