The coding agent “fx”, version 0.0.4, has been released as an open‑source command‑line tool written in Zig and compiled to WebAssembly, producing a binary of roughly 6 MB.

The software is intended for research and for embedding in resource‑constrained environments or agent sandboxes, emphasizing minimalism and performance.

According to the developers, the tool achieves cold‑start times of about 10 µs and does not perform unnecessary I/O before accepting input. Networking is handled via the browser’s fetch API, and all SDK components are configurable through the accompanying documentation. The 6 MB binary consumes a single‑digit megabyte baseline of memory, enabling multiple instances on a single machine. Its command‑line interface resembles a Unix shell, preserves scroll history by default, and generates minimal output to reduce token costs and improve time‑to‑first‑token performance. Extensibility is provided through a small core that can be expanded with skills, plugins, and MCP integrations, adhering to a Unix‑like philosophy.

The project remains in active development, with plans for frequent updates.