Changelog

PostPay refund logic moved into Postpay::refund() (overrides AbstractMethod::refund()); the previous around-plugin PostpayRefundPlugin is removed. CopeX_Plc integration is preserved — when CopeX_Plc is enabled, the override short-circuits so plc-m2's own plugin remains authoritative.

Post-Label input field is now reliably rendered on the credit memo create form, positioned above the "Items to Refund" section (injected via plugin on the credit memo Create\Items block); previous layout-XML approach added the block as an unrendered child of order_creditmemo.

Section 3.3 (DE/EN): corrected the button name to "Refund Offline" (PostPay is an offline payment method without an online gateway transaction — Magento's Payment::refund() reaches the gateway's refund() via the elseif ($gateway->isOffline()) branch, regardless of doTransaction).

PHPUnit infrastructure added (phpunit.xml, Test/autoload.php, Test/bootstrap.php, Test/run.php) so unit tests can run inside a Magento root without conflicting with project-level NonComposerComponentRegistration. Invoke via php Test/run.php. 62 unit tests, 164 assertions, all passing.

Standalone PostPay refund — module performs refunds via the PostPay REST API without requiring CopeX_Plc
New "Post-Label / Tracking-Number" input field on credit memo create form (required when CopeX_Plc is absent, hidden when present)
New database column sales_creditmemo.postpay_post_label to persist the tracking number per credit memo
New admin configuration group "PostPay Refund API (Standalone)" with API Key, API Secret, Test Mode, and endpoint URLs
OAuth2 client with token caching (TTL = expires_in - 60s) and 401-retry on stale tokens
Refund amount validation against the Post.at EUR 1200 hard limit

When CopeX_Plc is installed, the existing plc-m2 refund flow takes precedence and the new field is hidden — backwards compatible
Standalone mode integrates with Post.at REST API at https://postag.{test,prod}.apimanagement.ch20.hana.ondemand.com

1.0.5 - 2026-03-16¶