fix(stripe): disable adaptive pricing when modal checkout omits country

[rbcorrales]

All Submissions:

• Have you followed the Newspack Contributing guidelines?
• Does your code follow the WordPress coding standards and VIP Go coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

WooCommerce Stripe 10.8 enables Adaptive Pricing by default for eligible existing stores via a one-time migration (woocommerce/woocommerce-gateway-stripe#5492). With Adaptive Pricing active, the Stripe Checkout Sessions confirmation requires a billing country, but the Newspack modal checkout can be configured (Reader Revenue billing fields) to omit that field. On those sites, one-time donations and modal purchases fail with Missing value for confirm: billingAddress.address.country.

This PR adds a guard in the WooCommerce Gateway Stripe integration that disables Adaptive Pricing when the configured billing fields omit billing_country:

• On modal checkout requests (wp_loaded, using Modal_Checkout::is_modal_checkout()), so the fix lands on the same request that renders or processes the checkout.
• Right after WooCommerce Stripe runs its update migrations (woocommerce_stripe_updated), so the 10.8 default-on flip is reverted immediately on the request that performs it.

Sites that collect the country field, use the default billing fields (which include country), or check out via My Account (where the country field is rendered) are not affected.

How to test the changes in this Pull Request:

1. On a site with WooCommerce and WooCommerce Stripe 10.8+, configure Reader Revenue billing fields (Audience > Donations) to a custom set that does not include billing_country.
2. Enable Adaptive Pricing in WooCommerce > Settings > Payments > Stripe > advanced settings (or set adaptive_pricing to yes in the woocommerce_stripe_settings option).
3. Load a regular article page and confirm Adaptive Pricing stays enabled (the guard must not run outside modal checkout).
4. Open a donation modal checkout. Confirm adaptive_pricing flips to no, the checkout iframe shows no Adaptive Pricing currency selector, a one-time donation completes without the missing country error, and the change is logged.
5. Re-enable Adaptive Pricing and add billing_country to the billing fields. Confirm modal checkout leaves the setting enabled.
6. Re-enable Adaptive Pricing and clear the billing fields option (default field set). Confirm modal checkout leaves the setting enabled.
7. Re-enable Adaptive Pricing and trigger the post-migration hook (e.g. wp eval "do_action( 'woocommerce_stripe_updated' );"). Confirm the setting flips to no without a modal checkout request.
8. Deactivate newspack-blocks (or the Stripe gateway) and confirm checkout requests cause no errors (guards bail silently).

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully run tests with your changes locally?

[Copilot]

Pull request overview

This PR prevents WooCommerce Stripe “Adaptive Pricing” from breaking Newspack modal checkout flows when the site’s configured Reader Revenue billing fields omit billing_country, by automatically disabling Adaptive Pricing in that scenario.

Changes:

• Adds a wp_loaded guard that disables Adaptive Pricing only during modal checkout requests (via Modal_Checkout::is_modal_checkout()).
• Adds a woocommerce_stripe_updated hook handler to immediately revert Stripe’s 10.8+ migration default that enables Adaptive Pricing, when modal checkout can’t provide country.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.