Overview

This task tracks the pre- and post-launch work for the Truncation / Minerva Compact Lead experiment (T432075: [Epic] Truncation experiment). It is adapted from the team's Experiment Launch Checklist.

Planned launch date: Thursday, September 17, 2026 4:00 PM (CDT)

• Design Spec & Prototype: Prototype / T434919: [Design] Compact leads experiment
• Instrumentation: Measurement Plan / Instrumentation Spec / T432188: Instrumentation for truncation experiment
• Target Wikipedias: ar,es,fr,id,it,ja,pt,vi,zh
• Experiment Variations:
  • Control (control): Status quo (full lead section, default infobox layout)
  • Treatment 1 (trunc-lead-infobox): Truncated lead section + Lead infoboxes collapsed into a "Quick facts" section
  • Treatment 2 (trunc-lead): Truncated lead section only

Completed setup and implementation

• Feature code completion
  • Lead truncation implementation complete in MinervaNeue (T432187: [Truncation] Truncate lead sections)
  • Quick Facts server-side transform implemented in MobileFrontend (T432752: [Truncation] Collapse infoboxes into a Quick Facts section
• Core experiment implementation is complete: T432188: Instrumentation for truncation experiment
  • Experiment eligibility is limited to:
    • Anonymous/logged out users and temporary accounts
    • Main-namespace pages (Namespace 0)
    • Minerva skin (mobile view)
  • Experiment exposure events are implemented via experiment.sendExposure()
  • Experiment assignment is read from GrowthBook experiment platform data
• Experiment is configured in GrowthBook: https://growthbook.wikimedia.org/experiment/exp_2lq00w7nmtvpm33f#overview
  • GrowthBook variations include the intended experiment experiences
  • Primary metric (21-day reader retention) configured in GrowthBook
  • Secondary and guardrail metrics configured in GrowthBook (eg. lead section expansion rate, quick facts toggle rate, edit attempts)
• Local and development overrides are available
  • Feature is isolated behind configuration flags: $wgMinervaTruncateLeadSection and $wgMFQuickFacts
  • URL parameters:
    • ?mpo=minerva-compact-lead:control
    • ?mpo=minerva-compact-lead:trunc-lead-infobox
    • ?mpo=minerva-compact-lead:trunc-lead

Completed bug fixes & refinements

• T433583: [Truncation] Increase fade container height
• T433674: [Truncation] Align "read more" button and gradient with updated design spec
• T437943: lead truncation: support legacy parser

Before launch

Instrumentation and measurement

• Confirm all events in the instrumentation specification (T432188: Instrumentation for truncation experiment) are marked complete
• Manually verify all specified events and payloads:
  • experiment_exposure (control and treatments)
  • page_visit (control and treatments)
  • session length tick (control and treatments)
  • lead_section click interaction (expand)
  • quick_facts section click/toggle interaction (expand/collapse)
  • edit_attempt_init
• Verify instrumentation eligibility checks for anonymous users, main-namespace pages, and Minerva skin
• Confirm GrowthBook experiment key, variation keys, metrics, and measurement specification agree
• Ensure that ReaderExperiments is enabled on all target wikis. T438009: Enable ReaderExperiments on all target wikis

QA and bug bash

• Complete QA coverage, including accessibility audit: T437484: QA audit for truncation experiment
• Post-deployment production check
• Complete and close the bug bash ticket: T432189: Truncation bug bash

Patched bugs awaiting final QA/signoff

• ❌ [DECLINED] T433271: Truncation: fix "read more" button's accessibility issues ➡ Decision: non-launch blocking; team will not address this bug now; pulled the accessibility bug out of the parent bug bash and it's now a standalone ticket.
• ❌ [DECLINED] Team decided we'd address the special characters side box issue after the experiment (More details about div.side-box metadata side-box-right contains-special-characters noprint selfref can be found in this comment: T432752#12295253).

Release readiness

• Confirm all required patches (skins/MinervaNeue, extensions/MobileFrontend, extensions/ReaderExperiments) are deployed to production (MW 1.47.0-wmf.20 train)
• Confirm there are no launch-blocking regressions from the final QA pass
• Communicate the planned launch date to target wikis (Movement Communications/Eliza)
• Confirm translation are synced/deployed for all target wikis
  • minimal-minerva-lead-section-read-more | "Read more" | translatewiki
  • mobile-frontend-quick-facts | "Quick facts" | translatewiki

Immediately before launch

• Obtain final go/no-go signoff
• Complete final instrumentation QA: T436199#12334621
• Schedule or start the experiment in GrowthBook before 14:30 UTC, Monday through Thursday
• Record the experiment start time and expected end date in this task
  • Start date/time: Thursday, September 17, 2026 4:00 PM (CDT)
  • End date: October 15, 2026

Post-launch

• Confirm both control and treatment variation users are being enrolled across all target wikis
• Validate experiment_exposure events in production
• Validate page_visit, read_more button clicks, and quick_facts expand/collapse events in production
• Validate edit_attempt_init
• Check event volume by target wiki for unexpected gaps or sample ratio mismatches (SRM)
• Confirm GrowthBook is receiving data for primary, secondary, and guardrail metrics
• Document production-data QA findings in this task
• Monitor for regressions or community feedback during the initial launch period

After the experiment

• Stop the experiment at the agreed end date
• Complete experiment analysis
• Remove Truncation experiment instrumentation and temporary experiment code T437467: Remove truncation experiment