{
  "model": "gpc-1",
  "messages": [{"role": "user", "content": "A 200 cm rail is filled to 75%. Report filled length."}],
  "response_format": {"type": "json_schema", "json_schema": {"name": "rail", "strict": true, "schema": {"type": "object", "properties": {"filled_length": {"type": "number", "minimum": 0, "maximum": 200}}, "required": ["filled_length"], "additionalProperties": false}}},
  "gpc1": {"mode": "numeric101", "numeric_fields": [{"key": "filled_length", "description": "filled rail length", "minimum": 0, "maximum": 200, "unit": "cm"}]},
  "stream": false
}