Natural, the San Francisco startup building payments infrastructure for AI agents, has secured a credit facility of up to $100 million from Upper90 Capital Management, the company announced on August 19, 2026. The facility gives Natural additional capacity to fund the payments and credit products it sells to companies deploying agents, and it lands one month after the company closed a $30 million Series A. The structure matters here. Equity builds the product; debt funds the lending. Natural’s…