this could also serve the purpose of measuring each users' share of the total staked tokens over time, or that could be separate

if in the same contract:

• other contracts can cheaply compute the percent of total staked tokens a user had over a period
• but they must take custody at the beginning and end of the period anyway, or...
• the contract should store a list of snapshots a la the staker

if we store a list of snapshots in this fungible staked token, then the share of total staked tokens over any period can be computed externally without taking custody of the staked token

actually think this still has to be separate. even if you know the seconds per total staked over a period, you don't know the balance of each user over some arbitrary period