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, 43 insertions, 0 deletions

diff --git a/tools/swap-manager.test.js b/tools/swap-manager.test.js
new file mode 100644
index 0000000..7a83be1
--- /dev/null
+++ b/tools/swap-manager.test.js
@@ -0,0 +1,43 @@
+// Drives the SwapManager reverse flow end-to-end with a minimal wallet shim:
+// startReverse -> pay the hold invoice from cl -> manager auto-claims on-chain.
+// Run (stack up): bun tools/swap-manager.test.js
+import { HDKey } from '@scure/bip32';
+import * as btc from '@scure/btc-signer';
+import { secp256k1 } from '@noble/curves/secp256k1';
+import { randomBytes } from '@noble/hashes/utils';
+import { SwapManager, REGTEST } from '../src/swap.js';
+
+const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
+const ESPLORA = 'http://localhost:3000';
+// Fresh random seed per run (real wallet persists swaps so swapNode indices
+// increment; this shim's store is in-memory, so randomize to avoid preimage reuse).
+const acct = HDKey.fromMasterSeed(randomBytes(64)).derive("m/84'/1'/0'");
+
+let store = [];
+const wallet = {
+  loadSwaps: () => store,
+  saveSwaps: (l) => { store = l; },
+  nextSwapIndex: () => store.reduce((m, s) => Math.max(m, (s.swapIndex ?? -1) + 1), 0),
+  swapNode: (i) => acct.deriveChild(2).deriveChild(i),
+  freshReceive: () => ({ address: btc.p2wpkh(secp256k1.getPublicKey(acct.deriveChild(0).deriveChild(7).privateKey, true), REGTEST).address }),
+  api: {
+    addressUtxos: async (a) => { const r = await fetch(`${ESPLORA}/address/${a}/utxo`); return r.ok ? r.json() : []; },
+    broadcast: async (hex) => { const r = await fetch(`${ESPLORA}/tx`, { method: 'POST', body: hex }); const t = await r.text(); if (!r.ok) throw new Error(t); return t; },
+  },
+};
+
+const sm = new SwapManager({ wallet, network: 'regtest', getApi: () => 'http://localhost:9001', feeRate: 2, onUpdate: () => {} });
+const rec = await sm.startReverse(120000);
+console.log('startReverse ->', rec.id, rec.status, 'lockup', rec.lockupAddress);
+
+console.log('paying hold invoice from cl…');
+Bun.spawn(['docker', 'exec', 'cl', 'lightning-cli', '--regtest', 'pay', rec.invoice], { stdout: 'ignore', stderr: 'ignore' });
+
+for (let i = 0; i < 60; i++) {
+  await sleep(1000);
+  const r = sm.list().find((s) => s.id === rec.id);
+  if (r.status === 'claimed') { console.log(`\nPASS — SwapManager auto-claimed: ${r.received} sats, txid ${r.claimTxid}`); process.exit(0); }
+  if (r.lastError && i % 5 === 0) console.log('  …', r.lastError);
+}
+console.log('FAIL — not claimed:', JSON.stringify(sm.list()));
+process.exit(1);