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Nexus CLI is the easiest way to use Fireworks models in the coding harness you already use. It is an open-source CLI that rewrites your harness settings to call Fireworks, adds Fireworks models to the model picker, and restores your original settings when you turn it off. You do not need to host a service or edit config files by hand.
Nexus CLI was formerly called FireConnect. The command is now nexus, settings live in ~/.nexus, and the installer is at nexus.fireworks.ai. If you still have FireConnect installed, run fireconnect upgrade once or re-run the installer, and your command, settings, and connected harnesses migrate automatically.

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Connections

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Code

Claude Code

Claude Agent SDK

Codex CLI

OpenCode

Pi

DeepSeek

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

Requires Node.js 18 or later, git, and bash. On Windows, run it from Git Bash; PowerShell breaks the script’s line endings.
Sign in with your browser, or paste a Fireworks key.

Connect a harness

Replace claude with any harness from Coding Harnesses.

Restart and check

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 rewrites the harness config to call Fireworks and saves a snapshot under ~/.nexus/.
  • off restores file-based harnesses from that snapshot byte-for-byte. For IDE databases, it removes the settings and models Nexus CLI added.
  • nexus upgrade updates Nexus CLI and brings connected harnesses up to date, keeping the model you picked. Restart each harness the upgrade output names.
  • Sign-in credentials and harness configurations are stored separately. nexus login saves your credential through Nexus CLI’s secret store. If a harness requires the key in its own configuration, Nexus CLI copies it there and restricts the file permissions. Run nexus status to see the active storage backend without revealing the key.

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Choose a model

Connecting registers coding-ready Fireworks models, including auto. Use --model to add or select a specific model:
Restart or reopen the harness after changing a model. Browse IDs with nexus model list. See Open Models for aliases and pinned versions, and Coding Harnesses for app-specific rules. To pick between open models and the Anthropic or OpenAI models you have access to for each turn, use Nexus Auto. Nexus Auto covers the Nexus CLI command and the 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. Third-party mode hides the connector browser, so Nexus CLI imports those 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

Nexus CLI was formerly called FireConnect. The command is now nexus, settings live in ~/.nexus, and the installer is at nexus.fireworks.ai. Run fireconnect upgrade once or re-run the installer, and your command, settings, and connected harnesses migrate automatically.

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Codex and ChatGPT desktop app

  • Connected with FireConnect 0.9.9 or earlier? Run nexus upgrade 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 upgrade 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 upgrade so the Fireworks models appear in /models.

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Claude Code

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

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Upgrade and uninstall

For upgrade and uninstall commands, see the CLI Reference.