The Nostr card owns its built-in account; the exported key opens this wallet anywhere

Co-Authored-By: Claude Fable 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01M5kFodm9azZJVTQxnkDdKe

4 files changed, 84 insertions, 6 deletions

diff --git a/src/app.js b/src/app.js
index e68fc52..1a89ac7 100644
--- a/src/app.js
+++ b/src/app.js
@@ -2572,6 +2572,7 @@ function tabsBar() {
         ui.tab = id;
         ui.sendError = ''; // a stale send error never survives a tab change
         ui.revealShown = false; // re-mask the recovery phrase whenever tabs change
+        ui.nostrExportStep = false; // and the exported nostr key
         ui.txDetail = null; // back to the history list when leaving/returning
         ui.arkMoveDetail = null;
         ui.giftDetail = null;
diff --git a/src/features/nostrlogin.js b/src/features/nostrlogin.js
index 222b516..4c28ac5 100644
--- a/src/features/nostrlogin.js
+++ b/src/features/nostrlogin.js
@@ -9,7 +9,7 @@
 // published, because it means the nostr key can recover the money.
 
 import { newMnemonic } from '../wallet.js';
-import { npubOf } from '../nostr.js';
+import { npubOf, nsecOf } from '../nostr.js';
 import { t } from '../i18n.js';
 import { qrSvg } from '../qr.js';
 import {
@@ -289,6 +289,68 @@ export function nostrLoginFeature(ctx) {
     } catch (e) { fail(e); }
   }
 
+  // Reveal the seed-derived nostr key. A self-backup is published FIRST so
+  // the promise on the reveal screen is true: pasting this nsec into any
+  // coinos login finds the backup and opens THIS wallet, instead of
+  // key-deriving a fresh empty one (walletForSigner checks relays before
+  // deriving).
+  async function exportWalletKey() {
+    ui.nostrLoginError = '';
+    busy(true);
+    try {
+      const sk = wallet.nostr && wallet.nostr.sk;
+      if (!sk || !wallet.mnemonic) throw new Error(t('nlNeedSeed'));
+      await publishWalletBackup(keySigner(sk), { mnemonic: wallet.mnemonic, passphrase: wallet.passphrase || '' });
+      ui.nostrExportStep = 'shown';
+      busy(false);
+    } catch (e) { fail(e); }
+  }
+
+  // The built-in key, behind the same two-step gate as the recovery phrase:
+  // a warning you have to act on before anything secret is in the DOM.
+  function exportSection() {
+    const sk = wallet.nostr && wallet.nostr.sk;
+    if (!sk) return null;
+    if (ui.nostrExportStep === 'shown') {
+      const nsec = nsecOf(sk);
+      return h('div', { class: 'col', style: 'gap:8px' },
+        h('div', { class: 'addr-box break' }, nsec),
+        h('p', { class: 'small faint', style: 'margin:0' }, t('nlExportedNote')),
+        h('div', { class: 'row gap6' },
+          copyBtn(nsec, t('copy')),
+          h('button', { class: 'btn-sm grow', onClick: () => { ui.nostrExportStep = false; render(); } }, t('hide'))));
+    }
+    if (ui.nostrExportStep === 'warn') {
+      return h('div', { class: 'col', style: 'gap:8px' },
+        h('div', { class: 'warn-box' }, t('nlExportWarn')),
+        ui.nostrLoginError ? h('div', { class: 'notice err' }, ui.nostrLoginError) : null,
+        h('div', { class: 'row gap6' },
+          h('button', { class: 'btn-primary grow', disabled: ui.nostrLoginBusy, onClick: exportWalletKey },
+            ui.nostrLoginBusy ? h('span', { class: 'spinner' }) : t('nlExportReveal')),
+          h('button', { class: 'btn-sm', onClick: () => { ui.nostrExportStep = false; ui.nostrLoginError = ''; render(); } }, t('cancel'))));
+    }
+    return h('button', {
+      class: 'btn-block', disabled: ui.nostrLoginBusy,
+      onClick: () => { ui.nostrExportStep = 'warn'; ui.nostrLoginError = ''; render(); },
+    }, t('nlExportBtn'));
+  }
+
+  function linkSection() {
+    if (!ui.nostrLinkOpen) {
+      return h('button', {
+        class: 'btn-block', disabled: ui.nostrLoginBusy,
+        onClick: () => { ui.nostrLinkOpen = true; ui.nostrLoginError = ''; render(); },
+      }, t('nlChangeBtn'));
+    }
+    return h('div', { class: 'col', style: 'gap:10px' },
+      h('div', { class: 'row between' },
+        h('strong', { class: 'small' }, t('nlChangeBtn')),
+        h('span', { class: 'linklike small', onClick: () => { ui.nostrLinkOpen = false; ui.nostrLoginError = ''; render(); } }, t('cancel'))),
+      h('p', { class: 'small muted', style: 'margin:0' }, t('nlLinkDesc')),
+      h('div', { class: 'notice info small' }, t('nlBackupWarning')),
+      signerButtons(linkOpenWallet));
+  }
+
   function settingsCard() {
     if (wallet.watchOnly || !wallet.mnemonic) return null;
     const st = load();
@@ -306,11 +368,18 @@ export function nostrLoginFeature(ctx) {
           h('p', { class: 'small muted', style: 'margin:0' }, t('nlReconnectDesc')),
           signerButtons(reconnectSigner)));
     }
+    // No external account linked — but the wallet still HAS a nostr account:
+    // the one derived from its seed, already signing chat and holding the
+    // payment address. A bare login form here read as "no account yet", so
+    // the built-in identity comes first and both exporting its key and
+    // switching to another account are explicit steps behind buttons.
+    const npub = wallet.nostrNpub && wallet.nostrNpub();
     return h('div', { class: 'card col' },
       h('h3', {}, t('nlLinkTitle')),
-      h('p', { class: 'small muted', style: 'margin:0' }, t('nlLinkDesc')),
-      h('div', { class: 'notice info small' }, t('nlBackupWarning')),
-      signerButtons(linkOpenWallet));
+      npub ? h('div', { class: 'small muted break' }, npub) : null,
+      h('p', { class: 'small muted', style: 'margin:0' }, t('nlBuiltinDesc')),
+      exportSection(),
+      linkSection());
   }
 
   return {
diff --git a/src/i18n.js b/src/i18n.js
index fa0a48f..3295358 100644
--- a/src/i18n.js
+++ b/src/i18n.js
@@ -579,7 +579,13 @@ const STR = {
     nlCreateBtn: 'Create my wallet',
     nlCreated: 'Wallet created and linked',
     nlLinkTitle: 'Nostr account',
-    nlLinkDesc: 'Link this wallet to your Nostr account so you can open it on other devices by logging in with Nostr.',
+    nlLinkDesc: 'Log in with your own Nostr account instead — chat and your payment address will use its identity, and logging in with it on another device opens this wallet.',
+    nlBuiltinDesc: 'This wallet has a built-in Nostr account, derived from its seed. Chat and your payment address already use it — you don’t need to link anything.',
+    nlExportBtn: 'Export Nostr key',
+    nlExportWarn: 'This key opens this wallet. Anyone who has it can spend your money, read your chats, and change your payment address — guard it like your recovery phrase.',
+    nlExportReveal: 'Show the key',
+    nlExportedNote: 'Logging in with Nostr using this key opens this wallet.',
+    nlChangeBtn: 'Use a different Nostr account',
     nlLinkedDesc: 'This wallet opens when you log in with this Nostr account.',
     nlConnected: 'connected',
     nlDisconnected: 'not connected',
diff --git a/src/nostr.js b/src/nostr.js
index cf3cc88..98515fe 100644
--- a/src/nostr.js
+++ b/src/nostr.js
@@ -13,7 +13,7 @@ import * as nip06 from 'nostr-tools/nip06';
 import * as nip44 from 'nostr-tools/nip44';
 import * as nip04 from 'nostr-tools/nip04';
 import { getPublicKey, finalizeEvent, generateSecretKey } from 'nostr-tools/pure';
-import { decode as nip19decode, npubEncode } from 'nostr-tools/nip19';
+import { decode as nip19decode, npubEncode, nsecEncode } from 'nostr-tools/nip19';
 import { SimplePool } from 'nostr-tools/pool';
 import { randomBytes } from '@noble/hashes/utils';
 import { base64urlnopad } from '@scure/base';
@@ -112,6 +112,8 @@ export function parseNostrPubkey(input) {
 }
 // An npub or 64-hex nostr pubkey → hex, or null if it isn't one.
 export function npubOf(pkHex) { try { return npubEncode(pkHex); } catch { return null; } }
+// A raw secret key → nsec, for the one place that deliberately exports it.
+export function nsecOf(sk) { try { return nsecEncode(sk); } catch { return null; } }
 
 // Profiles live across the network, so look them up on popular relays (broader
 // than the sync relays).