{ "x402Version": 2, "id": 3143, "slug": "3143", "resource": "https://txguard.schemasure.com/v1/tx/preflight", "description": "Explain and preflight an unsigned Base transaction, EIP-712 typed data, or an EIP-3009 x402 payment authorization before you sign it. Decodes intent against verified ABIs, resolves proxies, classifies approvals, and checks a payment authorization against the quote it claims to pay: recipient, amount, asset, chain, freshness, and nonce replay. Returns unknown rather than guessing when a selector is ambiguous. Not a guarantee that a transaction is safe or profitable.", "type": "http", "accepts": [ { "scheme": "exact", "network": "eip155:8453", "payTo": "0x9876af0F6D8Ed5155Cd02d1ca56D128601612690", "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "amount": "10000", "maxTimeoutSeconds": 60 } ], "outputSchema": { "bazaar": { "info": { "input": { "body": { "expected_quote": { "amount": "10000", "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "extra": { "name": "USD Coin", "version": "2" }, "maxTimeoutSeconds": 60, "network": "eip155:8453", "payTo": "0x1a2B3c4D5E6F7a8B9c0D1e2F3A4b5C6d7E8F9a0b", "scheme": "exact" }, "unsigned_tx": { "data": "0xa9059cbb0000000000000000000000005d3e1a9b7c2f4e8a0b6d3c5f9e1a7b4d2c8f0a6e0000000000000000000000000000000000000000000000000000000000002710", "from": "0x9F2C5E4A8db1C3a7E6B0d4f8C1E2a5b7D9C0e3F4", "to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "value": "0" } }, "bodyType": "json", "method": "POST", "type": "http" }, "output": { "example": { "confidence": 1, "data_versions": { "abi_packs": "2026-08-03.1", "chain": "eip155:8453", "denylist": "2026-08-03.1", "policy": "2026-08-03", "signature_index": "2026-08-03.1" }, "evidence": [ { "code": "RECIPIENT_MISMATCH", "data": { "actual": "0x5D3e1a9b7c2f4E8A0b6d3c5F9E1A7b4D2C8f0a6E", "expected": "0x1a2B3c4D5E6F7a8B9c0D1e2F3A4b5C6d7E8F9a0b", "field": "payTo" }, "detail": "Pays 0x5D3e1a9b7c2f4E8A0b6d3c5F9E1A7b4D2C8f0a6E, but the quote names 0x1a2B3c4D5E6F7a8B9c0D1e2F3A4b5C6d7E8F9a0b. Signing this pays someone other than the party you are buying from.", "severity": "critical", "source": "quote-comparison" }, { "code": "RPC_UNAVAILABLE", "detail": "No Base RPC endpoint is configured, so chain-dependent fields are unknown rather than assumed. See result.unresolved.", "severity": "medium", "source": "rpc" } ], "ok": true, "policy_version": "2026-08-03", "request_hash": "sha256:6d5c717eb5eede165dada2645ad0944430ff492739cf58d0c2dad2b812f0ddb4", "result": { "approvals": [], "authorization_checks": [], "candidate_signatures": [], "chain": "eip155:8453", "denylist_hits": [], "expected_transfers": [ { "amount": "10000", "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "asset_kind": "erc20", "from": "0x9f2C5E4a8DB1C3A7e6b0d4f8C1e2A5b7d9c0E3f4", "source": "decode", "to": "0x5D3e1a9b7c2f4E8A0b6d3c5F9E1A7b4D2C8f0a6E", "token_id": null } ], "input_shape": "unsigned_tx", "intent": { "args": [ { "name": "to", "type": "address", "value": "0x5D3e1a9b7c2f4E8A0b6d3c5F9E1A7b4D2C8f0a6E" }, { "name": "amount", "type": "uint256", "value": "10000" } ], "calls": [], "decode_source": "bundled-abi", "depth": 0, "function_name": "transfer", "kind": "erc20_transfer", "selector": "0xa9059cbb", "signature": "transfer(address,uint256)", "standard": "erc20", "summary": "Transfer 10000 base units of token 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 to 0x5D3e1a9b7c2f4E8A0b6d3c5F9E1A7b4D2C8f0a6E.", "target": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "truncated": false, "value_wei": "0" }, "permit_scope": null, "proxy": { "address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "admin": null, "beacon": null, "detail": "no RPC endpoint is configured, so no slot could be read", "implementation": null, "kind": "unknown", "slots_probed": [], "upgradeable": null }, "quote_comparison": { "detail": "2 of 3 comparable fields match", "fields": [ { "actual": "0x5D3e1a9b7c2f4E8A0b6d3c5F9E1A7b4D2C8f0a6E", "expected": "0x1a2B3c4D5E6F7a8B9c0D1e2F3A4b5C6d7E8F9a0b", "field": "payTo", "matches": false }, { "actual": "10000", "expected": "10000", "field": "amount", "matches": true }, { "actual": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "expected": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "field": "asset", "matches": true }, { "actual": null, "expected": "8453", "field": "chainId", "matches": null }, { "actual": null, "expected": "USD Coin", "field": "extra.name", "matches": null }, { "actual": null, "expected": "2", "field": "extra.version", "matches": null } ], "matches": false, "present": true }, "rpc": { "configured": false, "endpoints": [], "reachable": null }, "simulation": { "asset_changes": [], "block_number": null, "detail": "simulation was not requested; send simulate: true to run one", "gas_used": null, "requested": false, "status": "not_requested" }, "spender": { "address": null, "detail": "this transaction grants no allowance, so it has no spender", "is_contract": null }, "unresolved": [ "proxy status of 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 is unknown: no RPC endpoint is configured, so no slot could be read" ] }, "risk_codes": [ "RECIPIENT_MISMATCH", "RPC_UNAVAILABLE" ], "verdict": "block", "warnings": [] }, "type": "json" } }, "schema": { "$schema": "https://json-schema.org/draft/2020-12/schema", "properties": { "input": { "additionalProperties": false, "properties": { "body": { "$schema": "https://json-schema.org/draft/2020-12/schema", "additionalProperties": false, "description": "Send exactly one of unsigned_tx, tx_hash, typed_data, or authorization.", "oneOf": [ { "required": [ "unsigned_tx" ] }, { "required": [ "tx_hash" ] }, { "required": [ "typed_data" ] }, { "required": [ "authorization" ] } ], "properties": { "authorization": { "additionalProperties": false, "description": "An EIP-3009 authorization, which is what an x402 `exact` payment is. value in base units, validAfter/validBefore in unix seconds, nonce 32 random bytes not a counter.", "properties": { "asset": { "pattern": "^0x[0-9a-fA-F]{40}$", "type": "string" }, "from": { "pattern": "^0x[0-9a-fA-F]{40}$", "type": "string" }, "kind": { "enum": [ "transfer", "receive" ], "type": "string" }, "nonce": { "pattern": "^0x[0-9a-fA-F]*$", "type": "string" }, "signature": { "pattern": "^0x[0-9a-fA-F]*$", "type": "string" }, "to": { "pattern": "^0x[0-9a-fA-F]{40}$", "type": "string" }, "validAfter": { "type": "string" }, "validBefore": { "type": "string" }, "value": { "type": "string" } }, "required": [ "from", "to", "value", "validAfter", "validBefore", "nonce" ], "type": "object" }, "expected_quote": { "additionalProperties": false, "description": "The x402 quote this payment claims to satisfy. Enables the comparison checks.", "properties": { "amount": { "type": "string" }, "asset": { "type": "string" }, "extra": { "type": "object" }, "maxTimeoutSeconds": { "type": "number" }, "network": { "type": "string" }, "payTo": { "type": "string" }, "scheme": { "type": "string" } }, "type": "object" }, "simulate": { "default": false, "description": "Run eth_simulateV1 with asset tracing. Priced at $0.015 instead of $0.01, and targets P50 2s / P95 5s rather than the static path's 500ms / 2s.", "type": "boolean" }, "tx_hash": { "description": "An existing Base transaction to explain.", "pattern": "^0x[0-9a-fA-F]{64}$", "type": "string" }, "typed_data": { "description": "EIP-712 payload. TransferWithAuthorization and ReceiveWithAuthorization get the x402 check table; any other primaryType is reported unrecognised, not analysed.", "properties": { "domain": { "type": "object" }, "message": { "type": "object" }, "primaryType": { "type": "string" }, "types": { "type": "object" } }, "required": [ "domain", "primaryType", "message" ], "type": "object" }, "unsigned_tx": { "additionalProperties": false, "description": "A transaction you are about to sign. `to: null` is a deployment.", "properties": { "data": { "pattern": "^0x[0-9a-fA-F]*$", "type": "string" }, "from": { "pattern": "^0x[0-9a-fA-F]{40}$", "type": "string" }, "to": { "type": [ "string", "null" ] }, "value": { "description": "Wei.", "type": "string" } }, "type": "object" } }, "title": "TxPreflightRequest", "type": "object" }, "bodyType": { "enum": [ "json", "form-data", "text" ], "type": "string" }, "method": { "enum": [ "POST" ], "type": "string" }, "type": { "const": "http", "type": "string" } }, "required": [ "type", "method", "bodyType", "body" ], "type": "object" }, "output": { "properties": { "example": { "$schema": "https://json-schema.org/draft/2020-12/schema", "properties": { "confidence": { "maximum": 1, "minimum": 0, "type": "number" }, "data_versions": { "required": [ "denylist", "abi_packs", "signature_index", "policy", "chain" ], "type": "object" }, "evidence": { "items": { "type": "object" }, "type": "array" }, "ok": { "type": "boolean" }, "policy_version": { "type": "string" }, "request_hash": { "pattern": "^sha256:[0-9a-f]{64}$", "type": "string" }, "result": { "properties": { "approvals": { "items": { "properties": { "scope": { "enum": [ "infinite", "effectively_infinite", "bounded" ], "type": "string" } }, "type": "object" }, "type": "array" }, "intent": { "properties": { "decode_source": { "enum": [ "verified-abi", "bundled-abi", "offline-index", "live-lookup", "unresolved" ], "type": "string" } }, "required": [ "kind", "summary", "decode_source", "calls", "truncated" ], "type": "object" }, "proxy": { "properties": { "kind": { "enum": [ "none", "eip1167", "eip1967", "eip1967-beacon", "eip1822", "zeppelinos", "diamond", "unknown" ], "type": "string" } }, "type": "object" } }, "required": [ "input_shape", "chain", "intent", "expected_transfers", "approvals", "permit_scope", "spender", "proxy", "authorization_checks", "quote_comparison", "simulation", "candidate_signatures", "denylist_hits", "unresolved", "rpc" ], "type": "object" }, "risk_codes": { "items": { "type": "string" }, "type": "array" }, "verdict": { "description": "Precedence: block, then unknown, then warn, then allow.", "enum": [ "allow", "warn", "block", "unknown" ], "type": "string" }, "warnings": { "items": { "type": "string" }, "type": "array" } }, "required": [ "ok", "verdict", "confidence", "risk_codes", "evidence", "result", "policy_version", "request_hash", "data_versions", "warnings" ], "title": "TxPreflightEnvelope", "type": "object" }, "type": { "type": "string" } }, "required": [ "type" ], "type": "object" } }, "required": [ "input" ], "type": "object" } } }, "tags": [ "bazaar" ], "sourceHost": "txguard.schemasure.com", "lastUpdated": "2026-09-18T07:40:55.884Z", "quality": { "calls30d": 32, "uniquePayers30d": 3, "lastCalledAt": "2026-09-18T07:40:55.618Z" }, "liveness": {}, "verified": false, "featured": false, "provider": { "host": "txguard.schemasure.com", "manifest_name": "txguard.schemasure.com", "source": "cdp-mirror", "source_manifest_url": "https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources", "submitted_at": "2026-09-18T22:00:31.484Z" } }