WordPress

Keep plugins fast on large sites: query discipline, caching, lazy loading and avoiding autoload bloat.

Ship blocks, block bindings and editor panels from a plugin, and register meta for the editor.

Declare plugin dependencies in the header, check for them at runtime and degrade gracefully.

Structure larger plugins with namespaces, classes, hook registration and clear responsibilities.

Use Composer autoloading and dependencies in plugins, and prefix vendor code to avoid conflicts.

Set up the WordPress test suite for a plugin, write integration tests, and run them in CI.

Check code against WordPress Coding Standards with PHPCS, fix issues automatically and add it to CI.

Run upgrade routines between plugin versions, migrate data in batches, and stay backwards compatible.

Network activation, per-site tables and options, and testing plugins on Multisite.

Hook into WordPress privacy tools so users can export and erase data your plugin stores.

Deliver updates outside WordPress.org, licence checks and GPL obligations.

Prepare the readme, pass review guidelines, use SVN releases and support users.

Updates, least-privilege users, file permissions, security headers and what security plugins can and cannot do.

Handle admin-ajax requests with nonces and capability checks, and when the REST API is better.

When to use Multisite, network setup, switching sites in code and network-wide plugins.

Add meta boxes, save post meta with nonces and sanitisation, and register meta for REST.

How WP-Cron runs, scheduling events, using a real cron, and handling long jobs. Canonical lesson.

Run large or delayed work reliably in batches with Action Scheduler, building on WP-Cron.

Use WordPress as a content API for a separate frontend, with REST or GraphQL, previews and trade-offs.

A review checklist for plugins: capabilities, nonces, sanitising, escaping, SQL and file handling.