Stable service-generated customer-group ID.

Customer (tenant) ID for the request. This is separate from authentication: you still pass your personal or service account API token in the Authorization header (Bearer <token>). See Get Started.

When to omit (most callers): If your personal or service account token belongs to a single customer, omit this header. The API resolves that customer from the token.

When to send: If your credential can access more than one customer, set X-Tenant-Id to the customer ID you want to act on. A service account can select an active direct or nested descendant of its home customer; the endpoint's normal permissions, entitlements, and resource-ownership checks still apply. A service-account target outside that customer subtree returns 403 Forbidden. Prefer this header over the legacy customerContext query parameter, which only applies to legacy API keys and is ignored by personal and service account tokens.