ACP — Agent Connection Protocol

The transport layer for autonomous AI agents.

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What is ACP?

ACP (Agent Connection Protocol) is an open standard for agent-to-agent and agent-to-service communication.

AI agents cannot talk to each other in any standardized way. Every platform defines its own connection model. Every integration requires custom code. There is no universal "send this message to that agent" primitive.

ACP solves this with a minimal, transport-agnostic message envelope and handshake protocol that any agent runtime can implement in an afternoon.

No ACP:   Agent A ──(custom)──► Service X
          Agent A ──(custom)──► Agent B
          Agent A ──(custom)──► Service Y

With ACP: Agent A ──[acp envelope]──► anyone

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The Stack

ACP is one layer of a three-layer agent trust and interoperability stack:

AgentAudit  →  Is this agent safe?           (security)
agAuth      →  Is this agent who it claims?  (identity)
ACP         →  How do agents talk?           (transport)  ← this repo

Layer	Repo
Security	AgentAudit
Identity	agauth
Transport	ACP (this repo)

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Core Concepts

Concept	Description
ACP Envelope	Standard message wrapper all ACP messages use
Agent Address	Routable identifier — agID or namespace address
ACP Manifest	acp.json file declaring an agent's connection capabilities
Capability	A declared action an agent can accept and respond to
Direct Connection	Agent-to-agent without a broker
Broker	Optional intermediary router (not required)

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Minimal Envelope

{
  "spec":         "acp/0.1",
  "id":           "msg-uuid-here",
  "from":         "ag-4f8a2c1b-000001-9e3d",
  "to":           "ag-7b3c9d2e-000042-ff1a",
  "timestamp":    "2026-02-12T00:00:00Z",
  "payload_type": "acp:invoke",
  "payload":      { },
  "auth":         "agtoken_here"
}

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Specification

• Full Specification →
• ACP Envelope Schema →
• ACP Manifest Schema →
• Payload Types →

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Reference Implementation

The canonical reference implementation is the DeltaZero MCP stack by Fabricated Industries LLC.

First ACP manifest in production: Architect-SIS/sis-skill

• agID: ag-4f8a2c1b-000001-9e3d
• Framework: BCOL / DeltaZero — ΣΔ = 0

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Implementations

Package	agID	Transport	Status
sis-skill	ag-4f8a2c1b-000001-9e3d	MCP, HTTP	✅ Genesis

Building an ACP implementation? Open a PR to add it here.

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Contributing

See CONTRIBUTING.md.

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License

MIT License — Copyright 2026 Fabricated Industries LLC (ThēÆrchītēcť)

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ACP — Agent Connection Protocol — Draft v0.1 https://github.com/Architect-SIS/acp