Two bugs in the model fallback system:
1. Nous login leaves stale model in config (provider=nous, model=opus
from previous OpenRouter setup). Fixed by deferring the config.yaml
provider write until AFTER model selection completes, and passing the
selected model atomically via _update_config_for_provider's
default_model parameter. Previously, _update_config_for_provider was
called before model selection — if selection failed (free tier, no
models, exception), config stayed as nous+opus permanently.
2. Codex/stale providers in auxiliary fallback can't connect but block
the auto-detection chain. Added _is_connection_error() detection
(APIConnectionError, APITimeoutError, DNS failures, connection
refused) alongside the existing _is_payment_error() check in
call_llm(). When a provider endpoint is unreachable, the system now
falls back to the next available provider instead of crashing.
02848d1a78