Propose, vote, veto, and quorum semantics for multi-agent systems.

A September 2026 analysis of every major agent interoperability protocol -- MCP, A2A, ACP, ANP, ERC-8004 -- found that voting and dissent preservation are universally absent. Agora is a reference implementation of exactly those missing primitives.

agora answers one question: how do a group of agents jointly decide, dissent, and record why -- without a new protocol?

$ npm install agora-protocol

GitHub npm

A veto beats a unanimous yes

Ties resolve to "rejected". A veto short-circuits the round regardless of the vote tally. Resolution is idempotent -- calling evaluate() again after resolution returns the same Resolution.

A veto reason is mandatory: an unexplained veto isn't auditable.

src/round.ts

import { Round } from "agora-protocol";

const round = Round.propose({
  id: "delete-prod-bucket",
  proposerId: "cleanup-agent",
  voters: ["cleanup-agent", "ops-agent"],
  vetoers: ["safety-agent"],
  quorum: { type: "count", value: 2 },
});

round.castVote({ agentId: "cleanup-agent", choice: "yes" });
round.castVeto({ agentId: "safety-agent", reason: "no confirmed backup" });

round.evaluate();
// { outcome: "vetoed", ... } -- unanimous "yes" still loses

Propose, vote or veto, resolve

Round.propose

Round.propose({ id, proposerId, voters, quorum })

Constructs a new pending round. Throws if voters are empty or quorum is unreachable.

castVote / castVeto

round.castVote({ agentId, choice }) / castVeto({ agentId, reason })

evaluate

round.evaluate(now?)

Resolves if veto, timeout, or quorum applies -- checked in that order. Idempotent once resolved.

Why this exists

Every major agent interoperability protocol handles messaging and tool calls -- none define a quorum primitive, a preference-aggregation rule, or a way to record that a proposal was rejected and why. Every team currently hand-rolls this logic, differently, inside their own orchestration code.

Agora is a small, dependency-free state machine for propose → vote/veto → resolve, plus reference adapters for MCP and A2A.

round: delete-prod-bucket

cleanup-agent yes · ops-agent yes

safety-agent VETO: "no confirmed backup"

evaluate() → outcome: vetoed

unanimous "yes" still loses to one veto

What agora doesn't do

Not Byzantine-fault-tolerant.
Assumes agents are identified and not actively malicious -- see Raft/PBFT for adversarial consensus.
No transport, no network layer.
It's a library; adapters shape data for the MCP/A2A messaging you already have.
No durable cross-round dissent log yet.
A Resolution carries its tally/veto reason; a permanent log is a planned follow-up.

Give your agents a way to disagree, on the record

Free and open source under the MIT license.

$ npm install agora-protocol

GitHub npm