This proposal is a profile of the ERC-8004 Reputation Registry for loan outcomes: loans opened, repaid on time, repaid late, defaulted. It adds no core contract. A lender posts ordinary giveFeedback entries with two tags, credit.statement and credit.defaulted, whose files travel inside the entry as data: URIs.
A statement commits, with a Merkle root, to every loan of an agent that closed in a block window at the lender's contracts. Each loan is a leaf naming the lender's own log that closed it. A reader holding nothing but an RPC endpoint can rebuild every leaf from those logs, check the root and the totals, and sample the money that moved.
A lender's statements for one agent are chained by hash over back-to-back windows. Skipping a window or revoking a statement is visible to every reader. Dropping a loan at a contract the lender declares is visible to every reader that rebuilds the statements, and so is a default after the last statement, which a lender that stops posting would otherwise leave out.
An optional part, a profile of ERC-8092, lets a lender publish which contracts its writer speaks for, as associations signed by both the lending contract (or its ERC-173 owner) and the writer. A reader then takes that list from the chain instead of from the writer's files.
Priors runs this draft on mainnet: its credit writer posts loan outcomes to the ERC-8004 Reputation Registry, and any reader rebuilds them from the pool's own logs. These panels read Robinhood Chain mainnet (4663) and change nothing. Nothing here sends a mainnet transaction.
Try it
On Robinhood Chain testnet (46630), with the reference contracts at their pinned commits and test tokens of no value. Each action shows the call it prepares before your wallet signs it, and each send is simulated first.
Set up
Four steps, once: your wallet on Robinhood Chain testnet, a little test ETH for its fees, test dollars of no value, and a testnet identity. The forms below fill from them.
1
Wallet
Not connected. Any browser wallet works: the lab switches it to Robinhood Chain testnet (46630) and sends nothing on another chain.
2
Test ETH
For the testnet's network fees. The lab's drip sends a little to a connected wallet once a day.
3
Test dollars
The Lab Test Dollar (no value) that lines lend and launches pair with.
4
Testnet identity
An ERC-8004 identity on the testnet registry, for the forms that take an agent id.
Your agent gets the same lab through the MCP server at https://lab.priors.trade/mcp or the HTTP API described by /openapi.json. It reads, and gets back unsigned testnet transactions to sign with its own testnet key. The lab holds no key of its own for you and never asks for one.
MCP tools for ERC-8466
lab_erc(8466)
What the draft does on the lab, its contracts and an agent's next calls.
lab_setup(address)
Test ETH, test dollars and the testnet identities of an address, with the calls to register one and mint test dollars.
Post a credit entry (as a lender's writer). Who signs: a lender's writer key
lab_check_contract(8466, chain, address)
The conformance read of any contract, on testnet or mainnet: supportsInterface and the views.
lab_feedback_draft(8466, note, txHash?)
The report text and the thread and issue links. It posts nothing.
HTTP
GET https://lab.priors.trade/api/lab/erc/8466
GET https://lab.priors.trade/api/lab/read/8466/testnet_statements?agent_id=<agent_id>&writer=<writer>
GET https://lab.priors.trade/api/lab/prepare/8466/post_credit_entry?agent_id=<agent_id>&tag1=<tag1>&value=<value>&value_decimals=<value_decimals>&feedback_uri=<feedback_uri>&feedback_hash=<feedback_hash>
GET https://lab.priors.trade/api/lab/check/8466/<chain>/<address>
GET https://lab.priors.trade/api/lab/setup/<address>
Connect it, for example in Claude Code: claude mcp add --transport http priors-lab https://lab.priors.trade/mcp
A prompt to copy
Use the Priors lab on Robinhood Chain testnet (chain id 46630), where every token is a test token of no value. Its MCP server is https://lab.priors.trade/mcp and this draft's page is https://lab.priors.trade/erc/8466.md. Try ERC-8466, Agent Credit History (a draft under review). Start with lab_setup for my testnet address to see my test ETH, test dollars and identities, then post a credit entry (as a lender's writer) with lab_prepare(8466, <action>, params). Each prepare returns an unsigned transaction { chainId: 46630, to, data, value }: sign and send it yourself with a testnet key, and refuse any other chain. Never ask me for a key. After each transaction, read the result back with lab_read and tell me what changed. If the draft or its reference code looks wrong, draft a report with lab_feedback_draft.
Check a contract
Paste any contract on either chain: ERC-8466 is a profile of the ERC-8004 reputation registry, with no interface of its own: the lab calls the registry's views. It only reads, so another implementer can test conformance with nothing signed.
Feedback
What you found goes where the draft is worked on: the discussion of the text in its thread on Ethereum Magicians, a bug in the reference code in its repository's issues. You post it under your own account. The lab posts nothing for anyone.