I let an agent pick our auth provider. Eight months in, I think it was the wrong call

Early on I asked Claude Code to recommend an auth setup and just went with what it suggested since I wanted to move fast. It picked a provider that was fine for the first few hundred users, but their pricing tier jumps hard once you cross a certain MAU threshold, and we hit that wall faster than expected.

Now I'm staring down a migration that touches every session and password hash in the system, during a period where I really cannot afford downtime or angry users getting logged out randomly.

For anyone who's picked infrastructure based on an agent's recommendation rather than researching it themselves, how did it hold up a year later?
Where do you draw the line between letting the agent decide and doing the research yourself first?