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Codex plugin

The REL plugin connects Codex to REL’s persistent embedded Chromium sessions. It configures the MCP server bundled with the installed app and adds the rel-browser skill for interactive browser work plus the crawl-websites-with-rel skill for restartable, history-preserving crawls.

Related documents: MCP server and CLI.

Requirements

Section titled “Requirements”
  • macOS 15 or later;
  • REL installed at /Applications/REL.app;
  • a Codex release with plugin marketplace support.

REL.app must be installed so Codex can start its bundled Contents/Resources/rel-mcp adapter. The app does not need to be running for plugin discovery or rel_status; other validated tool calls start it lazily.

Install

Section titled “Install”

Add this repository as a Codex marketplace, then install the rel plugin:

Terminal window
codex plugin marketplace add https://github.com/rel-me/rel-tools.git --ref main
codex plugin add rel@rel

Start a new Codex task after installation so the task loads the plugin’s skill and MCP tools.

Migrate the legacy marketplace

Section titled “Migrate the legacy marketplace”

If Codex reports that the rel marketplace is already installed from a different source, or installs plugin version 0.1.0, the marketplace is pinned to REL’s old repository branch. Replace only that plugin and marketplace entry, then install from the canonical main branch:

Terminal window
codex plugin remove rel@rel
codex plugin marketplace remove rel
codex plugin marketplace add https://github.com/rel-me/rel-tools.git --ref main
codex plugin add rel@rel

This removes only the cached Codex plugin. It does not remove REL.app or its browser sessions.

What the plugin adds

Section titled “What the plugin adds”

The plugin contains:

  • the bundled REL MCP server configuration, using the absolute installed-app path;
  • the rel-browser skill for safe session selection and browser workflows;
  • the crawl-websites-with-rel skill for rendered-link discovery, readiness, checkpoints, capture metadata, bounded retries, and session recovery;
  • all fourteen MCP tools, including bounded semantic reading, opt-in untrusted website notifications, observations, session-group closing, and inline or file-backed screenshots;
  • all eight canonical page actions: click, wait-for, type, clear, press, select, wait, and click-link.

The plugin does not add another browser backend. REL.app remains the only Chromium owner, and every tool call flows through the local versioned API. See the MCP tool reference for complete inputs and action semantics.

Verify

Section titled “Verify”

Begin with a read-only check in a new task:

Use the REL MCP server. Call rel_status, then rel_list_sessions. Do not navigate anywhere.

Codex should discover fourteen rel_* tools without opening REL. If REL is already running, rel_status reports the app, local agent, Browser Proxy, and embedded Chromium bridge. Otherwise it returns the local connection error without launching the app; rel_list_sessions then starts REL lazily.

Update

Section titled “Update”

Refresh the marketplace snapshot and reinstall the current plugin version:

Terminal window
codex plugin marketplace upgrade rel
codex plugin add rel@rel

Start another new task after updating so it uses the refreshed plugin cache.