How to Use GPT-5.5 Today at the CLI (Via Your Existing Codex Subscription)
Update 2026-04-26 Small 4/26 update before you run the commands below: Codex CLI 0.125.0 added GPT-5.5 to codex exec -m gpt-5.5 and the Codex MCP server. (For MCP, restart Claude Code after upgrading so the running server picks up the new binary.) The relay is no longer the only path to 5.5 from your terminal. The OpenAI public API still hasn’t shipped 5.5 as of today. I’m still keeping the relay for fast one-off pipes and as a backup connection