The short answerA private system gives one firm a dedicated operating instance. The useful questions are where records live, who can read them, who can change permissions, and what leaves with you.
A private setup gives the firm its own server or tenant, its own access rules and its own records. Someone still has to run it: updates, backups, logs and access reviews each need a named owner.
Private does not mean isolated from every provider. Model APIs, email systems and connected tools still have their own terms. Review each connection before client data moves through it. Building this yourself on an open-source AI agent platform is one path to a private setup; our AI agent platform guide walks through the broader SaaS-vs-self-hosted decision first.