claude-codex-settings is a collection of configurations and reusable extensions for Claude Code, OpenAI Codex, Cursor, and related coding tools. Developers use its skills, commands, hooks, agents, plugins, and MCP servers to shape coding-agent workflows and connect alternative model APIs. The catalogue entries are components of this collection that can be installed into supported coding tools.
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.
npx skills add fcakyon/claude-codex-settings --skill sandbox-nextgit clone --depth 1 https://github.com/fcakyon/claude-codex-settingsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/fcakyon/claude-codex-settings/sandbox-next)<a href="https://agentmods.dev/skills/fcakyon/claude-codex-settings/sandbox-next"><img src="https://agentmods.dev/badge/skills/fcakyon/claude-codex-settings/sandbox-next/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/fcakyon/claude-codex-settings/sandbox-next"><img src="https://agentmods.dev/badge/skills/fcakyon/claude-codex-settings/sandbox-next.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00039 | $0.01638 |
| Opus 5.5 | $0.00016 | $0.00655 |
| Sonnet 5.5 | $0.00008 | $0.00328 |
| Haiku 4.5 | $0.00004 | $0.00164 |
Grade A, and why
sandbox-next scanned grade A with 0 findings 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 17d ago.
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.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
98% identical to sandbox-next — 1 line differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 94 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Sandbox SDK — @next (1.0 preview)
Isolated Linux environments on Cloudflare Containers, driven from Workers.
Prefer preview docs and installed @next types over memory. APIs change; this skill is a gate, a contract, and a retrieval map—not a full manual.
We recommend new projects on this line. Apps still on the default package use sandbox-stable. Port only when asked, via sandbox-migrate-to-next.
1. Gate — confirm the package line
Before writing code, inspect the app:
| Check | Must match |
|---|---|
| npm dependency | @cloudflare/sandbox@next (or another preview tag) |
| Container image | Same line (e.g. cloudflare/sandbox:next, next-python) |
| If you find… | Action |
|---|---|
Default @cloudflare/sandbox (no @next) |
Stop. Load sandbox-stable. Do not apply this skill’s APIs. |
User wants to port stable → @next |
Stop. Load sandbox-migrate-to-next. |
| Self-deployed bridge only | Bridge is not on the 1.0 preview line yet. Keep bridge on stable package + image. Bridge (stable) |
Never mix an @next Worker package with a stable container image (or the reverse).
Skills install: Agent setup · cloudflare/skills
2. Contract — non-negotiables
sandbox.exec(argv)takes an argv list and resolves when the process starts. It returns a handle, not a finished command result.- Collect results with handle methods:
output(),logs(),waitForExit(),waitForPort(),waitForLog(),kill(signal?). - No implicit shell. Shell syntax needs an explicit shell, e.g.
["/bin/bash", "-lc", script]. - Each launch is independent. A
cd/exportin oneexecis not visible to the next. Passcwdandenvper launch, or one shell script. - Process handles have no stdin. Interactive use → terminals (
createTerminal+connect). - Local wait
timeout/AbortSignalcancel the wait only. They do not kill the process. Usekillorexec’s remotetimeout. getProcess/listProcesses/getTerminal/listTerminalsdo not start a container; they returnnull/[]when none is up.- Process and terminal IDs belong to the current container, not forever to a sandbox ID. For work that must survive replace, store the full job (argv, cwd, env, app state)—not only an id.
- Non-secret config only in
setEnvVars/ launchenv. Live credentials stay in the Worker; use outbound handlers when the sandbox calls external APIs. - Do not invent removed stable APIs (
gitCheckouton core, string-execcompletion, session execution,sandbox.terminal(request)). - Do not use one retry loop for every error (see Errors docs).
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 17d ago Changed 867b28335c27
- 1mo ago First seen · 94 lines · 39 tokens per session scan A 25e64ccc8f1d
sandbox-next is a skill published in the GitHub repository fcakyon/claude-codex-settings (1,181 stars, last pushed yesterday), licensed Apache-2.0. It adds 39 tokens to every session and 1,638 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 98% identical to sandbox-next, differing in 1 line, and is treated as a copy.
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