The _supports_json_response_format check only looked for
'openrouter.ai' in base_url, missing the Kilo gateway
('api.kilo.ai'). Free-tier models routed through ANY gateway
(Nvidia NeMo :free via OpenRouter OR Kilo) reject json_object
response format, causing the LLM to return content: null.
Error: 'the JSON object must be str, bytes or bytearray, not NoneType'
Fix: check model name for ':free' and 'stepfun/' directly,
regardless of gateway. This covers OpenRouter, Kilo, and any
future gateway.
busya
4376354aec