Customer units

A customer's own tree of teams, workspaces or tenants. Each unit has a key unique across your organisation; a signal can name a unit, so usage, spend and credit caps roll up the tree. A customer with an external ID has a root unit keyed by it, units nest at most 16 levels deep, and a unit that isn't billable makes usage from it and the units beneath it unbilled. Once a unit's credit spend reaches its cap, its usage (and that of the units beneath it) that would spend more credits in that currency is held, unbilled, until the next cap period.