529→Roth IRA rollover eligibility (SECURE 2.0 §126)

How much of a 529 balance can be rolled into the beneficiary's Roth IRA under SECURE 2.0 §126? The rollover is gated: the account must be 15+ years old, contributions from the last 5 years are excluded, each year is capped at the Roth IRA contribution limit (less the beneficiary's other IRA contributions for the year) and by the beneficiary's earned income, and there is a $35,000 lifetime cap per beneficiary. Returns the maximum this year, which cap binds, and how many years to exhaust the lifetime limit. Deterministic; not tax advice.