Feature request: Store Mollie transaction fees in order meta for analytics & cost tracking

[ricktibbe]

WooCommerce recently introduced a native “Cost of Goods Sold” (COGS) feature to help merchants calculate their profit margins more accurately. While the analytical part of this feature is still in development, I think it'd be a useful addition to add something similar for the payment gateway fees through the Mollie plugin.

This feature request proposes that the Mollie WooCommerce plugin automatically saves the transaction fee charged by Mollie as order meta, making it available for reporting, analytics, and cost tracking.

Use case

Merchants increasingly rely on WooCommerce Analytics to measure net profit per order. With COGS and shipping costs already supported, payment fees are the next logical step toward complete profitability insights.

By saving the Mollie transaction fee as order meta (e.g. _mollie_transaction_fee), merchants and developers can:

• Include the fee in custom profit calculations
• Export it via WooCommerce reports or REST API
• Integrate it into Google Data Studio / Metorik dashboards
• Display it in the WooCommerce Analytics > Orders or other reports

Suggested implementation

When Mollie returns the payment details through the API, the plugin should already have access to the transaction fee data.
It could simply save this value as order meta when the order status changes to “paid” or “completed”.

Optionally, it could also store the currency (e.g. _mollie_transaction_fee_currency), but the native COGS feature does not store this either.