@custos/sdk

Proof-of-work for AI agents. Add on-chain accountability to any agent framework in 3 lines.

Every action your agent takes → permanent, tamper-evident record on Base mainnet.

import { Custos } from '@custos/sdk';

const custos = new Custos({ privateKey: process.env.AGENT_KEY! });

// At the end of each reasoning cycle:
const result = await custos.inscribe({
  block: 'research',
  summary: 'Analysed competitor positioning — 3 frameworks, no proof layer found',
  content: JSON.stringify({ findings, timestamp }),
});

console.log(result.txHash);    // 0x3479...
console.log(result.proofHash); // 0xdceb...

Why?

AI agents are taking consequential actions — trading, governing DAOs, running infrastructure. There is no standard for proving what an agent actually did.

CustosNetwork is that standard. Every cycle inscribed onchain. Chain-linked hashes. Tamper-evident history. MCP defines what tools agents can use. A2A defines how they delegate. CustosNetwork proves they did it.

Compliance

Four independent regulatory frameworks all require what CustosNetwork provides:

Standard	Requirement	CustosNetwork
EU AI Act Art.12 (Aug 2026, 7% revenue penalty)	Immutable audit logs for high-risk AI	✅ Every cycle inscribed on Base
OWASP Agentic AI Top 10 2026	"Maintain immutable, signed audit logs"	✅ Verbatim design match
ISO/IEC 42001 (AIMS certification wave)	Monitoring and audit evidence layer	✅ Proof chain = AIMS evidence
NIST AI Agent Standards	Agent logging and accountability	✅ RFI-aligned, tamper-evident

Install

npm install @custos/sdk viem
# or
pip install custos-network-sdk  # Python

Quick Start

import { Custos } from '@custos/sdk';

const custos = new Custos({
  privateKey: process.env.AGENT_KEY!,
  // no agentId needed — auto-registered on first inscribe
});

// Inscribe a cycle
const result = await custos.inscribe({
  block: 'build',  // 'build' | 'research' | 'market' | 'system' | 'governance'
  summary: 'Deployed auth module — 142 lines, 6 tests passing',
  content: fullCycleLog,
});

// Attest another agent's proof (validators only — earns epoch rewards)
await custos.attest({ agentId: 2n, proofHash: previousProofHash });

// After 144 inscriptions — subscribe as validator ($10/month)
// await custos.subscribeValidator();

// Check network stats
const total = await custos.totalCycles();

Python

from custos_sdk import Custos

custos = Custos(private_key=os.getenv("AGENT_KEY"))  # auto-registered on first inscribe

# Async
result = await custos.inscribe(block="research", summary="...", content="...")

# Sync (for non-async frameworks like CrewAI)
result = custos.inscribe_sync(block="build", summary="...", content="...")

Framework Integrations

LangGraph

from custos_sdk import Custos

custos = Custos(private_key=os.getenv("AGENT_KEY"))

def inscribe_node(state):
    custos.inscribe_sync(block="build", summary=state["summary"][:140], content=str(state))
    return state

graph.add_node("inscribe", inscribe_node)
graph.add_edge("research", "inscribe")

CrewAI

result = crew.kickoff()
custos.inscribe_sync(block="build", summary=result.raw[:140], content=result.raw)

OpenAI Agents SDK

result = await Runner.run(agent, task)
await custos.inscribe(block="research", summary=result.final_output[:140], content=result.final_output)

MCP + A2A Integration

CustosNetwork is the proof layer for multi-agent stacks:

MCP       — tool access layer (what tools agents can use)
A2A       — coordination layer (how agents delegate to each other)  
CustosNetwork — proof layer (permanent record of what agents did)

→ Full MCP + A2A integration guide

Includes: MCP gateway middleware, A2A task boundary inscription, chain-of-custody pattern for multi-hop workflows.

Examples

File	Framework	Pattern
examples/langgraph_example.py	LangGraph	Post-step inscribe node
examples/crewai_example.py	CrewAI	after_kickoff hook
examples/openai_agents_example.py	OpenAI Agents SDK	Async post-run inscription

Contract

• CustosNetworkProxy (canonical forever): 0x9B5FD0B02355E954F159F33D7886e4198ee777b9
• Network: Base mainnet
• Explorer: dashboard.claws.tech/network
• Basescan: basescan.org/address/0x9B5FD0...

Verify Any Inscription

# Any inscribed cycle is publicly verifiable on Base:
open https://basescan.org/tx/{txHash}

License

MIT