Kez/nodejs/packages/kez-core/src/envelope.ts

// Wire types: claim payload, signature block, full envelope.
// Field names and ordering match Rust exactly so JCS bytes are identical.

import type { Identity } from "./identity.js";

export const CLAIM_TYPE = "kez.claim";
export const SIGCHAIN_EVENT_TYPE = "kez.sigchain.event";
export const FORMAT_VERSION = 1;
export const NOSTR_SCHNORR_ALG = "nostr-secp256k1-schnorr-sha256-jcs";
export const ED25519_SHA512_ALG = "ed25519-sha512-jcs";
export const COMPACT_PROOF_PREFIX = "kez:z1:";
export const COMPACT_CHAIN_PREFIX = "kez:zc1:";

export interface ClaimPayload {
  type: typeof CLAIM_TYPE;
  version: number;
  subject: string; // serialized Identity
  primary: string; // serialized Identity
  created_at: string; // RFC 3339
  expires_at?: string;
}

export interface SignatureBlock {
  alg: string;
  key: string; // serialized Identity (matches `primary`)
  sig: string; // hex
}

export interface SignedClaimEnvelope {
  kez: "claim";
  payload: ClaimPayload;
  signature: SignatureBlock;
}

/**
 * Spec §6 sigchain event payload. Field order/names match Rust exactly so
 * JCS-canonicalized bytes are byte-identical across implementations.
 */
export interface SigchainEventPayload {
  type: typeof SIGCHAIN_EVENT_TYPE;
  version: number;
  primary: string; // serialized Identity, e.g. "nostr:npub1..."
  seq: number;
  prev?: string; // "sha256:<hex>" of prior envelope; omitted iff seq === 0
  created_at: string;
  op: SigchainOp;
  payload: Record<string, unknown>;
}

export type SigchainOp = "add" | "revoke" | "rotate" | "add_device";

export interface SignedSigchainEvent {
  kez: "sigchain_event";
  payload: SigchainEventPayload;
  signature: SignatureBlock;
}

/** Build a fresh ClaimPayload with the right `type` and `version` fields. */
export function newClaimPayload(
  subject: Identity,
  primary: Identity,
  createdAt: Date,
): ClaimPayload {
  return {
    type: CLAIM_TYPE,
    version: FORMAT_VERSION,
    subject: subject.toString(),
    primary: primary.toString(),
    created_at: rfc3339Utc(createdAt),
  };
}

/** RFC 3339 / ISO 8601 in UTC, matching the format Rust's chrono emits. */
export function rfc3339Utc(date: Date): string {
  return date.toISOString().replace(/Z$/, "Z");
}