# TraceFast Proxy Contract Implementation History

> TraceFast Proxy Contract Implementation History is a paid API for AI agents from mpp.tracefast.xyz, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-19).

Returns the ordered history of implementation contracts a proxy has delegated to, detected via EIP-1167, EIP-1967, or OpenZeppelin v1 slots, with block ranges and replacement status.

## Facts

- Endpoint: GET https://mpp.tracefast.xyz/api/v1/chains/1/contracts/:address/proxy?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-19
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/tracefast-proxy-contract-implementation-history-035929f9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_f9uXUigO6TojIlEtxyuKx

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 tracefast-proxy-contract-implementation-history-035929f9
```

Example prompt: Can you pull the full implementation history for Ethereum proxy contract 0x1F98431c8aD98523631AE4a59f267346ea31F984 — I want to see every implementation it's delegated to, what blocks they were active, and whether any have been replaced?

## When to prefer this

Use this endpoint when you need the full historical record of proxy delegations for a specific Ethereum contract address, including detection across multiple proxy standards (EIP-1167, EIP-1967 implementation/beacon, OpenZeppelin v1). Prefer this over static code analysis tools when you need live, on-chain observed data with block-level granularity. Ideal for security audits, protocol research, upgrade monitoring, and any workflow that needs to know not just the current implementation but the complete lineage of implementations a proxy has used.

## Known failure modes

- Address is not a proxy contract — returns empty list or no-proxy indicator
- Invalid address format — returns 400 bad request
- Contract not indexed yet or very recent deployment — may return incomplete history
- Non-Ethereum chain ID — endpoint is scoped to chain ID 1 only
- Payment failure via x402 protocol — returns 402 Payment Required
- Network timeout on live chain data fetch — returns 503 or timeout error

## How this service works

TraceFast live Ethereum data: the implementations a proxy contract has been observed delegating to — from its EIP-1167 bytecode, its EIP-1967 implementation or beacon slot, or its OpenZeppelin v1 slot — newest first, each with the blocks it was seen at and whether it has since been replaced. Path address: The proxy contract address, `0x`-prefixed, 40 hex characters, any case. Docs: https://docs.tracefast.xyz/api/contract-proxy.md

## Output

An ordered list (newest first) of implementation contract addresses the proxy has delegated to, each entry including the implementation address, the block numbers at which it was first and last observed, the proxy detection method used (EIP-1167 bytecode, EIP-1967 implementation slot, EIP-1967 beacon slot, or OpenZeppelin v1 slot), and a flag indicating whether that implementation has since been superseded by a newer one.

## Request schema (JSON Schema)

```json
{
 "properties": {
  "input": {
   "required": [
    "method"
   ],
   "properties": {
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "pathParams": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/tracefast-proxy-contract-implementation-history-035929f9/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from mpp.tracefast.xyz](https://www.zero.xyz/host/mpp.tracefast.xyz/llms.txt)