Use MainSDK from Rust

You will add the mainsdk crate, run it on its local drivers, and wire an axum route. It takes about 15 minutes. The crate is native Rust: it shares no code with the TypeScript SDK, only main.yaml, the error codes and the wire formats.

You need

• Rust 1.85 or later and a main.yaml with schema: 1 (npx mainsdk init writes one).
• The crate is pre-release and not on crates.io. Use a path or git dependency from the MainSDK repository until it is published.

1. Add the crate

[dependencies]
mainsdk = { path = "../mainsdk/packages/rust/mainsdk", features = ["kv", "files", "axum"] }
tokio = { version = "1", features = ["rt-multi-thread", "macros"] }

Each interface sits behind a feature of the same name. config and log are on by default.

2. Call an interface

Calls are builders you .await directly. A tenant-scoped call needs a tenant, which travels in a task-local Context.

use mainsdk::prelude::*;

#[tokio::main]
async fn main() -> mainsdk::Result<()> {
    let app = App::load().await?;
    Context::new().tenant("tnt_a").user("u1").scope(async {
        app.kv().set("cart", 3).await?;
        let file = app.files().upload(b"hello".to_vec()).owner("u1").await?;
        app.log().info("uploaded").field("file", &file.id).await;
        Ok::<_, MainError>(())
    }).await
}

Spawn with mainsdk::spawn, not tokio::spawn, so the context follows the task. A call that needs a tenant and has none fails with MAIN-TENANT-0001.

3. Return problem details from axum

let router = axum::Router::new().route("/cart", handler).layer(app.layer());

The layer reads traceparent, sets the context, and renders any MainError as application/problem+json with its code, fix and trace_id.

4. Cancel and time out

Drop the future to cancel a call and release what it held. To stop one on purpose, pass a token with .cancel(token); the call fails with MAIN-SDK-0001.

5. Check the project

npx mainsdk check runs clippy (MAIN-RUST-0001), cargo-audit (MAIN-RUST-0002) and cargo-deny (MAIN-RUST-0003) with the usual gates. A missing tool is a warning, MAIN-RUST-0004, never a pass. Run cargo test too.

Next

• Key-value store, Files and the other first-cut interface pages show a Rust tab.
• Rust agents load the mainsdk-rust skill.