See Double opt-in proposed plan
A rough sketch, with more details to come:
We will record double opt ins as activities in CiviCRM, including the timestamp of the user action, email address (for clarity and auditability as the contact's primary email may change in the future). This will allow us to export a double opt-in boolean field to Acoustic and/or suppress the email in Acoustic, as required (pending future discussions on how email suppression is canceled in Acoustic).
When a user visits the wiki page with their unique link including cid and contact hash, we will validate their cid/hash combination and then create an activity as above (using an api call via CiviProxy).
If we succeed, we show the user a page indicating success. If we fail, we show a generic failure page asking them to retry or reach out for help. In the future, we could improve this to automatically resend a new link if the contact hash has expired (which happens after 2 months, so should be rare), to give the user more information about why the failure happened, and to generally handle errors more gracefully — but given the timeline and the relatively small group this will initially be rolled out to, we're going to keep things simple to start.
When a new donor will receive this link is a subject for future discussion. Existing donors will receive via Acoustic mailing.
Timeline for this need is TBD (initial plan was for the first email to go out Nov 11, but we may delay to Q3).