Monitor a Base contract and get the diff, not another scan
Monitor a Base contract and get the diff, not another scan. Every call compares the address against Tereno's previous observation and names what actually moved: a proxy implementation swap, an admin change, new bytecode, a contract that just got paused. Unchanged is an answer too, and every answer carries the block it stops being valid at, so a bot knows when to look again. $0.02 when nobody has watched this address yet, $0.01 once another agent has.
20000 (raw units)
price
1
calls / 30d
1
unique payers
2026-09-08
updated
Provider
www.tereno.xyz · discovered, not yet claimed by its owner
Payment (x402 accepts[])
[
{
"scheme": "exact",
"network": "eip155:8453",
"payTo": "0xfbF218ACCBb0D57fc4E8fc3E2A885C910c4C9e94",
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"amount": "20000",
"maxTimeoutSeconds": 300
}
]Output schema
{
"bazaar": {
"info": {
"input": {
"method": "GET",
"queryParams": {
"address": "0x1111111111111111111111111111111111111111"
},
"type": "http"
},
"output": {
"example": {
"capabilityId": "contract.change",
"capabilityVersion": "1.0.0",
"invocationId": "uuid",
"nextCall": {
"recheck": {
"capabilityId": "contract.change",
"listPriceUsdCeiling": 0.002,
"method": "GET",
"notBeforeBlock": 123462,
"payment": "x402",
"url": "https://www.tereno.xyz/api/v1/capabilities/contract.change/invoke?address=0x1111111111111111111111111111111111111111"
},
"validForSeconds": 10,
"validUntilBlock": 123461,
"watch": null
},
"pricing": {
"actualCacheStatus": "miss",
"creditAppliedUsd": 0,
"currency": "USDC",
"listPriceUsd": 0.001,
"pricePaidUsd": 0.001,
"quotedCacheStatus": "miss"
},
"receiptUrl": "/api/v1/receipts/uuid",
"result": {
"baselineCreated": false,
"changed": false,
"changes": [],
"current": {
"address": "0x1111111111111111111111111111111111111111",
"admin": null,
"bytecodeBytes": 4096,
"bytecodeHash": "0xabababababababababababababababababababababababababababababababab",
"computedAtBlock": 123456,
"implementation": null,
"network": "eip155:8453",
"paused": false,
"proxy": false
},
"validUntilBlock": 123456,
"verdict": "allow"
},
"verdict": "allow"
},
"type": "json"
}
},
"schema": {
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"method": {
"enum": [
"GET"
],
"type": "string"
},
"queryParams": {
"additionalProperties": false,
"properties": {
"address": {
"description": "Base contract address to compare with its previous Tereno observation.",
"pattern": "^0x[a-fA-F0-9]{40}$",
"type": "string"
},
"quote": {
"description": "Optional single-use quote id.",
"type": "string"
}
},
"required": [
"address"
],
"type": "object"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method"
],
"type": "object"
},
"output": {
"properties": {
"example": {
"properties": {
"capabilityId": {
"const": "contract.change"
},
"invocationId": {
"type": "string"
},
"nextCall": {
"type": [
"object",
"null"
]
},
"pricing": {
"type": "object"
},
"receiptUrl": {
"type": "string"
},
"result": {
"properties": {
"baselineCreated": {
"type": "boolean"
},
"changed": {
"type": "boolean"
},
"changes": {
"type": "array"
},
"current": {
"type": "object"
},
"validUntilBlock": {
"type": "integer"
}
},
"required": [
"changed",
"baselineCreated",
"changes",
"current",
"validUntilBlock"
],
"type": "object"
},
"verdict": {
"enum": [
"allow",
"review",
"block"
]
}
},
"required": [
"capabilityId",
"invocationId",
"verdict",
"result",
"pricing",
"receiptUrl"
],
"type": "object"
},
"type": {
"type": "string"
}
},
"required": [
"type"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}
},
"builder-code": {
"info": {
"a": "bc_8kag0yoi"
},
"schema": {
"$schema": "https://json-schema.org/draft/2020-12/schema",
"additionalProperties": false,
"properties": {
"a": {
"description": "App builder code",
"pattern": "^[a-z0-9_]{1,32}$",
"type": "string"
},
"s": {
"description": "Service builder codes",
"items": {
"pattern": "^[a-z0-9_]{1,32}$",
"type": "string"
},
"type": "array"
},
"w": {
"description": "Wallet builder code",
"pattern": "^[a-z0-9_]{1,32}$",
"type": "string"
}
},
"type": "object"
}
}
}Use it
curl
curl "https://www.tereno.xyz/api/v1/capabilities/contract.change/invoke" # -> 402 Payment Required, accepts[] lists how to pay # retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid
JavaScript
const res = await fetch("https://www.tereno.xyz/api/v1/capabilities/contract.change/invoke");
if (res.status === 402) {
const { accepts } = await res.json();
// pay one of accepts[] via an x402 client, then retry with the payment header
}Python
import httpx
res = httpx.get("https://www.tereno.xyz/api/v1/capabilities/contract.change/invoke")
if res.status_code == 402:
accepts = res.json()["accepts"]
# pay one of accepts[] via an x402 client, then retry with the payment headerMachine-readable
Everything on this page is also available as clean JSON at /resources/2462.json, and this resource appears in /discovery/resources and /discovery/search.