Connect through blind relays

The previous lesson pre-downloaded a model from a regular Hyperdrive seed. This one makes sure peers behind NATs can find each other.

Most peers are behind NATs or firewalls, so they can't accept incoming connections, which makes peer-to-peer model downloads hard. Blind relays solve this: they're public Hyperswarm nodes that help two peers find each other without seeing the actual traffic.

The SDK reads its config during initialization. The QVAC_CONFIG_PATH env var has to be set before the import "@qvac/sdk" line, since module evaluation reads the config at import time.

The configuration file is a regular JavaScript module that exports the relay list. swarmRelays is the only field: an array of hex-encoded public keys (one per relay). The vendored qvac.config.js for this lesson uses placeholder keys; real deployments need a relay you control or a trusted public relay:

// qvac.config.js
export default {
  swarmRelays: [
    "0000000000000000000000000000000000000000000000000000000000000001",
    "0000000000000000000000000000000000000000000000000000000000000002",
    "0000000000000000000000000000000000000000000000000000000000000003",
  ],
};

QVAC_CONFIG_PATH must be set BEFORE import '@qvac/sdk', since module evaluation reads the config at import time. The env-then-import sequence looks like:

process.env["QVAC_CONFIG_PATH"] = "./qvac.config.js";

async function main() {
  const modelId = await loadModel({ modelSrc: LLAMA_3_2_1B_INST_Q4_0 });
  await unloadModel({ modelId });

  await downloadAsset({
    assetSrc: LLAMA_3_2_1B_INST_Q4_0,
    onProgress: (p) => {
      const mb = (n: number) => (n / 1e6).toFixed(1);
      process.stderr.write(`▸ ${p.percentage.toFixed(0)}% (${mb(p.downloaded)}/${mb(p.total)} MB)\n`);
    },
  });
}

main().catch(console.error);

The relays help establish the peer connection through NAT. They don't see the actual model data. The download happens peer-to-peer once the connection is set up.

Note: blind relays only help with NAT traversal. They do not anonymize traffic or change what's downloaded.

Put it to the test

1. Set up the relay config (file + env var) and call loadModel followed by downloadAsset. Both should succeed via the configured relays.