Stewardship is what we call the long arrangement: a fixed retainer, a known team, a clear scope of what we look after and what we don't, reviewed openly once a year.
It is the opposite of being handed off between agencies, project managers, and ticketing systems. The engineer in the standup is the engineer who wrote the code is the engineer who'll fix the production incident. There's no abstract "account" between you and the people doing the work.
We deliberately keep the number of stewardship partnerships small, because the value depends on us actually knowing your system. If we can't say yes responsibly, we'll say so.