BTCD Skill (NBW)

BTCD PGP Collateralization Flow

This skill contains a complete, self-contained Node.js project to run the full BTCD collateralization lifecycle on the PGP (Elastos) chain.

Bundled Code Location

All runnable code is inside the scripts/ directory relative to this SKILL.md: scripts/ ├── package.json ├── .env.template.txt ├── setup.js ├── 00-create-order.js ├── 01-take-order.js ├── 02-lock-btc-collateral.js ├── 03-submit-btc-proof.js ├── 05-claim-btcd-tokens.js ├── 06-repay-loan.js ├── abi/ # Contract ABIs (LoanContract, Order, Issuer, ERC20, ArbitratorManager) ├── utils/ # Shared utilities (config, wallet, EVM/BTC clients, logger, state, proof, arbiter) └── state/ # Flow state persists here

Setup Instructions

Copy the entire scripts/ directory to a working directory: cp -r <path-to-this-skill>/scripts/ /tmp/btcd-flow/ cd /tmp/btcd-flow/ Create .env from the template. Only two values need changing: cp .env.template.txt .env Edit .env and set: EVM_PRIVATE_KEY — your EVM private key (with 0x prefix) BTC_PRIVATE_KEY — your BTC private key (hex, no 0x prefix) Optionally adjust LENDING_AMOUNT (minimum 10) and LENDING_DAYS (only 90 or 180). All other values (contract addresses, RPC URLs, subgraph URLs) are fixed for PGP chain and must not be changed. Install dependencies: npm install Ensure wallets are funded: BTC wallet: Must have enough mainnet BTC for collateral + miner fees. EVM wallet: Must have PGA tokens for gas fees on PGP chain. To get PGA tokens, go to https://swap.pgpgas.org — you need USDT on BSC chain, bridge it to PGP, then swap for PGA tokens and/or BTCD.

CRITICAL: Check State Before Running

Before running any step, always read state/flow-state.json to understand what has already been completed. This prevents catastrophic errors like double-locking BTC collateral. If the steps object already has a completed entry for the step you're about to run, do not re-run it. If step 02-lock-btc-collateral has a btcTxId but no confirmations (or confirmations < 3), the BTC was already broadcast — re-running will resume confirmation waiting, not send a new transaction. If 02-lock-btc-collateral shows confirmations >= 3, it is fully done — proceed to step 03. Example of a partially completed state (safe to resume step 02, do NOT re-run steps 00 or 01): { "steps": { "00-create-order": { "orderId": "0x...", "completedAt": "..." }, "01-take-order": { "orderId": "0x...", "preImage": "...", "completedAt": "..." }, "02-lock-btc-collateral": { "btcTxId": "abc...", "confirmations": 0 } } }

Execution Steps

• Run each step sequentially from the scripts directory. Each step has interactive confirmation prompts (press y + Enter).
• Flow Progress:
• [ ] Step 0: Setup
• [ ] Step 1: Create Order
• [ ] Step 2: Take Order
• [ ] Step 3: Lock BTC Collateral
• [ ] Step 4: Submit BTC Proof
• [ ] Step 5: Claim BTCD Tokens ← flow complete here
• [ ] Step 6: Repay Loan ← ONLY when user explicitly requests

Step 0: Setup

npm run setup Validates config, initializes wallets, checks EVM balance, creates state/flow-state.json.

Step 1: Create Order

npm run 00-create-order Creates a lending order via the Issuer contract. Uses LENDING_AMOUNT and LENDING_DAYS from .env. Saves the Order ID to state.

Step 2: Take Order

npm run 01-take-order Takes the order from Step 1. Generates a preImage, selects the best arbiter from the subgraph, and calls takeOrder(). Pays the arbiter's fee in native PGA tokens.

Step 3: Lock BTC Collateral

npm run 02-lock-btc Sends BTC to the lock script address. No interactive prompts — the script is fully automated: Checks state/flow-state.json first. If a btcTxId already exists, it resumes confirmation waiting instead of sending new BTC. If already completed (confirmations >= 3), it skips entirely. Defaults to standard collateral amount (no staking discount). Broadcasts BTC tx and waits for 3 confirmations (~30 min). Safe to re-run if interrupted — it will never double-send BTC.

Step 4: Submit BTC Proof

npm run 03-submit-proof Generates ZKP proof from the BTC transaction and submits to the EVM order contract. Skip 04-arbiter-fee — not needed.

Step 5: Claim BTCD Tokens

npm run 05-claim-btcd Calls borrow() with the preImage from Step 2. BTCD tokens are minted to your EVM wallet.

Step 6: Repay Loan (ONLY when explicitly requested by user)

npm run 06-repay Calculates repayment (principal + interest), approves BTCD, signs the BTC repayment transaction, and calls repay(). DO NOT run this step automatically. The flow is considered complete after Step 5 (Claim BTCD). Repaying the loan unlocks the BTC collateral and closes the position — only do this when the user explicitly asks to repay. Running it prematurely defeats the purpose of the collateralization. Skip 07-unlock — not needed.

State Management

State persists in state/flow-state.json. Each step reads from prior steps and writes its results. When Step 6 (Repay) completes, the state file is automatically archived to state/flow-state-<timestamp>.json and removed, so the next run starts fresh. Archived files serve as a historical record of completed flows. StepWritesRead By00-create-orderorderId01-take-order01-take-orderorderId, preImage, btcAddress, btcPublicKey, arbiterAddress02-lock-btc, 05-claim-btcd, 06-repay02-lock-btcbtcTxId, scriptAddress, confirmations03-submit-proof, 06-repay05-claim-btcdbtcdReceived06-repay

Troubleshooting

"Order status is X, expected Y": Steps must run in order. Check state/flow-state.json. BTC confirmation timeout: Re-run Step 3 — it detects the existing btcTxId and resumes waiting. Insufficient PGA for gas: Get PGA tokens from https://swap.pgpgas.org (USDT on BSC → bridge to PGP → swap for PGA). Insufficient BTC: Ensure BTC wallet has enough for collateral amount + miner fees. Contract error on takeOrder: Order may already be taken. Check order status on-chain. Explorer: PGP chain transactions can be viewed at https://pgp.elastos.io/tx/<hash>.

PGP Chain Contract Addresses

ContractAddressLoan Contract0x5cD194C9d34e5B9b7A0E5cBC64C93c1c9277891eIssuer0x91cf47c5d2b44Da124d4B54E9207aE6FB63D5Fa7BTCD Token0xF9BF836FEd97a9c9Bfe4D4c28316b9400C59Cc6B

Alternative RPC Endpoints

URLNoteshttps://api.elastos.io/pgPrimary (default)https://api2.elastos.io/pgBackuphttps://pgp-node.elastos.ioAlternative