# Sentinel Contract Safety — EVM Proxy Upgrade Checker

> Sentinel Contract Safety — EVM Proxy Upgrade Checker is a paid API for AI agents from www.0816.cn, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-19).

Checks whether an EVM contract on Base is upgradeable, who controls the upgrade, and what the upgrade risk level is by reading EIP-1967 proxy slots directly from chain state.

## Facts

- Endpoint: GET https://www.0816.cn/v1/base/proxy-upgrade
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-19
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sentinel-contract-safety-evm-proxy-upgrade-checker-8e182d35
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_C7cPSnGgG3xrXxEs4fZdM

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability sentinel-contract-safety-evm-proxy-upgrade-checker-8e182d35
```

Example prompt: Can you check if the contract at 0x4200000000000000000000000000000000000010 on Base is upgradeable, who the admin is, and whether there's any upgrade risk I should know about?

## When to prefer this

Choose this endpoint when you need to determine upgrade risk for a specific EVM contract on Base — particularly when evaluating whether a contract owner can silently swap out logic. It is purpose-built for EIP-1967 proxy pattern detection and admin slot inspection on Base, making it more targeted than general contract analysis tools.

## Known failure modes

- Invalid or malformed contract address returns an error
- Contract address not found on Base returns no proxy data
- Non-proxy contracts return upgradeability as false with no admin
- Rate limiting or payment failure for unpaid calls
- RPC/chain state read errors if Base node is unreachable

## How this service works

Upgradeable contract and proxy admin check for any EVM contract on Base (GET ?contract=0x… or POST body {contract}). Reads EIP-1967 implementation, admin and beacon slots directly from chain state. Returns whether the contract can be upgraded, who controls the upgrade, and an upgrade risk verdict. Call when an agent needs to know if a contract owner can silently change its logic. $0.02 USDC

## Output

Returns whether the contract is upgradeable, the admin address controlling the upgrade, the implementation address, beacon slot data (if applicable), and an upgrade risk verdict (e.g. low/medium/high), all sourced directly from Base chain state via EIP-1967 storage slots.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "contract"
     ],
     "properties": {
      "contract": {
       "type": "string",
       "description": "address (0x...) — also accepted in POST body"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sentinel-contract-safety-evm-proxy-upgrade-checker-8e182d35/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from www.0816.cn](https://www.zero.xyz/host/www.0816.cn/llms.txt)