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What is a transaction

A transaction is a signed message submitted to a blockchain that changes its state — transferring tokens, calling a contract function, or deploying a new contract. Once included in a block, transactions are permanent and irreversible. When you inspect an EVM transaction on a block explorer, its recorded parameters show everything that single submission includes:
Most modern EVM transactions use the EIP-1559 fee format. Legacy transactions with a single gasPrice field are still valid but less common.

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Transaction hash

Every submitted transaction receives a unique transaction hash (tx hash) — a hex string like 0x4a3f8b2c.... This is how you look up a transaction on a block explorer: Cobo returns the transaction hash after successful submission.

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Gas fees

On-chain transactions require a fee to compensate the network for computation and storage. The fee model differs between EVM chains and Solana.

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EVM chains

Gas is the unit of computational work. Every operation costs a fixed amount of gas, and the total fee depends on how much computation the transaction requires:
Gas is paid in the chain’s native token — ETH on Ethereum and Base, POL on Polygon, BNB on BNB Smart Chain, AVAX on Avalanche. Modern EVM transactions use the EIP-1559 fee model, which splits the gas price into two components: The maxFeePerGas field caps the total amount the sender is willing to pay. Any difference between maxFeePerGas and the actual base fee + priority fee is refunded. Gas prices fluctuate with network congestion. During high activity, fees can spike significantly.

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Solana

Solana uses a different fee model with two components:
Solana transactions also carry a recent blockhash that expires after approximately 150 blocks (~1 minute). If a transaction is not included within that window, it becomes invalid and must be resubmitted. Agents that submit transactions autonomously should account for this expiry when retrying.

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Transaction lifecycle in Cobo Agentic Wallet

This lifecycle is specific to Cobo Agentic Wallet. Other products and platforms may handle transaction submission and signing differently.
  1. Policy validation — the policy engine (governed by the pact) checks the transaction. If it violates a policy, it is blocked before reaching the network.
  2. MPC signing — if it passes, the transaction is co-signed: the agent and Cobo for agent-initiated transactions; the app and Cobo for app-initiated transactions.
  3. Broadcast — the signed transaction is sent to the network, included in a block, and confirmed.

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Transaction finality

TTransactions are not final the moment they are submitted. They must be included in a block and confirmed by subsequent blocks. For high-value operations, waiting for additional confirmations beyond the first provides stronger settlement guarantees. Cobo waits for block inclusion before marking a transaction as confirmed.