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Nexus CLI is the easiest way to use Fireworks models in the coding harness you already use. It’s an open-source CLI that:
  • Rewrites your harness settings to call Fireworks.
  • Adds Fireworks models to the harness’s model picker.
  • Restores your original settings when you turn it off.
You don’t host a service or edit config files by hand. Claude Desktop is the one harness that also runs a small local helper on your machine.
Nexus CLI was formerly called FireConnect. The command is now nexus, settings live in ~/.nexus, and the installer is at nexus.fireworks.ai. Still on FireConnect? Run fireconnect upgrade once, or re-run the installer. Your settings and connected harnesses carry over. See Upgrading from FireConnect.

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Connections

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Code

Claude Code

Claude Agent SDK

Codex CLI

OpenCode

Pi

DeepSeek Harness

Cursor IDE

VS Code

Copilot App

Copilot CLI

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Cowork

ChatGPT desktop app

Claude Desktop

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Quick start

Install and sign in

You need Node.js 22 or later, git, and bash. On Windows, run the installer from Git Bash. PowerShell breaks the script’s line endings.
Sign in with your browser, or paste a Fireworks API key (fw_...).

Connect a harness

Replace claude with your harness: chatgpt, codex, opencode, pi, cursor, vscode, copilot-app, copilot-cli, or deepseek. Claude Desktop uses nexus claude-desktop on. Each harness page in Coding Harnesses has the details.Quit Cursor IDE, VS Code, or the Copilot App before you connect them. A running app saves over the new settings.

Restart and check

Restart the harness, or start a new session. Then run:
status shows the provider, where the key comes from, and the configured model.
Rather configure it yourself? See Manual setup for when to use it and what changes.

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Connect and restore

  • Connect (nexus <harness>) rewrites the harness config to call Fireworks and saves a snapshot under ~/.nexus/. It only connects a harness that’s installed on this machine. If yours is installed somewhere Nexus CLI doesn’t look, pass --skip-install-check.
  • off (nexus <harness> off) restores file-based harnesses from that snapshot, byte for byte. For IDE databases, it removes only the settings and models Nexus CLI added.
  • nexus status lists every harness, whether it’s connected, and whether it’s installed.
  • nexus update updates Nexus CLI and brings connected harnesses up to date. It keeps the model you picked. Restart each harness the update output names. nexus upgrade still works. See what changed in Release Notes.
  • Your key is stored once. nexus login saves your Fireworks key in the OS keychain, or in an encrypted file when no keychain is available. Some harnesses need the key in their own config. Nexus CLI copies it there and makes the file readable only by you. Run nexus status to see the storage backend without revealing the key.

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Choose a model

Connecting registers coding-ready Fireworks models, including auto, and starts the harness on auto. Use --model to add or select a specific model:
Restart or reopen the harness after you change a model. Browse model IDs with nexus model list. See Open Models for aliases and pinned versions, and Coding Harnesses for app-specific rules. Nexus Auto picks between open models and the Anthropic or OpenAI models you have access to, one turn at a time. Nexus Auto covers the nexus auto command and which credentials each harness can send. Web search works through Fireworks with no extra setup. See Web Search for which harnesses support it.

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MCP servers

Your servers stay

Nexus CLI keeps every MCP server you configured, and nexus <harness> off leaves them in place. Claude Desktop is the exception. Its third-party mode hides the connector browser, so Nexus CLI imports your connectors, and you manage them with nexus claude-desktop mcp. See Connectors.

Tool search stays on

In Claude Code, Nexus CLI sets ENABLE_TOOL_SEARCH. In Codex and the ChatGPT desktop app, it turns on tool search for every model. Large MCP tool sets still load on demand.

Web search is built in

Native web search works through Fireworks in Claude Code, Claude Desktop, Codex, and the ChatGPT desktop app.

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Upgrading from earlier versions

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Upgrading from FireConnect

Run fireconnect upgrade once, or re-run the installer. Your command, settings, and connected harnesses move to Nexus CLI:
  • ~/.fireconnect moves to ~/.nexus, and the old path stays as a link.
  • Environment variables are now NEXUS_*. FIRECONNECT_* still works, but rename them in your scripts and shell profile.
  • A harness on a FireRouter model moves to auto. See Nexus Auto.
  • If ~/.nexus already exists and Nexus CLI didn’t create it, the update stops before changing anything.

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Codex and ChatGPT desktop app

  • Connected with FireConnect 0.9.9 or earlier? Run nexus update, or nexus codex (nexus chatgpt for the app). Then restart Codex or reopen the app. MCP and app connector tools then load through Codex’s tool search on every model.
  • If Codex was on FireRouter (firerouter or a route such as firerouter/opus), nexus update moves that selection to auto. Other models stay as they are. Run codex login if Codex asks.

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DeepSeek Harness

Connected before FireConnect 0.9.8? Run nexus deepseek once, so dsh 0.1.7 and later stop asking for a DeepSeek key.

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OpenCode

If your opencode.json uses OpenCode v2’s providers map and you connected with an earlier version, run nexus update. The Fireworks models then appear in /models.

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Claude Code

FireConnect versions before 0.9.7 installed the fireworks-websearch MCP server for Claude Code. nexus update removes it and leaves your other MCP servers in place. See Web Search.

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Update and uninstall

For update and uninstall commands, see the CLI Reference.