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Rennet

Install a coding harness

Rennet needs Claude Code or Codex in each environment where it reviews code. Install either one; install both to use Dual Harness and see two independent reads of the same evidence.

Claude Code

Section titled “Claude Code”

Follow Anthropic’s Claude Code setup guide, or install the current npm package:

Terminal window
npm install --global @anthropic-ai/claude-code

Launch claude once and finish its sign-in flow. Then verify the executable is available to Rennet:

Terminal window
claude --version

Codex

Section titled “Codex”

Follow OpenAI’s Codex CLI guide, or install the current npm package:

Terminal window
npm install --global @openai/codex

Launch codex once and sign in with your existing OpenAI or ChatGPT account. Then verify the executable:

Terminal window
codex --version

On macOS, Rennet can also use the Codex executable shipped with the ChatGPT desktop app. A separately installed Codex CLI takes precedence. On Windows, install Codex CLI because another application cannot execute the binary inside the Microsoft Store ChatGPT package.

Let Rennet detect it

Section titled “Let Rennet detect it”

Return to the first-run welcome and choose Check again, or open Settings → Environments after setup. If you already finished the welcome, reopen it with Settings → Appearance → First Run → Replay the first-run welcome. Detection runs separately on this machine, each WSL distro, and every paired environment. A harness installed on the host does not stand in for one missing inside WSL or on a remote machine.

Rennet launches the harness you installed and uses that harness’s existing authentication. It does not ask for a model API key or copy the harness’s credentials.

Work-order rounds use the harnesses enabled for that machine or WSL distro in Settings → Environments. A session’s first round selects an available enabled harness (Claude Code when both are enabled) and keeps that provider for later rounds. To start a Codex-backed session on a machine with both installed, disable Claude Code before dispatching its first round. Each round’s history row names the exact harness and version that ran it.

If the harness a session picked is later uninstalled or turned off, the round stops and says which harness it looked for and what it found. Rennet does not quietly run that round on the other provider.

If claude --version or codex --version works in a terminal but Rennet still cannot detect it, fully quit and reopen Rennet so the desktop process receives your current executable paths.