AI Gateways in 2026 — LiteLLM, Portkey, Helicone, and the OpenAI Façade
Why AI gateways became standard infrastructure in 2026. The OpenAI-compatible façade pattern, LiteLLM vs Portkey vs Helicone vs OpenRouter, fallbacks, caching, observability, cost control, and how to drop one in front of an existing app.