Open Agent

A minimal autonomous coding agent with full machine access, implemented in Rust.

Features

• HTTP API for task submission and monitoring
• Tool-based agent loop following the "tools in a loop" pattern
• Full toolset: file operations, terminal, machine-wide search, web access, git
• OpenRouter integration for LLM access (supports any model)
• SSE streaming for real-time task progress
• AI-maintainable Rust codebase with strong typing

Quick Start

Prerequisites

• Rust 1.70+ (install via rustup)
• An OpenRouter API key (get one here)

Installation

git clone <repo-url>
cd open_agent
cargo build --release

Running

# Set your API key
export OPENROUTER_API_KEY="sk-or-v1-..."

# Optional: configure model (default: anthropic/claude-sonnet-4.5)
export DEFAULT_MODEL="anthropic/claude-sonnet-4.5"

# Optional: default working directory for relative paths (absolute paths work everywhere)
# In production this is typically /root
export WORKING_DIR="."

# Start the server
cargo run --release

The server starts on http://127.0.0.1:3000 by default.

OpenCode Backend (External Agent)

Open Agent can delegate execution to an OpenCode server instead of using its built-in agent loop.

# Point to a running OpenCode server
export AGENT_BACKEND="opencode"
export OPENCODE_BASE_URL="http://127.0.0.1:4096"

# Optional: choose OpenCode agent (build/plan/etc)
export OPENCODE_AGENT="build"

# Optional: auto-allow all permissions for OpenCode sessions (default: true)
export OPENCODE_PERMISSIVE="true"

API Reference

Submit a Task

curl -X POST http://localhost:3000/api/task \
  -H "Content-Type: application/json" \
  -d '{"task": "Create a Python script that prints Hello World"}'

Response:

{
  "id": "550e8400-e29b-41d4-a716-446655440000",
  "status": "pending"
}

Get Task Status

curl http://localhost:3000/api/task/{id}

Response:

{
  "id": "550e8400-e29b-41d4-a716-446655440000",
  "status": "completed",
  "task": "Create a Python script that prints Hello World",
  "model": "openai/gpt-4.1-mini",
  "iterations": 3,
  "result": "I've created hello.py with a simple Hello World script...",
  "log": [...]
}

Stream Task Progress (SSE)

curl http://localhost:3000/api/task/{id}/stream

Events:

• log - Execution log entries (tool calls, results)
• done - Task completion with final status

Health Check

curl http://localhost:3000/api/health

Available Tools

Tool	Description
read_file	Read file contents (any path on the machine) with optional line range
write_file	Write/create files anywhere on the machine
delete_file	Delete files anywhere on the machine
list_directory	List directory contents anywhere on the machine
search_files	Search for files by name pattern (machine-wide; scope with path)
run_command	Execute shell commands (optionally in a specified cwd)
grep_search	Search file contents with regex (machine-wide; scope with path)
web_search	Search the web (DuckDuckGo)
fetch_url	Fetch URL contents
git_status	Get git status for any repo path
git_diff	Show git diff for any repo path
git_commit	Create git commits for any repo path
git_log	Show git log for any repo path

Configuration

Variable	Default	Description
OPENROUTER_API_KEY	(required)	Your OpenRouter API key
DEFAULT_MODEL	anthropic/claude-sonnet-4.5	Default LLM model
WORKING_DIR	. (dev) / /root (prod)	Default working directory for relative paths (agent still has full machine access)
HOST	127.0.0.1	Server bind address
PORT	3000	Server port
MAX_ITERATIONS	50	Max agent loop iterations

Architecture

┌─────────────────┐     ┌─────────────────┐
│   HTTP Client   │────▶│   HTTP API      │
└─────────────────┘     │   (axum)        │
                        └────────┬────────┘
                                 │
                        ┌────────▼────────┐
                        │   Agent Loop    │◀──────┐
                        │                 │       │
                        └────────┬────────┘       │
                                 │                │
                   ┌─────────────┼─────────────┐  │
                   ▼             ▼             ▼  │
            ┌──────────┐  ┌──────────┐  ┌──────────┐
            │   LLM    │  │  Tools   │  │  Tools   │
            │(OpenRouter)│ │(file,git)│ │(term,web)│
            └──────────┘  └──────────┘  └──────────┘
                   │
                   └──────────────────────────────┘
                            (results fed back)

Development

# Run with debug logging
RUST_LOG=debug cargo run

# Run tests
cargo test

# Format code
cargo fmt

# Check for issues
cargo clippy

Dashboard (Bun)

The dashboard lives in dashboard/ and uses Bun as the package manager.

cd dashboard
bun install
PORT=3001 bun dev

Calibration (Trial-and-Error Tuning)

Open Agent supports empirical tuning of its difficulty (complexity) and cost estimation via a calibration harness.

Run calibrator

export OPENROUTER_API_KEY="sk-or-v1-..."
cargo run --release --bin calibrate -- --workspace ./.open_agent_calibration --model openai/gpt-4.1-mini --write-tuning

This writes a tuning file at ./.open_agent_calibration/.open_agent/tuning.json. Move/copy it to your real workspace as ./.open_agent/tuning.json to enable it.

License

MIT