Inside a well-built WooCommerce extension
Use the WooCommerce data layer, never raw tables
The quickest way to write a plugin is also the quickest way to break a store: reading orders with get_post_meta or custom SQL against the posts table. Stores on high-performance order storage keep orders in separate tables, and that code simply returns nothing. Every extension we write reads and writes through WooCommerce objects, using wc_get_order, wc_get_orders and the getters and setters on orders and products, and declares its HPOS compatibility on load. The same discipline applies to the block checkout. A gateway or a checkout field needs a registered block integration, or it will not appear for stores that use blocks.
Gateways are mostly about what happens after the click
The payment form is the small part. The real work is state: an order is created as pending, the customer is sent to authenticate, and the provider reports the result by webhook. We verify webhook signatures, look the order up by a stored transaction reference, ignore duplicates and record a note on the order for each event. Refunds, partial captures and voids are mapped to the provider API. Card numbers never reach your server, because the form is hosted or tokenized by the provider.
Slow work goes to Action Scheduler
WooCommerce ships with Action Scheduler, a job queue with its own tables and an admin screen. We use it for anything that calls an outside system or loops over many records. Jobs are small and idempotent, they carry an order or product ID instead of a full payload, and a failure is logged and retried with a delay. Checkout stays fast even if the ERP is having a bad day. This pattern matters most for WordPress API integrations that move orders and stock between systems.
Settings, logs and the people who run the store
A plugin is used by shop managers long after developers leave. We build settings with the WooCommerce settings API so they look familiar, write to the WooCommerce logger so problems can be read under the status logs, and add an admin notice when something needs attention, such as an expired API key.
Packaging, versions and updates
Each plugin has semantic version numbers, a changelog, translation-ready strings and automated tests for its main paths. For a single store, updates are deployed from the repository through your release process. For plugins you distribute, we set up an update channel so customer sites see new versions in the normal WordPress updates screen. You own the code and the repository in both cases.
