Contracts enter the realm

Soroban is Stellar's smart contract platform. A contract is Rust compiled to WebAssembly, uploaded to the ledger and executed inside a sandboxed host — every power it has (storage, crypto, calling other contracts) arrives through host functions the protocol provides.

And here is the elegant part: calling one needs no new transaction format. The envelope you dissected carries a single operation — invoke_host_function — and inside rides the call: which contract, which function, which arguments.

Same envelope, same signatures, same ~5-second close. The classic realm and the contract realm share one bloodstream.