SQL execution certificate firewall

Review a SQL statement an agent is about to run against production, and certify it. Returns a policy verdict (pass / warn / block) with named risks - unbounded UPDATE or DELETE, tautological WHERE, DROP, TRUNCATE, DROP COLUMN, statement stacking, COPY ... FROM PROGRAM, GRANT/role changes, session_replication_role and trigger/constraint bypass, writes to pg_catalog - and, when the verdict is pass, an Ed25519 certificate binding that verdict to the SHA-256 of the exact statement. Your database layer verifies the certificate with sql-cert-verify before executing, so the check cannot be skipped by a confused or compromised agent. Literals and comments are scrubbed before analysis, so a keyword inside a string is never a false alarm. HONEST SCOPE: a lexical guard over a fixed, published risk catalogue - it catches the shapes that destroy production data, it is not a SQL parser and cannot know that a WHERE clause names the wrong tenant.

Input

Field	Type	Description
sql *	string	the exact statement you are about to execute
allow	array	risk ids to downgrade from block to warn (see riskCatalogue in the response)
allowMultiStatement	boolean	permit more than one statement in the submission (default false)
ttlSeconds	number	certificate lifetime, 30-3600 (default 300)

Example output

{
  "verdict": "pass",
  "mutating": true,
  "statementCount": 1,
  "sha256": "635cf20a…",
  "risks": [],
  "certificate": {
    "token": "eyJ2Ijox….signature",
    "expiresAt": "2026-07-28T20:05:00Z"
  }
}

Try it - see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/sql-guard \
  -H "Content-Type: application/json" \
  -d '{"sql":"UPDATE users SET plan = 'pro' WHERE id = 42"}'

The response is HTTP 402 Payment Required with exact payment requirements. Any x402 v2 client pays automatically and retries:

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/sql-guard", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "sql": "UPDATE users SET plan = 'pro' WHERE id = 42"
  }),
});

No wallet? Pay with compute

This is a pure-CPU tool, so an agent without a wallet can pay with proof-of-work instead of USDC: fetch a challenge, solve the sha256 puzzle (16 leading zero bits - a fraction of a second of CPU, no money, no AI tokens), and resend with the X-Pow-Solution header.

import { createHash } from "node:crypto";
const lz = (b) => { let t = 0; for (const x of b) { if (!x) { t += 8; continue; } t += Math.clz32(x) - 24; break; } return t; };
const c = await (await fetch("https://agent402.tools/api/pow/challenge?slug=sql-guard")).json();
let n = 0;
while (lz(createHash("sha256").update(c.challenge + ":" + n).digest()) < c.difficulty) n++;
await fetch("https://agent402.tools/api/sql-guard", { method: "POST", headers: { "X-Pow-Solution": c.token + ":" + n, "Content-Type": "application/json" }, body: JSON.stringify({"sql":"UPDATE users SET plan = 'pro' WHERE id = 42"}) });

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