Added based on issue 936

[ianbjacobs]

#936 (comment)

closes #936

The following tasks have been completed:

• Confirmed there are no ReSpec errors/warnings.
• Modified Web platform tests (link)
• Modified MDN Docs (link)
• Has undergone security/privacy review (link)

Implementation commitment:

• Safari (link to issue)
• Chrome (link to issue)
• Firefox (link to issue)
• Edge (public signal)

Impact on Payment Handler spec: Requires payment apps to ensure adequate user consent mechanisms.

---

Preview | Diff

[marcoscaceres]

Suggested change

	In particular, the {{PaymentMethodData.data}} and
	{{PaymentResponse.details}} members allow for the arbitrary exchange
	of data. In light of the wide range of data models used by existing
	payment methods, prescribing data specifics in this API would limit
	its usefulness. The {{PaymentResponse.details}} member carries data
	from the payment handler, whether Web-based (as defined by the
	[[Payment Handler API]]) or proprietary. The <a>user agent</a> MUST
	NOT support payment handlers unless they include adequate user
	consent mechanisms (such as awareness of parties to the transaction
	and mechanisms for demonstrating the intention to share data).
	In particular, the {{PaymentMethodData}}'s {{PaymentMethodData/data}} and
	{{PaymentResponse}}'s {{PaymentResponse/details}} members allow for the arbitrary exchange
	of data. In light of the wide range of data models used by existing
	payment methods, prescribing data specifics in this API would limit
	its usefulness. The {{PaymentResponse/details}} member carries data
	from the payment handler, whether Web-based (as defined by the
	[[[payment-handler]]]) or proprietary. The [=user agent=] MUST
	NOT support payment handlers unless they include adequate user
	consent mechanisms (such as awareness of parties to the transaction
	and mechanisms for demonstrating the intention to share data).

[marcoscaceres]

This seems reasonable (as far as proprietary/native payment handlers go), but it still puts the onus on the Payment Handler spec to do the "right thing"™️ with regards to privacy. That's going to be tricky with respect to the .details method because it's opaque to both the user agent and the end user.

[ianbjacobs]

Thank you, @marcoscaceres. I have incorporated your edits into the pull request.