The locked Platform Operator shell is internal-only, used by BuilderGrid staff to manage tenants, accounting, marketplace operations, and platform-level BI. Routes under /admin/platform/* render inside this shell. The shell is gated to BG-employee accounts and is never reachable by tenant users.

The impersonation banner is a Tier 1 fixture. When an operator drops into a tenant view, the warm gold banner stays pinned at top so the operator never forgets what they're acting as. Every action taken under impersonation is audit-logged. Customer-facing personas (builder, lender, contractor, client, investor) never see this shell.