NWC: lookup_invoice, so BTCPay Server can connect

BTCPay's NWC connector requires get_info, make_invoice, lookup_invoice
and list_transactions; we never offered lookup_invoice, so it refused the
connection string.

- ArkManager.lnLookup answers lookup_invoice from wallet state (by hash or
  bolt11, either direction; pending/settled/expired/failed, preimage once
  claimed). A retry's several actions on one hash defer to the furthest.
- The open app pushes a pending receive along before answering, so a
  merchant polling sees it settle.
- The service worker now answers make_invoice and lookup_invoice too, and
  claims a paid invoice's HTLCs during the lookup: a BTCPay sale settles
  with the wallet closed. Its list_transactions reports receives as well.
- get_info and the 13194 info event list the new method.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Dmcrt9KyNDKVWFKnb8BREo

5 files changed, 132 insertions, 12 deletions

diff --git a/src/ark/lightning.js b/src/ark/lightning.js
index 0ac80a5..568d0ab 100644
--- a/src/ark/lightning.js
+++ b/src/ark/lightning.js
@@ -61,6 +61,7 @@ export function decodeBolt11(invoice) {
     amountMsat,
     amountSat: amountMsat != null ? Number(amountMsat / 1000n) : null,
     expiresAt: (ts + expiry) * 1000,
+    createdAt: ts * 1000,
   };
 }
 
diff --git a/src/ark/manager.js b/src/ark/manager.js
index 4b65b27..dc80ca3 100644
--- a/src/ark/manager.js
+++ b/src/ark/manager.js
@@ -1068,6 +1068,50 @@ export class ArkManager {
     return this.driveLn(id);
   }
 
+  // A Lightning payment of this wallet's, either way, as NIP-47
+  // lookup_invoice reports it — found by payment hash or bolt11. null when
+  // the wallet never made or paid that invoice.
+  lnLookup({ paymentHash, invoice } = {}) {
+    const hashOf = (inv) => { try { return decodeBolt11(inv).paymentHash; } catch { return null; } };
+    const hash = String(paymentHash || (invoice && hashOf(invoice)) || '').toLowerCase();
+    if (!/^[0-9a-f]{64}$/.test(hash)) return null;
+    // a retry leaves several actions on one hash: the furthest along speaks
+    const rank = (x) => (x.step === 'done' ? 0 : x.step === 'failed' ? 2 : 1);
+    const a = (this.state.actions || []).filter((x) => (x.type === 'ln-recv' || x.type === 'ln-pay')
+      && (x.paymentHash === hash || (x.invoice && hashOf(x.invoice) === hash)))
+      .sort((x, y) => rank(x) - rank(y))[0];
+    const incoming = a ? a.type === 'ln-recv' : null;
+    const mv = (this.state.movements || []).filter((m) => (incoming == null
+      ? (m.type === 'ln-receive' || m.type === 'ln-send')
+      : m.type === (incoming ? 'ln-receive' : 'ln-send')) && (m.paymentHash === hash || (m.invoice && hashOf(m.invoice) === hash)));
+    const done = mv.find((m) => m.status === 'complete');
+    if (!a && !mv.length) return null;
+    const type = (a ? incoming : mv[0].type === 'ln-receive') ? 'incoming' : 'outgoing';
+    const inv = (a && a.invoice) || mv[0]?.invoice || '';
+    let dec = null; try { dec = inv ? decodeBolt11(inv) : null; } catch {}
+    const settled = (a && a.step === 'done') || !!done;
+    const sec = (ms) => (ms ? Math.floor(ms / 1000) : undefined);
+    let state = 'pending';
+    if (settled) state = 'settled';
+    else if ((a && a.step === 'failed') || (!a && mv.some((m) => m.status === 'failed'))) {
+      state = type === 'incoming' && dec?.expiresAt && Date.now() > dec.expiresAt ? 'expired' : 'failed';
+    } else if (type === 'incoming' && a && a.step === 'awaiting' && dec?.expiresAt && Date.now() > dec.expiresAt) state = 'expired';
+    let preimage = '';
+    if (settled) {
+      if (type === 'outgoing') preimage = (a && a.preimage) || done?.preimage || '';
+      else if (a && Number.isInteger(a.preimageIndex)) { try { preimage = hex.encode(this._lnPreimage(a.preimageIndex)); } catch {} }
+    }
+    const amountSat = (a && a.amountSat) || dec?.amountSat || done?.amountSat || 0;
+    return {
+      type, state, invoice: inv, payment_hash: hash, preimage,
+      description: '', amount: amountSat * 1000,
+      fees_paid: type === 'outgoing' ? ((a && a.feeSat) || 0) * 1000 : 0,
+      created_at: sec(dec?.createdAt || actionTs(a || {}) || mv[0]?.ts) || Math.floor(Date.now() / 1000),
+      expires_at: sec(dec?.expiresAt),
+      settled_at: settled ? sec(done?.ts || actionTs(a || {})) : undefined,
+    };
+  }
+
   lnAction(id) {
     return this.state.actions.find((a) => a.id === id && a.type.startsWith('ln-'));
   }
diff --git a/src/features/ark.js b/src/features/ark.js
index 67759c9..87bb5c9 100644
--- a/src/features/ark.js
+++ b/src/features/ark.js
@@ -3629,7 +3629,18 @@ export function arkFeature(ctx) {
     async arkMakeInvoice(amountSat, description) {
       const mgr = await connectArk();
       const a = await mgr.createLnInvoice(amountSat, description);
-      return { invoice: a.invoice, paymentHash: a.paymentHash, amountSat };
+      return { invoice: a.invoice, paymentHash: a.paymentHash, amountSat, expiresAt: a.expiresAt };
+    },
+    // NIP-47 lookup_invoice: a payment of ours by hash or bolt11. One that
+    // is still pending gets a push first (a receive whose HTLCs have
+    // arrived is claimed right here), so a merchant polling sees it settle.
+    async arkLnLookup(q) {
+      const mgr = await connectArk();
+      const found = mgr.lnLookup(q);
+      if (!found || found.state !== 'pending') return found;
+      const a = (mgr.state.actions || []).find((x) => x.paymentHash === found.payment_hash && x.type.startsWith('ln-'));
+      if (a) await Promise.race([mgr.driveLn(a.id).catch(() => {}), new Promise((r) => setTimeout(r, 8000))]);
+      return mgr.lnLookup(q);
     },
     arkMovements() { const s = arkStateNow(); return s ? (s.movements || []) : []; },
     // The wallet's reusable ark receive address (BIP-353 names publish it).
diff --git a/src/features/nwc.js b/src/features/nwc.js
index 4259207..9cf8d0b 100644
--- a/src/features/nwc.js
+++ b/src/features/nwc.js
@@ -40,7 +40,7 @@ const RES_KIND = 23195;
 const INFO_KIND = 13194;
 
 // What we can actually honour. No pay_keysend (Ark can't), no multi_pay.
-const METHODS = ['get_info', 'get_balance', 'pay_invoice', 'make_invoice', 'list_transactions'];
+const METHODS = ['get_info', 'get_balance', 'pay_invoice', 'make_invoice', 'lookup_invoice', 'list_transactions'];
 
 // Requests older than this are ignored — a relay replaying history must not
 // re-trigger payments.
@@ -461,12 +461,19 @@ export function nwcFeature(ctx) {
       const inv = await hook('arkMakeInvoice', sat, params.description || '');
       return {
         result: {
-          type: 'incoming', invoice: inv.invoice, payment_hash: inv.paymentHash,
+          type: 'incoming', state: 'pending', invoice: inv.invoice, payment_hash: inv.paymentHash,
           amount: sat * 1000, created_at: nowSec(), description: params.description || '',
+          expires_at: inv.expiresAt ? Math.floor(inv.expiresAt / 1000) : undefined,
         },
       };
     }
 
+    if (method === 'lookup_invoice') {
+      if (!params.payment_hash && !params.invoice) return errRes('OTHER', 'payment_hash or invoice required');
+      const tx = await hook('arkLnLookup', { paymentHash: params.payment_hash, invoice: params.invoice });
+      return tx ? { result: tx } : errRes('NOT_FOUND', 'invoice not found');
+    }
+
     if (method === 'list_transactions') {
       const movements = hook('arkMovements') || [];
       const txs = movements
@@ -474,7 +481,7 @@ export function nwcFeature(ctx) {
         .slice(-(params.limit || 20))
         .map((m) => ({
           type: m.type === 'ln-receive' ? 'incoming' : 'outgoing',
-          invoice: m.invoice || '', preimage: m.preimage || '',
+          state: 'settled', invoice: m.invoice || '', preimage: m.preimage || '',
           amount: (m.amountSat || 0) * 1000, fees_paid: 0,
           created_at: Math.floor((m.ts || Date.now()) / 1000),
           settled_at: Math.floor((m.ts || Date.now()) / 1000),
diff --git a/src/nwc-respond.js b/src/nwc-respond.js
index 7bf983b..27699e7 100644
--- a/src/nwc-respond.js
+++ b/src/nwc-respond.js
@@ -204,23 +204,80 @@ export async function respondFromBg(data, {
         alias: 'Coinos', color: '#15171a',
         network: rec.ark.network === 'mainnet' ? 'mainnet' : rec.ark.network,
         block_height: 0, block_hash: '',
-        methods: ['get_info', 'get_balance', 'pay_invoice', 'list_transactions'],
+        methods: ['get_info', 'get_balance', 'pay_invoice', 'make_invoice', 'lookup_invoice', 'list_transactions'],
       },
     });
     return true;
   }
+  // A merchant (BTCPay) mints an invoice per checkout and polls it until
+  // paid. Minting works like a CLINK offer; a lookup that finds the payer's
+  // HTLCs waiting claims them here, so the sale settles with the app closed.
+  if (method === 'make_invoice') {
+    const sat = Math.floor((params.amount || 0) / 1000);
+    if (!sat) { await publish(errRes('make_invoice', 'OTHER', 'amount required (msat)')); return true; }
+    if (!rec.keys5 || !rec.key4 || !rec.mgr) return false; // old mirror: wake the user
+    if (!rec.keys5[String(rec.mgr.nextLnRecvIndex || 0)]) return false; // preimage window exhausted
+    if (!rec.keys[String(rec.mgr.nextKeyIndex || 1)]) return false; // claim key window exhausted
+    let a;
+    try {
+      const mgr = await bgManager(rec, walletKey, saveFn);
+      a = await mgr.createLnInvoice(sat, String(params.description || '').slice(0, 100));
+      await saveFn(walletKey, rec);
+    } catch (e) {
+      await publish(errRes('make_invoice', 'INTERNAL', e.message || 'failed')).catch(() => {});
+      return true;
+    }
+    await publish({
+      result_type: 'make_invoice',
+      result: {
+        type: 'incoming', state: 'pending', invoice: a.invoice, payment_hash: a.paymentHash,
+        amount: sat * 1000, created_at: nowSec(), description: params.description || '',
+        expires_at: a.expiresAt ? Math.floor(a.expiresAt / 1000) : undefined,
+      },
+    });
+    log(`minted ${sat} sat invoice while closed`);
+    return true;
+  }
+  if (method === 'lookup_invoice') {
+    if (!params.payment_hash && !params.invoice) {
+      await publish(errRes('lookup_invoice', 'OTHER', 'payment_hash or invoice required'));
+      return true;
+    }
+    if (!rec.mgr) return false;
+    const q = { paymentHash: params.payment_hash, invoice: params.invoice };
+    // read straight off the mirror; the ASP is only needed to claim
+    const view = Object.assign(Object.create(ArkManager.prototype), { state: rec.mgr, account: shimAccount(rec) });
+    let tx = view.lnLookup(q);
+    const a = tx && tx.state === 'pending' && tx.type === 'incoming'
+      && (rec.mgr.actions || []).find((x) => x.type === 'ln-recv' && x.paymentHash === tx.payment_hash);
+    if (a) {
+      try {
+        const mgr = await bgManager(rec, walletKey, saveFn);
+        await Promise.race([mgr.driveLn(a.id).catch((e) => log('claim: ' + e.message)), new Promise((r) => setTimeout(r, PAY_WAIT_MS))]);
+        tx = mgr.lnLookup(q);
+        if (tx.state === 'settled') log(`received ${tx.amount / 1000} sat while closed`);
+      } catch (e) { log('ark init failed: ' + e.message); }
+    }
+    await publish(tx ? { result_type: 'lookup_invoice', result: tx } : errRes('lookup_invoice', 'NOT_FOUND', 'invoice not found'));
+    return true;
+  }
   if (method === 'get_balance') {
     await publish({ result_type: 'get_balance', result: { balance: spendableSat(rec) * 1000 } });
     return true;
   }
   if (method === 'list_transactions') {
-    const txs = (rec.spends || []).slice(-(params.limit || 20)).map((s) => ({
-      type: 'outgoing', invoice: s.invoice || '', preimage: s.preimage || '',
-      amount: (s.amountSat || 0) * 1000, fees_paid: (s.feeSat || 0) * 1000,
-      created_at: Math.floor((s.ts || Date.now()) / 1000),
-      settled_at: Math.floor((s.ts || Date.now()) / 1000),
-      description: '',
-    }));
+    // the mirrored wallet's Lightning history, both ways, as the open app reports it
+    const txs = ((rec.mgr && rec.mgr.movements) || [])
+      .filter((m) => (m.type === 'ln-send' || m.type === 'ln-receive') && m.status === 'complete')
+      .slice(-(params.limit || 20))
+      .map((m) => ({
+        type: m.type === 'ln-receive' ? 'incoming' : 'outgoing',
+        state: 'settled', invoice: m.invoice || '', preimage: m.preimage || '',
+        amount: (m.amountSat || 0) * 1000, fees_paid: 0,
+        created_at: Math.floor((m.ts || Date.now()) / 1000),
+        settled_at: Math.floor((m.ts || Date.now()) / 1000),
+        description: '',
+      }));
     await publish({ result_type: 'list_transactions', result: { transactions: txs } });
     return true;
   }