ETH Kolibrio OFA Searcher Connection

Summary: The interface is fully compatible with MEV Blocker. Connect to the WebSocket, include the X-Bev-Signature header, subscribe to partial pending transactions, and receive notifications via JSON‑RPC. Then, construct your backrun bundle and send it using eth_sendBundle.

Endpoint

wss://bev-relay.kolibr.io/eth

Required HTTP header when establishing the WebSocket session:

X-Bev-Signature: <signature>

The X-Bev-Signature header is used for authentication/authorization. The signature format and keys are provided by the Kolibrio team.

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Subscription

After a successful connection, send the following JSON‑RPC request to subscribe:

{"method": "eth_subscribe","params": ["mevblocker_partialPendingTransactions"]}

Expected response:

{"jsonrpc": "2.0", "id": 1, "result": "0xd58bbbc0f5190962eff01b6f0ec17724"}

After this, you’ll start receiving eth_subscription notifications when new relevant transactions appear.

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Incoming Signal Format

Example notification:

{
		"jsonrpc": "2.0",
		"method": "eth_subscription",
		"params": {
		"subscription": "0xd58bbbc0f5190962eff01b6f0ec17724",
				"result": {
						"chainId": "0x1",
						"to": "0x..",
						"value": "0x4fefa17b724000",
						"data": "0x",
						"accessList": [],
						"nonce": "0x10",
						"maxPriorityFeePerGas": "0x0",
						"maxFeePerGas": "0x7e1c65b04",
						"gas": "0x5208",
						"type": "0x2",
						"hash": "0xd...4c",
						"from": "0x.."
				}
		}
}

Note: All numeric fields are hex‑encoded.

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Sending a Bundle

Once you’ve built your signed backrun transaction, send it as a bundle via the same WebSocket or simple HTTP POST request:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "eth_sendBundle",
  "params": [
    {
      "txs": [
        "0x02abcd...", // target transaction hash (32 bytes)
        "0x02abcd..." // your signed bacrkun raw transaction
        ...
      ],
      "blockNumber": "0xb63dcd",
      "minTimestamp": 0,
      "maxTimestamp": 1615920932
    }
  ]
}

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Best Practices & Constraints

• Treat the target transaction hash as a 32‑byte hex string (with 0x prefix).

• Both transaction hashes and raw signed transactions are accepted in txs.

• The order of txs matters: target transaction first, followed by your backrun txs.

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Example Flow

1. Open WS connection → wss://bev-relay.kolibr.io/eth with X-Bev-Signature.

2. Send eth_subscribe to mevblocker_partialPendingTransactions.

3. Receive eth_subscription messages with result → process and build your backrun transaction.

4. Send eth_sendBundle containing the target hash and your signed transaction(s).

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Security Notes

• Keep your signing keys and X-Bev-Signature secrets secure.