Production agentic operations rarely live in one account. Personas — the named agentic identities through which the operating model addresses work — execute across separate accounts and substrates for reasons that are structural rather than accidental: blast-radius isolation, credential separation, role-segregated billing, sovereignty layering, and harness-version drift. This paper specifies the harness coordination layer that keeps multiple persona accounts operating coherently against a single governance envelope. The argument is that cross-account coordination is not federation of identities (which is an IAM problem) but persona-level orchestration the operating model must treat as first-class. A persona is bound to an account; the orchestrator routes work to a persona; the persona inherits its account's envelope but acts within the federation's governance envelope. Misalignment between account-level envelope and federation-level envelope is the dominant operational failure mode.