r/ArtificialInteligence: Production Team Documents Three Multi-Provider LLM Compatibility Approaches — OpenAI, Anthropic, Google Unified Interface Breaks on Streaming, Token Budgets, and Thinking Headers

A team that spent months unifying OpenAI, Anthropic, and Google models behind a single internal interface documents three compatibility approaches and where each broke in production. Identified pain points include response-format divergence, streaming behavior differences, and authentication model mismatches; token-budget signaling and Anthropic's thinking-mode headers emerged as the sharpest incompatibilities that defeated otherwise clean abstraction layers, with no unified spec covering all three providers' edge cases.