NoAllowedModelCredentialsError

Raised when models.allowed is active but none of its models can auth.

A NoCredentialsConfiguredError so existing deferred-start recovery keeps working, but distinguishable because the recovery differs: adding any credential fixes the base case, while here only a credential for a provider named in the allowlist helps. Handlers that would otherwise silently retry surface this message instead, so /auth never accepts a key and then appears to do nothing.