mei | updates

Jan 19, 2026

Shipping a smoother Mei demo (and a few protocol fixes)

We just cut a small but useful set of updates to the Mei prototype. This post walks through what changed, why, and how to run the new demo flow.

What changed

Spec alignment: HKDF labels now match the written spec (proto-v1/*), so other implementations can interop without surprises.
Configurable relay ports: The Elixir relay reads RELAY_PORT/PORT (default 4000). Handy for running multiple relays or avoiding conflicts.
CLI quality-of-life: Added --verbose to log every relay call, and the client now remembers relays you publish so inbox polling works even before you have contacts.
Demo script hardening: scripts/demo.sh spins up a relay on a free local port, preserves your host CARGO_HOME/RUSTUP_HOME, supports tracing (TRACE=1), and cleans up temp state unless you keep it.
Docs and hygiene: README now documents the relay API + demo troubleshooting, threat model calls out relay abuse/traffic-analysis limits, and we added Elixir ignores (_build/, deps/, PLTs, .elixir_ls/) to .gitignore.

Running the demo

The demo sets up two temp clients (Alice/Bob) and a temp relay, runs the invite/handshake, and sends a message.

Requirements: cargo, mix, curl, and python3 on PATH. Rust toolchain should be installed (rustup default stable if not).

# from repo root
make demo

If you want to peek under the hood and keep the temp state/logs:

TRACE=1 KEEP_STATE=1 make demo

Useful env toggles:

RELAY_URL=http://127.0.0.1:5005 – force a specific relay URL/port (otherwise the script finds a free port).
USE_EXISTING_RELAY=1 RELAY_URL=http://127.0.0.1:4000 – skip starting a relay and point at one you already run (mix run --no-halt).
KEEP_STATE=1 – keep temp dirs under /tmp instead of cleaning them up.
TRACE=1 – bash trace for the script.

During the demo the CLI prints the peer= value after handshake; that’s the key to use with send.

Manual quickstart (without the script)

# start relay on a chosen port
cd relay/kaheksa
RELAY_PORT=5005 mix run --no-halt

# terminal A (Alice)
cd crates/coral_cli
cargo run -- init
cargo run -- invite --relay http://127.0.0.1:5005

# terminal B (Bob)
cargo run -- init
cargo run -- accept "<INVITE_STRING_FROM_ALICE>"
cargo run -- recv

# back to Alice
cargo run -- recv
cargo run -- send <PEER_KEY> "hello from alice"

# Bob
cargo run -- recv

Add --verbose to any CLI command if you want to see relay URLs per call.