feat: seed phrase (BIP39) import and export in profile settings

Add UI and handlers for importing a private key from a 24-word seed
phrase and exporting an existing key as a mnemonic for paper backup.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: vveerrgg

src/full_settings.html

@@ -131,7 +131,24 @@ <h2 class="section-header">Keys</h2>
                     </div>
                 </div>
 
-                <!-- Normal save button (hidden when ncryptsec is detected) -->
+                <!-- Seed phrase import: shows when space-separated words detected -->
+                <div data-section="seedphrase-import" class="mt-3 p-3 border-2 border-monokai-brown rounded" style="display:none;">
+                    <p class="text-sm font-bold">Seed phrase detected (BIP39 mnemonic).</p>
+                    <p class="text-sm italic mt-1">Import your private key from this 24-word seed phrase.</p>
+                    <div
+                        id="seedphrase-import-error"
+                        class="text-red-500 text-sm font-bold mt-1"
+                        style="display:none;"
+                    ></div>
+                    <div class="mt-2">
+                        <button
+                            class="button"
+                            data-action="importSeedPhrase"
+                        >Import from Seed Phrase</button>
+                    </div>
+                </div>
+
+                <!-- Normal save button (hidden when ncryptsec or seed phrase is detected) -->
                 <div class="mt-3">
                     <button
                         class="button"
@@ -225,6 +242,38 @@ <h3 class="subsection-header">Export Encrypted Key (NIP-49)</h3>
             </div>
         </div>
 
+            <!-- Seed phrase export -->
+            <div class="mt-4" id="seedphrase-export-section" style="display:none;">
+                <h3 class="subsection-header">Show Seed Phrase (BIP39)</h3>
+                <p class="text-sm italic mt-1">
+                    Export your private key as a 24-word seed phrase you can write
+                    on paper. Keep it secret — anyone with these words controls your key.
+                </p>
+                <div class="mt-2">
+                    <button
+                        class="button"
+                        data-action="revealSeedPhrase"
+                    >Reveal Seed Phrase</button>
+                </div>
+                <div
+                    id="seedphrase-export-reveal"
+                    class="mt-2 p-3 border-2 border-red-700 rounded bg-red-50"
+                    style="display:none;"
+                >
+                    <p class="text-red-800 text-sm font-bold">Secret seed phrase — keep this safe!</p>
+                    <textarea
+                        id="seedphrase-export-text"
+                        class="input w-full font-mono text-xs mt-2"
+                        rows="3"
+                        readonly
+                    ></textarea>
+                    <div class="mt-2 flex gap-2">
+                        <button class="button" data-action="copySeedPhrase">Copy</button>
+                        <button class="button" data-action="hideSeedPhrase">Hide</button>
+                    </div>
+                </div>
+            </div>
+
         <!-- BUNKER CONNECTION (bunker profiles only) -->
         <div class="section" data-section="bunker" style="display:none;">
             <h2 class="section-header">Bunker Connection</h2>

src/options.js

@@ -19,6 +19,7 @@ import {
     humanPermission,
     validateKey,
     isNcryptsec,
+    looksLikeSeedPhrase,
 } from './utilities/utils';
 import { api } from './utilities/browser-polyfill';
 import QRCode from 'qrcode';
@@ -58,7 +59,15 @@ const state = {
     ncryptsecExportError: '',
     ncryptsecExportLoading: false,
     ncryptsecExportCopied: false,
-    
+
+    // Seed phrase state
+    seedPhraseDetected: false,
+    seedPhraseError: '',
+    seedPhraseLoading: false,
+    seedPhraseRevealed: false,
+    seedPhraseText: '',
+    seedPhraseCopied: false,
+
     // Bunker state
     profileType: 'local',
     bunkerUrl: '',
@@ -125,6 +134,19 @@ function initElements() {
     elements.ncryptsecExportResult = $('ncryptsec-export-result');
     elements.copyNcryptsecBtn = document.querySelector('[data-action="copyNcryptsecExport"]');
 
+    // Seed phrase import
+    elements.seedPhraseImportSection = document.querySelector('[data-section="seedphrase-import"]');
+    elements.seedPhraseImportError = $('seedphrase-import-error');
+    elements.importSeedPhraseBtn = document.querySelector('[data-action="importSeedPhrase"]');
+
+    // Seed phrase export
+    elements.seedPhraseExportSection = $('seedphrase-export-section');
+    elements.revealSeedPhraseBtn = document.querySelector('[data-action="revealSeedPhrase"]');
+    elements.seedPhraseRevealBox = $('seedphrase-export-reveal');
+    elements.seedPhraseText = $('seedphrase-export-text');
+    elements.copySeedPhraseBtn = document.querySelector('[data-action="copySeedPhrase"]');
+    elements.hideSeedPhraseBtn = document.querySelector('[data-action="hideSeedPhrase"]');
+
     // Bunker section
     elements.bunkerSection = document.querySelector('[data-section="bunker"]');
     elements.bunkerProfileNameInput = $('bunker-profile-name');
@@ -254,11 +276,42 @@ function renderLocalProfile() {
     if (elements.ncryptsecSection) {
         elements.ncryptsecSection.style.display = hasNcryptsec ? 'block' : 'none';
     }
+
+    // Seed phrase import section
+    if (elements.seedPhraseImportSection) {
+        elements.seedPhraseImportSection.style.display = state.seedPhraseDetected && !hasNcryptsec ? 'block' : 'none';
+    }
+    if (elements.seedPhraseImportError) {
+        elements.seedPhraseImportError.textContent = state.seedPhraseError;
+        elements.seedPhraseImportError.style.display = state.seedPhraseError ? 'block' : 'none';
+    }
+    if (elements.importSeedPhraseBtn) {
+        elements.importSeedPhraseBtn.disabled = state.seedPhraseLoading;
+        elements.importSeedPhraseBtn.textContent = state.seedPhraseLoading ? 'Importing...' : 'Import from Seed Phrase';
+    }
+
     if (elements.saveProfileBtn) {
-        elements.saveProfileBtn.style.display = hasNcryptsec ? 'none' : 'block';
+        elements.saveProfileBtn.style.display = hasNcryptsec || state.seedPhraseDetected ? 'none' : 'block';
         const needsSave = state.privKey !== state.pristinePrivKey || state.profileName !== state.pristineProfileName;
         elements.saveProfileBtn.disabled = !needsSave || !validateKey(state.privKey);
     }
+
+    // Seed phrase export section (only for local profiles with an existing key)
+    if (elements.seedPhraseExportSection) {
+        elements.seedPhraseExportSection.style.display = state.pristinePrivKey && !hasNcryptsec ? 'block' : 'none';
+    }
+    if (elements.seedPhraseRevealBox) {
+        elements.seedPhraseRevealBox.style.display = state.seedPhraseRevealed ? 'block' : 'none';
+    }
+    if (elements.seedPhraseText) {
+        elements.seedPhraseText.value = state.seedPhraseText;
+    }
+    if (elements.revealSeedPhraseBtn) {
+        elements.revealSeedPhraseBtn.style.display = state.seedPhraseRevealed ? 'none' : 'inline-block';
+    }
+    if (elements.copySeedPhraseBtn) {
+        elements.copySeedPhraseBtn.textContent = state.seedPhraseCopied ? 'Copied!' : 'Copy';
+    }
 
     // QR codes
     if (elements.npubQrContainer && state.npubQrDataUrl) {
@@ -552,14 +605,20 @@ async function refreshProfile() {
         payload: state.profileIndex,
     });
 
-    // Reset QR and ncryptsec state
+    // Reset QR, ncryptsec, and seed phrase state
     state.npubQrDataUrl = '';
     state.nsecQrDataUrl = '';
     state.showNsecQr = false;
     state.ncryptsecExportResult = '';
     state.ncryptsecExportError = '';
     state.ncryptsecExportPassword = '';
     state.ncryptsecExportConfirm = '';
+    state.seedPhraseDetected = false;
+    state.seedPhraseError = '';
+    state.seedPhraseLoading = false;
+    state.seedPhraseRevealed = false;
+    state.seedPhraseText = '';
+    state.seedPhraseCopied = false;
 
     if (state.profileType === 'local') {
         await loadLocalProfile();
@@ -696,6 +755,8 @@ function handleProfileNameInput(e) {
 
 function handlePrivKeyInput(e) {
     state.privKey = e.target.value;
+    state.seedPhraseDetected = looksLikeSeedPhrase(state.privKey);
+    state.seedPhraseError = '';
     render();
 }
 
@@ -803,6 +864,69 @@ async function handleCopyNcryptsecExport() {
     }, 1500);
 }
 
+async function handleImportSeedPhrase() {
+    state.seedPhraseError = '';
+    state.seedPhraseLoading = true;
+    render();
+
+    try {
+        const result = await api.runtime.sendMessage({
+            kind: 'seedPhrase.toKey',
+            payload: state.privKey,
+        });
+
+        if (result.success) {
+            await savePrivateKey(state.profileIndex, result.hexKey);
+            await refreshProfile();
+        } else {
+            state.seedPhraseError = result.error || 'Invalid seed phrase';
+        }
+    } catch (e) {
+        state.seedPhraseError = e.message || 'Import failed';
+    }
+
+    state.seedPhraseLoading = false;
+    render();
+}
+
+async function handleRevealSeedPhrase() {
+    try {
+        const result = await api.runtime.sendMessage({
+            kind: 'seedPhrase.fromKey',
+            payload: state.profileIndex,
+        });
+
+        if (result.success) {
+            state.seedPhraseText = result.seedPhrase;
+            state.seedPhraseRevealed = true;
+        } else {
+            state.seedPhraseText = '';
+            state.seedPhraseRevealed = false;
+            alert(result.error || 'Failed to reveal seed phrase');
+        }
+    } catch (e) {
+        alert(e.message || 'Failed to reveal seed phrase');
+    }
+    render();
+}
+
+function handleHideSeedPhrase() {
+    state.seedPhraseText = '';
+    state.seedPhraseRevealed = false;
+    state.seedPhraseCopied = false;
+    render();
+}
+
+async function handleCopySeedPhrase() {
+    await navigator.clipboard.writeText(state.seedPhraseText);
+    state.seedPhraseCopied = true;
+    render();
+    setTimeout(() => {
+        state.seedPhraseCopied = false;
+        render();
+    }, 1500);
+}
+
 async function handleConnectBunker() {
     state.bunkerError = '';
     state.bunkerConnecting = true;
@@ -1104,6 +1228,20 @@ function bindEvents() {
         elements.copyNcryptsecBtn.addEventListener('click', handleCopyNcryptsecExport);
     }
 
+    // Seed phrase
+    if (elements.importSeedPhraseBtn) {
+        elements.importSeedPhraseBtn.addEventListener('click', handleImportSeedPhrase);
+    }
+    if (elements.revealSeedPhraseBtn) {
+        elements.revealSeedPhraseBtn.addEventListener('click', handleRevealSeedPhrase);
+    }
+    if (elements.hideSeedPhraseBtn) {
+        elements.hideSeedPhraseBtn.addEventListener('click', handleHideSeedPhrase);
+    }
+    if (elements.copySeedPhraseBtn) {
+        elements.copySeedPhraseBtn.addEventListener('click', handleCopySeedPhrase);
+    }
+
     // Input changes for ncryptsec export
     if (elements.ncryptsecExportPassword) {
         elements.ncryptsecExportPassword.addEventListener('input', (e) => {