Codex harness (OpenAI Codex CLI)

Prefer codex exec from a host agent (no TUI). Use the TUI only with a real PTY.

Verified against codex-cli 0.147.0 via the official Windows installer. Re-check codex exec --help if flags look stale.

Do not invent terminal() / process() APIs. From Grok or PowerShell, call codex. Shared job shape: harness-offload. Not the ChatGPT desktop app (codex app). Do not install winget OpenAI.Codex or jcv8000.Codex.

Install (Windows)

$env:CODEX_NON_INTERACTIVE = '1'   # skip "Start Codex now?"
powershell -ExecutionPolicy Bypass -c "irm https://chatgpt.com/codex/install.ps1 | iex"