fx: A Tiny, Open Coding Agent Harness Written in Zig
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fx is a coding agent harness and CLI written in Zig, built for research and designed to be embedded in larger systems. It favors minimalism and performance throughout — the system prompt, tool set, and feature surface — and ships as a 6.17 MiB binary.
Its output reads closer to a Unix shell than a terminal IDE, which keeps it scriptable and easy to compose. The project is open source under Apache-2.0, model-agnostic, and runs against local or cloud inference. It targets developers embedding an agent into larger systems rather than IDE-style interactive use.