Add Boltz submarine + reverse swaps (Lightning <-> on-chain)

Non-custodial swaps via Boltz, fully client-side: hal holds the swap key +
preimage and claims (reverse) / refunds (submarine) on-chain via the taproot
script path, so Boltz can never strand funds.

- src/swap.js: tapleaf/tree construction (byte-exact vs boltz-core vectors),
  swap P2TR address derivation (MuSig2 internal key + taptweak), script-path
  claim/refund tx builder, bolt11 decode, Boltz api-v2 client, and a polling
  SwapManager (reverse auto-claim; submarine fund + status + refund).
- wallet.js: deterministic swap-key derivation (dedicated chain) + persistence.
- api.js: configurable Boltz REST/WS endpoints.
- app.js: ⚡ Swap tab — Receive over LN (reverse) + Pay an invoice (submarine).
- tools/swap-*.test.js: vectors, live-address, and end-to-end regtest tests.

Verified end-to-end on regtest against a local Boltz wired to coinos's bc +
a dedicated CLN/hold node.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

1 files changed, 57 insertions, 0 deletions

diff --git a/tools/swap-live.test.js b/tools/swap-live.test.js
new file mode 100644
index 0000000..f56105a
--- /dev/null
+++ b/tools/swap-live.test.js
@@ -0,0 +1,57 @@
+// Live integration check against the local Boltz (http://localhost:9001) +
+// regtest CLN. Confirms Hal's locally-derived swap address + tapleaves match
+// Boltz's lockupAddress + swapTree for BOTH flows — proving the MuSig2
+// internal-key order ([boltzKey, halKey]), the taptweak, and leaf construction.
+// Run (regtest Boltz stack up): bun tools/swap-live.test.js
+import { $ } from 'bun';
+import { secp256k1 } from '@noble/curves/secp256k1';
+import { sha256 } from '@noble/hashes/sha2';
+import { ripemd160 } from '@noble/hashes/legacy';
+import { randomBytes, bytesToHex, hexToBytes } from '@noble/hashes/utils';
+import { hash160, swapP2TR, buildSwapTree } from '../src/swap.js';
+
+const BOLTZ = process.env.BOLTZ_API || 'http://localhost:9001';
+const post = async (p, b) => {
+  const r = await fetch(BOLTZ + p, { method: 'POST', headers: { 'content-type': 'application/json' }, body: JSON.stringify(b) });
+  const j = await r.json();
+  if (!r.ok) throw new Error(`${p} -> ${r.status} ${JSON.stringify(j)}`);
+  return j;
+};
+const kp = () => { const sk = secp256k1.utils.randomPrivateKey(); return { sk, pk: secp256k1.getPublicKey(sk, true) }; };
+let fail = 0;
+const eq = (n, g, w) => { if (g === w) console.log(`  ok  ${n}`); else { fail++; console.log(`FAIL ${n}\n  got:  ${g}\n  want: ${w}`); } };
+
+// ---------- REVERSE (hal receives over LN; hal claims) ----------
+{
+  const claim = kp();
+  const preimage = randomBytes(32);
+  const res = await post('/v2/swap/reverse', {
+    invoiceAmount: 100000, from: 'BTC', to: 'BTC',
+    claimPublicKey: bytesToHex(claim.pk), preimageHash: bytesToHex(sha256(preimage)),
+  });
+  const boltzPub = hexToBytes(res.refundPublicKey); // Boltz refunds on reverse
+  const d = swapP2TR({ kind: 'reverse', preimageHash160: hash160(preimage), boltzPub33: boltzPub, halPub33: claim.pk, lockTime: res.timeoutBlockHeight, network: 'regtest' });
+  eq('reverse lockup address', d.address, res.lockupAddress);
+  eq('reverse claim leaf', bytesToHex(d.claimLeaf), res.swapTree.claimLeaf.output);
+  eq('reverse refund leaf', bytesToHex(d.refundLeaf), res.swapTree.refundLeaf.output);
+}
+
+// ---------- SUBMARINE (hal spends over LN; hal refunds) ----------
+{
+  const inv = JSON.parse(await $`docker exec clb lightning-cli --regtest invoice 100000000 hal-sub-${Date.now()} test`.text());
+  const payHash = inv.payment_hash;
+  const refund = kp(); // hal's refund key
+  const res = await post('/v2/swap/submarine', {
+    invoice: inv.bolt11, from: 'BTC', to: 'BTC', refundPublicKey: bytesToHex(refund.pk),
+  });
+  const boltzPub = hexToBytes(res.claimPublicKey); // Boltz claims on submarine
+  // tapscript embeds hash160(preimage) = ripemd160(payment_hash)
+  const ph160 = ripemd160(hexToBytes(payHash));
+  const d = swapP2TR({ kind: 'submarine', preimageHash160: ph160, boltzPub33: boltzPub, halPub33: refund.pk, lockTime: res.timeoutBlockHeight, network: 'regtest' });
+  eq('submarine lockup address', d.address, res.address);
+  eq('submarine claim leaf', bytesToHex(d.claimLeaf), res.swapTree.claimLeaf.output);
+  eq('submarine refund leaf', bytesToHex(d.refundLeaf), res.swapTree.refundLeaf.output);
+}
+
+console.log(fail ? `\n${fail} FAILED` : '\nall good');
+process.exit(fail ? 1 : 0);