@vdm-nexus/sdk reference

The base SDK for the Ed25519-signed prepaid flow. Two runtime deps. For the pay-per-call x402 flow, see @vdm-nexus/x402.

npm install @vdm-nexus/sdk

`class Agent`

The agent identity. Encapsulates a 64-byte Ed25519 keypair (32-byte seed + 32-byte derived public key).

`Agent.generate(): Agent`

Generate a fresh random keypair.

import { Agent } from "@vdm-nexus/sdk";
const a = Agent.generate();

`Agent.fromBase58(secretKeyBase58: string): Agent`

Restore an agent from a base58-encoded 64-byte secret.

const a = Agent.fromBase58(process.env.AGENT_SECRET!);

`agent.pubkey: string`

Getter — the agent's base58 public key (32 bytes encoded), identical to the Solana wallet address.

`agent.secretKeyBase58: string`

Getter — the full 64-byte secret encoded as base58. Save this; losing it means losing the agent.

`agent.signBody(body: string): string`

Sign an arbitrary UTF-8 string with Ed25519. Used internally by .inference(); exposed for callers who need to sign other request shapes.

Returns the base58-encoded 64-byte detached signature.

`agent.inference(endpoint, opts): Promise<InferenceResponse>`

Make a prepaid inference call. Signs the request body, posts to ${endpoint}/inference with the X-Agent-Pubkey + X-Nexus-Signature headers, parses the JSON response.

const reply = await agent.inference("https://nexus.vdmnexus.com/api/v1", {
  prompt: "Why Ed25519?",
  task_type: "fast", // "fast" | "reasoning" | "general"
});

reply.ok;                     // boolean
reply.result;                 // string — the model's response
reply.receipt;                // Receipt
reply.receipt?.cost_usdc;     // upstream cost
reply.receipt?.balance_remaining;

`InferenceOptions`

type InferenceOptions = {
  prompt: string;
  task_type?: "fast" | "reasoning" | "general";   // default "general"
  max_cost_usdc?: number;                         // route-cheaper-if-below
};

`Receipt`

type Receipt = {
  agent_pubkey: string;
  provider: string;
  model: string;
  cost_usdc: number;
  balance_remaining: number;
  prompt_hash: string;       // sha256 hex of the prompt string
  response_hash: string;     // sha256 hex of the response string
  timestamp: number;
  inference_id: string | null;
};

The prepaid flow debits a server-side credits_ledger. Topping up the ledger happens by sending devnet USDC to the Nexus deposit address (see Architecture) — the deposit watcher polls Solana for incoming transfers and credits the ledger keyed by sender.

The full self-topup story (Agent.deposit(...) that constructs and sends the transfer) is deferred until the @vdm-nexus/wallet package ships.

For pay-per-call, use @vdm-nexus/x402 instead — no topup needed, each call settles standalone.