rusty-harness
A tiny agent harness that's blazing fast. One Rust core runs the agent loop, serves it
over A2A 1.0, and ships to Rust, Python and JavaScript:
- One agent, every surface. A terminal UI and a web renderer, both plain A2A clients
of the same harness, with A2UI forms, images, voice and slash commands.
- Long-running tasks. A task stays open across turns, asks people for input through
channels, plans its work as a DAG, and survives restarts on Temporal (or runs in
process).
- Extensible. Tools, MCP servers, skills, plugins and hooks on every operation;
models from OpenAI (Responses API) and Anthropic, or any OpenAI-compatible endpoint.
- Small and fast. About 260 µs of harness per turn, a 26 ms TUI cold start and a
20 MB binary.
| Get | Install | Package |
|---|
The rusty-harness command | npm i -g @rusty-harness/cli · pip install "rusty_harness[cli]" | npm · PyPI |
| Rust | cargo add rusty_harness --features rt-tokio | crates.io |
| Python | pip install rusty_harness | PyPI |
| JS / TS (WebAssembly) | npm i rusty-harness | npm |
Quick start
export OPENAI_API_KEY=… # referenced as env:OPENAI_API_KEY, never stored
rusty-harness # writes ~/.rusty-harness/config.toml, starts the harness, opens the TUI
rusty-harness --no-tui # the A2A server alone, on 127.0.0.1:7474
The demo runs the whole thing (the TUI and the web
renderer on one harness, an A2UI ask, a task open across turns, Temporal Cloud) from a
checked-in configuration.
Layout
All logic lives in crates/rusty-harness; the Python
(crates/rusty-harness-py) and WebAssembly
(crates/rusty-harness-wasm) crates are thin adapters, and
web/ is the web renderer.
Documentation, including the architecture, the capabilities and local development for
every layer, is at https://madarauchiha-314.github.io/rusty-harness/ and in
docs/.
