Features: extract swaps, Ark, and SP behind a plugin seam

First step toward optional build profiles. app.js gains a small feature
registry (ctx + FEATURES + hook helpers); swaps/Ark/silent-payments UI
moves wholesale to src/features/{swaps,ark,sp}.js, each exporting a
factory returning integration hooks:

  init/stop/networkChanged        wallet lifecycle
  receiveModes/receiveTakeover    receive tab
  isSendDest/matchSendText/
  interceptReview/sendView/
  hideSendControls/sendFormNote   send flow
  historyEntries/historyDetail/
  txDetailSection                 history
  balanceLines/settingsCards      balance card + settings

No behavior change: ark + gift browser e2e suites pass, and a probe
confirms LN receive, all receive modes, and the three settings cards
render as before. Gifts extraction and build flags come next.

Co-Authored-By: Claude Fable 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01QFAcD4V284DvYZZHP7Rxxy

3 files changed, 704 insertions, 0 deletions

diff --git a/src/features/ark.js b/src/features/ark.js
new file mode 100644
index 0000000..24acfea
--- /dev/null
+++ b/src/features/ark.js
@@ -0,0 +1,429 @@
+// Ark feature — off-chain payments via an ASP (Second's bark/captaind
+// protocol, spoken natively by ../ark). Receive address + boarding, instant
+// sends, history entries, refresh/consolidation, server settings.
+
+import { ArkManager } from '../ark/manager.js';
+import { getNetwork, arkPresets, getArkProviderId, setArkProviderId, getArkCustom, setArkCustom, getArkConfig } from '../api.js';
+import { t } from '../i18n.js';
+import { qrSvg } from '../qr.js';
+import { shortAddr, shortTxid, timeAgo } from '../format.js';
+
+// t?ark1… bech32m — an Ark address for this or another ASP.
+export function isArkAddress(a) { return /^t?ark1[a-z0-9]{20,}$/i.test((a || '').trim()); }
+
+export function arkFeature(ctx) {
+  const { h, ui, render, wallet, blankSend, fmtAmount, unitLabel, unitTag, copyBtn, toast, openExternal } = ctx;
+
+  // One manager per open wallet; null when Ark is off in Settings, watch-only,
+  // or not yet dialed (lazy: fresh wallets connect on first use).
+  let ark = null;
+  let arkTimer = null;
+  let arkConnectPromise = null;
+  let arkInitGen = 0; // guards against a stale init() resolving after a wallet switch
+
+  function stopArk() {
+    arkInitGen++;
+    if (arkTimer) clearInterval(arkTimer);
+    arkTimer = null;
+    if (ark) ark.stopMailboxStream();
+    ark = null;
+    arkConnectPromise = null;
+  }
+
+  function arkAvailable() {
+    return !!getArkConfig() && !wallet.watchOnly && !!wallet.account;
+  }
+
+  function arkWanted() {
+    const st = wallet.loadArkState();
+    return !!(st && ((st.vtxos || []).length || (st.movements || []).length
+      || (st.actions || []).some((a) => !['done', 'failed'].includes(a.step))));
+  }
+
+  function initArk() {
+    stopArk();
+    ui.arkError = '';
+    if (arkAvailable() && arkWanted()) connectArk().catch(() => {});
+  }
+
+  function connectArk() {
+    if (ark) return Promise.resolve(ark);
+    if (arkConnectPromise) return arkConnectPromise;
+    if (!arkAvailable()) return Promise.reject(new Error(t('arkNotConnected')));
+    const cfg = getArkConfig();
+    const gen = arkInitGen;
+    const mgr = new ArkManager({
+      account: wallet.account(),
+      storage: { load: () => wallet.loadArkState(), save: (s) => wallet.saveArkState(s) },
+      arkUrl: cfg.ark,
+      esploraUrl: cfg.esplora,
+      network: getNetwork(),
+      onUpdate: () => render(),
+    });
+    ui.arkError = '';
+    arkConnectPromise = mgr.init().then(() => {
+      if (gen !== arkInitGen) throw new Error('superseded'); // wallet switched mid-connect
+      ark = mgr;
+      const tick = () => mgr.sync().catch(() => {});
+      tick();
+      // Receives arrive in real time over the mailbox stream; the poll is the
+      // fallback and what drives in-flight boards/refreshes forward.
+      mgr.startMailboxStream();
+      arkTimer = setInterval(() => { if (ark === mgr) tick(); }, getNetwork() === 'regtest' ? 5000 : 30000);
+      render();
+      return mgr;
+    }).catch((e) => {
+      if (gen === arkInitGen) { ui.arkError = e.message; render(); }
+      throw e;
+    }).finally(() => { arkConnectPromise = null; });
+    render();
+    return arkConnectPromise;
+  }
+
+  function arkBalance() {
+    if (!ark || !ark.state) return null;
+    return ark.balance();
+  }
+
+  function arkSendReview() {
+    if (ui.arkSent) {
+      return h(
+        'div',
+        {
+          class: 'card col',
+          style: 'align-items:center;text-align:center;gap:14px;cursor:pointer;padding:48px 20px',
+          onClick: () => { ui.arkSent = null; ui.send = blankSend(); render(); },
+        },
+        h('div', { class: 'check-badge' }, '✓'),
+        h('h2', { style: 'margin:0' }, t('arkSentTitle')),
+        h('div', { class: 'amount-neg', style: 'font-size:18px' }, '-' + fmtAmount(ui.arkSent.amountSat) + ' ' + unitLabel()),
+        h('div', { class: 'small muted' }, t('tapToProceed'))
+      );
+    }
+    const a = ui.arkSend;
+    const row = (k, v) => h('div', { class: 'row between' }, h('span', { class: 'small muted' }, k), h('span', { class: 'small' }, v));
+    return h(
+      'div',
+      { class: 'card col', style: 'gap:12px' },
+      h('h3', {}, t('arkSendTitle')),
+      row(t('lnPayAmount'), fmtAmount(a.amountSat) + ' ' + unitLabel()),
+      row(t('arkPayTo'), shortAddr(a.address, 14)),
+      row(t('networkFee'), t('arkNoFee')),
+      ui.sendError ? h('div', { class: 'notice err' }, ui.sendError) : null,
+      h('div', { class: 'row gap6' },
+        h('button', { class: 'btn-ghost', onClick: () => { ui.arkSend = null; ui.sendError = ''; render(); } }, t('back')),
+        ui.busy
+          ? h('button', { class: 'btn-primary grow', disabled: true }, h('span', { class: 'spinner' }))
+          : h('button', { class: 'btn-primary grow', onClick: doArkSend }, t('arkSendBtn'))
+      )
+    );
+  }
+
+  async function doArkSend() {
+    const a = ui.arkSend;
+    ui.busy = true; ui.sendError = ''; render();
+    try {
+      const mgr = await connectArk();
+      await mgr.send(a.address, a.amountSat);
+      ui.arkSent = { amountSat: a.amountSat };
+      ui.arkSend = null;
+    } catch (e) {
+      ui.sendError = e.message;
+    }
+    ui.busy = false; render();
+  }
+
+  function arkHistoryItem(m) {
+    const incoming = m.type !== 'send';
+    const label = m.type === 'receive' ? t('received') : m.type === 'board' ? t('arkBoarded') : t('sent');
+    return h(
+      'div',
+      { class: 'item', style: 'cursor:pointer', onClick: () => { ui.arkMoveDetail = m.id; render(); } },
+      h('div', { class: `ico ${incoming ? 'in' : 'out'}` }, incoming ? '↓' : '↑'),
+      h('div', { class: 'grow' },
+        h('div', { class: 'row gap6' },
+          label,
+          h('span', { class: 'tag' }, 'Ark'),
+          m.status !== 'complete' ? h('span', { class: 'tag pending' }, m.status) : null),
+        h('div', { class: 'small faint' }, timeAgo(m.ts / 1000))),
+      h('div', { style: 'text-align:right' },
+        h('div', { class: incoming ? 'amount-pos' : 'amount-neg' }, (incoming ? '+' : '-') + fmtAmount(m.amountSat)))
+    );
+  }
+
+  function arkMoveDetailView(m) {
+    const incoming = m.type !== 'send';
+    const label = m.type === 'receive' ? t('received') : m.type === 'board' ? t('arkBoarded') : t('sent');
+    const row = (k, v) => h('div', { class: 'row between', style: 'gap:12px' },
+      h('span', { class: 'small muted', style: 'flex-shrink:0' }, k), h('span', { class: 'small', style: 'text-align:right;word-break:break-all' }, v));
+    const url = m.txid ? wallet.api.explorerTx(m.txid) : null;
+    return h(
+      'div',
+      { class: 'card col', style: 'gap:10px' },
+      h('div', { class: 'row gap6', style: 'align-items:center' },
+        h('h3', { style: 'margin:0' }, label),
+        h('span', { class: 'tag' }, 'Ark'),
+        m.status !== 'complete' ? h('span', { class: 'tag pending' }, m.status) : null),
+      h('div', { class: incoming ? 'amount-pos' : 'amount-neg', style: 'font-size:20px' },
+        (incoming ? '+' : '-') + fmtAmount(m.amountSat) + ' ' + unitLabel()),
+      row(t('dateLabel'), new Date(m.ts).toLocaleString()),
+      m.to ? row(t('arkPayTo'), shortAddr(m.to, 16, 12)) : null,
+      m.vtxoId ? row(t('arkVtxoId'), shortTxid(m.vtxoId)) : null,
+      m.detail ? row(t('detailsLabel'), m.detail) : null,
+      m.txid
+        ? h('div', { class: 'col', style: 'gap:6px' },
+            h('div', { class: 'small muted' }, t('transactionId')),
+            h('div', { class: 'addr-box', style: 'width:100%' }, m.txid),
+            h('div', { class: 'row gap6' },
+              copyBtn(m.txid, t('copyTxid')),
+              h('a', { class: 'btn btn-sm', href: url, target: '_blank', rel: 'noopener', onClick: (e) => { e.preventDefault(); openExternal(url); } }, t('viewOnMempool'))))
+        : null,
+      m.to ? copyBtn(m.to, t('copyAddress')) : null,
+      h('button', { class: 'btn-ghost btn-block', onClick: () => { ui.arkMoveDetail = null; render(); } }, t('back'))
+    );
+  }
+
+  function arkCard() {
+    const net = getNetwork();
+    const id = getArkProviderId(net);
+    const custom = getArkCustom(net);
+    const presets = arkPresets(net);
+    const applyProvider = (v) => {
+      setArkProviderId(v, net);
+      ui.receiveType = null;
+      initArk();
+      render();
+    };
+    const head = [
+      h('h3', {}, '⚔ Ark'),
+      h('p', { class: 'small muted', style: 'margin:0' }, t('arkDesc')),
+      h('select', { onChange: (e) => applyProvider(e.target.value) },
+        presets.map((p) => h('option', { value: p.id, selected: p.id === id }, p.label))),
+      id === 'custom'
+        ? h('div', { class: 'col', style: 'gap:8px' },
+            h('label', { class: 'field' },
+              h('span', { class: 'lab' }, t('arkServerUrl')),
+              h('input', {
+                type: 'text', class: 'mono-input', placeholder: 'https://ark.example.com',
+                autocapitalize: 'none', autocomplete: 'off', spellcheck: 'false', value: custom.ark,
+                onChange: (e) => { setArkCustom({ ark: e.target.value.trim(), esplora: custom.esplora }, net); initArk(); render(); },
+              })),
+            h('label', { class: 'field' },
+              h('span', { class: 'lab' }, t('arkEsploraUrl')),
+              h('input', {
+                type: 'text', class: 'mono-input', placeholder: 'https://mempool.example.com/api',
+                autocapitalize: 'none', autocomplete: 'off', spellcheck: 'false', value: custom.esplora,
+                onChange: (e) => { setArkCustom({ ark: custom.ark, esplora: e.target.value.trim() }, net); initArk(); render(); },
+              })))
+        : null,
+      ui.arkError ? h('div', { class: 'notice err' }, ui.arkError) : null,
+    ];
+    if (id === 'off' || wallet.watchOnly) {
+      return h('div', { class: 'card col' }, ...head,
+        wallet.watchOnly && id !== 'off' ? h('div', { class: 'small faint' }, t('arkWatchOnly')) : null);
+    }
+    if (!ark || !ark.state) {
+      return h('div', { class: 'card col' }, ...head,
+        arkConnectPromise
+          ? h('div', { class: 'row gap6', style: 'align-items:center' },
+              h('span', { class: 'spinner sm' }), h('span', { class: 'small muted' }, t('arkConnecting')))
+          : h('button', { class: 'btn-ghost btn-block', onClick: () => connectArk().catch(() => {}) }, t('arkConnectBtn')));
+    }
+  
+    const spendables = ark.vtxos().filter((v) => v.state === 'spendable');
+    const pendingActions = ark.pendingActions();
+    const row = (k, v) => h('div', { class: 'row between' }, h('span', { class: 'small muted' }, k), h('span', { class: 'small' }, v));
+  
+    return h(
+      'div',
+      { class: 'card col', style: 'gap:10px' },
+      ...head,
+      spendables.length ? row(t('arkVtxos'), String(spendables.length)) : null,
+      pendingActions.length
+        ? h('div', { class: 'small muted' }, t('arkPendingActions', { n: pendingActions.length }) + ' — ' + pendingActions.map((a) => `${a.type}:${a.step}`).join(', '))
+        : null,
+      spendables.length >= 1
+        ? h('button', { class: 'btn-ghost btn-block', disabled: !!ui.arkBusy, onClick: doArkRefresh },
+            ui.arkBusy === 'refresh' ? h('span', { class: 'spinner sm' }) : t('arkRefreshBtn', { n: spendables.length }))
+        : null
+    );
+  }
+
+  async function doArkBoard() {
+    const sats = parseInt((ui.arkBoardAmt || '').trim(), 10);
+    if (!sats) return;
+    ui.arkBusy = 'board'; ui.arkError = ''; render();
+    try {
+      const { actionId, fundingAddress, feeSat } = await ark.startBoard(sats);
+      const feeRate = (wallet.feeRates && wallet.feeRates.halfHourFee) || 5;
+      const draft = wallet.buildTx({ recipients: [{ address: fundingAddress, amount: sats }], feeRate, noSort: true });
+      const hexTx = wallet.sign(draft.tx);
+      const txid = await wallet.broadcast(hexTx);
+      await ark.completeBoard(actionId, txid);
+      ui.arkBoardAmt = '';
+      ui.arkBoarded = { txid, netSat: sats - feeSat };
+      wallet.scan().catch(() => {});
+    } catch (e) {
+      ui.arkError = e.message;
+    }
+    ui.arkBusy = null; render();
+  }
+
+  async function doArkRefresh() {
+    ui.arkBusy = 'refresh'; ui.arkError = ''; render();
+    try {
+      await ark.refresh();
+      toast(t('arkRefreshStarted'), 5000);
+    } catch (e) {
+      ui.arkError = e.message;
+    }
+    ui.arkBusy = null; render();
+  }
+
+  // The Ark receive pane: connect-on-demand, then address + board form.
+  function arkReceivePane(seg) {
+  if (true) {
+      if (!ark) {
+        connectArk().catch(() => {});
+        return h(
+          'div',
+          { class: 'card col', style: 'align-items:center;gap:14px' },
+          seg,
+          ui.arkError
+            ? h('div', { class: 'notice err', style: 'width:100%' }, ui.arkError)
+            : h('div', { class: 'row gap6', style: 'align-items:center;padding:24px 0' },
+                h('span', { class: 'spinner sm' }), h('span', { class: 'small muted' }, t('arkConnecting')))
+        );
+      }
+      const arkAddr = ark.address();
+      const minBoard = ark.info.minBoardAmountSat || 0;
+      const canBoard = wallet.spendable >= minBoard;
+      return h(
+        'div',
+        { class: 'card col', style: 'align-items:center;gap:14px' },
+        seg,
+        h('p', { class: 'small muted', style: 'margin:0;text-align:center' }, t('arkReceiveIntro')),
+        h('div', { html: qrSvg(arkAddr) }),
+        h('div', { class: 'addr-box break', style: 'width:100%;font-size:11px' }, arkAddr),
+        copyBtn(arkAddr, t('copyAddress')),
+        // Board: fund your Ark balance from this wallet's on-chain coins.
+        h('div', { class: 'col', style: 'width:100%;gap:8px;border-top:1px solid var(--border,rgba(128,128,128,.2));padding-top:14px' },
+          h('div', { class: 'small muted', style: 'text-align:center' }, t('arkBoardIntro')),
+          h('div', { class: 'input-group' },
+            h('input', {
+              type: 'number', inputmode: 'numeric', min: '0',
+              placeholder: t('arkBoardPlaceholder', { n: minBoard.toLocaleString() }),
+              value: ui.arkBoardAmt || '',
+              onInput: (e) => { ui.arkBoardAmt = e.target.value; },
+            }),
+            h('button', { class: 'btn-sm', disabled: !!ui.arkBusy || !canBoard, onClick: doArkBoard },
+              ui.arkBusy === 'board' ? h('span', { class: 'spinner sm' }) : t('arkBoardBtn'))),
+          canBoard
+            ? h('div', { class: 'small faint', style: 'text-align:center' }, t('arkBoardAvailable', { n: fmtAmount(wallet.spendable) + ' ' + unitLabel() }))
+            : h('div', { class: 'small faint', style: 'text-align:center' }, t('arkBoardNoFunds', { n: minBoard.toLocaleString() })),
+          ui.arkError ? h('div', { class: 'notice err' }, ui.arkError) : null)
+      );
+    }
+    throw new Error('unreachable');
+  }
+
+  // "Payment received!" takeover for unseen Ark receives.
+  function arkCelebration() {
+    // An Ark payment landed — same celebration as an on-chain receive, dismissed
+    // with a tap (the ack persists in the ark state so it shows exactly once).
+    const arkUnseen = ark && ark.state ? ark.unseenReceives() : [];
+    if (arkUnseen.length) {
+      const amt = arkUnseen.reduce((n, m) => n + m.amountSat, 0);
+      return h(
+        'div',
+        {
+          class: 'card col',
+          style: 'align-items:center;text-align:center;gap:14px;cursor:pointer;padding:48px 20px',
+          onClick: () => { ark.ackReceives(); render(); },
+        },
+        h('div', { class: 'check-badge' }, '✓'),
+        h('h2', { style: 'margin:0' }, t('paymentReceived')),
+        amt ? h('div', { class: 'amount-pos', style: 'font-size:18px' }, '+' + fmtAmount(amt) + ' ' + unitLabel()) : null,
+        h('div', { class: 'small muted' }, t('tapToProceed'))
+      );
+    }
+    return null;
+  }
+
+  // Boarding success screen (txid + explorer link) until dismissed.
+  function arkBoardedScreen() {
+    // A board just broadcast — show its success screen until dismissed.
+    if (ui.arkBoarded) {
+      const b = ui.arkBoarded;
+      const url = wallet.api.explorerTx(b.txid);
+      return h(
+        'div',
+        { class: 'card col', style: 'align-items:center;text-align:center;gap:14px;padding:40px 20px' },
+        h('div', { class: 'check-badge' }, '✓'),
+        h('h2', { style: 'margin:0' }, t('arkBoardedTitle')),
+        h('div', { class: 'amount-pos', style: 'font-size:18px' }, '+' + fmtAmount(b.netSat) + ' ' + unitLabel()),
+        h('p', { class: 'small muted', style: 'margin:0' }, t('arkBoardedNote')),
+        h('div', { class: 'addr-box', style: 'width:100%' }, b.txid),
+        h('div', { class: 'row gap6' },
+          copyBtn(b.txid, t('copyTxid')),
+          h('a', { class: 'btn btn-sm', href: url, target: '_blank', rel: 'noopener', onClick: (e) => { e.preventDefault(); openExternal(url); } }, t('viewOnMempool'))),
+        h('button', { class: 'btn-primary btn-block', onClick: () => { ui.arkBoarded = null; render(); } }, t('done'))
+      );
+    }
+    return null;
+  }
+
+  return {
+    id: 'ark',
+    init() { initArk(); },
+    stop() { stopArk(); },
+    receiveModes() {
+      if (!arkAvailable()) return [];
+      return [{ id: 'ark', label: t('receiveArkTab'), render: (seg) => arkReceivePane(seg) }];
+    },
+    receiveTakeover() {
+      const boarded = arkBoardedScreen();
+      if (boarded) return boarded;
+      return arkCelebration();
+    },
+    isSendDest(a) { return isArkAddress(a) && arkAvailable(); },
+    hideSendControls(a) { return isArkAddress(a); },
+    sendFormNote(a) {
+      return isArkAddress(a) ? h('div', { class: 'small faint' }, t('arkSendHint')) : null;
+    },
+    interceptReview(s) {
+      if (s.recipients.length === 1 && isArkAddress(s.recipients[0].address)) {
+        if (!arkAvailable()) throw new Error(t('arkNotConnected'));
+        const sats = ctx.parseAmount(s.recipients[0].amount, ctx.getUnit());
+        if (!sats || sats <= 0) throw new Error(t('enterValidAmtForN', { n: 1 }));
+        ui.arkSend = { address: s.recipients[0].address.trim(), amountSat: sats };
+        render();
+        return true;
+      }
+      return false;
+    },
+    sendView() {
+      if (ui.arkSent || ui.arkSend) return arkSendReview();
+      return null;
+    },
+    historyEntries() {
+      if (!ark || !ark.state) return [];
+      return ark.movements()
+        .filter((m) => ['receive', 'send', 'board'].includes(m.type) && m.status === 'complete')
+        .map((m) => ({ time: m.ts, render: () => arkHistoryItem(m) }));
+    },
+    historyDetail() {
+      if (!ui.arkMoveDetail) return null;
+      const m = ark && ark.state ? ark.movements().find((x) => x.id === ui.arkMoveDetail) : null;
+      if (m) return arkMoveDetailView(m);
+      ui.arkMoveDetail = null;
+      return null;
+    },
+    balanceLines() {
+      const b = arkBalance();
+      if (!b || (b.spendableSat + b.pendingSat) <= 0) return [];
+      return [{ label: t('arkBalance'), sat: b.spendableSat + b.pendingSat }];
+    },
+    settingsCards() { return [arkCard()]; },
+  };
+}
diff --git a/src/features/sp.js b/src/features/sp.js
new file mode 100644
index 0000000..0960cdf
--- /dev/null
+++ b/src/features/sp.js
@@ -0,0 +1,57 @@
+// Silent payments (BIP-352) feature — the reusable sp1… receive address and
+// the tweak-indexer settings. (The SP scanning/spending machinery itself lives
+// in wallet.js/silentpay.js and ships with the core wallet for now.)
+
+import { isSilentPaymentAddress } from '../silentpay.js';
+import { getNetwork, getSpIndexerConfig, setSpIndexerConfig, spIndexerPresets } from '../api.js';
+import { t } from '../i18n.js';
+import { qrSvg } from '../qr.js';
+
+export function spFeature(ctx) {
+  const { h, ui, render, wallet, copyBtn } = ctx;
+
+  function spIndexerCard() {
+    if (!wallet.silentPaymentKeys || !wallet.silentPaymentKeys()) return null;
+    const net = getNetwork();
+    const cfg = getSpIndexerConfig(net);
+    return h(
+      'div',
+      { class: 'card col' },
+      h('h3', {}, t('spIndexerTitle')),
+      h('p', { class: 'small muted', style: 'margin:0' }, t('spIndexerDesc')),
+      h('select', { onChange: (e) => { setSpIndexerConfig({ server: e.target.value, url: cfg.url }, net); render(); } },
+        spIndexerPresets(net).map((o) => h('option', { value: o.id, selected: o.id === cfg.server }, o.id === 'custom' ? o.label : o.url.replace(/^\w+:\/\//, '')))),
+      cfg.server === 'custom'
+        ? h('label', { class: 'field' },
+            h('span', { class: 'lab' }, t('spIndexerUrl')),
+            h('input', {
+              type: 'text', class: 'mono-input', placeholder: 'https://your-indexer:8888',
+              autocapitalize: 'none', autocomplete: 'off', spellcheck: 'false', value: cfg.url,
+              onChange: (e) => { setSpIndexerConfig({ server: 'custom', url: e.target.value.trim() }, net); render(); },
+            }),
+            h('div', { class: 'small faint' }, t('spIndexerHint')))
+        : null
+    );
+  }
+
+  return {
+    id: 'sp',
+    receiveModes() {
+      const spAddr = wallet.silentPaymentsAvailable && wallet.silentPaymentsAvailable() ? wallet.silentPaymentAddress() : null;
+      if (!spAddr) return [];
+      return [{
+        id: 'sp', label: t('receiveSpTab'),
+        render: (seg) => h(
+          'div',
+          { class: 'card col', style: 'align-items:center;gap:14px' },
+          seg,
+          h('div', { html: qrSvg(spAddr) }),
+          h('div', { class: 'addr-box break', style: 'width:100%;font-size:12px' }, spAddr),
+          copyBtn(spAddr, t('copyAddress'))
+        ),
+      }];
+    },
+    isSendDest(a) { return isSilentPaymentAddress(a); },
+    settingsCards() { return [spIndexerCard()]; },
+  };
+}
diff --git a/src/features/swaps.js b/src/features/swaps.js
new file mode 100644
index 0000000..636a9f8
--- /dev/null
+++ b/src/features/swaps.js
@@ -0,0 +1,218 @@
+// Lightning swaps feature (Boltz reverse/submarine) — receive over LN,
+// pay bolt11 invoices, provider settings. Extracted from app.js; the
+// protocol layer lives in ../swap.js.
+
+import { SwapManager } from '../swap.js';
+import { getNetwork, getBoltzApi, BOLTZ_PRESETS, getBoltzProviderId, setBoltzProviderId, getBoltzCustom, setBoltzCustom } from '../api.js';
+import { t } from '../i18n.js';
+import { qrSvg } from '../qr.js';
+import { fmtBtc } from '../format.js';
+
+// A bolt11 Lightning invoice (any network prefix); long ln-prefixed bech32 string.
+function isLnInvoice(v) { v = (v || '').trim(); return /^ln[a-z0-9]+$/i.test(v) && v.length > 50; }
+
+export function swapsFeature(ctx) {
+  const { h, ui, render, wallet, blankSend, fmtAmount, unitLabel, copyBtn } = ctx;
+
+  // Boltz swap orchestrator (reverse = receive over LN, submarine = spend over LN).
+  const swaps = new SwapManager({
+    wallet, network: getNetwork(), getApi: getBoltzApi,
+    feeRate: 2, onUpdate: () => render(),
+  });
+
+  function lnReceiveContent() {
+    if (!ui.swapLimits && !ui._swapLimitsLoading) {
+      ui._swapLimitsLoading = true;
+      swaps.reverseLimits().then((l) => { ui.swapLimits = l; ui._swapLimitsLoading = false; render(); }).catch(() => { ui._swapLimitsLoading = false; });
+    }
+    const lim = ui.swapLimits;
+    let rec = ui.lnReceiveId ? swaps.list().find((s) => s.id === ui.lnReceiveId) : null;
+    if (rec && ['claimed', 'success'].includes(rec.status)) {
+      // Claimed — the coin is credited on-chain (swap.js → creditReceive), so the
+      // generic "Payment received!" celebration shows it like any receive. Just
+      // reset the Lightning flow back to its form.
+      ui.lnReceiveId = null;
+      rec = null;
+    }
+    if (rec) {
+      let svg = null;
+      try { svg = qrSvg(rec.invoice.toUpperCase(), { ec: 'L', mode: 'Alphanumeric' }); } catch {}
+      return [
+        h('p', { class: 'small muted', style: 'margin:0;text-align:center' }, t('lnReceiveAwaiting')),
+        svg ? h('div', { html: svg }) : null,
+        h('div', { class: 'addr-box break', style: 'width:100%;font-size:11px' }, rec.invoice),
+        copyBtn(rec.invoice, t('copyInvoice')),
+        h('div', { class: 'row gap6', style: 'align-items:center' }, h('span', { class: 'spinner sm' }), h('span', { class: 'small muted' }, t('lnReceiveWatching'))),
+        h('button', { class: 'btn-ghost btn-block', onClick: () => { ui.lnReceiveId = null; ui.swapReverseAmt = ''; ui.swapError = ''; render(); } }, t('back')),
+      ];
+    }
+    return [
+      h('p', { class: 'small muted', style: 'margin:0;text-align:center' }, t('lnReceiveIntro')),
+      h('label', { class: 'field', style: 'width:100%' },
+        h('span', { class: 'lab' }, t('amountSatsLabel')),
+        h('input', { type: 'number', inputmode: 'numeric', placeholder: '', value: ui.swapReverseAmt || '', onInput: (e) => { ui.swapReverseAmt = e.target.value; } }),
+        lim ? h('span', { class: 'small muted' }, `Min ${lim.min.toLocaleString()} · max ${lim.max.toLocaleString()} sats`) : null),
+      ui.swapError ? h('div', { class: 'notice err' }, ui.swapError) : null,
+      h('button', { class: 'btn-primary btn-block', disabled: !!ui.swapBusy, onClick: doReverse }, ui.swapBusy ? h('span', { class: 'spinner' }) : t('lnCreateInvoice')),
+    ];
+  }
+
+  async function doReverse() {
+    const amt = parseInt((ui.swapReverseAmt || '').trim(), 10);
+    const lim = ui.swapLimits || (ui.swapLimits = await swaps.reverseLimits());
+    if (!amt || amt < lim.min || amt > lim.max) { ui.swapError = `Enter ${lim.min.toLocaleString()}–${lim.max.toLocaleString()} sats`; return render(); }
+    ui.swapError = ''; ui.swapBusy = true; render();
+    try { const rec = await swaps.startReverse(amt); ui.lnReceiveId = rec.id; ui.swapReverseAmt = ''; }
+    catch (e) { ui.swapError = e.message; }
+    ui.swapBusy = false; render();
+  }
+
+  async function doRefund(id) {
+    ui.swapError = ''; ui.swapBusy = true; render();
+    try { await swaps.refundSubmarine(id); }
+    catch (e) { ui.swapError = e.message; }
+    ui.swapBusy = false; render();
+  }
+
+  function boltzProviderCard() {
+    const id = getBoltzProviderId();
+    const custom = getBoltzCustom();
+    return h(
+      'div',
+      { class: 'card col' },
+      h('h3', {}, '⚡ Swap provider'),
+      h('p', { class: 'small muted', style: 'margin:0' }, 'Boltz-compatible provider for Lightning swaps. Non-custodial: a provider can fail a swap but never take your funds.'),
+      h('select', { onChange: (e) => { setBoltzProviderId(e.target.value); ui.swapLimits = null; render(); } },
+        BOLTZ_PRESETS.map((p) => h('option', { value: p.id, selected: p.id === id }, p.label))),
+      id === 'custom'
+        ? h('div', { class: 'col', style: 'gap:8px' },
+            h('label', { class: 'field' },
+              h('span', { class: 'lab' }, 'API URL'),
+              h('input', {
+                type: 'text', class: 'mono-input', placeholder: 'https://api.example.com',
+                autocapitalize: 'none', autocomplete: 'off', spellcheck: 'false', value: custom.api,
+                onChange: (e) => { setBoltzCustom({ api: e.target.value.trim(), ws: custom.ws }); ui.swapLimits = null; render(); },
+              })),
+            h('label', { class: 'field' },
+              h('span', { class: 'lab' }, 'WebSocket URL (optional)'),
+              h('input', {
+                type: 'text', class: 'mono-input', placeholder: 'wss://api.example.com/v2/ws',
+                autocapitalize: 'none', autocomplete: 'off', spellcheck: 'false', value: custom.ws,
+                onChange: (e) => { setBoltzCustom({ api: custom.api, ws: e.target.value.trim() }); render(); },
+              }),
+              h('div', { class: 'small faint' }, 'Left blank, the WS is derived from the API URL.')))
+        : h('div', { class: 'small faint', style: 'word-break:break-all' }, getBoltzApi())
+    );
+  }
+
+  function swapTxDetailSection(swap, tx) {
+    const u = ' ' + unitLabel();
+    const line = (k, v) => h('div', { class: 'line' }, h('span', { class: 'k' }, k), h('span', { class: 'v' }, v));
+    const head = (txt) => h('div', { style: 'font-weight:600;margin:12px 0 2px' }, txt);
+    if (swap.refundTxid === tx.txid)
+      return h('div', { class: 'summary col', style: 'gap:0' }, head('↩ Lightning swap refund'), line(t('status'), 'Refunded ✓'));
+    if (swap.kind === 'submarine') {
+      const fee = (swap.expectedAmount || 0) - (swap.invoiceAmount || 0);
+      const st = swap.status === 'success' ? 'Invoice paid ✓'
+        : swap.status === 'refundable' ? 'Payment failed — refundable'
+        : swap.status === 'refunded' ? 'Refunded' : 'Paying…';
+      return h('div', { class: 'summary col', style: 'gap:0' },
+        head('⚡ Paid over Lightning'),
+        swap.invoiceAmount != null ? line('Invoice', fmtAmount(swap.invoiceAmount) + u) : null,
+        fee > 0 ? line('Swap fee', fmtAmount(fee) + u) : null,
+        line(t('status'), st),
+        swap.status === 'refundable'
+          ? h('button', { class: 'btn-sm btn-block', style: 'margin-top:8px', disabled: !!ui.swapBusy, onClick: () => doRefund(swap.id) }, 'Refund on-chain')
+          : null);
+    }
+    // reverse swap claim
+    return h('div', { class: 'summary col', style: 'gap:0' },
+      head('⚡ Received over Lightning'),
+      line(t('status'), swap.status === 'claimed' ? 'Settled ✓' : swap.status));
+  }
+
+  async function startLnSend(invoice) {
+    ui.sendError = ''; ui.lnSend = null; ui.lnSent = null; ui.lnSendBusy = true; render();
+    try { ui.lnSend = await swaps.quoteSubmarine(invoice); }
+    catch (e) { ui.sendError = e.message; }
+    ui.lnSendBusy = false; render();
+  }
+
+  async function doLnPay() {
+    if (!ui.lnSend) return;
+    ui.sendError = ''; ui.lnSendBusy = true; render();
+    try { const rec = await swaps.fundQuotedSubmarine(ui.lnSend); ui.lnSent = { amount: ui.lnSend.invoiceAmount, id: rec.id }; }
+    catch (e) { ui.sendError = e.message; }
+    ui.lnSendBusy = false; render();
+  }
+
+  function lnSendReview() {
+    const u = ' ' + unitLabel();
+    if (ui.lnSent) {
+      return h('div', { class: 'col', style: 'gap:16px' },
+        h('div', { class: 'card col', style: 'align-items:center;text-align:center;gap:8px' },
+          h('div', { class: 'check-badge' }, '⚡'),
+          h('h2', { style: 'margin:0' }, t('lnPaySentTitle')),
+          ui.lnSent.amount ? h('div', { class: 'amount-pos', style: 'font-size:18px' }, fmtAmount(ui.lnSent.amount) + u) : null,
+          h('p', { class: 'muted', style: 'margin:0' }, t('lnPaySentBody'))),
+        h('button', { class: 'btn-primary btn-block', onClick: () => { ui.lnSent = null; ui.lnSend = null; ui.send = blankSend(); ui.tab = 'history'; render(); } }, t('done')));
+    }
+    const q = ui.lnSend;
+    const row = (label, sats, bold) => h('div', { class: 'row', style: 'justify-content:space-between' + (bold ? ';font-weight:600' : '') },
+      h('span', { class: bold ? '' : 'small muted' }, label), h('span', {}, fmtAmount(sats) + u));
+    return h('div', { class: 'col', style: 'gap:12px' },
+      h('div', { class: 'card col', style: 'gap:10px' },
+        h('h3', { style: 'margin:0' }, t('lnPayTitle')),
+        q.invoiceAmount != null ? row(t('lnPayAmount'), q.invoiceAmount) : null,
+        q.boltzFee != null ? row(t('lnPayBoltzFee'), q.boltzFee) : null,
+        row(t('lnPayNetworkFee'), q.networkFee),
+        h('div', { style: 'border-top:1px solid var(--line, #ddd);margin:2px 0' }),
+        row(t('lnPayTotal'), q.total, true)),
+      ui.sendError ? h('div', { class: 'notice err' }, ui.sendError) : null,
+      h('button', { class: 'btn-primary btn-block', disabled: !!ui.lnSendBusy, onClick: doLnPay }, ui.lnSendBusy ? h('span', { class: 'spinner' }) : t('lnPayConfirm')),
+      h('button', { class: 'btn-ghost btn-block', onClick: () => { ui.lnSend = null; ui.sendError = ''; render(); } }, t('back')));
+  }
+
+  return {
+    id: 'swaps',
+    // wallet activated: re-attach in-flight swap watchers
+    init() {
+      swaps.network = getNetwork();
+      if (!wallet.watchOnly) { try { swaps.resumeAll(); } catch {} }
+    },
+    networkChanged(net) { swaps.network = net; ui.swapLimits = null; },
+    receiveModes() {
+      // a reverse swap needs our keys to claim on-chain
+      if (wallet.watchOnly) return [];
+      return [{
+        id: 'ln', label: t('receiveLnTab'),
+        render: (seg) => h('div', { class: 'card col', style: 'align-items:center;gap:14px' }, seg, ...lnReceiveContent()),
+      }];
+    },
+    // a pasted/typed/scanned bolt11 auto-advances to its own confirmation
+    matchSendText(text) {
+      const inv = (text || '').trim().replace(/^lightning:/i, '');
+      if (ui.send.recipients.length === 1 && !ui.lnSendBusy && !ui.lnSend && isLnInvoice(inv)) {
+        startLnSend(inv);
+        return true;
+      }
+      return false;
+    },
+    interceptReview(s) {
+      const target = s.recipients.length === 1 ? (s.recipients[0].address || '').trim().replace(/^lightning:/i, '') : '';
+      if (isLnInvoice(target)) { startLnSend(target); return true; }
+      return false;
+    },
+    sendView() {
+      if (ui.lnSent || ui.lnSend) return lnSendReview();
+      if (ui.lnSendBusy) return h('div', { class: 'card col', style: 'align-items:center;gap:14px;padding:32px 14px' }, h('span', { class: 'spinner' }), h('p', { class: 'muted', style: 'margin:0' }, t('lnQuoting')));
+      return null;
+    },
+    txDetailSection(tx) {
+      const swap = swaps.findByTxid(tx.txid);
+      return swap ? swapTxDetailSection(swap, tx) : null;
+    },
+    findByTxid(txid) { return swaps.findByTxid(txid); },
+    settingsCards() { return [boltzProviderCard()]; },
+  };
+}