Homepage modal: update release logic to make modal visible to a % of users when flipper is enabled

[jilladams]

Description

12/21 new scope request from Dave C: investigate and estimate what would be required to display the homepage modal to a % of users and gradually ramp to 100%, rather than binary off/on flipper.

This is complicated as the gradual-roll-out logic that comes with flipper pertains to authenticated users only. So: we will need to implement this for _un_authenticated users as well.

The chatbot previously did some similar % release to unauthed users, and our team removed the logic that controlled it. That logic is applicable / reusable for this use case.

• 9332

• PR for removing that: https://github.com/department-of-veterans-affairs/vets-website/pull/21363/files

% rollout will begin with 25%. Release plan will document the plan for progression.

Nice to have: testing, future proofing

1. This will be the 2nd time we've needed a method for % phased rollout to unauthed users. It behooves us to think about how to make this extensible / reusable for future needs. Ryan notes:
   • The previous implementation is not utilizing any sort of hook, which likely has the effect of running the calculation logic every time the render function is called (which is likely a lot more than once.
   • A custom hook is probably the way to go, and that'd make this reusable as well.

This issue is time-sensitive, so if making this reusable increases LOE, it can be broken out into a separate ticket.

2. For testing purposes, it would be very helpful to have a means of forcing the modal to appear even if you are not in the 25%.

Additional context

va_home_preview_modal flipper is still available for off/on logic to display the modal at all.

Acceptance Criteria

• [ ] The homepage modal is present for 25% of users on page load of VA.gov
  • Decision re: what % to start with: https://dsva.slack.com/archives/C52CL1PKQ/p1671644635556979
• [ ] Document a mechanism for forcing the modal to appear if it is not served on page load (TBD technical feasibility)
• [ ] Google Analytics event is sent when modal is displayed. (Goal: a mechanism to track # of users who see the modal)
  • This AC may be met by #12048
• [ ] EITHER: Method is written in a reusable way for future simillar needs OR that requirement is broken out into a separate ticket for future work

CMS Team

Please check the team(s) that will do this work.

• [ ] Program
• [ ] Platform CMS Team
• [ ] Sitewide Crew
• [ ] ⭐️ Sitewide CMS
• [X] ⭐️ Public Websites
• [ ] ⭐️ Facilities
• [ ] ⭐️ User support

[jilladams]

Spike notes: https://dsva.slack.com/archives/C52CL1PKQ/p1671643860406759 tl;dr: we can use the chatbot logic. Converting to become an implementation ticket.

[jilladams]

Since this was primarily tested locally, and not possible to confirm in a review instance with the given QA steps, I'm moving to PO Review column for Staging verification once it hits staging.

[jilladams]

Tested on Staging & verified:

Positive: Modal should appear for user assigned show-homepage-soft-launch-modal <=25

• Load http://staging.va.gov
• Check local storage => show-homepage-soft-launch-modal = 13
  • Dismiss, reload: modal doesn't appear
  • Close tab, load in new tab: modal appears

Negative: modal should not appear for show-homepage-soft-launch-modal >25

• Edit show-homepage-soft-launch-modal and set to 26
  • Reload page: modal doesn't appear
  • Close tab, load in new tab: modal doesn't appear

I then reset the show-homepage-soft-launch-modal to 13, reload: modal appears.

Great success. Closing.