Dogfood on an HDR display
Open treatment on the Talks section
Compare with control in another tab
Confirm Florian and Phil still look like Ultra HDR in both arms
Where: same Talks grid — their files already contain gain maps
Check Vivek, Chiara, Kathy, Max and Pat look brighter on HDR treatment
Where: Talks grid + each speaker circle under their bio
On an SDR screen, confirm treatment still looks like a normal JPEG
Where: same treatment URL on a non-HDR display or with HDR display disabled
Lab and kill switch
Find the rollout card on Lab
Where: http://uxbri.local/lab/ — card “2026 homepage Ultra HDR”
Force control with the kill-switch query
Before promoting to experiment
Register homepage_ultrahdr in GA4 Admin (user + event scoped)
Where: https://analytics.google.com/ → Admin → Custom definitions
When ready, change projects.yml to experiment / 50% and update the JS phase constants
Where: _data/projects.yml id homepage-ultrahdr-ab and scripts/modules/homepageUltrahdrAb.js