fx - AIおもしろツール

fxとは？

fx is a CLI-based coding agent written in Zig. It is designed to run from the terminal, work as a native process, and fit into larger systems through embedding or protocol-based integrations. The project emphasizes a small binary, minimal output, and a workflow that is closer to a Unix shell than a full terminal IDE.

The documentation describes fx as model-agnostic and open source under Apache-2.0. It can be used interactively in a project directory, resumed across sessions, or run noninteractively with fx ask. The same runtime can also be exposed over Agent Client Protocol or compiled to WebAssembly for JavaScript-based interfaces.

fxでできること

Minimal native CLI

fx is a terminal-first coding agent with a shell-like interface, designed to keep output compact and focus on the current workspace.

Interactive and noninteractive modes

Users can start a fresh session with `fx`, continue an existing session with `fx resume`, or run a single request with `fx ask`.

Workspace-aware execution

The current directory becomes the primary workspace, and commands such as reading, searching, and listing files work within that context.

Permission-aware actions

fx starts in auto permission mode, reviews sensitive calls, and prompts before actions that can change files or run commands. Permission mode can be changed with `/permissions`.

Multiple deployment surfaces

The same agent can run natively in the terminal, serve over ACP with `fx acp`, or be loaded from JavaScript through the experimental WebAssembly SDK.

Extensible agent runtime

The docs mention skills, plugins, MCP, browser integration, and configurable SDK behavior for authentication, storage, command execution, and network requests.

利用シーン

“Terminal-based code assistance”

Work in a repository, ask fx to inspect files, explain code, add tests, or run the test suite while the transcript shows tool calls as they happen.

“Session-based development workflows”

Resume prior work, inspect saved sessions, and recover context when you return to a project later.

“Embedded coding-agent interfaces”

Use fx as the runtime behind an editor, application, or service that needs coding-agent behavior without building the agent from scratch.

“JavaScript or browser-hosted agent experiences”

Load the WebAssembly build into a JS application when you need a headless agent or an interactive terminal-like interface.

“Controlled automation with approvals”

Use fx in environments where file access and command execution should be reviewed before they run.

よくある質問

What is fx?

fx is a CLI-based AI coding agent and harness for working with code from the terminal or embedding the agent into other systems.

How do I start using it?

The docs show installation with `curl -fsSL https://fx.sh/setup.sh | bash`, followed by `fx login` for Vercel authentication or setup of an AI Gateway API key.

Can fx run without an interactive terminal session?

Yes. The docs document `fx ask` for one-off requests, along with commands such as `fx status`, `fx models`, and `fx permissions` for inspection and configuration.

Does fx only work with one model provider?

No. The site describes fx as model-agnostic and suitable for local models, gateways, direct provider API access, or subscriptions.

Can fx be embedded in other products?

Yes. The docs describe native ACP support and an experimental WebAssembly SDK for JavaScript-based integrations.

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