nucleus-substrate-core

The categorical core of the Nucleus substrate. Three load-bearing types and one signed envelope:

• Session — the agent-action object every projection projects from
• Projection — sealed, adjacently-tagged sum: Identity, Capability, Flow, Economic (#[non_exhaustive])
• Receipt — Ed25519-signed colimit envelope binding a session to any subset of its projections

The categorical claim is proved in Lean 4 — see receipt_factors_through_projections in formal/Nucleus/Substrate/Colimit.lean.

Quick example

use nucleus_substrate_core::{Session, Receipt, Projection};
use ed25519_dalek::SigningKey;

let sk = SigningKey::from_bytes(&[7u8; 32]);
let session = Session {
    session_id: "spiffe://test/agent-x".into(),
    issuer_kid: "test-kid".into(),
    issued_at_micros: 1_717_000_000_000_000,
    parent_chain: vec![],
};
let projection = Projection::Identity(serde_json::json!({
    "sub": "spiffe://test/agent-x",
    "aud": "nucleus-substrate-test",
}));
let receipt = Receipt::sign(session, vec![projection], &sk);
let vk: [u8; 32] = sk.verifying_key().to_bytes();
receipt.verify(&vk).expect("self-built receipt verifies");

Position in the substrate

This crate is the only required dependency for projection-lifter crates and the SDK. Server-side hub crates depend on it for the typed VCG wire shapes in mechanism::vcg. Everything else in the substrate stack composes on top of these three types.

License

Dual-licensed under MIT OR Apache-2.0. See LICENSE-MIT and LICENSE-APACHE.