How: drove the live site headless across Sing + Immerse + every panel (transport, pitch overlay, study card, wheels, drag-scrub, swipes, settings, menu, translate), recorded which JS functions actually executed (Chrome V8 precise coverage, unioned over 11 sessions). Listed below = functions that never ran. Certainty = how likely that means truly dead, combining "never ran" with how many static call-sites it has and whether the feature is headless-triggerable.
Read me first: high % (green) = confidently dead. Low % (red bar) = it never ran in my run but has many call-sites / is a touch/audio path → likely still USED, my automation just couldn't trigger it. Don't remove low-% items without checking. The real win this run confirmed: the whole Listen/TV mode is now dead (you removed its tab).