Codex

Codex connects to ReUI in one step: point its CLI at the hosted ReUI MCP server, sign in once, and start building UI from the ReUI registry by chat. The endpoint is https://mcp.reui.io over Streamable HTTP, the same one every agent uses - see MCP Server for the shared background.

Connect ReUI

codex mcp add reui --url https://mcp.reui.io

codex mcp list

codex mcp login reui

codex mcp add reui --url https://mcp.reui.io \
  --bearer-token-env-var REUI_LICENSE_KEY

[mcp_servers.reui]
url = "https://mcp.reui.io"
bearer_token_env_var = "REUI_LICENSE_KEY"

Install the ReUI skill

Run the one-line installer so Codex follows ReUI's build workflow:

curl -fsSL https://mcp.reui.io/install | node -

For Codex it writes 3 things: the skill to .agents/skills/reui in your project, the reui entry in ~/.codex/config.toml (always the global file, even in project mode; the project-scoped .codex/config.toml above is a manual setup), and ReUI's design rules (installed components first, semantic color tokens, the spacing ladder, type sizes, motion values, empty, loading and error states, a short UI plan before code, and the skill's self-check before finishing) to AGENTS.md, which Codex reads as project instructions. With the skill in place, Codex knows how to discover blocks, assemble components, and wire them together the ReUI way instead of guessing, and it reads the deeper rules for color, theming, motion, and layout as it needs them.

The rules sit between <!-- BEGIN:reui-agent-rules --> and <!-- END:reui-agent-rules --> markers. Nothing outside the markers changes, so an existing AGENTS.md keeps your text and a re-run only refreshes the block. The installer creates AGENTS.md only when the project has no CLAUDE.md, .claude/CLAUDE.md or CLAUDE.local.md; otherwise it prints the block for you to paste. REUI_AGENTS_MD changes that:

• REUI_AGENTS_MD=0 writes no AGENTS.md (or GEMINI.md).
• REUI_AGENTS_MD=create creates AGENTS.md even beside a CLAUDE.md. Combined with REUI_GLOBAL=1, it opts in to ~/.codex/AGENTS.md instead, which every Codex session on your machine reads.
• REUI_AGENTS_MD=remove takes the ReUI block out of AGENTS.md and GEMINI.md (with REUI_GLOBAL=1, out of ~/.codex/AGENTS.md) and writes nothing else. Every install prints this command for you.

curl -fsSL https://mcp.reui.io/install | REUI_AGENTS_MD=remove node -

With REUI_GLOBAL=1 the skill goes to ~/.agents/skills/reui and no AGENTS.md is written unless you opt in as above. To see every file a run would touch first, add REUI_DRY_RUN=1: it prints each planned write and writes nothing.

Build with ReUI

Describe the interface you want in plain language and Codex pulls the right ReUI components, examples, and blocks from the registry, then wires them into your project.

Use ReUI to scaffold an admin app - the app-shell with a collapsible sidebar and top bar, and a dashboard page with stat cards and a chart.

Add a data-grid of orders with sorting, column filters, pagination, and row selection, wired to my /api/orders endpoint.

Build a multi-step "create project" wizard with the ReUI stepper and form components, with validation on each step.

Add a kanban board for support tickets with drag and drop, grouped by status, and a filters bar above it.

Unlock premium items

Free items (the 27 components and every c-* example) install with no license. To let Codex install premium blocks and icons too, grab a Pro or Ultimate license - one license unlocks the whole premium registry and removes the daily MCP request limit. Then add your key to the project - two quick steps:

REUI_LICENSE_KEY=your-license-key-here

{
  "registries": {
    "@reui": {
      "url": "https://reui.io/r/{style}/{name}.json",
      "headers": {
        "Authorization": "Bearer ${REUI_LICENSE_KEY}"
      }
    }
  }
}

That is it - Codex can now install any premium item the MCP returns, and free items keep working through the same config. See License Setup for the full guide, or compare plans on the Pricing page.

Troubleshooting

Most hiccups are a stale browser sign-in, and reconnecting fixes them. The one exception is a personal token, which cannot be re-authenticated - it has to be replaced.

• Tools missing, greyed out, or "not connected" - the server did not finish connecting. To fix it, run codex mcp login reui, then restart Codex. /mcp in the TUI shows which servers still need authorizing.
• 401 and you signed in through the browser - your ReUI session expired. To fix it, run codex mcp login reui to sign in again.
• 401 and you use a personal token (headless or CI) - the token has expired or been revoked. codex mcp login will not help, because it renews the stored OAuth credential, not the bearer token your job sends. Create a new token at Account → MCP and update the environment variable or CI secret. The 401 body names which of the two it was.
• Requests hang or the session drops mid-build - long sessions can lose the connection. To fix it, run codex mcp login reui and retry your last prompt.
• Sign-in appears to work but every call still 401s - check whether you have a bearer_token_env_var, http_headers, or env_http_headers line on the reui server in config.toml. A configured credential is sent on every request and overrides the OAuth credential the sign-in stores, so while it is there running codex mcp login reui cannot take effect. The two are alternatives, not layers: use the header only on the headless path, and remove it if you want the browser sign-in.
• "Your free ReUI MCP allowance ... is used up" in a tool result - the free plan has a daily MCP request allowance and today's is used up. It arrives as a normal tool result Codex shows you, not an HTTP error, so there is no status code to look for, and it resets at UTC midnight. For unlimited requests use a Pro or Ultimate license key, or a personal token from a licensed account, as your MCP credential, or wait for the reset.
• Every ReUI call fails and nothing asks you to sign in - the stored OAuth connection is dead (revoked, expired, or invalidated after a suspicious reuse), and the client is silently retrying a credential that can never work again. Account → MCP shows the connection as Disconnected when this is the case. Reconnect the same way as the 401 fix above; retrying without signing in again cannot recover it.