Quorum

Attested multi-agent consensus with a shared blackboard — an MCP server.

An orchestrator opens a proposal, participating agents write context to a shared blackboard and vote with reasoning, Quorum applies a principled aggregation algorithm from the social choice literature, and every step — proposal, writes, votes, outcome — is attested via Stamp and traced to Telinea. The record is immutable, tamper-evident, and independently verifiable.

Hosted endpoint (no sign-in, public): https://quorum-mcp.terradev.cloud/mcp

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Why

Majority vote among LLM agents fails on disputed questions because agents trained on overlapping data share systematic blind spots — they are not the independent voters the Condorcet Jury Theorem requires. And when agents do decide together, the decision process — who voted, what they said, what context they worked from — is invisible.

Quorum is the complete primitive: algorithm plus state plus provenance.

Tools

• register — one-time account setup: bind your api_key (a Quorum key you choose) to your telinea_key. The Telinea key is stored encrypted under a key derived from your Quorum key (AES-256-GCM, HKDF) — the Quorum key itself is never stored. Every span for your proposals is then pushed with your Telinea key, standard OTLP bearer auth.

• propose — open a proposal: name (becomes the proposal id), question, voters (expected identities), deadline_minutes. Optional: api_key (from register — binds the proposal to your Telinea account for span streaming; omit for anonymous use), namespace (tenant prefix — the id becomes ns:name, so different teams can reuse names without colliding), options (default ["yes","no"]), algorithm (default approval), quorum (min % of voters, default 100), threshold (supermajority share, default 66.67), description. Returns the proposal id, creation attestation id, deadline, and blackboard URI.

• write — append key/value to the proposal's blackboard, with optional author. Writes are appended, never replaced — the full ordered history is preserved and attested.

• read — read the blackboard: every write in order with timestamp, author, and attestation id. Optional key filter. The deliberation record before voting.

• vote — submit a ballot from an expected voter identity, with optional reasoning (stored in the attested record, never affects the outcome). Ballot shape depends on the algorithm — see below. Duplicate votes and post-deadline votes are rejected with structured errors.

• resolve — apply the algorithm and attest the outcome. Callable once quorum is met (or after the deadline); also fires automatically when the deadline passes with quorum. Idempotent. Condorcet cycles and missed supermajority thresholds return co_winners with status unresolved — genuine ambiguity is surfaced, never hidden.

• history — the complete attested record: creation, every write, every vote with reasoning, the outcome. Optional filter: all | writes | votes | outcome. The compliance artifact.

Algorithms

Algorithm	Ballot	Use when
plurality	option string	Binary decisions only
approval	option or list of options	Default. No strategic incentive; weak/multiple preferences
borda	ranking of all options	3–5 options; surfaces the broadly-acceptable choice
condorcet	ranking or single option	Rational preference aggregation; cycles returned as co_winners
opinion_pool	{option: probability} summing to 1	Genuine probabilistic beliefs; returns full distribution
supermajority	option string	High-stakes decisions needing >50% (set threshold)

The blackboard

LLM consensus failures are often information failures, not algorithm failures — agents vote in isolation. The blackboard is shared working memory scoped to one proposal: agents write analysis, read each other's findings, then vote informed. Write-first, read-second ordering and immutable pre-deadline votes are the conformity-bias defenses.

Tracing

Every proposal is one Telinea trace. The root span (proposal) opens at propose and closes at resolve or deadline expiry — its duration is the deliberation time. Each write, vote, and the resolution is a child span emitted in real time with its Stamp attestation id. Root status: OK decided, UNRESOLVED ambiguous, ERROR expired without quorum.

Span ids are deterministic (uuid5 over proposal id + event seq), so replays and restarts stay idempotent. Push is fire-and-forget and fail-safe — telemetry can never break a vote.

Auth is per-account: spans are pushed with the Telinea key registered via register, so ingest attributes them to the correct account. The key is stored encrypted (AES-256-GCM under HKDF of your Quorum key — never stored); a proposal-scoped re-encryption under the server-held QUORUM_DATA_KEY lets spans authenticate after restarts without re-presenting the Quorum key. A database dump exposes only ciphertext.

Config: TELINEA_INGEST_URL (default https://ingest.terradev.cloud/v1/traces), TELINEA_WORKSPACE_ID, TELINEA_PROJECT_ID, TELINEA_DISABLED=1, QUORUM_DATA_KEY, QUORUM_ACCOUNTS (account store path, default ~/.quorum/accounts.json).

HTTP transport

Endpoint	Method	Description
/mcp	POST	JSON-RPC 2.0 — single or batch; notifications → 202
/mcp	GET	SSE keep-alive channel
/	GET/POST	Service identity / MCP alias
/health	GET	{"status":"ok"}
/v1/info	GET	Self-describing service info (tools, auth, spans, docs)
/.well-known/agent.json	GET	Agent card
/.well-known/oauth-protected-resource	GET	RFC 9728 — public, no auth

Concurrency capped at 100 simultaneous POST /mcp via asyncio.Semaphore.

Rate limiting is per-proposal: write and vote are capped at QUORUM_PROPOSAL_RATE events/min per proposal id (default 120), so one hot proposal can't starve the rest. The edge per-IP zone in Caddy is a coarse backstop only.

Attestation is queued and coalesced: concurrent events share one NTP sample per drain batch instead of one query per event — each event still gets its own Stamp record (unique id, own payload hash), so throughput isn't bound by NTP round-trips.

State

Event-sourced: one append-only JSONL file per proposal under ~/.quorum/proposals (override QUORUM_DATA_DIR). Namespaced proposals live in per-namespace subdirectories (proposals/<ns>/<name>.jsonl). The log is the history — history is a filtered read of the same file the tools append to. Nothing is rewritten or deleted.

Self-hosting

git clone https://github.com/theoddden/quorum-mcp.git
cd quorum-mcp
docker compose up -d --build

Caddy handles TLS once DNS points at the host. See deploy/Caddyfile.

License

Copyright 2026 theoddden. Licensed under the Apache License, Version 2.0.