The "paid ceiling" for the CURRENT cycle = the highest plan price already CHARGED this cycle. Persisted in subscription
metadata (raised on each above-ceiling upgrade), guarded by the period end so it auto-resets at the next renewal. Falls
back to the current item price — a defer-change lowers the item price (for next cycle's billing) but NOT the ceiling, so
a later change to ANY plan ≤ the ceiling stays free (you already paid for that level); only EXCEEDING it charges. PURE.
The "paid ceiling" for the CURRENT cycle = the highest plan price already CHARGED this cycle. Persisted in subscription metadata (raised on each above-ceiling upgrade), guarded by the period end so it auto-resets at the next renewal. Falls back to the current item price — a defer-change lowers the item price (for next cycle's billing) but NOT the ceiling, so a later change to ANY plan ≤ the ceiling stays free (you already paid for that level); only EXCEEDING it charges. PURE.