OAuth Token Vault Patterns for AI Agents

OAuth Token Vault Patterns for AI Agents AI agents that call external APIs have a problem most tutorials skip over: tokens expire, and when they do mid-pipeline, your agent crashes in the worst possible way. I learned this the hard way. I had an agent handling Stripe checkout flows -- it would authenticate at the start of a session, store the token in memory, and happily process orders. One night it lost Stripe access mid-checkout because the OAuth token had a 1-hour TTL and the session ran long. The order went through on the customer side, but the webhook couldn't be verified because the token was gone. Refund chaos. Support tickets. A very bad morning. The fix wasn't just "refresh tokens more aggressively." It required thinking carefully about where tokens live, who can access them, and what happens when things go wrong. Here are the four patterns I now use in every production AI agent system. The Core Problem AI agents need persistent API access. Unlike a web app where a user authen