sCrypt CAT Smart Contracts

A collection of CATful smart contracts for BTC written in sCrypt.

Configure Private Key

First, we need to create a .env file with our private key, which should contain some signet funds:

PRIVATE_KEY="cTE..."

You may obtain signet funds via these faucets:

• https://signetfaucet.com/
• https://alt.signetfaucet.com
• https://x.com/babylon_chain/status/1790787732643643575

Build

npm run build

Testing Locally

npm run test

Testing on Signet

To run the tests on the signet network, we need to run a local bitcoin inquisition node.

Step 1: Install Bitcoin Core Inquisition

Download the Bitcoin Core Inquisition from GitHub.

Step 2: Connect to a CAT-ready Relay Node

The Bitcoin client will automatically find nearby relay nodes for broadcasting transactions. However, these nodes may not support the new OP_CAT version and could refuse to broadcast it due to default policies against OP_SUCCESSXX. Thus, we need to configure our node to relay transactions to an inquisition node.

Add the following to the node configuration:

signet=1
daemon=1

[signet]
addnode=inquisition.taprootwizards.com

Step 3: Broadcast transactions

Once we have our node up and running, we can start broadcasting our transactions. The tests by default output the serialized transactions which run the smart contract.

For example if we'd like to test the counter smart contract on signet, we'd first run the local test individually:

npx scrypt-cli@latest compile -i "src/contracts/counter.ts" && \
NETWORK=testnet npx mocha --no-config --require ts-node/register tests/counter.test.ts

Test SmartContract `Counter`
...
txFee (serialized): 
....
tx0 (serialized): 
...
tx1 (serialized): 
...
tx2 (serialized): 
...

We can now broadcast the serialized transactions one by one using bitcoin-cli, which is bundled with your node software:

./bin/bitcoin-cli --conf=<path to node configuration> sendrawtransaction 020000000001022...

If everything succeeds, the command should output a TXID.

Note, that the TX may not be immediately visible on block explorers such as Mempool, since they only accept the transaction once it's mined into a block by an inquisition node.