What this is
App and hardware carts are tracked separately in session state — $_SESSION['cart'] for app purchases and $_SESSION['hwcart'] for hardware orders — reflecting that these are genuinely different purchase flows with different downstream logic (instant app access versus a physical order needing fulfillment).
How it works
cartAppIds() and cartCount() work against the app cart specifically, while hwCartLines() and hwCartTotal() are the hardware-cart equivalents — a developer building cart-related tooling needs to know which cart they're actually working with, since the two aren't interchangeable.
Holding BOT for this path
Standard commerce-category BOT holding requirement for development access — note that cart contents themselves (what's actually being purchased) may include BOT-payable items, which is a separate, purchase-side use of BOT from the development access requirement.
Related paths in E-Commerce