OpenAI officially blesses previously undocumented /backend-api/codex/responses endpoint

A backend Codex endpoint people were already relying on just got explicitly blessed. /backend-api/codex/responses had been undocumented and reverse engineered, yet tools like Pi and Opencode were already built on top of it anyway.

What changed

An OpenAI staffer confirmed it's officially supported, described as the first public confirmation. That flips the risk profile: this wasn't a stable, acknowledged surface before, just something that worked. Now there's a clear support signal behind the exact path those tools are using, which makes shipping against it a lot less of a gamble.