A Quality Gate for Node.js SaaS Text Summarization Chat APIs

Choose a text-summary API by the percentage of outputs that pass a source-grounded evaluation, then compare latency, regional controls, and cost only among the candidates that clear that bar. For a JavaScript subscription app serving US and EU users, the decisive constraint is rarely the cheapest advertised token rate. It is the complete production path: cleaning an article, fitting or splitting it, generating a summary, validating claims, and recovering safely when a request is interrupted. Short answer: use a narrow internal completion interface, test it with representative long documents, and keep the provider choice behind an adapter. A direct hosted endpoint is the simpler default for one approved backend. Add a self-hosted gateway only when routing, policy enforcement, or repeated provider comparisons justify another service to operate. I start this kind of decision in a notebook, but I don't stop at a few outputs that sound good. Fluent summaries can omit the one qualification that changes an article's meaning. The useful unit of comparison is an accepted summary, not a successful API response. What should a US and EU text summary API evaluation measure? Define acceptance before sending the first request. For a long article, I usually want a short abstract, the central claims, preserved numbers, and explicit uncertainty where the source is uncertain. Those fields form an output contract. The evaluator then asks whether each claim is supported by the input and whether any required idea disappeared. Build the corpus from document shapes the product expects: clean prose, copied navigation, tables flattened into text, repeated paragraphs, empty sections, contradictory statements, and inputs near the application's size limit. Keep a held-out slice for release decisions. Otherwise prompt tuning turns the evaluation set into a memory test. The regional review belongs beside quality, but it answers a different question. An API being reachable from Europe does not est