Synnoesis

syn (together) + noēsis (thinking) — "minds thinking together."

A signed message mesh for AI agents. Give each agent an Ed25519 identity, and they can send each other messages — on one machine over the filesystem, or across machines over an MQTT broker — with every message verified locally by the receiver against its own keyring.

The broker moves bytes. It never vouches for identity.

Built and published by Groupe Kioptix Inc.

What works today

Loop containment composes a per-process reply-rate budget with a signed hop-counter that bounds reply-chain depth across the mesh (SYN_MAX_HOPS).

Not yet: no authorization layer (a signature proves who sent a message, not that they were allowed to ask), no end-to-end encryption (signing authenticates, it does not conceal — the broker sees message bodies), and no process supervisor (running listen / agent under systemd / launchd is the operator's choice). See Roadmap.

The message contract — send by agent-id → inbox record; read the inbox tail — is the stable part. Transports underneath it may still change while the version is 0.x.

Install

pip install synnoesis                # file floor, no dependencies
pip install "synnoesis[signing]"     # + Ed25519 signing
pip install "synnoesis[mqtt]"        # + cross-machine transport (includes signing)

Python 3.10+. The bare install stays dependency-free on purpose: a single-machine mesh should never fail to build.

⚠️ Check your Python first — a too-old one fails confusingly, not loudly. On Python < 3.10, pip install synnoesis may not error at all: it can quietly resolve to the ancient 0.0.1 name-reservation placeholder (the only release permitting 3.9), which installs "successfully" and does nothing. macOS in particular still ships python3 as 3.9.x on older systems, so build the venv with an explicit python3.12 -m venv .venv and confirm with python -V once it's activated.

60 seconds: two agents, one machine

Open two shells. Give each an identity:

export PA_AGENT_ID=alice        # shell 1   ($env:PA_AGENT_ID = "alice" on PowerShell)
export PA_AGENT_ID=bob          # shell 2

Alice sends:

synnoesis send --local --to bob "hello from alice"

Bob reads:

synnoesis read --agent-id bob

That's the whole contract. No broker, no daemon, no config file.

The message arrives marked [!UNSIGNED] — you haven't generated any keys yet, and Synnoesis says so rather than pretending. Run synnoesis keygen on each side and exchange public keys (synnoesis keyring --add) to get verify=ok; the quickstart walks through it.

Across machines

Point both machines at a broker and run the receiver:

export SYN_BROKER=broker.example.net:8883
export SYN_BROKER_TLS_CA=/path/to/ca.pem
synnoesis listen

send now publishes to the broker instead of the local floor, and announces which transport it used — an auto-selected network egress is never silent. --local forces the file path; --via {auto,file,mqtt} selects explicitly, and mqtt errors rather than quietly falling back.

Full walkthrough, including key exchange: docs/quickstart.md.

Security model

The design assumption is that the broker is hostile — it is infrastructure you may not control, sitting between agents that trust each other.

What it deliberately does not do

• Signing is not encryption. Messages are authenticated, not confidential. A broker operator can read every body. Use TLS for transport confidentiality, and don't put secrets in message bodies.
• The replay bound is honest. It is "no replay older than SYN_MAX_AGE_SEC", not "replay-proof." Widening the window widens replay tolerance by exactly the same amount — that tradeoff is yours to set deliberately.
• No authorization layer. A valid signature proves who sent it, not that they were allowed to ask for it. What an agent does with a verified message is the agent's problem.
• The hop-counter is a bound, not a proof. It contains accidental loops and honest-but-injected chains, not a malicious keyholder — who can sign _hops = 0 under their own key. It is a loop/runaway guard, not an anti-abuse control. As of 0.6.1, a verified message carrying an unauthenticated _hops (a legacy signature does not cover the field) has that hop count stripped and logged rather than enforced, so the ceiling acts only on hops it can stand behind; the bound is fully closed once legacy signature acceptance is dropped.

Roadmap

Condition-gated (not version-scheduled): drop legacy signature acceptance — closing the last hop-injection surface — once no v0.5-form emitters remain on the mesh, confirmed by a dated review of emitted signature forms rather than by a release date.

Usage & compliance

Synnoesis is an orchestration layer. It routes to model providers — Anthropic's Claude and others — directly or through gateways like OpenRouter, always using your own credentials. It bundles no API keys and grants no model access of its own.

• Personal / single-user (Anthropic): a Claude subscription via the official Claude CLI is fine.
• Multi-user / commercial: use your own API key (Anthropic's Commercial Terms, or a commercial gateway such as OpenRouter) — not a personal subscription. Routing other users through personal subscription credentials violates Anthropic's terms.
• You're responsible for the terms of every provider and gateway you use — e.g. Anthropic, OpenRouter. Provider terms flow through a gateway: using Claude via OpenRouter still binds you to Anthropic's terms.
• Export & eligibility: model access is subject to each provider's geographic availability and to applicable export-control and sanctions law (U.S. export controls restricted some frontier models for foreign nationals in 2026; gateways like OpenRouter likewise forbid circumventing geo-restrictions). Ensuring you and your users are eligible is your responsibility. Synnoesis is model-agnostic and guarantees no specific model's availability.
• Data path: prompts and outputs routed through a gateway pass through that gateway and the downstream provider, each with its own retention and privacy terms. Keep gateway prompt-logging off for sensitive data.

Bottom line: use Synnoesis commercially all you like — just bring your own keys, so you stay compliant and protected.

License

Released under the Apache License 2.0 — free to use, modify, and distribute, including commercially. See LICENSE.

Trademarks

"Kioptix", "Synnoesis", and associated logos are trademarks of Groupe Kioptix Inc. and are not licensed under Apache 2.0 (see §6). Use the software freely; please don't use the names or logos to brand your own product or imply endorsement.