aegis-buy 0.1.0

Trust-gated x402 buyer client — pay for machine-economy APIs safely (pre-payment trust gate, local spend policy, receipts ledger). Powered by Aegis (aegis.borisinc.com).

aegis-buy

Trust-gated buyer client for the x402 machine economy. Your agent wants to pay APIs with USDC over HTTP 402 — this package makes sure it never pays the wrong service, the wrong amount, or more than you allowed.

Powered by Aegis, the trusted agent-commerce hub.

probe (free) -> parse price -> Aegis trust gate -> local spend policy -> pay -> receipt

Every step before "pay" is free and local. Nothing settles unless the service passes the trust gate and your policy caps.

Install

pip install aegis-buy            # library
pip install 'aegis-buy[mcp]'     # + MCP server (aegis-buy-mcp)

Quickstart

from aegis_buy import BuyClient

client = BuyClient()  # key from AEGIS_BUY_KEY env
r = client.get("https://api.example.com/price?symbol=ETH")
print(r["ok"], r["price_usd"], r["data"])

# Don't know a provider? Let the hub find a trusted one within budget:
r = client.procure("live ETH price", budget=0.01)

# Test everything without spending a cent:
client = BuyClient(dry_run=True)

Environment variables

Var	Meaning	Default
AEGIS_BUY_KEY	EVM private key of the buyer wallet (funds USDC on Base)	—
AEGIS_BUY_POLICY	Path to spend policy JSON	~/.aegis-buy/policy.json
AEGIS_BUY_LEDGER	Path to sqlite receipts ledger	~/.aegis-buy/ledger.db
AEGIS_HUB	Aegis hub base URL	https://aegis.borisinc.com
AEGIS_BUY_DRY_RUN	1 = MCP server never actually pays	off

Spend policy (~/.aegis-buy/policy.json)

{
  "max_per_call_usd": 0.05,
  "max_per_day_usd": 1.00,
  "max_total_usd": 10.00,
  "min_tier": "provisional",
  "allow_domains": [],
  "deny_domains": ["sketchy.example"],
  "trust_mode": "basic"
}

• max_per_call_usd / max_per_day_usd / max_total_usd — hard USD caps. Day and total spend are computed from the local ledger.
• min_tier — minimum Aegis trust tier: unverified < provisional < trusted. Services flagged by Aegis are always blocked.
• allow_domains / deny_domains — domain allow/deny lists (subdomains match).
• trust_mode — basic (free Aegis signals), strict (paid $0.002 verification-backed trust check per service, itself policy-capped), or off.

Missing file = safe defaults (5¢/call, $1/day, provisional+, basic gate).

MCP server

Give Claude Desktop (or any MCP client) a safe x402 wallet:

{
  "mcpServers": {
    "aegis-buy": {
      "command": "aegis-buy-mcp",
      "env": {
        "AEGIS_BUY_KEY": "0xYOUR_BUYER_WALLET_PRIVATE_KEY",
        "AEGIS_BUY_POLICY": "~/.aegis-buy/policy.json"
      }
    }
  }
}

Tools: buy_get(url, params_json) · procure(need, budget) · trust_gate(url) · spend_stats().

Safety model

1. Local spend policy — per-call, per-day, and lifetime USD caps enforced before any payment; domain allow/deny lists. The wallet's downside is bounded by config.
2. Pre-payment trust gate — services are checked against Aegis's continuously verified registry before money moves. Unknown services default to unverified; flagged services are always blocked.
3. Receipts ledger — every attempt (paid, blocked, failed, dry-run) lands in a local sqlite ledger; caps are computed from it, so they survive restarts.
4. No blind buys — if the price can't be parsed from the 402 challenge, the purchase is refused.
5. Delivery protection via Aegis — routes purchased through the hub use auth-then-capture: your payment only settles after the upstream actually delivers, so you are never charged for non-delivery.

Use a dedicated buyer wallet funded with only what you're willing to spend — defense in depth on top of the policy caps.

Links

• Hub: https://aegis.borisinc.com — free discovery: GET /discover?query=...
• x402 protocol: HTTP 402 + USDC on Base (eip155:8453)

MIT license.

LangChain

from aegis_buy.langchain_adapter import get_tools
tools = get_tools()  # buy_get, procure, trust_gate, spend_stats