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import config from "$config";
import { s } from "$lib/db";
import { l } from "$lib/logging";
import { CHILD_VSIZE } from "$lib/p2a";
import { fail, sats } from "$lib/utils";
import rpc from "@coinos/rpc";
const bc = rpc(config.bitcoin);
export function estimateBumpCost(
parentFee: number,
parentVsize: number,
targetFeeRate: number,
): number {
const packageVsize = parentVsize + CHILD_VSIZE;
const requiredPackageFee = Math.ceil(targetFeeRate * packageVsize);
return Math.max(0, requiredPackageFee - parentFee);
}
export async function createCpfpChild(payment: any, targetFeeRate: number) {
const { hash: parentTxid, p2aVout, parentVsize, fee: parentFee, bumpReserve } = payment;
if (p2aVout < 0) fail("no P2A output on this transaction");
const childFee = estimateBumpCost(parentFee, parentVsize, targetFeeRate);
if (childFee <= 0) fail("transaction already meets target fee rate");
if (childFee > bumpReserve) fail("bump cost exceeds reserve");
// Get a confirmed wallet UTXO to fund the child
const utxos = await bc.listUnspent(1);
if (!utxos.length) fail("no confirmed wallet UTXOs available for bump");
const walletUtxo = utxos[0];
const walletUtxoValue = sats(walletUtxo.amount);
const p2aValue = 240;
const changeValue = walletUtxoValue + p2aValue - childFee;
if (changeValue < 0) fail("wallet UTXO too small for bump");
// Get a change address from the wallet
const changeAddress = await bc.getRawChangeAddress();
// Build child tx inputs
const inputs = [
{ txid: parentTxid, vout: p2aVout },
{ txid: walletUtxo.txid, vout: walletUtxo.vout },
];
// Build child tx outputs
const outputs = [{ [changeAddress]: parseFloat((changeValue / 1e8).toFixed(8)) }];
// Create raw transaction with nVersion=3 (TRUC child must also be v3)
let raw = await bc.createRawTransaction(inputs, outputs);
raw = "03000000" + raw.substring(8);
// Sign — wallet signs the wallet input, P2A input needs no signature (keyless anchor)
if ((config.bitcoin as any).walletpass) await bc.walletPassphrase((config.bitcoin as any).walletpass, 300);
const { hex } = await bc.signRawTransactionWithWallet(raw);
// Verify child vsize ≤ 1000 (TRUC child limit)
const decoded = await bc.decodeRawTransaction(hex);
if (decoded.vsize > 1000) fail("child transaction exceeds TRUC 1kvB limit");
// Try mempool accept, fall back to package submission
let childTxid: string;
try {
const r = await bc.testMempoolAccept([hex]);
if (r[0].allowed) {
childTxid = await bc.sendRawTransaction(hex);
} else {
// Parent might not be in mempool — try package submission
const parentHex = await bc.getRawTransaction(parentTxid);
const pkg = await bc.submitPackage([parentHex, hex]);
if (pkg["tx-results"]) {
const results = Object.values(pkg["tx-results"]) as any[];
const childResult = results[results.length - 1];
childTxid = childResult?.txid || decoded.txid;
} else {
fail("package submission failed");
}
}
} catch (e) {
// Try package submission as fallback
try {
const parentHex = await bc.getRawTransaction(parentTxid);
const pkg = await bc.submitPackage([parentHex, hex]);
if (pkg["tx-results"]) {
const results = Object.values(pkg["tx-results"]) as any[];
const childResult = results[results.length - 1];
childTxid = childResult?.txid || decoded.txid;
} else {
fail("package submission failed");
}
} catch (e2) {
fail(`bump failed: ${e2.message}`);
}
}
// Update payment
payment.childTxid = childTxid;
payment.bumpedFee = childFee;
await s(`payment:${payment.id}`, payment);
l("CPFP bump", parentTxid, "->", childTxid, "fee:", childFee);
return { txid: childTxid, childFee };
}
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