Harakiri | Onchain Gossip

Ask what anyone is doing on-chain. The agent pays for the answer with its own wallet.

Live app: https://harakiri-one.vercel.app

The problem

Wallet activity is public, but reading it is not. Block explorers show raw hex, hundreds of spam airdrops and decoded events nobody understands. Good transaction data sits behind API keys and subscriptions. Harakiri turns "what is this wallet up to?" into a plain-English answer: the agent pays for the data itself (per request, over x402, no API key or account) and reports the newest, biggest and weirdest moves, with a link for every claim.

Key features

• An agent with its own wallet. It signs x402 payments (EIP-3009 USDC on Base Sepolia) to buy data from GoldRush, 0.02 USDC per lookup.
• Real mainnet data. Ethereum, Base, Arbitrum, Optimism and Polygon transactions, not mocks.
• ENS resolution. Ask about vitalik or nick.eth; it finds the address.
• Dossier card. Each lookup shows in/out counts, tokens, and IN / OUT / TAGGED pills that link to the explorer.
• Sus-o-meter. Every answer ends with a 0-10 rating and a one-line reason.
• Spend guardrails in code. At most $0.05 per payment and 2 paid lookups per question; testnet only.
• Prompt-injection defenses. Token names are treated as untrusted data, and only explorer links are clickable (allowlist).
• Multi-wallet questions. Covers 2 wallets per question and names the ones it skipped.

Supported AI models

Provider	Model	Notes
Groq (OpenAI-compatible API, openai SDK 7.25.0)	openai/gpt-oss-120b	Default. Tool calling.

You can swap in any Groq model that supports tool use with GROQ_MODEL in .env. There is no in-app model switcher.

Tools

Tool	Cost	What it does
resolve_name	Free	ENS name to address.
get_wallet_activity	0.02 test USDC (x402)	Newest 40 transactions for an address on a chosen chain, via GoldRush.
get_my_wallet	Free	The agent's own address and ETH/USDC balance.

The details are in The tools.

Tech stack

Layer	What	Version
Runtime	Node.js	20+ (built on 24.19.0)
Framework	Next.js (App Router, API routes)	16.4.0
UI	React / React DOM	19.3.0
Styling	Tailwind CSS, shadcn/ui, Base UI	4.3.3 / 4.21.5 / 1.9.0
Markdown replies	react-markdown, remark-gfm	10.1.0 / 4.0.1
Icons	lucide-react	1.57.0
LLM client	openai (pointed at Groq)	7.25.0
Wallet / chain	viem	2.57.6
Payments	@x402/core, @x402/fetch, @x402/evm	2.28.0
Data	GoldRush transactions_v3 over x402	-
Language	TypeScript	5.9.3

Future scope

• Week 3: watchlists with alerts when a followed wallet makes a big move; gossip about NFT and DeFi positions, not just transfers.
• Rate limiting and a per-day spend budget for the public endpoint.
• ZK proof that the agent's data really came from the paid API (verifiable gossip).
• Agent-to-agent: let other agents pay this one over x402 for a gossip report.

Social

• X / Twitter: https://x.com/harakiripigeon
• GitHub: https://github.com/Shahnilsharma/harakiri-

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How it answers

"What's vitalik doing on-chain?"

1. The agent resolves vitalik to vitalik.eth and then to 0xd8dA…6045 (free ENS lookup).
2. It pays GoldRush 0.02 test USDC over x402 for that address's real recent transactions.
3. It picks out the newest move, the biggest move, and anything weird, then rates it on a sus-o-meter.

You pay with test USDC on Base Sepolia, but the data is real mainnet activity (Ethereum, Base, Arbitrum, Optimism, Polygon).

Built on the agentmaxxin template (Next.js + a viem wallet), running on Groq through its OpenAI-compatible API.

Prerequisites

1. Node.js 20 or newer.
2. A free Groq API key from console.groq.com/keys.
3. Test USDC on Base Sepolia from Circle's faucet. Each lookup costs 0.02 USDC. You don't need ETH, because x402 payments are gasless signatures and GoldRush's facilitator pays the gas.

Setup

Step 1. Install

npm install

Step 2. Add your Groq key

Create .env in the project root:

GROQ_API_KEY=your_key_here

Step 3. Start the app

npm run dev

Open http://localhost:3000.

Step 4. Create and fund the wallet

1. In the Setup panel, click Create wallet. The key is saved to .agent-wallet.json.
2. Copy the address. On faucet.circle.com, pick Base Sepolia and send USDC to it.
3. Click refresh next to Balance. It shows ETH and USDC, for example 0 ETH · 10 USDC.

Don't use a well-known test key (such as Hardhat/Anvil's 0xac0974… / 0xf39F…6266) in WALLET_PRIVATE_KEY. Those accounts are EIP-7702-delegated to sweeper contracts on public testnets, and GoldRush rejects their payments with invalid_exact_evm_signature. Use a fresh wallet.

Using it

Prompt	What happens
What's vitalik doing on-chain?	resolve_name → get_wallet_activity on eth-mainnet → gossip and a sus-o-meter.
Anything sus in jessepollak.eth's Base activity?	Same flow, but on base-mainnet.
What's in your wallet?	Shows the agent's address and its ETH and USDC balance.

Each answer comes with a dossier card showing the fetched transactions: in/out counts, tokens, and colored IN / OUT / TAGGED pills (TAGGED means someone else's tx that only airdropped to the address). Each row links to the explorer. The reply ends with a 10-segment sus-o-meter.

Any ENS name or 0x address works. Name the chain in your prompt to switch from Ethereum. Click a tool entry above a reply to see the raw inputs, the trimmed transactions, and the payment (with a Basescan link when GoldRush returns a settlement tx).

About "sus": the transactions are real; the sus-o-meter is the AI's opinion. The persona is told never to claim intent or accuse anyone, and to point out spam tokens airdropped to famous wallets, which make up most of the "weird" activity.

Which famous names work

An ENS name resolving does not mean the celebrity owns it. Anyone could have registered modi.eth or srk.eth. As of 2026-10-14:

• Good for demos (names these people are publicly known to use; most carry matching Twitter/website records): vitalik.eth, parishilton.eth, markcuban.eth, loganpaul.eth, barmstrong.eth (Brian Armstrong), cozomomedici.eth (Snoop Dogg), garyvee.eth, balajis.eth, stani.eth, haydenadams.eth.
• Resolve, but ownership is unverified (probably squatters): elonmusk.eth, modi.eth, waqarzaka.eth, trump.eth, donaldtrump.eth, realdonaldtrump.eth, salmankhan.eth, shahrukhkhan.eth, srk.eth. Don't present their activity as the celebrity's.
• Don't resolve: elon.eth, narendramodi.eth, snoopdogg.eth, jimmyfallon.eth, cz.eth.

Tip: say "what's Snoop Dogg doing? his ENS is cozomomedici.eth". The agent won't guess the alias on its own.

The tools

Tool	Cost	What it does
resolve_name	Free	ENS name → address, via a public Ethereum RPC. Falls back to a few hardcoded names (vitalik, nick, sassal, jessepollak, punk6529) so the demo never fails on resolution.
get_wallet_activity	0.02 USDC	GoldRush transactions_v3 (tier=medium) over x402. Returns the newest 40 transactions, trimmed to time, direction (in / out / involved = someone else's tx that only airdropped to this address), value, USD value, decoded event, up to 3 token transfers (ones touching the address first), and an explorer link. The agent cites those links, and the payment's Basescan link shows under the tool call.
get_my_wallet	Free	The agent's own address and balance.

How It Works

The agent loop

The loop lives in agent/agent.ts.

1. Your message and the list of tools are sent to Groq (openai SDK, baseURL: https://api.groq.com/openai/v1).
2. If the model replies with tool_calls, the matching run functions are executed and each result goes back as a role: "tool" message with its tool_call_id.
3. This repeats until the model replies with plain text, which becomes the final answer.
4. The loop stops after eight rounds to prevent runaway tool calls, and refuses a third paid lookup in one question.

Real x402 (GoldRush)

x402Fetch in agent/wallet.ts speaks the real protocol, using the official @x402/fetch and @x402/evm packages:

1. The request gets back 402 with a PAYMENT-REQUIRED header (price, USDC contract, recipient, network eip155:84532).
2. The wallet signs an EIP-3009 transferWithAuthorization for exactly that amount.
3. The request is retried with the signature. GoldRush's facilitator settles the USDC transfer on Base Sepolia and the API returns the data.

Project Structure

Path	Description
agent/tools.ts	The tools, including resolve_name and get_wallet_activity.
agent/agent.ts	The agent loop and the gossip-detective persona (SYSTEM_PROMPT).
agent/wallet.ts	The agent wallet, the ETH and USDC balance, and real x402 payments (x402Fetch).
app/page.tsx	The page: setup steps, tools list, and chat (saved in the browser until you click Clear).
components/gossip.tsx	The dossier card, markdown replies and the sus-o-meter.
components/swing-chain.tsx	The swinging 3D chain hanging off the logo.
app/api/agent/route.ts	The server endpoint that runs the agent.
app/api/wallet/route.ts	The server endpoint that creates and reads the agent wallet.
components/ui/	Interface components from shadcn/ui. You do not need to edit these.
.env	Your API key and optional settings.
.agent-wallet.json	The agent wallet, created when you click Create wallet. Never share this file.

Configuration

All settings live in the .env file.

Variable	Required	Description
GROQ_API_KEY	Yes	Your Groq API key.
GROQ_MODEL	No	The Groq model to use. Defaults to openai/gpt-oss-120b. It must support tool use. llama-3.3-70b-versatile is no longer offered.
WALLET_PRIVATE_KEY	No	Use an existing wallet instead of the Create wallet button. A private key starting with 0x. When set, it takes priority over .agent-wallet.json.

Restart npm run dev after changing any value in .env.

The Agent Wallet

Clicking Create wallet generates a new private key and saves it to .agent-wallet.json. The file is listed in .gitignore, so it is never committed.

Once the wallet exists, the Setup panel shows:

1. The wallet address, with a button to copy it.
2. The current ETH and USDC balance on Base Sepolia, with a refresh button.
3. A link to view the wallet on the Base Sepolia block explorer.
4. A link to faucets. For this agent you need test USDC from faucet.circle.com, not ETH.

To start again with a new wallet, stop the server, delete .agent-wallet.json, restart, and click Create wallet again.

To use a wallet you already have, set WALLET_PRIVATE_KEY in .env instead.

Security note: Only ever use this wallet for testing. Never send real funds to it. Private keys in .agent-wallet.json and .env are stored as plain text.

Troubleshooting

Problem	Solution
The page says to add GROQ_API_KEY	Add your key to .env and restart npm run dev.
A tool fails with "no wallet yet"	Click Create wallet in the Setup panel, then ask again.
402 ... invalid_exact_evm_signature	The wallet is EIP-7702-delegated, which usually means it's a public test key. Remove WALLET_PRIVATE_KEY from .env, delete .agent-wallet.json, restart, and click Create wallet.
402 with no error, or a balance error	The wallet needs Base Sepolia USDC from faucet.circle.com.
"does not resolve to an address"	That ENS name has no address set. Pass a 0x address instead.
Port 3000 is already in use	Run npm run dev -- -p 3001 and open that port instead.
A model error appears in the chat	Check that your API key is valid, or set a different model in GROQ_MODEL.
413 Request too large ... tokens per minute	Groq's free tier caps tokens per minute. Lower MAX_TOOL_CHARS in agent/agent.ts, or upgrade the Groq tier.
429 errors	Rate limited. The SDK retries automatically with exponential backoff (up to 5 times, honoring retry-after). If it still fails, wait a minute.

License

MIT