dev.preflight

Check whether a shell command is runnable before you (or an agent) run it — a pre-execution gate. POST { command } with a command that targets the network (curl, wget, httpie, or anything carrying a URL). Parses out the HTTP method, target URL, and headers, then returns a structured verdict: verdict ('runnable' or 'invalid'), a runnable boolean, and a checks breakdown (hasTarget, urlValid, schemeOk, hostPresent, methodValid, privateTarget). By default the check is STATIC and deterministic — no network call — answering 'is there a well-formed http(s) target and a valid method?' (a command with no URL is invalid). Pass probe=true to also run a guarded HEAD request against the target and report dnsResolves, reachable, tlsValid, and httpStatus — answering 'would this actually connect right now?'. Private/loopback/reserved targets are refused (SSRF-safe). Built for gating agent-generated commands and CI pipelines.

price
$0.0010 USDC per call
method
POST/api/dev/preflight
payment
x402 v2 · USDC on Base (EIP-3009) or Solana (SPL transfer)
auth
None. Sign the payment, retry with PAYMENT-SIGNATURE.
tier
Tier 0 — no paid upstream

Parameters

NameTypeDescription
commandrequiredstring
min 1 chars · max 8192 chars
probeboolean

Code samples

cURLbash
# 1. Probe the endpoint with no auth — receive 402 with PaymentRequirements
curl -sS -X POST 'https://2s.io/api/dev/preflight' \
  -H 'Content-Type: application/json' \
  -d '{"command":"example","probe":false}'

# 2. Sign the EIP-3009 transferWithAuthorization for the advertised price +
#    payTo from the 402 envelope, then retry with PAYMENT-SIGNATURE:
curl -sS -X POST 'https://2s.io/api/dev/preflight' \
  -H 'Content-Type: application/json' \
  -H 'PAYMENT-SIGNATURE: <base64-json-payload>' \
  -d '{"command":"example","probe":false}'

# Or just use the canonical runner — it handles the whole loop:
#   EVM_PRIVATE_KEY=0x... node --env-file=.env.local \
#     --experimental-strip-types scripts/x402-pay.ts \
#     'https://2s.io/api/dev/preflight'
TypeScript / Node — @2sio/sdktypescript
import { TwoS } from '@2sio/sdk'

const client = new TwoS({
  privateKey: process.env.EVM_PRIVATE_KEY as `0x${string}`,
})

const result = await client.dev.preflight({
  "command": "example",
  "probe": false
})

console.log('endpoint:', result.endpoint)
console.log('cost:', result.costUsd, 'USDC')
console.log('tx:', result.settlement?.txHash)
console.log('data:', result.data)
Python — 2siopython
import os
from twosio import TwoS

client = TwoS(private_key=os.environ["EVM_PRIVATE_KEY"])

result = client.dev.preflight(command="example", probe=False)

print("endpoint:", result.endpoint)
print("cost:", result.cost_usd, "USDC")
print("tx:", (result.settlement or {}).get("tx_hash"))
print("data:", result.data)
MCP — Claude Desktop / AgentKit / any MCP hostjson
// 1. Add @2sio/mcp to your MCP host config (Claude Desktop example below).
//    EVM_PRIVATE_KEY funds x402 payments per call.

// claude_desktop_config.json
{
  "mcpServers": {
    "2sio": {
      "command": "npx",
      "args": ["-y", "@2sio/mcp"],
      "env": { "EVM_PRIVATE_KEY": "0x..." }
    }
  }
}

// 2. Once the server is running, agents call this tool via standard MCP:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "dev.preflight",
    "arguments": {
      "command": "example",
      "probe": false
    }
  }
}

Response

FieldTypeDescription
okboolean
one of: true
itemsarray
totalintegerTotal matching rows upstream; null when unknown.
sourceobject
Example response datajson
{
  "ok": true,
  "items": [
    {
      "command": "example",
      "tool": "example",
      "method": "example",
      "url": "example",
      "targets": [
        "example"
      ],
      "verdict": "example",
      "runnable": false,
      "mode": "example",
      "reason": "example",
      "checks": {
        "hasTarget": false,
        "urlValid": false,
        "schemeOk": false,
        "hostPresent": false,
        "methodValid": false,
        "privateTarget": false,
        "dnsResolves": false,
        "reachable": false,
        "tlsValid": false,
        "httpStatus": 1
      },
      "note": "example"
    }
  ],
  "total": 1,
  "source": {
    "provider": "example",
    "url": "example",
    "license": "example"
  }
}

Discovery

2s.io is x402-native. Every call is paid per-request from a USDC-funded EVM wallet on Base — no signup, no API keys, no monthly fees. Source code: github.com/2s-io/sdk.