Modifying the TaxonomicFilter

The TaxonomicFilter is the picker users hit to choose any "thing PostHog knows about" — events, properties, actions, cohorts, groups. It's the on-ramp into almost every analytics and replay configuration. Code lives in frontend/src/lib/components/TaxonomicFilter/.

Two unbreakable rules:

1. Changes that demote items users actually pick are regressions, even with all tests passing. Read "Product reality" before deciding any change is safe. Ordering, promotion, or position-0 changes need explicit human sign-off — don't let an agent decide alone.
2. There are three live variants behind two feature flags, and the rebuild is a parallel reimplementation of the legacy data + group layer — not a skin over it. A behaviour change usually has to land in both the legacy code and the rebuild, or the two arms of the experiment diverge. Read "Three variants" and "Mirroring changes" before assuming one edit is enough.