If you're building an AI-powered app today, you're probably juggling multiple model providers. OpenAI for GPT. DeepSeek for cost savings. A Chinese model for specific tasks. Maybe Anthropic for Claude. Each provider has its own SDK, its own auth flow, its own quirks. That's not just annoying—it's fragile. Switching models means rewriting code. Adding a new provider means more maintenance burden. There's a cleaner approach: one gateway that speaks OpenAI's protocol, but routes to multiple backends. This isn't about replacing your provider. It's about abstracting the integration layer so you can swap, compare, and combine models without touching your application code. Let's walk through what this looks like in practice, using ChinaLLM as a concrete example of a publicly documented gateway. Why OpenAI-compatible matters more than another SDK The OpenAI API format has become a de facto standard.…