Installation

Requirements

CS-Cart or Multi-Vendor 4.17.2 – 4.21.x.
PHP 7.2.5 – 8.3, as supported by your CS-Cart version.
Tested on CS-Cart Ultimate 4.17.2, Multi-Vendor 4.17.2 and Multi-Vendor 4.21.2.
Inventory tracking can be on or off. Pre-order products use the core “Buy in advance” out-of-stock action, which the add-on sets for you.
A storefront theme based on Responsive or Nova (the default themes and most third-party themes).
Recommended: a cron job that runs every hour (see Configuration).

Install

Go to Add-ons → Manage add-ons, click the gear button and choose Manual installation.
Upload kv_pre_orders_backorders-<version>.zip and click Upload & install.
On the License tab of the settings, enter your license key and save. If you bought the add-on on the CS-Cart Marketplace and entered the license number in Add-ons → Manage add-ons, you can skip this step. Until a key is verified, the add-on works for 14 days (see License).
Check the Settings tab: the default deposit, when the balance is requested and what happens when it is overdue.
Open a product and use the new Pre-order tab.

What the installation does:

creates five tables (cscart_kv_pob_*) for product settings, the deposit records of orders, their items, an order history and a rate limiter;
creates the order status Deposit paid (stock stays reserved, not counted as paid, not counted for vendor payouts) and selects it in the settings; if the status exists from an earlier installation, it is reused;
creates five e-mail templates in Design → E-mail templates and a secret cron key.

No core files are changed.

Upgrade

Upload the new package over the installed add-on (same steps as installing). On the next admin page load the add-on brings its tables, settings and language variables up to date by itself. Product settings, order records and settings are kept.

Disable

Disabling the add-on (status Off) turns pre-order products back into ordinary “Buy in advance” products: no labels, no deposits, new orders are paid in full. Orders that already have a deposit keep their data; payments of those orders are charged in full while the add-on is off, so finish open balances first or enable the add-on again. Everything you entered comes back when you enable it.

Uninstall

Add-ons → Manage add-ons → Pre-Orders & Deposits → gear → Uninstall:

removes the add-on’s tables, settings, language variables, e-mail templates and run marks;
gives pre-order products their previous out-of-stock action back (the release dates stay as core “Available since” dates);
deletes the Deposit paid status if no order uses it; otherwise the status stays so those orders keep a valid status.

Orders themselves are never changed or deleted.