evm transaction dry run

The problem

Sending transactions blindly to the mempool is a gamble. Relying on wallet simulations is often insufficient because they fail to account for the gap between a static snapshot and a live broadcast environment.

What it does

• Simulates specific EVM transactions on a mainnet fork at a precise block height.
• Decodes raw calldata to verify intended functions, addresses, and parameters.
• Identifies state changes including balance shifts, token approvals, and internal contract calls.
• Detects sandwich attack risks, high slippage, and unexpected intermediary redirects.
• Executes multi-step scripts (e.g., approve then swap) using Forge to test complex sequences.

Frameworks & tools

Foundry (Anvil, Cast, Forge) and EVM-compatible RPC endpoints.

Why this beats prompting it yourself

Generic prompts often hallucinate CLI flags or fail to account for environment variables that can trigger accidental live broadcasts. This skill enforces strict protocols for block-height reproducibility and explicitly identifies "sim-to-broadcast" risks that standard AI responses overlook.

Use cases

• Test a complex DeFi swap for hidden fees or high slippage before signing.
• Verify that a contract approval is scoped correctly and not over-permissioned.
• Dry-run an agent-generated transaction to ensure it won't revert on-chain.
• Analyze a transaction's execution trace to uncover unexpected internal hops.

Known limitations

Simulation results are snapshots. They cannot guarantee outcome if mempool conditions, oracle prices, or proxy logic changes before the real broadcast. Requires Foundry to be installed for full execution.