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# fx documentation

> fx is a coding agent for your terminal. libfx runs the fx agent from JavaScript in Node.js or the browser.

Each link below opens a Markdown version of the documentation.

## getting started

- [Quick start](https://fx.sh/docs.md): Install fx and send your first prompt.
- [Installation](https://fx.sh/docs/getting-started/installation.md): Install and update fx on macOS or Linux.
- [Authentication](https://fx.sh/docs/getting-started/authentication.md): Connect an account or API key for model requests.
## using fx

- [Working with fx](https://fx.sh/docs/using-fx/working-with-fx.md): Send a prompt, steer fx, and review the result.
- [Sessions](https://fx.sh/docs/using-fx/sessions.md): Return to a conversation, recover interrupted work, and manage context.
- [Context compaction](https://fx.sh/docs/using-fx/context-compaction.md): Understand when fx compacts a conversation and what it keeps.
- [Subagents](https://fx.sh/docs/capabilities/subagents.md): Delegate independent work and continue it with follow-up prompts.
- [Web search](https://fx.sh/docs/capabilities/web-search.md): Search current public information or read a known URL.
- [Vision](https://fx.sh/docs/capabilities/vision.md): Give fx screenshots, diagrams, and other images to work with.
## configure fx

- [Models](https://fx.sh/docs/configure-fx/models.md): Choose a model and adjust its reasoning effort.
- [Custom model connections](https://fx.sh/docs/configure-fx/custom-model-connections.md): Connect fx to Ollama, vLLM, OpenRouter, and compatible endpoints.
- [Permissions](https://fx.sh/docs/configure-fx/permissions.md): Control tool execution with modes, rules, and session grants.
- [Project instructions](https://fx.sh/docs/configure-fx/project-instructions.md): Give fx the commands and conventions it needs for your project.
- [Additional workspaces](https://fx.sh/docs/configure-fx/additional-workspaces.md): Give fx access to additional directories while keeping one primary workspace.
## extend fx

- [Skills](https://fx.sh/docs/capabilities/skills.md): Discover, load, install, and create reusable agent instructions.
- [MCP](https://fx.sh/docs/capabilities/mcp.md): Connect fx to MCP servers, sign in, and use their tools.
## reference

- [CLI commands](https://fx.sh/docs/using-fx/cli.md): Reference for top-level fx commands and global flags.
- [Slash commands](https://fx.sh/docs/using-fx/slash-commands.md): Reference for commands inside the interactive shell.
- [Configuration](https://fx.sh/docs/configure-fx/configuration.md): Reference for fx settings, scopes, defaults, and environment variables.
- [Context limits](https://fx.sh/docs/configure-fx/context-limits.md): Adjust how much text fx loads from instructions, skills, MCP tools, and image analysis.
- [Tools](https://fx.sh/docs/capabilities/tools.md): Built-in tools available to the fx agent.
- [MCP protocol reference](https://fx.sh/docs/capabilities/mcp/protocol.md): Transports, protocol coverage, schema handling, and isolation for the fx MCP client.
- [fx ask](https://fx.sh/docs/using-fx/fx-ask.md): Run noninteractive requests, return JSON, and continue saved sessions.
- [ACP server](https://fx.sh/docs/using-fx/acp.md): Run fx from editors and clients that support Agent Client Protocol.
## help

- [Troubleshooting](https://fx.sh/docs/using-fx/troubleshooting.md): Diagnose install, authentication, model, permission, session, and terminal problems.
- [Usage and costs](https://fx.sh/docs/using-fx/usage-and-costs.md): Check usage, spend, and plan limits from your provider.
- [Data and privacy](https://fx.sh/docs/using-fx/data-and-privacy.md): Understand what leaves your machine and what fx stores locally.
- [Share feedback](https://fx.sh/docs/using-fx/share-feedback.md): Report an fx problem and collect private diagnostics for terminal issues.
## libfx / getting started

- [Overview](https://fx.sh/docs/lib.md): Run the fx agent from JavaScript in Node.js or the browser.
- [Quick start](https://fx.sh/docs/lib/quick-start.md): Install libfx and stream your first reply.
- [Examples](https://fx.sh/docs/lib/examples.md): Build with libfx in Node.js, the browser, Next.js, and Nuxt.
## libfx / build an agent

- [Prompts and streaming](https://fx.sh/docs/lib/prompts.md): Send prompts, read events, and continue a conversation.
- [Models](https://fx.sh/docs/lib/models.md): Choose a model, reasoning effort, and fast mode.
- [Providers](https://fx.sh/docs/lib/providers.md): Run on AI Gateway, a ChatGPT or Grok plan, or an OpenAI-compatible server.
- [Tools](https://fx.sh/docs/lib/tools.md): Give the agent JavaScript functions to call.
- [Images](https://fx.sh/docs/lib/images.md): Send images alongside a prompt.
- [Steering](https://fx.sh/docs/lib/steering.md): Send follow-up instructions while the agent works.
- [Save and restore](https://fx.sh/docs/lib/checkpoints.md): Save a conversation and continue it in a new agent.
- [Durability](https://fx.sh/docs/lib/durability.md): Keep sessions running through crashes, deploys, and function timeouts.
## libfx / integrations

- [MCP](https://fx.sh/docs/lib/mcp.md): Connect MCP server tools to a libfx agent.
- [Skills](https://fx.sh/docs/lib/skills.md): Load skill instructions into an agent.
## libfx / runtimes

- [Node.js](https://fx.sh/docs/lib/node.md): Run libfx with a native addon or WebAssembly in Node.js.
- [WebAssembly](https://fx.sh/docs/lib/webassembly.md): Run a libfx agent in the browser through WebAssembly.
- [Terminal](https://fx.sh/docs/lib/terminal.md): Embed the fx terminal and connect storage, login, and workspace adapters.
## libfx / reference

- [API reference](https://fx.sh/docs/lib/api.md): Interfaces, options, methods, return types, and events for libfx.

## Complete documentation

- [Homepage](https://fx.sh/index.md): What fx is, in one page.
- [All fx documentation in one file](https://fx.sh/llms-full.txt): Every documentation page combined for large-context agents.

## Project and policies

- [Changelog](https://fx.sh/changelog.md): New features, improvements, and fixes in fx.
- [Source](https://github.com/vercel-labs/fx): Source code, issues, and releases.
- [libfx on npm](https://www.npmjs.com/package/libfx): Native and WebAssembly builds.

- [About fx](https://fx.sh/about.md): What fx is, who builds it, and where development happens.
- [Contact](https://fx.sh/contact.md): Bug reports, security disclosures, and privacy questions.
- [Privacy](https://fx.sh/privacy.md): What data fx and this website send, store, and do not collect.

- [fx logo, black](https://fx.sh/brand/fx-logo-black.svg): SVG wordmark for light backgrounds.
- [fx logo, white](https://fx.sh/brand/fx-logo-white.svg): SVG wordmark for dark backgrounds.
- [fx app icon](https://fx.sh/icon.svg): Square SVG icon.
- [fx logos](https://fx.sh/brand/fx-logos.zip): ZIP with the black and white logos and the app icon as SVG and 1024px PNG.