HubSpot Agency Multi-Portal Overview Operate a fleet of HubSpot portals for agency clients without cross-portal contamination, attribution loss, or onboarding bottlenecks. This is not a getting-started guide — it is the infrastructure your agency runs on day one with client one and scales to client one hundred without revisiting. The six production failures this skill prevents: 1. Cross-portal credential contamination — a shared env var causes API writes intended for Client A to silently land in Client B's CRM. The HubSpot API does not reject the call; it accepts it. Data corruption is silent…