AI SDK harness layer now supports native subscription authentication
Source
vercel.com
Author
Felix Arntz
Date
Context
Vercel's AI SDK can use an installed coding AI agentAn AI system that doesn't just answer once but works toward a goal in a loop — taking actions, reading the results, and deciding what to do next.Full definition →'s native subscription login when that agent supports it. The authentication update lets applications retain the same agent interface while authentication is resolved on the host.
Credential precedence matters: direct mode uses explicit provider credentials first, then an available native subscription. Automatic mode follows that path only when gateway credentials are absent; gateway mode never reads native subscriptions. Subscription credentials and their refresh remain on the host. This enables supported subscription logins without changing application code, while preserving the distinction between native and gateway authentication.
Terms in this piece · Glossary
AI agent — An AI system that doesn't just answer once but works toward a goal in a loop — taking actions, reading the results, and deciding what to do next.
agent harness — The scaffolding around a model that turns it into a working agent — the loop, the tools it can call, and the rules for when to stop.
token — The chunk of text a model reads and writes in — roughly three-quarters of a word — and the unit AI usage is billed in.
