Background

We are unable to reliably ship features in the mobile site to only logged out users. We should fix that!

From T388036 - we were surprised to see that setting a configuration of

'wgMinervaDonateBanner' => [
	'default' => [
		'base' => true,
		'loggedin' => false,
		'amc' => false,
	],
],

did not correctly disable the feature for logged in users as we had expected. There is further discussion in that ticket (in particular https://phabricator.wikimedia.org/T388036#10608151), but the summary is that base is itself a conditional which is true for all non-beta users, which means this configuration is targeting all non-beta users (functionally all users now), and the loggedin => false section is ignored

Additional note: It does work when $wgEnableBeta is set to true o_o

User story

As a member of the web team, I want to be able to target anonymous users specifically using our feature management system

Requirements

• there is a mechanism by which we can target logged out users using our feature management system

Acceptance criteria

1. we are satisfied that future releases can be deployed to logged out users only via the feature management system
2. For the purpose of this task, provide an explict logged_out and logged_in key that replace base and loggedin. Logic for beta can be left alone for the purpose of this task. loggedin and base remain as aliases for logged_in and logged_out.
3. Confirm feature flag configuration supports explicitly logged out users.
4. Confirm logged-in users do not receive features targeted only to logged users.
5. Verify logged-out users receive features targeted to them, regardless of $wgEnableBeta state.
6. Tests are in place to verify correct behavior and prevent regressions for logged out users
7. Documentation includes examples and notes on targeting logged out users.

Rollback plan

Depends on implementation, which hasn't yet been nailed down - presumably if we are changing the inner workings of the system rather than adding a logged out user mode we will have a revert plan incase it has unintended effects on the existing features