codex

A production root filesystem and initial boot environment that includes the OpenAI Codex command-line tool. It packages the command-line tool, HTTPS certificate files, and the sandbox user accounts needed to run it in a Linux guest.

In plain words
What is it for?
Use it as the runtime for workflow steps that execute Codex or agent specifications configured with the Codex provider, using an API key or Codex authentication file.
Why use it?
It removes the need to assemble these runtime pieces manually when a workflow or agent needs to run Codex. It also supports checking downloaded versions against SHA-256 hashes.

Agent

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/the-void-ia/void-box/codex
Clone the repo
git clone --depth 1 https://github.com/the-void-ia/void-box
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,748 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.01748
Opus 5 $0.00000 $0.00874
Sonnet 5 $0.00000 $0.00350
Haiku 4.5 $0.00000 $0.00175

Measured yesterday against content hash b90e4a345e12, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

codex scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

awk + curl + sha256sum/shasum are available.
docs/agents/codex.md · 160 lines

How it starts

The opening of the file, as written. The whole thing — 160 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Codex flavor — scripts/build_codex_rootfs.sh

Production OpenAI-Codex-capable rootfs/initramfs.

What it bundles

  • The codex CLI binary (Rust musl-static, no shared libraries needed).
  • SSL CA certificates for HTTPS API calls.
  • /etc/passwd + /etc/group for the sandbox user (uid 1000).

When to use

  • kind: workflow specs that exec codex as a workflow step.
  • kind: agent specs with llm.provider: codex. Requires OPENAI_API_KEY in the host environment or a valid ~/.codex/auth.json (see Auth section below).

Discovery

The script locates the codex binary in priority order:

  1. CODEX_BIN env var pointing at a Linux ELF binary — local dev only.
  2. codex on PATH (Linux host only — the macOS Mach-O binary cannot run inside the Linux guest) — local dev only.
  3. CODEX_VERSION set → explicit override; requires a matching CODEX_SHA256 env var (SHA-256 of the downloaded tarball) so developers supply the hash they are asking the build to trust.
  4. Default: download the version and URL pinned in scripts/agents/manifest.toml and verify against the pinned SHA-256 (computed against the tarball as it lands on disk — the build then extracts the binary from the verified tarball).

Pinning and verification (R-B5c.1)

The default build path is hash-pinned. scripts/agents/manifest.toml holds one table per (agent, platform, arch) tuple with a version, url template, and sha256. build_codex_rootfs.sh fetches the URL, computes SHA-256 of the downloaded tarball, and fails the build if the digest does not match — the expected and observed digests are both printed on failure.

Parser choice: shell + awk (scripts/lib/agent_manifest.sh). No Python or Rust sidecar is required, which keeps the builder working anywhere bash + awk + curl + sha256sum/shasum are available.

Hash updates are reviewed PRs, not silent upstream events. The weekly workflow .github/workflows/bump-agents.yml (Mondays 09:00 UTC) checks for new upstream versions and opens one PR per agent containing the bumped arches, with per-arch SHA-256s listed in the PR body.

Read the full file on GitHub · 160 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 160 lines · 0 tokens per session scan A b90e4a345e12

Subscribe to this mod's changes

codex is an agent published in the GitHub repository the-void-ia/void-box (88 stars, last pushed 4d ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 1,748 tokens. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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