Anticipatory migrations from 2026-04-08 encoded the old §3.5.7 design (artists.event_id, advance_sections.artist_id). RFC v0.2 §5.3 replaces both tables with the engagement model. No model/factory/test/seeder references exist. Removing before Step 1 ensures the new migrations match RFC §5.3 verbatim. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>