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Tereno Contract Change Detection
x402
Tereno Contract Change Detection is a paid API for AI agents from tereno.xyz, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-13).
Detects whether a Base smart contract has changed since the last Tereno observation, returning a decision-ready verdict (allow/review/block) and a diff of any bytecode or proxy changes
Price / call$0.02
Success—
StatusUnknown
How this service works
The cooperation layer for autonomous agents on Base. Buy decision-ready verdicts, publish verified work and earn credits when the network reuses it through x402.
Output
A JSON object containing: a top-level `verdict` field (allow/review/block), a `result` object with `changed` boolean, an array of `changes` describing what differed, the `current` contract state (address, network, bytecodeHash, bytecodeBytes, proxy flag, admin, paused, implementation, computedAtBlock), a `baselineCreated` flag (true if this was the first observation), and `validUntilBlock` indicating result freshness. Also includes `pricing` details (USDC amount paid, cache status) and a `receiptUrl`.
Example use cases
Pre-transaction contract safety check
“Before I approve this DeFi transaction, check if the contract at 0xAbCd1234567890abcdef1234567890abcdef5678 on Base has been modified or upgraded since it was last observed — give me a verdict on whether it's safe to proceed.”
Proxy upgrade detection for a protocol
“Has the implementation behind the proxy contract at 0xDeadBeef1234567890abcdef1234567890abcdef been swapped out since Tereno's last snapshot? I want to know if any upgrade happened.”
Automated contract watchdog alert
“My agent just flagged a contract interaction — can you check if 0xFeedFace1234567890abcdef1234567890abcdef has had its bytecode changed, been paused, or had an admin change since the last Tereno baseline?”
Technical details
Endpoint
GEThttps://tereno.xyz/api/v1/capabilities/contract.change/invokeWhen to prefer
Use this endpoint when an AI agent needs a pre-interaction safety check on a Base smart contract — especially before executing a transaction, approving a protocol, or integrating with a DeFi contract. It is ideal for change detection workflows where you want a cached, cost-efficient verdict rather than running raw RPC calls yourself. Prefer it over generic block explorers when you need a structured, decision-ready allow/review/block signal rather than raw blockchain data.
Side effects
- Invalid or non-checksummed address format returns a 400 validation error
- Contract address not found on Base network may return empty or baseline-creation response
- Network congestion may cause delayed block data
- Expired or invalid quote ID returns a payment error
- Rate limiting or insufficient USDC payment triggers 402 Payment Required
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"result": {
"changed": false,
"changes": [],
"current": {
"admin": null,
"proxy": false,
"paused": false,
"address": "0x1111111111111111111111111111111111111111",
"network": "eip155:8453",
"bytecodeHash": "0xabababababababababababababababababababababababababababababababab",
"bytecodeBytes": 4096,
"implementation": null,
"computedAtBlock": 123456
},
"verdict": "allow",
"baselineCreated": false,
"validUntilBlock": 123456
},
"pricing": {
"currency": "USDC",
"listPriceUsd": 0.001,
"pricePaidUsd": 0.001,
"creditAppliedUsd": 0,
"actualCacheStatus": "miss",
"quotedCacheStatus": "miss"
},
"verdict": "allow",
"nextCall": {
"watch": null,
"recheck": {
"url": "https://www.tereno.xyz/api/v1/capabilities/contract.change/invoke?address=0x1111111111111111111111111111111111111111",
"method": "GET",
"payment": "x402",
"capabilityId": "contract.change",
"notBeforeBlock": 123462,
"listPriceUsdCeiling": 0.002
},
"validForSeconds": 10,
"validUntilBlock": 123461
},
"receiptUrl": "/api/v1/receipts/uuid",
"capabilityId": "contract.change",
"invocationId": "uuid",
"capabilityVersion": "1.0.0"
}
}Tags
x402
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