WordPress

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.

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.

Find tickets, set up the core development environment, write patches and get them reviewed.

Sanitise input, validate it, and escape output with the right function for each context.

Environments, database search and replace, media, configuration per environment and rollbacks.

What nonces are and are not, adding them to forms, AJAX and REST requests, and verifying them.

Create a plugin with a header, hook into WordPress and activate it.

Run custom queries with $wpdb->prepare, table prefixes, and when to avoid raw SQL.

Organise files, prefix everything, guard direct access and keep the main file small.

Store settings with the Options API, cache expensive results with transients, and watch autoloaded data.