Files
mpc/cmd/mpcd
zooqueen df4791d374 reveal: a node that cannot answer openings still signs
serveReveal returning an error aborted startup, so a new capability
could stop a ring from doing the thing it already existed to do.
Signing was working before openings were possible and should keep
working when one is not.

Nothing is hidden by carrying on. The failure is logged here, and an
opening that goes short already reports how many answered out of how
many it needed — which is the number that matters and the place someone
is looking when it does.
2026-08-20 14:18:28 -07:00
..

mpcd — MPC Daemon

mpcd is a threshold-signature daemon. It speaks ZAP wire protocol over TLS 1.3 directly between peers — no NATS, no Consul, no PostgreSQL in the critical path. The daemon is the same binary in every deployment shape; the operating mode is selected entirely by flags.

Operating modes

There is exactly one start command (mpcd start) and the topology is determined by the --peer and --threshold flags:

Topology Flags Use
Standalone (1-of-1 self-loop) --threshold 1 (no --peer) Smoke tests, dev sandbox
Networked t-of-n cluster --threshold t --peer ... (n−1 peers) Production

In all cases mpcd runs the consensus-embedded transport (pkg/transport). The "consensus" here is local PoA membership over the node's own Ed25519 identities — it is intentionally not the Lux mainnet chain, because key shares must never leave the cluster.

Standalone (1-of-1)

mpcd start \
    --node-id solo \
    --listen :9999 \
    --api :9800 \
    --data /var/lib/mpcd \
    --threshold 1

Starts mpcd with itself as the only quorum member. /healthz will report signing_quorum: true immediately. Keygen and signing of fresh wallets require ≥2 parties — CGGMP21 and FROST cannot produce shares with a single party — so this mode exists only for boot-up smoke tests, e2e harness fixtures, and verifying TLS / membership / API plumbing. For real signing, run a multi-node cluster.

Networked (t-of-n)

# Node 0
mpcd start --node-id node0 --listen :9999 --api :9800 \
    --data /data/node0 --threshold 2 \
    --peer [email protected]:9999 --peer [email protected]:9999

# Node 1
mpcd start --node-id node1 --listen :9999 --api :9800 \
    --data /data/node1 --threshold 2 \
    --peer [email protected]:9999 --peer [email protected]:9999

# Node 2 — same pattern

The daemon expects the cluster size n = len(peers) + 1 and rejects start when threshold > n. See pkg/transport/registry.go::HasSigningQuorum for the quorum arithmetic.

Smoke test

go test -tags=integration ./cmd/mpcd/... -count=1 -timeout 90s

standalone_test.go builds mpcd, runs it with --threshold 1 on free ports and a fresh data directory, polls /healthz until quorum holds, and asserts the response shape. It does not exercise keygen — see e2e/ for that.