Review a PSBT before signing

For: anyone about to sign. Goal: know that what your wallet is asking you to sign is what StampDEX told you it was. Prerequisites: a transaction on screen. Chain and network: Bitcoin mainnet.

Safety: this is the last point at which anything is reversible. After you sign and broadcast, Bitcoin decides.

The rule

StampDEX builds transactions. Your wallet displays them and signs them, or refuses. Nothing spends your funds without a signature made in your wallet. So the review screen and the wallet screen must agree, and if they do not, the correct action is to refuse.

What to check on a buy

Check	Why
The total amount leaving your wallet	It should equal the listing total plus your service fee plus the network fee
The destination address	It should match the payment address on the review panel
The fee rate	You chose it. A rate you did not choose is a reason to stop
Nothing else is being spent	A buy should not touch unrelated outputs

What to check on a listing

Check	Why
Only your one anchor input is signed	The listing uses SIGHASH_ALL | ANYONECANPAY on your input alone
The token amount	It should match what you typed
The escrow addresses	They are the ones the prepare step returned, not addresses that arrived later

If your wallet cannot show you an unfinalized PSBT clearly, that is a wallet limitation, not a reason to sign blind.

The service fee output

Every SRC-20 settlement carries the service fee as its own output to a fixed pay-to-Taproot address:

bc1pl0xdhr5delrk80d6s5h5qa9awsf7qzc45jl8na6ns8vp3e0vv7wqxattxy

It is a constant, not a per-user address, and it is visible on chain in every SRC-20 settlement and in every deploy, mint, or transfer StampDEX builds. You can check it yourself in any explorer. A transaction claiming a StampDEX service fee to a different address is not one of ours.

The small outputs are not a mistake

An SRC-20 transaction has several tiny outputs. They carry the protocol’s data and markers, not value:

Output	Value	What it is
Recipient marker	330 sats	The output the SRC-20 transfer credits
Data chunks	330 sats each	The pay-to-witness-script-hash outputs carrying the encoded transfer
Seller anchor	548 sats	The marker output the listing flow spends and returns

Seeing a handful of 330 and 548 sat outputs in a token transaction is normal. Seeing them in a plain BTC send is not.

Signing a message is not signing a transaction

Cancelling a listing, and every other mutation, asks your wallet to sign a short text message rather than a transaction. That message names the action, your address, a hash of the exact request, a single-use value, and an expiry. It cannot move funds, and it works once. If you are asked to sign the same challenge twice, something failed in between; read the order state before retrying.

Never do this

No wallet needs your recovery phrase or a private key to work with StampDEX, and StampDEX never asks for either. If any page, in any tab, asks you to type a recovery phrase or import a seed in order to trade, close it.

Related

• Safety and trust
• Fees
• Wallets