BTCD Skill (NBW)

Run the BTCD collateralization flow on PGP chain. Use when the user asks to run a BTCD loan, collateralization flow, create/take orders, lock BTC, submit pro...

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

1. Copy the entire scripts/ directory to a working directory:

   cp -r <path-to-this-skill>/scripts/ /tmp/btcd-flow/
   cd /tmp/btcd-flow/
   

2. 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.

3. Install dependencies:

   npm install
   

4. 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.

Step	Writes	Read By
00-create-order	orderId	01-take-order
01-take-order	orderId, preImage, btcAddress, btcPublicKey, arbiterAddress	02-lock-btc, 05-claim-btcd, 06-repay
02-lock-btc	btcTxId, scriptAddress, confirmations	03-submit-proof, 06-repay
05-claim-btcd	btcdReceived	06-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

Contract	Address
Loan Contract	0x5cD194C9d34e5B9b7A0E5cBC64C93c1c9277891e
Issuer	0x91cf47c5d2b44Da124d4B54E9207aE6FB63D5Fa7
BTCD Token	0xF9BF836FEd97a9c9Bfe4D4c28316b9400C59Cc6B

Alternative RPC Endpoints

URL	Notes
https://api.elastos.io/pg	Primary (default)
https://api2.elastos.io/pg	Backup
https://pgp-node.elastos.io	Alternative