Google Antigravity Rust SDK

The Google Antigravity SDK is a Rust library for building AI agents powered by Antigravity and Gemini. It provides a secure, scalable, and stateful infrastructure layer that abstracts the agentic loop, letting you focus on what your agent does rather than how it runs.

Installation

Add the SDK to your project using Cargo:

cargo add antigravity-sdk-rust

Or add it manually to your Cargo.toml:

[dependencies]
antigravity-sdk-rust = "0.1.0"
tokio = { version = "1", features = ["full"] }

Obtain the localharness binary: The SDK relies on a compiled native Go runtime binary (localharness) to orchestrate agent operations. You have two options to install it:
- Option A: Without Python/pip (Recommended for Rust-only environments & web servers) Run the helper installer script to download and extract the binary directly from PyPI (wheels are standard ZIP files):
```
./scripts/install_harness.sh
export ANTIGRAVITY_HARNESS_PATH="$(pwd)/bin/localharness"
```
- Option B: Using Python/pip If Python is already installed on your development machine, simply run:
```
pip install google-antigravity
```
  The Rust SDK will automatically locate the binary inside the Python package installation directory fallback.

Quickstart

Get started by setting your API key and running the hello_world example:

export GEMINI_API_KEY="your_api_key_here"
cargo run --example hello_world

Concepts

Simple Agent

The Agent struct manages the full lifecycle — binary discovery, tool wiring, hook registration, and policy defaults.

use antigravity_sdk_rust::agent::{Agent, AgentConfig};
use antigravity_sdk_rust::policy;

#[tokio::main]
async fn main() -> Result<(), anyhow::Error> {
    let mut config = AgentConfig::default();
    config.policies = Some(vec![policy::allow_all()]);

    let mut agent = Agent::new(config);
    agent.start().await?;

    let response = agent.chat("Say 'Hello World!'").await?;
    println!("Agent: {}", response.text);

    agent.stop().await?;
    Ok(())
}

Advanced Usage with Conversation

For full control over the connection lifecycle, use Conversation with a ConnectionStrategy directly. Conversation is a stateful session that accumulates step history:

use antigravity_sdk_rust::agent::AgentConfig;
use antigravity_sdk_rust::conversation::Conversation;
use antigravity_sdk_rust::local::LocalConnectionStrategy;
use antigravity_sdk_rust::tools::ToolRunner;
use antigravity_sdk_rust::types::GeminiConfig;
use std::sync::Arc;

#[tokio::main]
async fn main() -> Result<(), anyhow::Error> {
    let tool_runner = ToolRunner::new();
    let strategy = LocalConnectionStrategy::new(
        "localharness".to_string(), // path to harness
        GeminiConfig::default(),
        Default::default(),
        None,
        None,
        vec![],
        vec![],
        Some(tool_runner),
        None,
        "my_conversation_id".to_string(),
    );

    let connection = strategy.connect().await?;
    let conversation = Conversation::new(Arc::new(connection), None);

    let response = conversation.chat_to_completion("What files are here?").await?;
    println!("Agent: {}", response.text);

    Ok(())
}

Features

Custom Tools

use antigravity_sdk_rust::agent::{Agent, AgentConfig};
use antigravity_sdk_rust::tools::Tool;
use async_trait::async_trait;
use serde_json::Value;

struct WeatherTool;

#[async_trait]
impl Tool for WeatherTool {
    fn name(&self) -> &str {
        "get_weather"
    }

    fn description(&self) -> &str {
        "Get the current weather for a city."
    }

    fn parameters_json_schema(&self) -> &str {
        r#"{
            "type": "object",
            "properties": {
                "city": {
                    "type": "string"
                }
            },
            "required": ["city"]
        }"#
    }

    async fn call(&self, args: Value) -> Result<Value, anyhow::Error> {
        let city = args.get("city").and_then(|c| c.as_str()).unwrap_or("Tokyo");
        Ok(serde_json::json!({ "weather": format!("It's sunny in {}", city) }))
    }
}

Hooks and Policies

Control agent behavior with a declarative policy system:

use antigravity_sdk_rust::policy::{self, Policy};

let policies = vec![
    policy::deny_all(),                          // Block all tools by default
    policy::allow("VIEW_FILE"),                  // Allow reading/viewing files
];

Web Integration

The SDK provides two patterns for building web applications with AI agents:

Leptos + Axum (Native)

For standard web servers (VPS, Docker, bare metal). The Agent runs in-process with full SDK features.

cd examples/leptos_axum
echo "GEMINI_API_KEY=your-key" > .env
cargo leptos serve
# Open http://localhost:3000

Leptos + Spin/WASI (Edge)

For edge/serverless deployments on Fermyon Spin. Since Spin components cannot make outbound TCP/WebSocket connections, two modes are supported:

Sidecar Mode (Full SDK):

# Terminal 1: Start the agent sidecar
cd examples/agent_server
GEMINI_API_KEY=your-key cargo run

# Terminal 2: Start Spin
cd examples/leptos_ssr_axum
spin build --up
# Open http://localhost:3000

Direct Mode (Lightweight, no sidecar):

cd examples/leptos_ssr_axum
spin build --up --variable gemini_api_key="your-key"

See examples/README.md for detailed architecture diagrams and configuration options.

GeminiDirectClient

For environments where TCP/WebSocket is unavailable (e.g. WASI, embedded), the SDK provides a transport-agnostic Gemini API client that builds HTTP request payloads and parses responses — the caller provides the HTTP transport:

use antigravity_sdk_rust::direct::{GeminiDirectClient, ChatEntry};
use antigravity_sdk_rust::types::GeminiConfig;

let client = GeminiDirectClient::new(&GeminiConfig::default())
    .with_system_instruction("You are a helpful assistant.".to_string());

// Build the request (URL, headers, body) — send via your HTTP client
let request = client.build_request("your-api-key", "Hello!", &[]).unwrap();

// Parse the response
let text = GeminiDirectClient::parse_response(&response_bytes).unwrap();

Local Development

This project uses just to manage development tasks.

Check Code Quality: Run all style, lint, and test checks.
```
just check
```
Install Local Harness: Download and configure the required localharness binary.
```
just install
```
Bump version & Release tag: Bump the package version, update Cargo.lock, commit using --no-verify (skipping git hooks), and tag the release.
```
# Auto-bump patch version (e.g., 0.1.0 -> 0.1.1)
just version

# Or force/override with a specific version
just version 0.2.0
```
Publish to Crates.io: Manually publish the package to crates.io (runs just check first).
```
just publish
```

Architecture

For more information, see ARCHITECTURE.md.

License

This project is licensed under the MIT License.

antigravity-sdk-rust 0.1.3