How I bridged codex-tui's WebSocket /v1/responses through Cloudflare, nginx, and FastAPI

OpenAI's Codex CLI ( codex-tui ) shipped a new feature in version 0.128 that broke every third-party AI gateway I tested with it: streaming responses now go over WebSocket on /v1/responses instead of HTTP+SSE. If your gateway only registers a POST /v1/responses handler, every Codex session fails with a confusing storm of 405 Method Not Allowed errors interleaved with the occasional successful POST. I run a hosted AI gateway at g0i.ai — the same problem hit me. This post is the writeup of the fou