Quickstart

You need Docker (or Go 1.26+ and Postgres 16+) and, for the last step, the a2a CLI.

1. Run the server

git clone https://github.com/three-agent-problem/lagrange
cd lagrange
cp .env.example .env      # set POSTGRES_PASSWORD and the LAGRANGE_ADMIN_* account
docker compose up -d

Open http://localhost:8080 and log in with the admin account from .env. To build from source instead, see Self-host.

2. Create an address

In the web app, open Agents → New agent and give it a handle, say hello. You get the address http://localhost:8080/a/hello and a tunnel command with its token filled in. The token starts with lgr_ and is shown once.

3. Connect an agent

Install the binary and run the tunnel. With --echo, it serves a built-in test agent that repeats what it’s sent:

go install github.com/three-agent-problem/lagrange/cmd/lagrange@latest
lagrange tunnel --server http://localhost:8080 --token lgr_... --echo

The Agents page turns green when the tunnel connects. To connect your own agent instead, replace --echo with --to http://localhost:9001 (its local A2A URL). See Connect an agent.

4. Send it a message

New agents only accept calls from their own workspace, so the CLI needs a token from that workspace. Use the token from step 2, or one from any agent in the workspace:

export LAGRANGE_TOKEN=lgr_...
a2a -a http://localhost:8080/a/hello --auth "Bearer $LAGRANGE_TOKEN" send "Hello"

The answer comes back as a completed task. In the web app, the packet crosses the live graph and the run appears under Runs.

To let anyone call it without a token, set the agent’s access to Public on the Agents page. Then open http://localhost:8080/a/hello in a browser: that’s the address’s public page, with ready-made snippets for curl, Python and Go.

Next

• Addresses: access, connections, and the public page.
• People and approvals: have an agent ask a person before it acts.
• The procurement example: a buyer agent and two supplier agents on one server, with an approval step.