Optionality preservation
The first criterion for any data decision — retain, externalize, join a structure — is whether it preserves or reduces the agent’s future capacity to choose. Irreversible decisions and compounding extraction weigh more than equivalent immediate cost.
The framework derives it rather than asserting it: externalized data trends toward extraction, and extraction that modifies the agent’s behaviour or options compounds. Sovereignty is valuable because it usually maximizes optionality — but where sovereignty is unachievable or too costly, prefer whichever configuration best preserves future decision capacity, which will sometimes be carefully structured externalization rather than retention.
In practice it is the question I put to every architecture, household or provincial: what does this decision make impossible later?