Transaction simulation

Transaction simulation is the execution of a proposed transaction against a node's current state to preview its outcome without submitting it to the network.

Simulation answers 'what would this transaction do' before any gas is spent or state changed. It replays the call against current chain state and returns the balance changes, emitted events and whether it would succeed or revert. This is essential for catching a failing swap, an unexpected token approval or a drained transfer. Our tx primitives include a simulate step between build and broadcast, so a non-custodial application can show the user exactly what will happen — decoded — and only then have them sign and broadcast.