Some validation happens before the assistant session is fully created. If it fails at that stage, the logging pipeline hasn’t attached yet. So nothing gets written to call logs. So from your perspective it feels like: “I’m using a managed service… why am I blind?” Totally fair. What’s happening under the hood is more like: SIP connects Config is fetched Pre-session validation runs It fails Session never initializes → no logs That’s why it feels like hunting in the dark. Practically speaking, when debugging configs like this, the most reliable move is still diffing against a working config and isolating the delta. If you want, I can help you structure a safer validation layer on your side so you catch schema issues before Vapi even sees them. That removes this whole blind-debug problem.