Rig merges a coding agent of Bevy plugins, and does not publish it

Pull request 2771 on 0xPlaygrounds/rig merged at 03:57 UTC on 15 October 2026. The merge commit is c9c928d4. The title is “feat(rig-harness): a thin coding agent over rig libraries, with rig-ecs and rig-tools.” The LICENSE file at that commit is the MIT license, copyright 2024 Playgrounds Analytics Inc.

The agent is in the source tree. It is not a release. cargo install rig from crates.io does not give you this agent today.

What merged

The README at that commit describes a terminal coding agent. rig is a launcher. It generates a small Cargo project, builds it, and runs it. The agent is a Bevy app. The kernel, rig-ecs, treats agents, turns, and tool calls as entities, with one recorded effect path and session logs. The harness, rig-harness, is what the binary needs in order to run and be relaunched. Coding tools (read, write, edit, search, shell) live in rig-tools. The harness README says every other feature is a plugin crate under plugins/, listed in plugins.toml, built only against public API. Any entry can be removed.

/reload rebuilds the agent with the changed plugins and restarts it on the same session. The root README says a rebuild that fails to compile leaves the current build running, and that a new build which crashes during startup is rolled back. Typed during a turn, /reload waits until no turn is running.

The pull request says the idea comes from the pi coding agent: a minimal core where every feature is an extension. On 15 October that URL redirects to earendil-works/pi, the repository in the 1 October note on Pi 1.0.

What you can install today

The same README says, in one sentence, that cargo install rig also installs the terminal agent, and in the next sentences that rig-harness, rig-ecs, rig-tools, and the plugin crates are not published yet, so the agent builds only from a checkout. The harness README repeats that none of those crates is published. The pull request says they have publish = false, and that the published rig facade ships a standard-library launcher and depends on none of them.

crates.io, read on 15 October, matches the unpublished side of that paragraph. rig and rig-core are at 0.44.0, created 7 October 2026, before this merge. rig-harness 0.44.1 and rig-tools 0.44.1 were published at 03:48 UTC on 15 October, about nine minutes before the merge, and each description says the crate is a placeholder reserving the name. The real crate, the text says, will be published from the GitHub repository.

The path the READMEs give for the agent itself is a checkout:

git clone https://github.com/0xPlaygrounds/rig && cd rig
cargo install --path .

The root README also shows RIG_SOURCE pointed at that checkout. It says the agent needs Rust 1.97.1 or newer and runs on Linux and macOS. Windows is not supported yet. Those requirements are the project’s, not a run performed here.

Bevy, and the crate docs.rs already has

The workspace Cargo.toml at the merge commit pins Bevy with =0.20.0 on bevy, bevy_ecs, bevy_app, and the other Bevy crates it lists. The comment says the pin is exact, from crates.io, never git. bevy 0.20.0 is on crates.io, created 8 October 2026, with license “MIT OR Apache-2.0”. An earlier commit message inside the same pull request still says the work started on Bevy 0.20.0-rc.2. The merged file says =0.20.0.

docs.rs/rig-ecs/latest currently serves rig-ecs 0.44.0. The pull request says the new rig-ecs is not published, and that when it is published it will replace the older rig-ecs 0.43 and 0.44 and will share no API with them. The page at “latest” is that older published crate. It is not the kernel from this merge. The pull request also tells users of the old crate to pin rig-ecs = "0.44" if they need to stay on it.

Steel is a lexical guard

Code mode is optional and off by default. The plugin is rig-steel: a run_steel tool whose Steel program, in Scheme, spawns agents, messages them, and calls tools. The plugin README calls that Steel’s sandboxed engine. The pull request is more specific. It says the sandbox is a lexical guard, not process isolation: host modules for process, git, network, and foreign functions are emptied, and a program that names module loading, eval, procedural macros, threads, blocking sleeps, or engine-private functions is refused before it runs. The same paragraph says Steel has no memory limit.

PLUGINS.md is the guide for writing another plugin against rig-harness. Nothing in the merge publishes that guide’s crates.