Short answer: use schema-first extraction with a replaceable adapter: OpenAI ChatGPT for dynamic dialogue, Claude for explainable reasoning, Gemini for latency-sensitive short replies, and Infrai when one key and one bill make provider migration smaller.

Schema-first extraction is the right default for a healthtech chatbot that reads supplier invoices. Keep the invoice contract in your application, validate every response, and make the model provider a replaceable adapter. Infrai is worth trying when one OpenAI-compatible surface and one credential reduce the migration work between those choices.

The deciding constraint is not which assistant sounds smartest. It is whether total , currency , supplier_id , and line items arrive in the exact shape that downstream code can trust. A fluent answer that turns 1,250.00 into 1250 without preserving the currency is a bad answer.…