---
title: "Codex"
description: "Run OpenAI's Codex CLI autonomously within approval-gated Cloudflare Sandboxes."
---

> Documentation Index
> Fetch the complete documentation index at: https://tryshiba.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Codex

Shiba packages OpenAI's [Codex CLI](https://github.com/openai/codex) inside the container image, providing fast, automated execution for tasks optimized for OpenAI coding models.

## Agent Overview

| Attribute | Specification |
| --- | --- |
| **Harness ID** | `codex` |
| **CLI Binary** | `codex` |
| **Pinned Version** | `0.157.1` (in Dockerfile) |
| **Default Model** | `openai/gpt-5.3-codex` |
| **Supported Models** | `openai/gpt-5.3-codex`, `openai/o3-mini`, `openai/gpt-4o`, `openai/gpt-4.5-preview` |
| **Credential Model** | AI Gateway BYOK (dummy key inside sandbox; real key injected at egress) |
| **Invocation** | `codex exec --json --dangerously-bypass-approvals-and-sandbox "<task>"` |

## How It Works

```
Developer Request
  └── CodingOrchestrator generates delegate_coding_task({ harness: "codex" })
      └── Human signs off on exact prompt & repository
          └── Ephemeral Cloudflare Sandbox boots
              ├── Clones repository via scoped git token
              ├── Executes: codex exec --json "<task>"
              ├── Streams structured JSON output to the Worker
              └── Emits diff and pull request receipts
```

> **API Key Security**
>
> Just like Claude Code, Codex authenticates with an OpenAI API key managed in Cloudflare AI Gateway. The container holds dummy credentials, preventing any repository scripts from exfiltrating account credentials.

## Configuration & Deployment

### 1. Configure the Provider Key in AI Gateway
Store your OpenAI API key in your Cloudflare AI Gateway under the provider ID `openai`. Egress traffic to `api.openai.com` is intercepted and authorized at the Cloudflare edge.

### 2. Set Default Model
In your environment or `wrangler.jsonc`:

```bash
# Set default harness to Codex
pnpm wrangler secret put AGENT_HARNESS --config apps/backend/wrangler.jsonc # enter "codex"

# Set default model for Codex
pnpm wrangler secret put CODEX_MODEL --config apps/backend/wrangler.jsonc # enter "openai/gpt-5.3-codex"
```

## Selecting Codex in a Task

Specify `harness: "codex"` in any task request:

```json
{
  "repoUrl": "https://github.com/acme/frontend",
  "task": "Add optimistic UI updates to the checkout mutation",
  "baseBranch": "main",
  "harness": "codex",
  "codingModel": "openai/gpt-5.3-codex"
}
```

## Event Parsing & Safety

Codex runs non-interactively with `codex exec --json`. Each emitted line is parsed for:
- Command and execution steps
- Modified files and staged changes
- Structured error envelopes (surfaced directly as honest failures)

## Related Documentation

- [Coding Harnesses Overview](/docs/claude-code/)
- [Approval Gates](/docs/approval-gates/)
- [Security & Credential Boundaries](/docs/security/)

Source: https://tryshiba.dev/docs/agents/codex/index.mdx