Journal
Technical notes, case breakdowns, and opinions from building software for merchants.
Before ArmPay can call register.do against a real bank, the bank has to email us VPOS test credentials. The protocol for getting there is not REST or GraphQL — it is email templates, phone numbers, and a few business days of waiting.
Shopify will not let a non-partner app live inside checkout, so ArmPay attaches itself to the order status page instead. The bridge is a theme app extension in extensions/armpay-thankyou/, and it is the smallest piece of the system that has the biggest design constraints.
Ameria's VPOS documentation was... incomplete. Here's what it took to turn a PDF of fields and example requests into a Shopify-grade payment gateway that passes App Store review.
Every 3PL project we've done has hit the same wall: a receiving station in the corner of a warehouse where the signal drops. Here's how we build for it.