Create your first library extension. Reference: extensions/web/ for working example.

Help: { "command": "core playbooks show build_getting-started" }

Prerequisites

  • Rust toolchain installed
  • SystemPrompt template cloned
  • Basic Rust knowledge

Structure

extensions/hello/
├── Cargo.toml
└── src/
    └── lib.rs

Step 1: Create Extension Crate

mkdir -p extensions/hello
cd extensions/hello

Create Cargo.toml:

[package]
name = "hello-extension"
version = "0.1.0"
edition = "2021"

[lib]
crate-type = ["rlib"]

[dependencies]
systemprompt = { workspace = true }

Step 2: Implement Extension

Create src/lib.rs. See extensions/web/src/extension.rs:15-45 for reference.

use systemprompt::extension::prelude::*;

#[derive(Debug, Default)]
pub struct HelloExtension;

impl Extension for HelloExtension {
    fn metadata(&self) -> ExtensionMetadata {
        ExtensionMetadata {
            id: "hello",
            name: "Hello Extension",
            version: env!("CARGO_PKG_VERSION"),
        }
    }
}

register_extension!(HelloExtension);

pub const PREFIX: &str = "hello";

Step 3: Add to Workspace

In root Cargo.toml:

[workspace]
members = [
    "extensions/hello",
]

[dependencies]
hello-extension = { path = "extensions/hello" }

In template src/lib.rs. See extensions/web/src/lib.rs:1-10 for reference.

pub use hello_extension as hello;

pub fn __force_extension_link() {
    let _ = core::hint::black_box(&hello::PREFIX);
}

Step 5: Build and Verify

cargo build
cargo run -- extensions list

Output should include:

- hello (v0.1.0, priority: 100)

Checklist

  • Cargo.toml with crate-type = ["rlib"]
  • Extension trait implemented
  • register_extension! macro called
  • PREFIX constant exported
  • Added to workspace members
  • Linked in __force_extension_link()

Troubleshooting

Issue Solution
Extension not showing Verify register_extension! called
Missing in list Check workspace members in root Cargo.toml
Linker strips extension Add to __force_extension_link()
Compilation errors Run cargo clean && cargo build

Quick Reference

Task Command
Create crate mkdir -p extensions/hello
Build cargo build --workspace
Verify cargo run -- extensions list
Clean build cargo clean && cargo build

-> See Create Library Extension for full extension -> See Rust Standards for code style -> See Add Database Schema for next step