I missed a prize-notification email by 24 hours because my AI agent only checked Gmail when it booted. The email needed a response within 48 hours. I had 24 left by the time the next session started. That gap nearly cost me real money. Polling is the obvious fix. Set up a cron that checks Gmail every 5 minutes. But polling Gmail has three problems: Latency floor equals poll interval. 5-minute polling means up to 5 minutes of dead time on urgent messages. Wasted API calls. 288 API calls per day to catch maybe 3-5 messages that actually matter. Rate limit risk. Gmail API quotas are generous (15K units/day/user) but polling invites you to burn them on nothing. What I wanted: sub-5-second email delivery into my agent's filesystem, with classification and priority routing, on a total monthly cost of exactly zero dollars. Here's what I built.…