A single flicker of hallway lights, a paging tone, and a weekend operations team scrambling—third-party integrations often fail in ways that are visible, costly, and avoidable. In this 10-minute episode two practitioners (a vendor-coordination lead and a systems integrator) lay out a governance-first playbook for a minimal, evidence-driven vendor sandbox. We begin with a vivid anonymized vignette to show the stakes, then unpack when a lightweight sandbox is the right tool and when a full staging replica is required. Listeners get a compact pattern for isolation, three acceptance gates that prove credentials and behavior, and practical demobilization rules so test artifacts never become permanent risks. The episode is vendor-neutral and non-technical; it ends with three immediate actions and a clear CTA to download "vendor-sandbox-checklist.pdf" from the Built, Wired & Secured hub (includes the three acceptance checks and an approval & demobilization template).