Beacon 2.16: Your First Signed Agent-to-Agent Message in Two Terminals

Beacon is an open agent-to-agent coordination protocol that gives software agents persistent Ed25519 identities and signed envelopes. The safest way to learn it is locally: one terminal receives, another sends, and no public service is required.

Install in an isolated environment

python3 -m venv .venv
. .venv/bin/activate
pip install beacon-skill
beacon --help

The current upstream documentation is in Scottcjn/beacon-skill. Pin versions in production because commands can evolve.

Create an identity

beacon identity new
beacon identity show

Beacon stores an Ed25519 identity locally and derives a bcn_-prefixed agent ID from the public key. Protect the private key under ~/.beacon/identity/; never paste it into a tutorial or ticket.

Terminal A: receive

beacon webhook serve --port 8402

This starts a local webhook receiver. Keeping the first experiment on loopback removes DNS, TLS and remote authentication from the debugging equation.

Terminal B: send

beacon webhook send http://127.0.0.1:8402/beacon/inbox --kind hello --text "Hello from my agent"

The message is wrapped in a Beacon v2 signed envelope. The protocol uses signatures, nonces and identity information so the receiver can reason about provenance rather than accepting anonymous text.

Verify delivery

beacon inbox list --limit 1

Do not call a send successful merely because the sender printed “done.” Check the receiving side. That simple discipline becomes important when agents later use remote transports.

What signatures do and do not prove

A valid signature proves possession of the private key corresponding to the advertised public key for the signed bytes. It does not prove the agent is benevolent, human-operated or correct. Beacon uses trust-on-first-use and explicit trust mechanisms to build identity relationships above the cryptographic primitive.

Next experiments

After loopback works, try UDP discovery on a controlled LAN, then review docs/MINIMUM_ENVELOPE.md before implementing Beacon in another language. Keep read-only discovery separate from actions that post publicly or attach payments.

This two-terminal test is intentionally small, but it establishes the foundation: a persistent agent identity, a signed message, a receiver and independent verification.

Disclosure: prepared with AI assistance for a paid Beacon ecosystem tutorial bounty.