How do rules 184.3.c (control cannot change while Contested) and 444.2/444.2.a (establishing control and clearing Contested status) interact? Which happens first?

Ruling: Control is checked constantly through the cleanup mechanism. When a battlefield stops being Contested (444.2.a), control is immediately lost if a player has no units there (184.4.c), triggering a cleanup that removes hidden cards before any new actions can be taken.

Sequence:

• Contested status is cleared (444.2.a)
• Control is immediately lost if no units remain (184.4.c)
• Status change triggers cleanup (319.6)
• Hidden cards are removed during cleanup
• Control is established by remaining player (444.2)

Nuances:

• The word "immediately" in 184.4.c and the cleanup step in 322.6 create apparent tension, but cleanup is the mechanism by which "constant" control checking occurs
• In edge cases where units from both players remain (e.g., deathknell unit dies and reaction speed unit is played), 444.2/444.2.a don't execute because units are controlled by different players
• The current rules text could be clearer about the ordering, particularly moving "clear Contested" before "establish control" in the resolution sequence