[andrii-vysotskyi-cko]

Description

Native alternative payment improvements that don't depend on payment finalization, ported from #539.

Solution

• Poll only while payment is PENDING; new steps are now accepted while awaiting completion.
• Ignore redirect-result-unexpected and redirect-result-unexpected-for-step when resolving return deep links; polling picks up the actual state.
• setState(with:) reports its own failures with the response's payment state; callers only handle request errors.
• Store payment state in interactor states and report it in didFail.
• cancel() always fails the payment, unless it is already completed. Check cancellation before state changes and before starting a redirect.
• In submit(), separate request errors (recoverable) from response handling errors.
• Add Task.poCheckCancellation() and metadata to POInvoiceCreationRequest.
• Clarify enableHeadlessMode: it only skips the first redirect's confirmation, has no effect when redirectButton is nil, and with deep links start() usually returns while payment is pending.

Notes

• Unknown or failed states returned while polling now fail right away instead of after the timeout.

[Copilot]

🟡 Changes recommended

Automatic redirects retain the awaiting-completion state, causing valid pending → redirect → pending flows to fail with a generic error instead of resuming polling.

1 open issue

• Automatic redirects fail when the continuation returns PENDING · New

What changed in this PR

This PR improves native alternative payment handling across polling, redirects, cancellation, and failure reporting.

Changes:

• Poll only while payment is pending, allowing new steps and terminal states to be handled immediately.
• Preserve payment-state context in failures, strengthen cancellation handling, and ignore obsolete redirect-result errors.
• Add invoice metadata support and clarify headless-mode documentation.

File	Description
Sources/​ProcessOutUI/​Sources/​Modules/​NativeAlternativePayment/​Interactor/​NativeAlternativePaymentInteractorState.swift	Stores payment state for failure reporting.
Sources/​ProcessOutUI/​Sources/​Modules/​NativeAlternativePayment/​Interactor/​NativeAlternativePaymentDefaultInteractor.swift	Updates transitions, cancellation, submission errors, and deep-link handling.
Sources/​ProcessOutUI/​Sources/​Modules/​NativeAlternativePayment/​Interactor/​Adapter/​DefaultNativeAlternativePaymentServiceAdapter.swift	Limits polling to pending payments.
Sources/​ProcessOutUI/​Sources/​Modules/​NativeAlternativePayment/​Configuration/​PONativeAlternativePaymentConfiguration.swift	Clarifies headless redirect behavior in documentation.
Sources/​ProcessOut/​Sources/​Repositories/​Shared/​Responses/​Failure/​POFailureCode.swift	Adds unexpected redirect-result failure codes.
Sources/​ProcessOut/​Sources/​Repositories/​Invoices/​Requests/​POInvoiceCreationRequest.swift	Adds optional invoice metadata.
Sources/​ProcessOut/​Sources/​Core/​Utils/​Task+Cancellation.swift	Adds a cancellation check that throws POFailure.

_{Review effort: Balanced}

[Copilot]

🟡 Changes recommended

A critical polling flaw can repeatedly reset the configured timeout, and cancellation during the redirect delegate callback can still allow an external redirect to launch.

2 open issues

• Prevent pending polling responses from resetting the confirmation timeout · New
• Automatic redirects fail when the continuation returns PENDING

1 previously missed issue

In code that hasn't changed since last review

Recheck cancellation after willStartRedirect before opening the deep link

Sources/​ProcessOutUI/​Sources/​Modules/​NativeAlternativePayment/​Interactor/​NativeAlternativePaymentDefaultInteractor.swift:415

If the synchronous willStartRedirect delegate callback calls the component's cancel(), the payment enters failure after this cancellation check, but a deep-link redirect still reaches UIApplication.open. Recheck cancellation and terminal state after notifying the delegate so cancelling at this boundary does not launch the external redirect.

_{Review effort: Balanced}