When using Nous Portal (or any non-OpenRouter provider), child agents
spawned by delegate_task failed with "No pricing available" or "Unknown
model" errors because they had no valid API key.
The delegate tool passed base_url but not api_key to child AIAgent
instances. Without an explicit key, children fell back to the empty
OPENROUTER_API_KEY env var, causing auth failures.
Extract the parent's API key from _client_kwargs and pass it through.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
0310170869