Point of sale: a bill, an optional tip prompt, one invoice, and a ledger that keeps tips apart.

A new deferred feature (src/features/pos.js): type the amount in the display
unit, optionally a note, Charge. With the tip prompt on, the customer sees
the bill and picks a percentage (configurable, default 10/15/20), their own
figure, or no tip; one Lightning invoice is made for the total through the
Ark feature's receive (new hooks arkLnInvoice/arkLnWatch/arkLnUnwatch/
arkLnCancel wrap createLnInvoice and pollArkLn). Paid, expired and cancelled
sales are recorded with the bill and the tip as separate figures, and the
fiat rate at the time; the amount screen shows today's bills, tips and total.

Doors: Settings → Payments card, and a button under the payment address on
Receive (a receiveExtras hook the names pane renders).

Co-Authored-By: Claude Fable 5.1 <[email protected]>

7 files changed, 416 insertions, 3 deletions

diff --git a/src/features/ark.js b/src/features/ark.js
index 5327a23..ef5d8fc 100644
--- a/src/features/ark.js
+++ b/src/features/ark.js
@@ -3238,6 +3238,16 @@ export function arkFeature(ctx) {
     },
     arkSpendableSat() { const b = arkBalance(); return b ? b.spendableSat : 0; },
     arkReady() { return arkAvailable(); },
+    // A Lightning invoice for another feature to watch (point of sale):
+    // the action id is the handle, the poller tells it when it settles.
+    async arkLnInvoice(amountSat, description) {
+      const mgr = await connectArk();
+      const a = await mgr.createLnInvoice(amountSat, description);
+      return { id: a.id, invoice: a.invoice, paymentHash: a.paymentHash, amountSat, expiresAt: a.expiresAt };
+    },
+    arkLnWatch(id, onSettle) { pollArkLn(id, onSettle); return true; },
+    arkLnUnwatch(id) { stopArkLnPoll(id); return true; },
+    async arkLnCancel(id) { const mgr = await connectArk(); await mgr.cancelLnInvoice(id); return true; },
     async arkMakeInvoice(amountSat, description) {
       const mgr = await connectArk();
       const a = await mgr.createLnInvoice(amountSat, description);
diff --git a/src/features/index.js b/src/features/index.js
index a32bced..73369c3 100644
--- a/src/features/index.js
+++ b/src/features/index.js
@@ -22,14 +22,15 @@ import { syncFeature } from './sync.js';
 import { messagesFeature } from './messages.js';
 
 export function buildFeatures(ctx) {
-  return [{}, arkFeature(ctx), nostrLoginFeature(ctx), namesFeature(ctx), zapsFeature(ctx), {}, {}, syncFeature(ctx), messagesFeature(ctx)];
+  return [{}, arkFeature(ctx), nostrLoginFeature(ctx), namesFeature(ctx), zapsFeature(ctx), {}, {}, syncFeature(ctx), messagesFeature(ctx), {}];
 }
 export async function loadDeferredFeatures(ctx, features) {
   const late = [];
   await Promise.all([
     import('./gifts.js').then((m) => { late.push(features[0] = m.giftsFeature(ctx)); }),
     import('./nwc.js').then((m) => { late.push(features[5] = m.nwcFeature(ctx)); }),
-    import('./hats.js').then((m) => { late.push(features[6] = m.hatsFeature(ctx)); })
+    import('./hats.js').then((m) => { late.push(features[6] = m.hatsFeature(ctx)); }),
+    import('./pos.js').then((m) => { late.push(features[9] = m.posFeature(ctx)); }),
   ]);
   return late;
 }
diff --git a/src/features/names.js b/src/features/names.js
index f05ac09..0024847 100644
--- a/src/features/names.js
+++ b/src/features/names.js
@@ -588,7 +588,8 @@ export function namesFeature(ctx) {
             onClick: () => copy(addr),
             html: '<svg width="15" height="15" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><rect width="14" height="14" x="8" y="8" rx="2" ry="2"/><path d="M4 16c-1.1 0-2-.9-2-2V4c0-1.1.9-2 2-2h10c1.1 0 2 .9 2 2"/></svg>',
           }))),
-      moreSection());
+      moreSection(),
+      (ctx.hook && ctx.hook('receiveExtras')) || null);
   }
 
   // ---- BOLT 12 offers with a memo ----------------------------------------
diff --git a/src/features/pos.js b/src/features/pos.js
new file mode 100644
index 0000000..c7e5882
--- /dev/null
+++ b/src/features/pos.js
@@ -0,0 +1,264 @@
+// Point of sale: a bill for a stated amount, an optional tip prompt for the
+// customer (a few percentages, or their own figure), one Lightning invoice
+// for the total — and a ledger that keeps the bill and the tip apart, so a
+// day's tips can be counted on their own.
+//
+// Everything money-shaped goes through the Ark feature's Lightning receive
+// (the same invoices the Receive tab hands out); this file is the flow and
+// the ledger. Amounts are typed in the display unit (sats / BTC / your
+// currency) and kept in sats, with the fiat rate at the time of the sale
+// remembered so a receipt reads the same later.
+import { qrSvg } from '../qr.js';
+import { rateNow, getCurrency, fmtFiat } from '../rates.js';
+import { t } from '../i18n.js';
+
+export function posFeature(ctx) {
+  const { h, ui, render, wallet, toast, copy, fmtAmount, unitLabel, unitTag, parseAmount, getUnit } = ctx;
+  const hook = ctx.hook || (() => null);
+
+  // ---- state ---------------------------------------------------------------
+  // { sales: [{ id, at, billSat, tipSat, tipPct, note, invoice, lnId, status: 'open'|'paid'|'void', fiat: { code, rate } }],
+  //   askTip: true, tips: [10, 15, 20] }
+  const st = () => {
+    const s = wallet.loadFeatureState('pos', {}) || {};
+    s.sales ||= [];
+    if (s.askTip == null) s.askTip = true;
+    if (!Array.isArray(s.tips) || !s.tips.length) s.tips = [10, 15, 20];
+    return s;
+  };
+  const save = (s) => { try { wallet.saveFeatureState('pos', s); } catch {} };
+  const SALES_MAX = 500;
+
+  const fiatLine = (sats, rate = rateNow(), code = getCurrency()) => (rate ? fmtFiat(sats, rate, code) : '');
+  const pct = (sats, p) => Math.round(sats * p / 100);
+  const dayKey = (ms) => new Date(ms).toDateString();
+
+  // ---- flow ----------------------------------------------------------------
+  // ui.pos: { step: 'amount'|'tip'|'invoice'|'paid', amount, note, tipMode, tipCustom, sale, error, busy }
+  function open() {
+    ui.pos = { step: 'amount', amount: '', note: '', tipMode: null, tipCustom: '', sale: null, error: '' };
+    render();
+  }
+  function close() {
+    const p = ui.pos;
+    if (p && p.sale && p.sale.status === 'open') voidSale(p.sale);
+    ui.pos = null;
+    render();
+  }
+  function billSat() {
+    const p = ui.pos;
+    const n = parseAmount(p.amount, getUnit());
+    return n && n > 0 ? n : 0;
+  }
+  function charge() {
+    const p = ui.pos;
+    const bill = billSat();
+    if (!bill) { p.error = t('posEnterAmount'); render(); return; }
+    p.error = '';
+    if (!hook('arkReady')) { p.error = t('posNeedsSpending'); render(); return; }
+    if (st().askTip) { p.step = 'tip'; p.tipMode = null; p.tipCustom = ''; render(); return; }
+    makeSale(bill, 0, 0);
+  }
+  function tipSat() {
+    const p = ui.pos, bill = billSat();
+    if (p.tipMode == null || p.tipMode === 'none') return 0;
+    if (p.tipMode === 'custom') { const n = parseAmount(p.tipCustom, getUnit()); return n && n > 0 ? n : 0; }
+    return pct(bill, p.tipMode);
+  }
+  async function makeSale(bill, tip, tipPct) {
+    const p = ui.pos;
+    p.busy = true; p.error = ''; render();
+    const s = st();
+    const sale = {
+      id: 's' + Date.now().toString(36) + Math.random().toString(36).slice(2, 6),
+      at: Date.now(), billSat: bill, tipSat: tip, tipPct, note: (p.note || '').trim().slice(0, 80),
+      status: 'open', fiat: rateNow() ? { code: getCurrency(), rate: rateNow() } : null,
+    };
+    try {
+      const memo = (sale.note ? sale.note + ' · ' : '') + t('posMemo', { bill: fmtAmount(bill) + ' ' + unitLabel(), tip: tip ? fmtAmount(tip) + ' ' + unitLabel() : '0' });
+      const inv = await hook('arkLnInvoice', bill + tip, memo.slice(0, 120));
+      if (!inv || !inv.invoice) throw new Error(t('posInvoiceFailed'));
+      sale.invoice = inv.invoice; sale.lnId = inv.id;
+      s.sales.push(sale);
+      if (s.sales.length > SALES_MAX) s.sales = s.sales.slice(-SALES_MAX);
+      save(s);
+      p.sale = sale; p.step = 'invoice';
+      hook('arkLnWatch', inv.id, (a) => settle(sale, a));
+    } catch (e) {
+      p.error = e.message || String(e);
+    }
+    p.busy = false; render();
+  }
+  function settle(sale, action) {
+    const s = st();
+    const row = s.sales.find((x) => x.id === sale.id);
+    const paid = action && action.step === 'done';
+    if (row) { row.status = paid ? 'paid' : 'void'; if (paid) row.paidAt = Date.now(); save(s); }
+    if (ui.pos && ui.pos.sale && ui.pos.sale.id === sale.id) {
+      ui.pos.sale = row || sale;
+      ui.pos.step = paid ? 'paid' : 'amount';
+      if (!paid) ui.pos.error = t('posInvoiceExpired');
+    }
+    render();
+  }
+  function voidSale(sale) {
+    const s = st();
+    const row = s.sales.find((x) => x.id === sale.id);
+    if (row && row.status === 'open') { row.status = 'void'; save(s); }
+    if (sale.lnId) { hook('arkLnUnwatch', sale.lnId); Promise.resolve(hook('arkLnCancel', sale.lnId)).catch(() => {}); }
+  }
+  function newSale() {
+    const p = ui.pos;
+    if (p.sale && p.sale.status === 'open') voidSale(p.sale);
+    Object.assign(p, { step: 'amount', amount: '', note: '', tipMode: null, tipCustom: '', sale: null, error: '' });
+    render();
+  }
+
+  // ---- screens -------------------------------------------------------------
+  const big = (text) => h('div', { class: 'pos-big' }, text);
+  const money = (sats, rate) => h('div', { class: 'col', style: 'align-items:center;gap:2px' },
+    big(fmtAmount(sats) + ' ' + unitLabel()),
+    fiatLine(sats, rate) && getUnit() !== 'fiat' ? h('div', { class: 'muted' }, fiatLine(sats, rate)) : null);
+  const back = () => h('button', { class: 'btn-ghost btn-block', onClick: close }, t('back'));
+
+  function amountScreen(p) {
+    const s = st();
+    return h('div', { class: 'col', style: 'gap:16px' },
+      ctx.brandHeader(false),
+      h('div', { class: 'card col', style: 'gap:12px' },
+        h('h3', { style: 'margin:0' }, t('posTitle')),
+        h('div', { class: 'input-group' },
+          h('input', {
+            type: 'text', inputmode: 'decimal', class: 'pos-amount', placeholder: '0', value: p.amount, autofocus: true,
+            onInput: (e) => { p.amount = e.target.value; },
+            onKeydown: (e) => { if (e.key === 'Enter') charge(); },
+          }),
+          unitTag()),
+        getUnit() !== 'fiat' && billSat() && fiatLine(billSat()) ? h('div', { class: 'small muted', style: 'text-align:right' }, fiatLine(billSat())) : null,
+        h('input', { type: 'text', placeholder: t('posNoteHint'), value: p.note, maxlength: '80', onInput: (e) => { p.note = e.target.value; } }),
+        p.error ? h('div', { class: 'notice error small' }, p.error) : null,
+        h('button', { class: 'btn-primary btn-block', disabled: !!p.busy, onClick: charge }, p.busy ? h('span', { class: 'spinner sm' }) : t('posCharge'))),
+      tipSettingsCard(s),
+      salesCard(s),
+      back());
+  }
+  function tipSettingsCard(s) {
+    return h('div', { class: 'card col', style: 'gap:8px' },
+      h('label', { class: 'row gap6', style: 'align-items:center;cursor:pointer' },
+        h('input', { type: 'checkbox', checked: !!s.askTip, style: 'width:18px;height:18px;accent-color:var(--accent);margin:0',
+          onChange: (e) => { const x = st(); x.askTip = e.target.checked; save(x); render(); } }),
+        h('span', {}, t('posAskTip'))),
+      s.askTip ? h('label', { class: 'row gap6', style: 'align-items:center' },
+        h('span', { class: 'small muted', style: 'flex:0 0 auto' }, t('posTipChoices')),
+        h('input', { type: 'text', class: 'grow', value: s.tips.join(', '), inputmode: 'numeric',
+          onChange: (e) => {
+            const x = st();
+            const list = [...new Set(e.target.value.split(/[\s,]+/).map((v) => parseInt(v, 10)).filter((n) => n > 0 && n <= 100))].slice(0, 5);
+            if (list.length) { x.tips = list; save(x); }
+            render();
+          } }),
+        h('span', { class: 'small muted' }, '%')) : null);
+  }
+  function salesCard(s) {
+    const sales = [...s.sales].reverse();
+    if (!sales.length) return null;
+    const today = dayKey(Date.now());
+    const paidToday = sales.filter((x) => x.status === 'paid' && dayKey(x.paidAt || x.at) === today);
+    const sum = (k) => paidToday.reduce((n, x) => n + (x[k] || 0), 0);
+    const row = (x) => h('div', { class: 'row between pos-sale' + (x.status === 'paid' ? '' : ' faint') },
+      h('div', { class: 'col', style: 'min-width:0;gap:1px' },
+        h('span', {}, fmtAmount(x.billSat) + ' ' + unitLabel() + (x.tipSat ? ' + ' + fmtAmount(x.tipSat) + ' ' + t('posTipWord') : '')),
+        h('span', { class: 'small muted', style: 'overflow:hidden;text-overflow:ellipsis;white-space:nowrap' },
+          new Date(x.paidAt || x.at).toLocaleTimeString([], { hour: '2-digit', minute: '2-digit' }) + (x.note ? ' · ' + x.note : '')
+          + (x.status === 'open' ? ' · ' + t('posAwaiting') : x.status === 'void' ? ' · ' + t('posVoid') : ''))),
+      h('span', { class: 'amount-pos', style: 'white-space:nowrap' }, (x.status === 'paid' ? '+' : '') + fmtAmount(x.billSat + x.tipSat)));
+    return h('div', { class: 'card col', style: 'gap:8px' },
+      h('h3', { style: 'margin:0' }, t('posSalesToday')),
+      h('div', { class: 'row between' }, h('span', { class: 'muted' }, t('posBills')), h('span', {}, fmtAmount(sum('billSat')) + ' ' + unitLabel())),
+      h('div', { class: 'row between' }, h('span', { class: 'muted' }, t('posTips')), h('span', {}, fmtAmount(sum('tipSat')) + ' ' + unitLabel())),
+      h('div', { class: 'row between', style: 'font-weight:600' }, h('span', {}, t('posTotal')), h('span', {}, fmtAmount(sum('billSat') + sum('tipSat')) + ' ' + unitLabel())),
+      h('div', { class: 'col', style: 'gap:6px;margin-top:4px' }, ...sales.slice(0, 30).map(row)));
+  }
+  // The customer's screen: the bill, and how much to add to it.
+  function tipScreen(p) {
+    const bill = billSat();
+    const s = st();
+    const choice = (mode, label, sub) => h('button', {
+      class: 'pos-tip' + (p.tipMode === mode ? ' on' : ''), type: 'button',
+      onClick: () => { p.tipMode = mode; render(); },
+    }, h('span', { class: 'pos-tip-label' }, label), sub ? h('span', { class: 'small muted' }, sub) : null);
+    const tip = tipSat();
+    return h('div', { class: 'col', style: 'gap:16px' },
+      ctx.brandHeader(false),
+      h('div', { class: 'card col', style: 'gap:14px;align-items:center' },
+        h('div', { class: 'muted' }, t('posYourBill')),
+        money(bill),
+        h('div', { class: 'muted', style: 'margin-top:6px' }, t('posAddTip')),
+        h('div', { class: 'pos-tips' },
+          ...s.tips.map((n) => choice(n, n + '%', '+' + fmtAmount(pct(bill, n)) + ' ' + unitLabel())),
+          choice('custom', t('posTipCustom'), null),
+          choice('none', t('posNoTip'), null)),
+        p.tipMode === 'custom' ? h('div', { class: 'input-group', style: 'width:100%' },
+          h('input', { type: 'text', inputmode: 'decimal', placeholder: '0', value: p.tipCustom, autofocus: true, onInput: (e) => { p.tipCustom = e.target.value; render(); } }),
+          h('span', { class: 'small muted', style: 'align-self:center;padding:0 8px' }, unitLabel())) : null,
+        p.tipMode != null ? h('div', { class: 'small muted' }, t('posTotalLine', { n: fmtAmount(bill + tip) + ' ' + unitLabel() })) : null,
+        h('button', { class: 'btn-primary btn-block', disabled: p.tipMode == null || !!p.busy,
+          onClick: () => makeSale(bill, tip, p.tipMode === 'custom' || p.tipMode === 'none' ? 0 : p.tipMode) },
+          p.busy ? h('span', { class: 'spinner sm' }) : t('posContinue'))),
+      h('button', { class: 'btn-ghost btn-block', onClick: () => { p.step = 'amount'; render(); } }, t('back')));
+  }
+  function invoiceScreen(p) {
+    const sale = p.sale;
+    const total = sale.billSat + sale.tipSat;
+    return h('div', { class: 'col', style: 'gap:16px' },
+      ctx.brandHeader(false),
+      h('div', { class: 'card col', style: 'gap:12px;align-items:center' },
+        h('div', { class: 'muted' }, t('posScanToPay')),
+        money(total, sale.fiat && sale.fiat.rate),
+        sale.tipSat ? h('div', { class: 'small muted' }, t('posBreakdown', { bill: fmtAmount(sale.billSat), tip: fmtAmount(sale.tipSat), u: unitLabel() })) : null,
+        h('div', { class: 'pos-qr', html: qrSvg(sale.invoice.toUpperCase()) }),
+        h('div', { class: 'row gap6', style: 'width:100%' },
+          h('button', { class: 'grow', onClick: () => copy(sale.invoice) }, t('copy')),
+          h('button', { class: 'btn-ghost grow', onClick: newSale }, t('cancel'))),
+        h('div', { class: 'row gap6', style: 'align-items:center' }, h('span', { class: 'spinner sm' }), h('span', { class: 'small muted' }, t('posWaiting')))));
+  }
+  function paidScreen(p) {
+    const sale = p.sale;
+    return h('div', { class: 'col', style: 'gap:16px' },
+      ctx.brandHeader(false),
+      h('div', { class: 'card col', style: 'gap:12px;align-items:center' },
+        h('div', { class: 'pos-check' }, '✓'),
+        h('h3', { style: 'margin:0' }, t('posPaid')),
+        money(sale.billSat + sale.tipSat, sale.fiat && sale.fiat.rate),
+        sale.tipSat ? h('div', { class: 'small muted' }, t('posBreakdown', { bill: fmtAmount(sale.billSat), tip: fmtAmount(sale.tipSat), u: unitLabel() })) : null,
+        h('button', { class: 'btn-primary btn-block', onClick: newSale }, t('posNewSale'))),
+      back());
+  }
+  function posScreen() {
+    const p = ui.pos;
+    if (p.step === 'tip') return tipScreen(p);
+    if (p.step === 'invoice' && p.sale) return invoiceScreen(p);
+    if (p.step === 'paid' && p.sale) return paidScreen(p);
+    return amountScreen(p);
+  }
+
+  return {
+    id: 'pos',
+    screenView() {
+      if (ui.screen !== 'wallet' || !ui.pos) return null;
+      return posScreen();
+    },
+    // Settings → Payments: the door, and the tip choices.
+    settingsCards() {
+      return [h('div', { class: 'card col', style: 'gap:8px' },
+        h('h3', {}, t('posTitle')),
+        h('p', { class: 'small muted', style: 'margin:0' }, t('posDesc')),
+        h('button', { class: 'btn-primary', onClick: open }, t('posOpen')))];
+    },
+    // Under the payment address on Receive.
+    receiveExtras() {
+      return h('button', { class: 'btn-sm', onClick: open }, '\u{1F9FE} ' + t('posTitle'));
+    },
+    openPos: open,
+  };
+}
diff --git a/src/i18n.js b/src/i18n.js
index 5ce4a18..721bf98 100644
--- a/src/i18n.js
+++ b/src/i18n.js
@@ -245,6 +245,36 @@ const STR = {
     feedSumFollowsPlus: 'Everyone you follow + {n} more',
     feedSumPeople: '{n} people',
     feedPacks: 'Follow packs',
+    posTitle: 'Point of sale',
+    posDesc: 'Charge a customer a set amount, with an optional tip prompt. Bills and tips are counted separately.',
+    posOpen: 'Open',
+    posEnterAmount: 'Enter an amount first',
+    posNeedsSpending: 'Point of sale takes Lightning into Spending — connect first',
+    posNoteHint: 'Note (optional)',
+    posCharge: 'Charge',
+    posAskTip: 'Ask the customer for a tip',
+    posTipChoices: 'Tip choices',
+    posYourBill: 'Your bill',
+    posAddTip: 'Add a tip?',
+    posTipCustom: 'Other',
+    posNoTip: 'No tip',
+    posTotalLine: 'Total {n}',
+    posContinue: 'Continue',
+    posScanToPay: 'Scan to pay',
+    posBreakdown: 'Bill {bill} + tip {tip} {u}',
+    posWaiting: 'Waiting for payment…',
+    posPaid: 'Paid',
+    posNewSale: 'New sale',
+    posInvoiceFailed: 'Could not create an invoice',
+    posInvoiceExpired: 'That invoice expired before it was paid',
+    posMemo: 'Bill {bill}, tip {tip}',
+    posSalesToday: 'Today',
+    posBills: 'Bills',
+    posTips: 'Tips',
+    posTotal: 'Total',
+    posTipWord: 'tip',
+    posVoid: 'cancelled',
+    posAwaiting: 'awaiting payment',
     linkHandlerTitle: 'Open links here',
     linkHandlerDesc: 'Make this app the one your browser opens for nostr links (what njump calls "Your default web app") and bitcoin: links.',
     linkHandlerNostr: 'nostr links',
diff --git a/src/style.css b/src/style.css
index e9bc882..2feab6e 100644
--- a/src/style.css
+++ b/src/style.css
@@ -590,6 +590,17 @@ hr.divider { margin: 16px 0; }
    post's full width so each is a comfortable target, quiet until one carries
    a count or you've used it. */
 .note-acts { margin-top: 8px; justify-content: space-between; gap: 4px; max-width: 340px; }
+/* point of sale */
+.pos-amount { font-size: 28px; font-weight: 600; text-align: right; }
+.pos-big { font-size: 34px; font-weight: 700; line-height: 1.1; letter-spacing: -.5px; }
+.pos-tips { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; width: 100%; }
+.pos-tip { display: flex; flex-direction: column; align-items: center; gap: 2px; padding: 12px 6px; border: 1px solid var(--line); border-radius: 12px; background: var(--surface2); color: var(--ink); cursor: pointer; }
+.pos-tip.on { border-color: var(--accent); background: var(--accent); color: var(--accent-fg); }
+.pos-tip.on .muted { color: inherit; opacity: .8; }
+.pos-tip-label { font-size: 20px; font-weight: 600; }
+.pos-qr svg { width: min(260px, 70vw); height: auto; display: block; }
+.pos-check { width: 64px; height: 64px; border-radius: 50%; background: var(--green, #2e7d32); color: #fff; display: flex; align-items: center; justify-content: center; font-size: 34px; }
+.pos-sale.faint { opacity: .55; }
 /* the feeds row: pills that scroll sideways, the one on screen filled */
 .feed-chips { gap: 6px; flex-wrap: nowrap; overflow-x: auto; margin: 0 -14px; padding: 2px 14px; scrollbar-width: none; -webkit-overflow-scrolling: touch; }
 .feed-chips::-webkit-scrollbar { display: none; }
diff --git a/tools/pos-test.js b/tools/pos-test.js
new file mode 100644
index 0000000..3dad594
--- /dev/null
+++ b/tools/pos-test.js
@@ -0,0 +1,96 @@
+// Point of sale: amount → tip prompt → one invoice for the total → paid, with
+// the bill and the tip counted apart. The Ark side is faked: no relays, no
+// server, no money. Run: bun tools/pos-test.js
+import assert from 'node:assert/strict';
+import puppeteer from 'puppeteer-core';
+
+const app = await Bun.file('src/app.js').text();
+const domHelper = app.slice(app.indexOf('function h(tag,'), app.indexOf('// ---------------------------------------------------------------- morphing'));
+const entry = `
+import { posFeature } from './src/features/pos.js';
+${domHelper}
+const state = {};
+const ui = { screen: 'wallet' };
+let watch = null, cancelled = [], invoices = 0;
+const wallet = { loadFeatureState: (k, d) => (k in state ? state[k] : d), saveFeatureState: (k, v) => { state[k] = JSON.parse(JSON.stringify(v)); } };
+const ctx = {
+  h, ui, wallet, render, toast: (m) => (window.toasts = (window.toasts || [])).push(m), copy: (x) => (window.copied = x),
+  fmtAmount: (n) => Number(n).toLocaleString('en-US'), unitLabel: () => 'sats', unitTag: () => h('span', { class: 'unit-tag' }, 'sats'),
+  parseAmount: (v) => { const n = Number(String(v).replace(/,/g, '')); return isFinite(n) ? Math.round(n) : null; }, getUnit: () => 'sats',
+  brandHeader: () => null,
+  hook(name, ...a) {
+    if (name === 'arkReady') return true;
+    if (name === 'arkLnInvoice') { invoices++; return Promise.resolve({ id: 'ln' + invoices, invoice: 'lnbc' + a[0] + 'n1testinvoice' + invoices, amountSat: a[0] }); }
+    if (name === 'arkLnWatch') { watch = { id: a[0], cb: a[1] }; return true; }
+    if (name === 'arkLnUnwatch') { if (watch && watch.id === a[0]) watch = null; return true; }
+    if (name === 'arkLnCancel') { cancelled.push(a[0]); return Promise.resolve(true); }
+    return null;
+  },
+};
+const feature = posFeature(ctx);
+function render() { document.querySelector('#app').replaceChildren(feature.screenView() || h('div', { id: 'closed' }, 'closed')); }
+window.test = { open: () => { feature.openPos(); }, settle: (ok) => { const w = watch; watch = null; w.cb({ step: ok ? 'done' : 'failed' }); }, get watch() { return watch && watch.id; }, get cancelled() { return cancelled; }, get sales() { return (state.pos || {}).sales || []; }, ui };
+render();
+`;
+const bundle = await Bun.build({
+  entrypoints: ['pos-test-entry'], target: 'browser',
+  plugins: [{ name: 'pos-test', setup(build) {
+    build.onResolve({ filter: /^pos-test-entry$/ }, () => ({ path: 'entry', namespace: 'pos-test' }));
+    build.onLoad({ filter: /.*/, namespace: 'pos-test' }, () => ({ contents: entry, loader: 'js', resolveDir: process.cwd() }));
+  } }],
+});
+assert(bundle.success, bundle.logs.join('\n'));
+const css = await Bun.file('src/style.css').text();
+const js = await bundle.outputs[0].text();
+const html = `<!doctype html><meta name="viewport" content="width=device-width, initial-scale=1"><style>${css}</style><div id="app"></div><script type="module">${js}</script>`;
+const server = Bun.serve({ port: 0, fetch: () => new Response(html, { headers: { 'content-type': 'text/html' } }) });
+const browser = await puppeteer.launch({ executablePath: '/usr/bin/google-chrome', headless: true, args: ['--no-sandbox'] });
+const page = await browser.newPage();
+const errors = [];
+page.on('pageerror', (e) => errors.push(e.message));
+const pause = (ms) => new Promise((r) => setTimeout(r, ms));
+const check = (name, value) => { assert(value, name); console.log(' ✓ ' + name); };
+const text = () => page.evaluate(() => document.body.innerText.replace(/\s+/g, ' '));
+const click = (label) => page.evaluate((x) => { const b = [...document.querySelectorAll('button')].find((n) => (n.querySelector('.pos-tip-label') || n).textContent.trim() === x); if (!b) return false; b.click(); return true; }, label);
+const type = async (sel, v) => { await page.evaluate((s) => { const i = document.querySelector(s); i.value = ''; }, sel); await page.type(sel, v); };
+try {
+  await page.setViewport({ width: 390, height: 844 });
+  await page.goto(server.url.href);
+  await page.waitForSelector('#closed');
+  await page.evaluate(() => test.open()); await pause(50);
+  check('the point of sale opens on the amount screen', /Point of sale/.test(await text()) && !!(await page.$('.pos-amount')));
+  await click('Charge'); await pause(50);
+  check('charging nothing asks for an amount', /Enter an amount first/.test(await text()));
+  await type('.pos-amount', '1000'); await type('input[placeholder="Note (optional)"]', 'Table 4');
+  await click('Charge'); await pause(50);
+  check('the tip prompt shows the bill and the tip choices', /Your bill 1,000 sats/.test(await text()) && /10%.*15%.*20%.*Other.*No tip/.test(await text()));
+  await click('15%'); await pause(50);
+  check('a percentage shows the total', /Total 1,150 sats/.test(await text()));
+  await click('Continue'); await pause(100);
+  check('one invoice is made for bill plus tip', await page.evaluate(() => test.watch === 'ln1') && /1,150 sats/.test(await text()) && /Bill 1,000 \+ tip 150 sats/.test(await text()) && !!(await page.$('.pos-qr svg')));
+  await click('Copy');
+  check('copy hands over the invoice', await page.evaluate(() => window.copied === 'lnbc1150n1testinvoice1'));
+  await page.evaluate(() => test.settle(true)); await pause(50);
+  check('settlement shows Paid with the breakdown', /Paid/.test(await text()) && /Bill 1,000 \+ tip 150 sats/.test(await text()));
+  await click('New sale'); await pause(50);
+  check('the ledger keeps the bill and the tip apart', /Bills 1,000 sats/.test(await text()) && /Tips 150 sats/.test(await text()) && /Total 1,150 sats/.test(await text()) && /Table 4/.test(await text()));
+
+  console.log('\n[a custom tip, then a cancelled sale]');
+  await type('.pos-amount', '2000'); await click('Charge'); await pause(50);
+  await click('Other'); await pause(50);
+  await page.evaluate(() => { const i = document.querySelector('input[placeholder="0"]:not(.pos-amount)'); i.value = '50'; i.dispatchEvent(new Event('input')); }); await pause(50);
+  check('a custom tip adds what was typed', /Total 2,050 sats/.test(await text()));
+  await click('Continue'); await pause(100);
+  await click('Cancel'); await pause(50);
+  check('cancelling voids the sale and the invoice', await page.evaluate(() => test.cancelled.includes('ln2') && test.sales.find((s) => s.billSat === 2000).status === 'void') && /cancelled/.test(await text()));
+  check('a cancelled sale does not count', /Bills 1,000 sats/.test(await text()) && /Tips 150 sats/.test(await text()));
+
+  console.log('\n[no tip prompt]');
+  await page.click('input[type=checkbox]'); await pause(50);
+  await type('.pos-amount', '300'); await click('Charge'); await pause(100);
+  check('with the prompt off, Charge goes straight to the invoice', /Scan to pay/.test(await text()) && /300 sats/.test(await text()) && await page.evaluate(() => test.watch === 'ln3'));
+  await page.evaluate(() => test.settle(false)); await pause(50);
+  check('an expired invoice returns to the amount screen and says so', /That invoice expired/.test(await text()));
+  check('no browser errors', errors.length === 0);
+} finally { await browser.close(); server.stop(true); }
+console.log('\n✅ point of sale');