Type: Action hook When Fired: During plugin initialization (on plugins_loaded or init) Purpose: Allows third-party code to register custom payment gateways Usage: Hook into this action to instantiate and register your gateway class Example: add_action( 'agency_pulse_invoice_register_gateways', 'my_register_custom_gateway' ) Type: Filter hook Parameter: Array of registered gateway objects Purpose: Retrieve all registered gateways or modify gateway array Return Value: Modified array of gateway objects Usage: Use filter to add, remove, or modify gateways in the system Type: Action hook (dynamic) When Fired: When gateway configuration page is displayed Parameter: $gateway_id = your gateway's unique identifier Purpose: Output custom settings fields for your gateway Usage: Render HTML form for