PagePreviews feature will be available only as a normal feature or Beta feature. Additionally, we want to enable PagePreviews for all beta users who enabled Popups previously.

We use the same Opt-In UserPreference key (https://github.com/wikimedia/mediawiki-extensions-Popups/blob/mpga/includes/PopupsContext.php#L61) to store user opt-in state for PagePreviews both for normal/Beta mode. All users who previously enabled PagePreviews Beta feature will have enabled PagePreviews after rollout.
If someone disables the PagePreviews after rollout and then we rollback the code -> user will also have disabled Beta PagePreviews.

@ovasileva Some acceptance criteria overlap with those in T157700.

(This will touch config so added Wikimedia-Site-requests).

Open question: This is currently scheduled for sprint 92 but timeline wise it looks like we won't be ready to do this until sprint 93 at earliest.

Depends on when we merge the new branch. Can we work on this in parallel? The plan would be:

1. {156290}
2. Complete this task and QA
3. Deploy to stage 0 wikis T136602: Graduate the Page Previews beta feature on stage 0 wikis

Change 340706 had a related patch set uploaded (by Phuedx):
[operations/mediawiki-config] Re-enable Page Previews instrumentation

https://gerrit.wikimedia.org/r/340706

I scheduled rOMWC9022281fc027: Re-enable Page Previews instrumentation to be deployed during today's European SWAT.

Change 340706 merged by Phuedx:
[operations/mediawiki-config] Re-enable Page Previews instrumentation

https://gerrit.wikimedia.org/r/340706

This is blocked on T158221

Note that this is blocked on T158221, which is blocked by T156800

Are blockers up to date?

T160614: Horizontal gradient appearing on wrong side of text for RTL page previews is currently a blocker for Hebrew.

^ Moving this to To Do as we could defer graduation on hewiki until T160614: Horizontal gradient appearing on wrong side of text for RTL page previews is deployed there (Wednesday, 22nd).

@ovasileva: Per my standup email, is this blocked by T160744: A generic preview is not shown for pages that do not exist?

In T136602#3113797, @phuedx wrote:

@ovasileva: Per my standup email, is this blocked by T160744: A generic preview is not shown for pages that do not exist?

Answer: No.

Performance-Team: Be aware that the JS and CSS payload on it-, ru-, el-, and cawiki will increase by ~14 KB and 3.5 KB respectively when the feature is graduated. If we choose to be more aggressive in T158999: Popups is not independent from EventLogging anymore, then we can decrease the JS payload size by 2-3 KB.

Services/Performance-Team: Be aware that this we're lining this up for today's morning SWAT (6-7 PM UTC).

Is the 3.5kb loaded in head or via js (i think it is the latter?)

The latter. None of the Page Previews RL modules are loaded in the head.

Change 343675 had a related patch set uploaded (by Phuedx):
[operations/mediawiki-config] pagePreviews: Enable by default on "stage 0" wikis

https://gerrit.wikimedia.org/r/343675

Change 343675 merged by jenkins-bot:
[operations/mediawiki-config] pagePreviews: Enable by default on "stage 0" wikis

https://gerrit.wikimedia.org/r/343675

Mentioned in SAL (#wikimedia-operations) [2017-03-20T18:28:15Z] <thcipriani@tin> Synchronized wmf-config/InitialiseSettings.php: SWAT: [[gerrit:343675|pagePreviews: Enable by default on "stage 0" wikis]] T136602 (duration: 00m 42s)

feature works on all wikis. No immediate bugs found. Further bugs will be tracked under T156292: Page Previews full feature QA