Add RBF fee bumping for unconfirmed sends

- Signal opt-in RBF (BIP125, sequence 0xfffffffd) on all new sends so
  they're replaceable.
- "Bump fee" on an unconfirmed sent tx (its detail view): rebuilds the
  same inputs + recipient outputs at the Priority rate, taking the extra
  fee from the change output (pulling in a confirmed coin if change can't
  cover it), re-signs, and routes to a "Replace with a higher fee?"
  confirmation showing old → new fee before broadcasting.
- New keys translated into all 19 locales.

Honest scope: P2A/TRUC/package-relay are L2/pre-signed-tx + node-relay
features that don't apply to a single-sig wallet broadcasting single txs
via public explorers, so they're intentionally out. CPFP (for receives /
unbumpable sends) is a possible follow-up.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

23 files changed, 194 insertions, 21 deletions

diff --git a/src/api.js b/src/api.js
index 23a1c2d..08f03b2 100644
--- a/src/api.js
+++ b/src/api.js
@@ -200,6 +200,11 @@ export class Api {
     return this.#get(`/address/${address}/txs`);
   }
 
+  // Full transaction (vin with prevouts, vout, status) — used for fee bumping.
+  getTx(txid) {
+    return this.#get(`/tx/${txid}`);
+  }
+
   async feeRates() {
     for (const host of this._hosts) {
       if (host.cooldownUntil > Date.now()) continue;
diff --git a/src/app.js b/src/app.js
index c43ec6f..5f64e90 100644
--- a/src/app.js
+++ b/src/app.js
@@ -1008,7 +1008,7 @@ function broadcastConfirmView() {
   return h(
     'div',
     { class: 'card col' },
-    h('h3', {}, t('broadcastScanned')),
+    h('h3', {}, b.bump ? t('bumpConfirm') : t('broadcastScanned')),
     h(
       'div',
       { class: 'summary col', style: 'gap:0' },
@@ -1018,6 +1018,11 @@ function broadcastConfirmView() {
           h('span', { class: 'v' }, fmtAmount(o.value), ' ', unitTag())
         )
       ),
+      b.bump
+        ? h('div', { class: 'line' },
+            h('span', { class: 'k' }, t('networkFee')),
+            h('span', { class: 'v' }, fmtAmount(b.bump.oldFee) + ' → ' + fmtAmount(b.bump.newFee) + ' ' + unitLabel()))
+        : null,
       h('div', { class: 'line' },
         h('span', { class: 'k' }, t('transactionId')),
         h('span', { class: 'v mono break' }, shortTxid(b.txid))
@@ -1028,11 +1033,31 @@ function broadcastConfirmView() {
       h('button', { class: 'btn-ghost', onClick: () => { ui.broadcastTx = 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: broadcastScanned }, t('broadcastNow'))
+        : h('button', { class: 'btn-primary grow', onClick: broadcastScanned }, b.bump ? t('replaceTx') : t('broadcastNow'))
     )
   );
 }
 
+// Build a higher-fee RBF replacement of an unconfirmed send and route it to the
+// broadcast confirmation. Bumps to the Priority rate.
+async function bumpFee(txid) {
+  if (wallet.offline) { toast(t('scanOffline')); return; }
+  const rate = (wallet.feeRates && wallet.feeRates.fastestFee) || 10;
+  ui.busy = true;
+  render();
+  try {
+    const d = await wallet.bumpTx(txid, rate);
+    ui.broadcastTx = { hex: d.hex, txid: d.txid, outputs: d.outputs, bump: { oldFee: d.oldFee, newFee: d.fee } };
+    ui.txDetail = null;
+    ui.tab = 'send';
+    ui.sendError = '';
+  } catch (e) {
+    toast(e.message);
+  }
+  ui.busy = false;
+  render();
+}
+
 async function broadcastScanned() {
   if (wallet.offline) { ui.sendError = t('scanOffline'); render(); return; }
   ui.busy = true;
@@ -1480,6 +1505,12 @@ function txDetailView(tx) {
       copyBtn(tx.txid, t('copyId')),
       h('a', { class: 'btn btn-sm', href: wallet.api.explorerTx(tx.txid), target: '_blank', rel: 'noopener' }, t('viewOnMempool'))
     ),
+    // RBF: an unconfirmed send can be rebroadcast at a higher fee.
+    !tx.confirmed && !incoming && !wallet.offline
+      ? (ui.busy
+          ? h('button', { class: 'btn-primary btn-block', disabled: true }, h('span', { class: 'spinner' }))
+          : h('button', { class: 'btn-primary btn-block', onClick: () => bumpFee(tx.txid) }, t('bumpFee')))
+      : null,
     h('button', { class: 'btn-ghost btn-block', onClick: () => { ui.txDetail = null; render(); } }, t('backToHistory'))
   );
 }
diff --git a/src/i18n.js b/src/i18n.js
index 91234d7..396c0f7 100644
--- a/src/i18n.js
+++ b/src/i18n.js
@@ -110,6 +110,9 @@ const STR = {
     scanUnrecognized: 'Couldn’t read a Bitcoin address from that QR.',
     broadcastScanned: 'Broadcast transaction?',
     broadcastNow: 'Broadcast',
+    bumpFee: 'Bump fee',
+    bumpConfirm: 'Replace with a higher fee?',
+    replaceTx: 'Replace',
     scanOffline: 'You’re offline — reconnect to broadcast this transaction.',
     broadcastFailed: 'Broadcast failed: {msg}',
     signingFailed: 'Signing failed: {msg}',
diff --git a/src/locales/ar.json b/src/locales/ar.json
index aecf68e..11cfd61 100644
--- a/src/locales/ar.json
+++ b/src/locales/ar.json
@@ -141,5 +141,8 @@
   "copy": "نسخ",
   "switchUnit": "تبديل BTC / sats",
   "footerMadeBy": "صُنع بواسطة",
-  "footerSourceOn": "الكود المصدري على"
+  "footerSourceOn": "الكود المصدري على",
+  "bumpFee": "رفع الرسوم",
+  "bumpConfirm": "استبدال برسوم أعلى؟",
+  "replaceTx": "استبدال"
 }
\ No newline at end of file
diff --git a/src/locales/bn.json b/src/locales/bn.json
index 55c3a3a..43785aa 100644
--- a/src/locales/bn.json
+++ b/src/locales/bn.json
@@ -141,5 +141,8 @@
   "copy": "কপি",
   "switchUnit": "BTC / sats পাল্টান",
   "footerMadeBy": "তৈরি করেছেন",
-  "footerSourceOn": "সোর্স কোড"
+  "footerSourceOn": "সোর্স কোড",
+  "bumpFee": "ফি বাড়ান",
+  "bumpConfirm": "বেশি ফি দিয়ে প্রতিস্থাপন করবেন?",
+  "replaceTx": "প্রতিস্থাপন"
 }
\ No newline at end of file
diff --git a/src/locales/de.json b/src/locales/de.json
index 9e44612..3a59f78 100644
--- a/src/locales/de.json
+++ b/src/locales/de.json
@@ -141,5 +141,8 @@
   "copy": "Kopieren",
   "switchUnit": "BTC / sats wechseln",
   "footerMadeBy": "gemacht von",
-  "footerSourceOn": "Quellcode auf"
+  "footerSourceOn": "Quellcode auf",
+  "bumpFee": "Gebühr erhöhen",
+  "bumpConfirm": "Mit höherer Gebühr ersetzen?",
+  "replaceTx": "Ersetzen"
 }
\ No newline at end of file
diff --git a/src/locales/es.json b/src/locales/es.json
index fbdf21d..b9bddab 100644
--- a/src/locales/es.json
+++ b/src/locales/es.json
@@ -141,5 +141,8 @@
   "copy": "Copiar",
   "switchUnit": "Cambiar BTC / sats",
   "footerMadeBy": "hecho por",
-  "footerSourceOn": "código disponible en"
+  "footerSourceOn": "código disponible en",
+  "bumpFee": "Aumentar comisión",
+  "bumpConfirm": "¿Reemplazar con una comisión más alta?",
+  "replaceTx": "Reemplazar"
 }
\ No newline at end of file
diff --git a/src/locales/fr.json b/src/locales/fr.json
index a629174..c09408d 100644
--- a/src/locales/fr.json
+++ b/src/locales/fr.json
@@ -141,5 +141,8 @@
   "copy": "Copier",
   "switchUnit": "Basculer BTC / sats",
   "footerMadeBy": "fait par",
-  "footerSourceOn": "code source sur"
+  "footerSourceOn": "code source sur",
+  "bumpFee": "Augmenter les frais",
+  "bumpConfirm": "Remplacer avec des frais plus élevés ?",
+  "replaceTx": "Remplacer"
 }
\ No newline at end of file
diff --git a/src/locales/hi.json b/src/locales/hi.json
index b40b0ca..fd0d997 100644
--- a/src/locales/hi.json
+++ b/src/locales/hi.json
@@ -141,5 +141,8 @@
   "copy": "कॉपी",
   "switchUnit": "BTC / sats बदलें",
   "footerMadeBy": "द्वारा बनाया",
-  "footerSourceOn": "सोर्स यहाँ"
+  "footerSourceOn": "सोर्स यहाँ",
+  "bumpFee": "फ़ीस बढ़ाएँ",
+  "bumpConfirm": "अधिक फ़ीस के साथ बदलें?",
+  "replaceTx": "बदलें"
 }
\ No newline at end of file
diff --git a/src/locales/id.json b/src/locales/id.json
index 57e87ee..4edc234 100644
--- a/src/locales/id.json
+++ b/src/locales/id.json
@@ -141,5 +141,8 @@
   "copy": "Salin",
   "switchUnit": "Ganti BTC / sats",
   "footerMadeBy": "dibuat oleh",
-  "footerSourceOn": "sumber tersedia di"
+  "footerSourceOn": "sumber tersedia di",
+  "bumpFee": "Naikkan biaya",
+  "bumpConfirm": "Ganti dengan biaya lebih tinggi?",
+  "replaceTx": "Ganti"
 }
\ No newline at end of file
diff --git a/src/locales/ja.json b/src/locales/ja.json
index e107ab0..6bc532b 100644
--- a/src/locales/ja.json
+++ b/src/locales/ja.json
@@ -141,5 +141,8 @@
   "copy": "コピー",
   "switchUnit": "BTC / sats を切替",
   "footerMadeBy": "作成者:",
-  "footerSourceOn": "ソースは"
+  "footerSourceOn": "ソースは",
+  "bumpFee": "手数料を上げる",
+  "bumpConfirm": "より高い手数料で置き換えますか？",
+  "replaceTx": "置き換える"
 }
\ No newline at end of file
diff --git a/src/locales/ko.json b/src/locales/ko.json
index 765838a..e46b7c7 100644
--- a/src/locales/ko.json
+++ b/src/locales/ko.json
@@ -141,5 +141,8 @@
   "copy": "복사",
   "switchUnit": "BTC / sats 전환",
   "footerMadeBy": "만든 사람:",
-  "footerSourceOn": "소스 공개:"
+  "footerSourceOn": "소스 공개:",
+  "bumpFee": "수수료 올리기",
+  "bumpConfirm": "더 높은 수수료로 교체할까요?",
+  "replaceTx": "교체"
 }
\ No newline at end of file
diff --git a/src/locales/mr.json b/src/locales/mr.json
index 7b369a0..36dfd56 100644
--- a/src/locales/mr.json
+++ b/src/locales/mr.json
@@ -141,5 +141,8 @@
   "copy": "कॉपी",
   "switchUnit": "BTC / sats बदला",
   "footerMadeBy": "द्वारे बनवले",
-  "footerSourceOn": "सोर्स येथे"
+  "footerSourceOn": "सोर्स येथे",
+  "bumpFee": "फी वाढवा",
+  "bumpConfirm": "जास्त फीसह बदला?",
+  "replaceTx": "बदला"
 }
\ No newline at end of file
diff --git a/src/locales/pt.json b/src/locales/pt.json
index 277622d..01e07eb 100644
--- a/src/locales/pt.json
+++ b/src/locales/pt.json
@@ -141,5 +141,8 @@
   "copy": "Copiar",
   "switchUnit": "Alternar BTC / sats",
   "footerMadeBy": "feito por",
-  "footerSourceOn": "código disponível no"
+  "footerSourceOn": "código disponível no",
+  "bumpFee": "Aumentar taxa",
+  "bumpConfirm": "Substituir com uma taxa maior?",
+  "replaceTx": "Substituir"
 }
\ No newline at end of file
diff --git a/src/locales/ru.json b/src/locales/ru.json
index 7c700b8..dad4ba4 100644
--- a/src/locales/ru.json
+++ b/src/locales/ru.json
@@ -141,5 +141,8 @@
   "copy": "Копировать",
   "switchUnit": "Переключить BTC / sats",
   "footerMadeBy": "сделано —",
-  "footerSourceOn": "исходный код на"
+  "footerSourceOn": "исходный код на",
+  "bumpFee": "Поднять комиссию",
+  "bumpConfirm": "Заменить с более высокой комиссией?",
+  "replaceTx": "Заменить"
 }
\ No newline at end of file
diff --git a/src/locales/sw.json b/src/locales/sw.json
index 4921e66..6e5c0bc 100644
--- a/src/locales/sw.json
+++ b/src/locales/sw.json
@@ -141,5 +141,8 @@
   "copy": "Nakili",
   "switchUnit": "Badilisha BTC / sats",
   "footerMadeBy": "imetengenezwa na",
-  "footerSourceOn": "msimbo unapatikana"
+  "footerSourceOn": "msimbo unapatikana",
+  "bumpFee": "Ongeza ada",
+  "bumpConfirm": "Badilisha kwa ada ya juu zaidi?",
+  "replaceTx": "Badilisha"
 }
\ No newline at end of file
diff --git a/src/locales/ta.json b/src/locales/ta.json
index b30ebb5..dadd598 100644
--- a/src/locales/ta.json
+++ b/src/locales/ta.json
@@ -141,5 +141,8 @@
   "copy": "நகலெடு",
   "switchUnit": "BTC / sats மாற்று",
   "footerMadeBy": "உருவாக்கியவர்",
-  "footerSourceOn": "மூலம்"
+  "footerSourceOn": "மூலம்",
+  "bumpFee": "கட்டணத்தை உயர்த்து",
+  "bumpConfirm": "அதிக கட்டணத்துடன் மாற்றவா?",
+  "replaceTx": "மாற்று"
 }
\ No newline at end of file
diff --git a/src/locales/te.json b/src/locales/te.json
index fc2b2d0..1380942 100644
--- a/src/locales/te.json
+++ b/src/locales/te.json
@@ -141,5 +141,8 @@
   "copy": "కాపీ",
   "switchUnit": "BTC / sats మార్చు",
   "footerMadeBy": "తయారు చేసినవారు",
-  "footerSourceOn": "సోర్స్ ఇక్కడ"
+  "footerSourceOn": "సోర్స్ ఇక్కడ",
+  "bumpFee": "ఫీజు పెంచు",
+  "bumpConfirm": "ఎక్కువ ఫీజుతో భర్తీ చేయాలా?",
+  "replaceTx": "భర్తీ చేయి"
 }
\ No newline at end of file
diff --git a/src/locales/tr.json b/src/locales/tr.json
index 80c352f..adb8d36 100644
--- a/src/locales/tr.json
+++ b/src/locales/tr.json
@@ -141,5 +141,8 @@
   "copy": "Kopyala",
   "switchUnit": "BTC / sats değiştir",
   "footerMadeBy": "yapan:",
-  "footerSourceOn": "kaynak kodu"
+  "footerSourceOn": "kaynak kodu",
+  "bumpFee": "Ücreti artır",
+  "bumpConfirm": "Daha yüksek ücretle değiştirilsin mi?",
+  "replaceTx": "Değiştir"
 }
\ No newline at end of file
diff --git a/src/locales/ur.json b/src/locales/ur.json
index dc48572..bb5c028 100644
--- a/src/locales/ur.json
+++ b/src/locales/ur.json
@@ -141,5 +141,8 @@
   "copy": "کاپی",
   "switchUnit": "BTC / sats بدلیں",
   "footerMadeBy": "بنایا از",
-  "footerSourceOn": "سورس کوڈ یہاں"
+  "footerSourceOn": "سورس کوڈ یہاں",
+  "bumpFee": "فیس بڑھائیں",
+  "bumpConfirm": "زیادہ فیس کے ساتھ بدلیں؟",
+  "replaceTx": "بدلیں"
 }
\ No newline at end of file
diff --git a/src/locales/vi.json b/src/locales/vi.json
index 0a4d413..2c17f7d 100644
--- a/src/locales/vi.json
+++ b/src/locales/vi.json
@@ -141,5 +141,8 @@
   "copy": "Sao chép",
   "switchUnit": "Đổi BTC / sats",
   "footerMadeBy": "làm bởi",
-  "footerSourceOn": "mã nguồn tại"
+  "footerSourceOn": "mã nguồn tại",
+  "bumpFee": "Tăng phí",
+  "bumpConfirm": "Thay thế với phí cao hơn?",
+  "replaceTx": "Thay thế"
 }
\ No newline at end of file
diff --git a/src/locales/zh.json b/src/locales/zh.json
index c26db60..0ac43c2 100644
--- a/src/locales/zh.json
+++ b/src/locales/zh.json
@@ -141,5 +141,8 @@
   "copy": "复制",
   "switchUnit": "切换 BTC / sats",
   "footerMadeBy": "制作者",
-  "footerSourceOn": "源代码见"
+  "footerSourceOn": "源代码见",
+  "bumpFee": "提高手续费",
+  "bumpConfirm": "用更高手续费替换？",
+  "replaceTx": "替换"
 }
\ No newline at end of file
diff --git a/src/wallet.js b/src/wallet.js
index 0f71454..a107fdc 100644
--- a/src/wallet.js
+++ b/src/wallet.js
@@ -587,6 +587,7 @@ export class Wallet {
         ...pay,
         txid: u.txid,
         index: u.vout,
+        sequence: 0xfffffffd, // signal opt-in RBF (BIP125) so sends are bumpable
         witnessUtxo: { script: pay.script, amount: BigInt(u.value) },
       };
     });
@@ -667,6 +668,82 @@ export class Wallet {
     return { txid: tx.id, total, outputs };
   }
 
+  // Build + sign an RBF replacement of an unconfirmed outgoing tx at a higher
+  // fee rate. Reuses the original inputs and recipient outputs, taking the extra
+  // fee from the change output (pulling in a confirmed coin if change can't
+  // cover it). Returns a signed draft { hex, txid, fee, oldFee, feeRate, outputs }.
+  async bumpTx(origTxid, feeRate) {
+    const orig = await this.api.getTx(origTxid);
+    if (orig.status && orig.status.confirmed) throw new Error('Transaction already confirmed.');
+
+    // Every input of our own send is ours; reconstruct them with values + paths.
+    const ins = [];
+    let totalIn = 0;
+    for (const vin of orig.vin || []) {
+      const a = vin.prevout && vin.prevout.scriptpubkey_address;
+      const p = a && this.addrMap.get(a);
+      if (!p) throw new Error('Can only bump your own transactions.');
+      totalIn += vin.prevout.value;
+      ins.push({ txid: vin.txid, vout: vin.vout, value: vin.prevout.value, chain: p.chain, index: p.index });
+    }
+
+    // Split outputs: our first change-chain output is the change we'll shrink;
+    // everything else is a recipient and stays fixed.
+    const recipients = [];
+    let outTotal = 0;
+    let changeSeen = false;
+    for (const o of orig.vout || []) {
+      outTotal += o.value;
+      const p = o.scriptpubkey_address && this.addrMap.get(o.scriptpubkey_address);
+      if (p && p.chain === 1 && !changeSeen) { changeSeen = true; continue; }
+      recipients.push({ address: o.scriptpubkey_address, value: o.value });
+    }
+    const recipTotal = recipients.reduce((s, r) => s + r.value, 0);
+    const oldFee = totalIn - outTotal;
+
+    const rate = Math.max(1, Math.round(feeRate));
+    const DUST = 294; // p2wpkh dust
+    const vsizeOf = (nIn, nOut) => 11 + 68 * nIn + 31 * nOut;
+    const usedIds = new Set(ins.map((i) => `${i.txid}:${i.vout}`));
+    const spare = this.utxos.filter((u) => u.confirmed && !usedIds.has(utxoId(u)));
+    const extra = [];
+
+    const plan = () => {
+      const nIn = ins.length + extra.length;
+      const inAmt = totalIn + extra.reduce((s, u) => s + u.value, 0);
+      let nOut = recipients.length + 1;
+      let fee = Math.ceil(vsizeOf(nIn, nOut) * rate);
+      let change = inAmt - recipTotal - fee;
+      if (change < DUST) { nOut = recipients.length; fee = inAmt - recipTotal; change = 0; }
+      // BIP125: beat old fee by at least the replacement's vsize (incremental relay).
+      const minFee = oldFee + vsizeOf(nIn, nOut);
+      if (change > 0 && fee < minFee) {
+        fee = minFee; change = inAmt - recipTotal - fee;
+        if (change < DUST) { fee = inAmt - recipTotal; change = 0; }
+      }
+      return { inAmt, fee, change, ok: inAmt - recipTotal >= fee && fee > oldFee };
+    };
+    let pl = plan();
+    while (!pl.ok && spare.length) { extra.push(spare.shift()); pl = plan(); }
+    if (!pl.ok) throw new Error('Not enough funds to bump at this rate. Try a lower rate or CPFP.');
+
+    const allIns = [...ins, ...extra.map((u) => ({ txid: u.txid, vout: u.vout, value: u.value, chain: u.chain, index: u.index }))];
+    const t = new btc.Transaction();
+    for (const i of allIns) {
+      const pay = p2wpkh(this.derive(i.chain, i.index).pubkey, this.netCfg.net);
+      t.addInput({ ...pay, txid: i.txid, index: i.vout, sequence: 0xfffffffd, witnessUtxo: { script: pay.script, amount: BigInt(i.value) } });
+    }
+    for (const r of recipients) t.addOutputAddress(r.address, BigInt(r.value), this.netCfg.net);
+    const changeAddr = this.freshChange().address;
+    if (pl.change > 0) t.addOutputAddress(changeAddr, BigInt(pl.change), this.netCfg.net);
+    for (let k = 0; k < allIns.length; k++) t.signIdx(this.node(allIns[k].chain, allIns[k].index).privateKey, k);
+    t.finalize();
+
+    const outputs = recipients.map((r) => ({ address: r.address, value: r.value }));
+    if (pl.change > 0) outputs.push({ address: changeAddr, value: pl.change, change: true });
+    return { hex: t.hex, txid: t.id, fee: pl.fee, oldFee, feeRate: rate, outputs, replaces: origTxid };
+  }
+
   // --- realtime (mempool.space WebSocket) ---------------------------------
   // Pushes us new mempool/confirmed transactions for our addresses so history
   // and balances update with no polling.