- Sources: fx repository, fx.sh, HN discussion
- Summary: fx is a coding agent harness and CLI written in Zig under Apache 2.0, model agnostic, aimed at research and embedding inside larger systems rather than at being a terminal IDE, with the repository marking the status experimental at 284 stars and a 7.8 MiB binary. It builds as a native binary or WebAssembly, and hosts can supply network transport, session storage, configuration, permission handling, and terminal I/O through
createFxAgent with fx-core.wasm, createFxTerminal with fx-term.wasm, or fx acp for Agent Client Protocol clients. It ships skills, MCP, subagents, and a permissions model with stored rules addressable by stable rule IDs, and building from source needs Zig 0.16.0 or later. - Why it matters: Compiling an agent loop to WebAssembly puts it inside a host process rather than behind a subprocess, and ACP support makes it addressable from existing clients without a bespoke integration.
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