I've completed the instrumentation review and spec for the Usability Improvements projects, which defines all the instrumentation that will be needed to measure the metrics in the measurement plan.

Based on my review, additional instrumentation is needed to track desktop talk page views associated with sessions where the user engages on a talk page (defined as clicks an affordance to start a new discussion/reply, subscribes, or edits). See details below. I've confirmed all other events we need to track for this project are already instrumented in EditAttemptStep, talk_page_edit, and mediawiki_history.

NEEDED INSTRUMENTATION

• Event: A user views a talk page on desktop
• Needed for the following metrics identifed in the measurement plan: "Increase in the proportion of Junior Contributors who visit a talk page and engage with it." ; "Of all the Junior or Senior Contributors that post on a talk page, the average time from when a Senior Contributor views a talk page to starting any new edit on a talk page"; * "The percentage of Junior Contributors that view a talk page and successfully publish at least one comment or new discussion"
• Instrumentation option: We can use the DesktopWebUIActions schema, which currently tracks desktop page views (recorded as `action = 'init'). To use this schema, we would need to confirm the following [i] : (1) that the events in DesktopWebUIActions can be joined with EditAttemptStep and Talk_page_edit events using the session_id and (2) we can synchronize the sampling rates and methods so the same events are sampled. [ii]

[i]This is related to work being done in T303653 and T303654 except focused on desktop pageviews vs mobile web pageviews.
[ii] Sampling rate considerations: Per T294738#7492873, DesktopWebUIActionsTracking schema is only active for desktop improvement projects, so doesn't include English Wikipedia and DesktopWebUIActionsTracking schema is currently sampled with a rate of 20% for logged out users, and a rate of 100% for logged in users (per T287545#7449966)