Simulator
Try a transaction before you spend a single rao
Pick an action and a signer. Preflight runs it against real chain state and reports whether it would succeed, the fee, the effects and the balance changes. Every result says honestly whether it executed on a fork or was predicted
Try it before you pay for it
The example is a coldkey with 0 TAO registering on SN64. Press Simulate to see why it would fail before a rao moves