feat(market): save others' offers as favorites (Wallapop-style)

Adds a Favorites feature: a heart on the offer detail saves another
person's listing to an encrypted, per-identity SavedOffersStore
(keystore JSON snapshot, no plaintext at rest). A new /favorites screen
(wired from the drawer) lists saved offers offline-first and, when a
relay is reachable, flags ones that are gone as "no longer available".
i18n en/es/pt/ast; store + screen + detail-heart tests.

apps/app_seeds/lib/app.dart

@@ -17,6 +17,7 @@ import 'services/offer_outbox.dart';
 import 'services/onboarding_store.dart';
 import 'services/profile_cache.dart';
 import 'services/profile_store.dart';
+import 'services/saved_offers_store.dart';
 import 'services/social_account_store.dart';
 import 'services/social_connection.dart';
 import 'services/social_service.dart';
@@ -28,6 +29,7 @@ import 'ui/auto_backup_gate.dart';
 import 'ui/calendar_screen.dart';
 import 'ui/chat_list_screen.dart';
 import 'ui/chat_screen.dart';
+import 'ui/favorites_screen.dart';
 import 'ui/home_screen.dart';
 import 'ui/intro_screen.dart';
 import 'ui/inventory_list_screen.dart';
@@ -58,6 +60,7 @@ class TaneApp extends StatelessWidget {
     this.messageStore,
     this.profileStore,
     this.profileCache,
+    this.savedOffers,
     this.socialAccounts,
     this.inbox,
     this.notifications,
@@ -76,6 +79,7 @@ class TaneApp extends StatelessWidget {
           messageStore,
           profileStore,
           profileCache,
+          savedOffers,
           socialAccounts,
           inbox,
         ) {
@@ -112,6 +116,9 @@ class TaneApp extends StatelessWidget {
   /// Optional cache of peers' published display names.
   final ProfileCache? profileCache;
 
+  /// Optional store of the user's saved ("favorite") market offers.
+  final SavedOffersStore? savedOffers;
+
   /// Optional store of the active social identity, for the profile switcher.
   final SocialAccountStore? socialAccounts;
 
@@ -140,6 +147,7 @@ class TaneApp extends StatelessWidget {
     MessageStore? messageStore,
     ProfileStore? profileStore,
     ProfileCache? profileCache,
+    SavedOffersStore? savedOffers,
     SocialAccountStore? socialAccounts,
     InboxService? inbox,
   ) {
@@ -173,9 +181,18 @@ class TaneApp extends StatelessWidget {
                 mine: offer.authorPubkeyHex == social.publicKeyHex,
                 profileCache: profileCache,
                 selfPubkey: social.publicKeyHex,
+                savedOffers: savedOffers,
               );
             },
           ),
+        if (social != null && savedOffers != null)
+          GoRoute(
+            path: '/favorites',
+            builder: (context, state) => FavoritesScreen(
+              savedOffers: savedOffers,
+              connection: connection,
+            ),
+          ),
         if (messageStore != null)
           GoRoute(
             path: '/messages',

apps/app_seeds/lib/bootstrap.dart

@@ -18,6 +18,7 @@ import 'services/offer_outbox.dart';
 import 'services/onboarding_store.dart';
 import 'services/profile_cache.dart';
 import 'services/profile_store.dart';
+import 'services/saved_offers_store.dart';
 import 'services/social_account_store.dart';
 import 'services/social_connection.dart';
 import 'services/social_service.dart';
@@ -85,6 +86,7 @@ class _BootstrapState extends State<Bootstrap> {
       messageStore: getIt<MessageStore>(),
       profileStore: getIt<ProfileStore>(),
       profileCache: getIt<ProfileCache>(),
+      savedOffers: getIt<SavedOffersStore>(),
       socialAccounts: getIt<SocialAccountStore>(),
       inbox: inbox,
       notifications: notifications,

apps/app_seeds/lib/di/injector.dart

@@ -39,6 +39,7 @@ import '../services/message_store.dart';
 import '../services/offer_outbox.dart';
 import '../services/profile_cache.dart';
 import '../services/profile_store.dart';
+import '../services/saved_offers_store.dart';
 import '../services/social_account_store.dart';
 import '../services/social_connection.dart';
 import '../services/social_service.dart';
@@ -184,6 +185,9 @@ Future<void> configureDependencies() async {
     ..registerSingleton<ProfileCache>(
       ProfileCache(secretStore, accountScope: scope),
     )
+    ..registerSingleton<SavedOffersStore>(
+      SavedOffersStore(secretStore, accountScope: scope),
+    )
     ..registerSingleton<ExportImportService>(
       ExportImportService(
         repository: varietyRepository,
@@ -301,6 +305,8 @@ Future<void> switchSocialAccount(int account) async {
   await getIt.unregister<MessageStore>();
   await getIt.unregister<ProfileStore>();
   await getIt.unregister<ProfileCache>();
+  await getIt<SavedOffersStore>().close();
+  await getIt.unregister<SavedOffersStore>();
 
   // Re-register the per-identity stores under the new scope, then the identity.
   getIt
@@ -313,6 +319,9 @@ Future<void> switchSocialAccount(int account) async {
     ..registerSingleton<ProfileCache>(
       ProfileCache(secretStore, accountScope: scope),
     )
+    ..registerSingleton<SavedOffersStore>(
+      SavedOffersStore(secretStore, accountScope: scope),
+    )
     ..registerSingleton<UnreadService>(
       UnreadService(getIt<MessageStore>(), secretStore),
     );

apps/app_seeds/lib/i18n/ast.i18n.json

@@ -5,6 +5,13 @@
     "illustration": "O escueyi un dibuxu",
     "remove": "Quitar"
   },
+  "favorites": {
+    "title": "Favoritos",
+    "empty": "Entá nun tienes favoritos. Guarda ofertes que te presten del mercáu.",
+    "save": "Guardar en favoritos",
+    "remove": "Quitar de favoritos",
+    "unavailable": "Yá nun ta disponible"
+  },
   "seedSaving": {
     "title": "Guardar la so semiente",
     "subtitle": "Lo que fai falta pa caltener la variedá fiel",

apps/app_seeds/lib/i18n/en.i18n.json

@@ -5,6 +5,13 @@
     "illustration": "Or pick an illustration",
     "remove": "Remove"
   },
+  "favorites": {
+    "title": "Favorites",
+    "empty": "No favorites yet. Save offers you like from the market.",
+    "save": "Save to favorites",
+    "remove": "Remove from favorites",
+    "unavailable": "No longer available"
+  },
   "seedSaving": {
     "title": "Saving its seed",
     "subtitle": "What it takes to keep the variety true",

apps/app_seeds/lib/i18n/es.i18n.json

@@ -5,6 +5,13 @@
     "illustration": "O elige un dibujo",
     "remove": "Quitar"
   },
+  "favorites": {
+    "title": "Favoritos",
+    "empty": "Aún no tienes favoritos. Guarda ofertas que te gusten del mercado.",
+    "save": "Guardar en favoritos",
+    "remove": "Quitar de favoritos",
+    "unavailable": "Ya no está disponible"
+  },
   "seedSaving": {
     "title": "Conservar su semilla",
     "subtitle": "Lo que hace falta para mantener la variedad fiel",

apps/app_seeds/lib/i18n/pt.i18n.json

@@ -5,6 +5,13 @@
     "illustration": "Ou escolhe um desenho",
     "remove": "Remover"
   },
+  "favorites": {
+    "title": "Favoritos",
+    "empty": "Ainda não tens favoritos. Guarda ofertas que gostes do mercado.",
+    "save": "Guardar nos favoritos",
+    "remove": "Remover dos favoritos",
+    "unavailable": "Já não está disponível"
+  },
   "seedSaving": {
     "title": "Guardar a sua semente",
     "subtitle": "O que é preciso para manter a variedade fiel",

apps/app_seeds/lib/i18n/strings.g.dart

@@ -4,9 +4,9 @@
 /// To regenerate, run: `dart run slang`
 ///
 /// Locales: 4
-/// Strings: 2032 (508 per locale)
+/// Strings: 2052 (513 per locale)
 ///
-/// Built on 2026-07-12 at 10:59 UTC
+/// Built on 2026-07-13 at 05:54 UTC
 
 // coverage:ignore-file
 // ignore_for_file: type=lint, unused_import

apps/app_seeds/lib/i18n/strings_ast.g.dart

@@ -40,6 +40,7 @@ class TranslationsAst extends Translations with BaseTranslations<AppLocale, Tran
 
 	// Translations
 	@override late final _Translations$avatar$ast avatar = _Translations$avatar$ast._(_root);
+	@override late final _Translations$favorites$ast favorites = _Translations$favorites$ast._(_root);
 	@override late final _Translations$seedSaving$ast seedSaving = _Translations$seedSaving$ast._(_root);
 	@override late final _Translations$calendar$ast calendar = _Translations$calendar$ast._(_root);
 	@override late final _Translations$app$ast app = _Translations$app$ast._(_root);
@@ -99,6 +100,20 @@ class _Translations$avatar$ast extends Translations$avatar$en {
 	@override String get remove => 'Quitar';
 }
 
+// Path: favorites
+class _Translations$favorites$ast extends Translations$favorites$en {
+	_Translations$favorites$ast._(TranslationsAst root) : this._root = root, super.internal(root);
+
+	final TranslationsAst _root; // ignore: unused_field
+
+	// Translations
+	@override String get title => 'Favoritos';
+	@override String get empty => 'Entá nun tienes favoritos. Guarda ofertes que te presten del mercáu.';
+	@override String get save => 'Guardar en favoritos';
+	@override String get remove => 'Quitar de favoritos';
+	@override String get unavailable => 'Yá nun ta disponible';
+}
+
 // Path: seedSaving
 class _Translations$seedSaving$ast extends Translations$seedSaving$en {
 	_Translations$seedSaving$ast._(TranslationsAst root) : this._root = root, super.internal(root);
@@ -1312,6 +1327,11 @@ extension on TranslationsAst {
 			'avatar.fromPhoto' => 'Facer o escoyer una semeya',
 			'avatar.illustration' => 'O escueyi un dibuxu',
 			'avatar.remove' => 'Quitar',
+			'favorites.title' => 'Favoritos',
+			'favorites.empty' => 'Entá nun tienes favoritos. Guarda ofertes que te presten del mercáu.',
+			'favorites.save' => 'Guardar en favoritos',
+			'favorites.remove' => 'Quitar de favoritos',
+			'favorites.unavailable' => 'Yá nun ta disponible',
 			'seedSaving.title' => 'Guardar la so semiente',
 			'seedSaving.subtitle' => 'Lo que fai falta pa caltener la variedá fiel',
 			'seedSaving.lifeCycle' => 'Ciclu',

apps/app_seeds/lib/i18n/strings_en.g.dart

@@ -41,6 +41,7 @@ class Translations with BaseTranslations<AppLocale, Translations> {
 
 	// Translations
 	late final Translations$avatar$en avatar = Translations$avatar$en.internal(_root);
+	late final Translations$favorites$en favorites = Translations$favorites$en.internal(_root);
 	late final Translations$seedSaving$en seedSaving = Translations$seedSaving$en.internal(_root);
 	late final Translations$calendar$en calendar = Translations$calendar$en.internal(_root);
 	late final Translations$app$en app = Translations$app$en.internal(_root);
@@ -108,6 +109,30 @@ class Translations$avatar$en {
 	String get remove => 'Remove';
 }
 
+// Path: favorites
+class Translations$favorites$en {
+	Translations$favorites$en.internal(this._root);
+
+	final Translations _root; // ignore: unused_field
+
+	// Translations
+
+	/// en: 'Favorites'
+	String get title => 'Favorites';
+
+	/// en: 'No favorites yet. Save offers you like from the market.'
+	String get empty => 'No favorites yet. Save offers you like from the market.';
+
+	/// en: 'Save to favorites'
+	String get save => 'Save to favorites';
+
+	/// en: 'Remove from favorites'
+	String get remove => 'Remove from favorites';
+
+	/// en: 'No longer available'
+	String get unavailable => 'No longer available';
+}
+
 // Path: seedSaving
 class Translations$seedSaving$en {
 	Translations$seedSaving$en.internal(this._root);
@@ -2315,6 +2340,11 @@ extension on Translations {
 			'avatar.fromPhoto' => 'Take or choose a photo',
 			'avatar.illustration' => 'Or pick an illustration',
 			'avatar.remove' => 'Remove',
+			'favorites.title' => 'Favorites',
+			'favorites.empty' => 'No favorites yet. Save offers you like from the market.',
+			'favorites.save' => 'Save to favorites',
+			'favorites.remove' => 'Remove from favorites',
+			'favorites.unavailable' => 'No longer available',
 			'seedSaving.title' => 'Saving its seed',
 			'seedSaving.subtitle' => 'What it takes to keep the variety true',
 			'seedSaving.lifeCycle' => 'Cycle',
@@ -2818,6 +2848,8 @@ extension on Translations {
 			'sale.currencyHint' => '€, Ğ1, hours… (optional)',
 			'sale.hours' => 'hours',
 			'sale.note' => 'Note (optional)',
+			_ => null,
+		} ?? switch (path) {
 			'sale.save' => 'Save',
 			'sale.delete' => 'Remove',
 			'sale.removeConfirm' => 'Remove this sale?',

apps/app_seeds/lib/i18n/strings_es.g.dart

@@ -40,6 +40,7 @@ class TranslationsEs extends Translations with BaseTranslations<AppLocale, Trans
 
 	// Translations
 	@override late final _Translations$avatar$es avatar = _Translations$avatar$es._(_root);
+	@override late final _Translations$favorites$es favorites = _Translations$favorites$es._(_root);
 	@override late final _Translations$seedSaving$es seedSaving = _Translations$seedSaving$es._(_root);
 	@override late final _Translations$calendar$es calendar = _Translations$calendar$es._(_root);
 	@override late final _Translations$app$es app = _Translations$app$es._(_root);
@@ -99,6 +100,20 @@ class _Translations$avatar$es extends Translations$avatar$en {
 	@override String get remove => 'Quitar';
 }
 
+// Path: favorites
+class _Translations$favorites$es extends Translations$favorites$en {
+	_Translations$favorites$es._(TranslationsEs root) : this._root = root, super.internal(root);
+
+	final TranslationsEs _root; // ignore: unused_field
+
+	// Translations
+	@override String get title => 'Favoritos';
+	@override String get empty => 'Aún no tienes favoritos. Guarda ofertas que te gusten del mercado.';
+	@override String get save => 'Guardar en favoritos';
+	@override String get remove => 'Quitar de favoritos';
+	@override String get unavailable => 'Ya no está disponible';
+}
+
 // Path: seedSaving
 class _Translations$seedSaving$es extends Translations$seedSaving$en {
 	_Translations$seedSaving$es._(TranslationsEs root) : this._root = root, super.internal(root);
@@ -1314,6 +1329,11 @@ extension on TranslationsEs {
 			'avatar.fromPhoto' => 'Hacer o elegir una foto',
 			'avatar.illustration' => 'O elige un dibujo',
 			'avatar.remove' => 'Quitar',
+			'favorites.title' => 'Favoritos',
+			'favorites.empty' => 'Aún no tienes favoritos. Guarda ofertas que te gusten del mercado.',
+			'favorites.save' => 'Guardar en favoritos',
+			'favorites.remove' => 'Quitar de favoritos',
+			'favorites.unavailable' => 'Ya no está disponible',
 			'seedSaving.title' => 'Conservar su semilla',
 			'seedSaving.subtitle' => 'Lo que hace falta para mantener la variedad fiel',
 			'seedSaving.lifeCycle' => 'Ciclo',
@@ -1817,6 +1837,8 @@ extension on TranslationsEs {
 			'sale.hours' => 'horas',
 			'sale.note' => 'Nota (opcional)',
 			'sale.save' => 'Guardar',
+			_ => null,
+		} ?? switch (path) {
 			'sale.delete' => 'Quitar',
 			'sale.removeConfirm' => '¿Quitar esta venta?',
 			_ => null,

apps/app_seeds/lib/i18n/strings_pt.g.dart

@@ -40,6 +40,7 @@ class TranslationsPt extends Translations with BaseTranslations<AppLocale, Trans
 
 	// Translations
 	@override late final _Translations$avatar$pt avatar = _Translations$avatar$pt._(_root);
+	@override late final _Translations$favorites$pt favorites = _Translations$favorites$pt._(_root);
 	@override late final _Translations$seedSaving$pt seedSaving = _Translations$seedSaving$pt._(_root);
 	@override late final _Translations$calendar$pt calendar = _Translations$calendar$pt._(_root);
 	@override late final _Translations$app$pt app = _Translations$app$pt._(_root);
@@ -99,6 +100,20 @@ class _Translations$avatar$pt extends Translations$avatar$en {
 	@override String get remove => 'Remover';
 }
 
+// Path: favorites
+class _Translations$favorites$pt extends Translations$favorites$en {
+	_Translations$favorites$pt._(TranslationsPt root) : this._root = root, super.internal(root);
+
+	final TranslationsPt _root; // ignore: unused_field
+
+	// Translations
+	@override String get title => 'Favoritos';
+	@override String get empty => 'Ainda não tens favoritos. Guarda ofertas que gostes do mercado.';
+	@override String get save => 'Guardar nos favoritos';
+	@override String get remove => 'Remover dos favoritos';
+	@override String get unavailable => 'Já não está disponível';
+}
+
 // Path: seedSaving
 class _Translations$seedSaving$pt extends Translations$seedSaving$en {
 	_Translations$seedSaving$pt._(TranslationsPt root) : this._root = root, super.internal(root);
@@ -1311,6 +1326,11 @@ extension on TranslationsPt {
 			'avatar.fromPhoto' => 'Tirar ou escolher uma foto',
 			'avatar.illustration' => 'Ou escolhe um desenho',
 			'avatar.remove' => 'Remover',
+			'favorites.title' => 'Favoritos',
+			'favorites.empty' => 'Ainda não tens favoritos. Guarda ofertas que gostes do mercado.',
+			'favorites.save' => 'Guardar nos favoritos',
+			'favorites.remove' => 'Remover dos favoritos',
+			'favorites.unavailable' => 'Já não está disponível',
 			'seedSaving.title' => 'Guardar a sua semente',
 			'seedSaving.subtitle' => 'O que é preciso para manter a variedade fiel',
 			'seedSaving.lifeCycle' => 'Ciclo',

apps/app_seeds/lib/services/saved_offers_store.dart

@@ -0,0 +1,123 @@
+import 'dart:async';
+import 'dart:convert';
+
+import 'package:commons_core/commons_core.dart';
+
+import '../security/secret_store.dart';
+
+/// A person's saved ("favorite") market offers — other people's listings they
+/// bookmarked, Wallapop-style. Keystore-backed (no plaintext at rest) and
+/// namespaced by the active identity's [accountScope], like [ProfileStore].
+///
+/// We keep a *snapshot* of each offer (not just its coordinate) so the Favorites
+/// list renders offline, and so a since-withdrawn offer can still be shown as
+/// "no longer available" instead of vanishing. The stable key is the offer's
+/// addressable coordinate `authorPubkeyHex:id` ([keyOf]).
+class SavedOffersStore {
+  SavedOffersStore(this._store, {String accountScope = ''})
+    : _key = accountScope.isEmpty
+          ? 'tane.social.saved_offers'
+          : 'tane.social.$accountScope.saved_offers';
+
+  final SecretStore _store;
+  final String _key;
+
+  final _changes = StreamController<void>.broadcast();
+
+  /// Emits whenever the saved set changes, so open screens can refresh.
+  Stream<void> get changes => _changes.stream;
+
+  /// The stable per-offer key: its NIP-99 addressable coordinate without the
+  /// kind (`authorPubkeyHex:id`). Same offer → same key on every device.
+  static String keyOf(Offer offer) => '${offer.authorPubkeyHex}:${offer.id}';
+
+  /// Every saved offer, newest first (by save time).
+  Future<List<Offer>> list() async {
+    final raw = await _store.read(_key);
+    if (raw == null || raw.isEmpty) return const [];
+    final entries = (jsonDecode(raw) as List)
+        .cast<Map<String, dynamic>>()
+        .toList()
+      ..sort((a, b) => (b['savedAt'] as int).compareTo(a['savedAt'] as int));
+    return [for (final e in entries) _decode(e)];
+  }
+
+  /// Whether [key] (from [keyOf]) is currently saved.
+  Future<bool> isSaved(String key) async =>
+      (await _rawList()).any((e) => e['key'] == key);
+
+  /// Saves [offer] (idempotent on its key). Newer snapshot replaces an older one.
+  Future<void> save(Offer offer, {required int savedAt}) async {
+    final key = keyOf(offer);
+    final list = await _rawList()..removeWhere((e) => e['key'] == key);
+    list.add({..._encode(offer), 'key': key, 'savedAt': savedAt});
+    await _writeRaw(list);
+  }
+
+  /// Removes the saved offer with [key] (from [keyOf]); no-op if absent.
+  Future<void> remove(String key) async {
+    final list = await _rawList()..removeWhere((e) => e['key'] == key);
+    await _writeRaw(list);
+  }
+
+  /// Toggles [offer]'s saved state; returns the new state (true = now saved).
+  Future<bool> toggle(Offer offer, {required int savedAt}) async {
+    if (await isSaved(keyOf(offer))) {
+      await remove(keyOf(offer));
+      return false;
+    }
+    await save(offer, savedAt: savedAt);
+    return true;
+  }
+
+  Future<List<Map<String, dynamic>>> _rawList() async {
+    final raw = await _store.read(_key);
+    if (raw == null || raw.isEmpty) return [];
+    return (jsonDecode(raw) as List).cast<Map<String, dynamic>>().toList();
+  }
+
+  Future<void> _writeRaw(List<Map<String, dynamic>> list) async {
+    await _store.write(_key, jsonEncode(list));
+    if (!_changes.isClosed) _changes.add(null);
+  }
+
+  Map<String, dynamic> _encode(Offer o) => {
+    'id': o.id,
+    'author': o.authorPubkeyHex,
+    'summary': o.summary,
+    'type': o.type.name,
+    'status': o.status.name,
+    if (o.category != null) 'category': o.category,
+    'geohash': o.approxGeohash,
+    if (o.radiusKm != null) 'radiusKm': o.radiusKm,
+    if (o.priceAmount != null) 'priceAmount': o.priceAmount,
+    if (o.priceCurrency != null) 'priceCurrency': o.priceCurrency,
+    if (o.exchangeTerms != null) 'exchangeTerms': o.exchangeTerms,
+    if (o.imageUrl != null) 'imageUrl': o.imageUrl,
+    if (o.expiresAt != null) 'expiresAt': o.expiresAt!.millisecondsSinceEpoch,
+    'isOrganic': o.isOrganic,
+  };
+
+  Offer _decode(Map<String, dynamic> e) => Offer(
+    id: e['id'] as String,
+    authorPubkeyHex: e['author'] as String,
+    summary: e['summary'] as String,
+    type: OfferType.values.byName(e['type'] as String),
+    status: OfferLifecycle.values.byName(e['status'] as String? ?? 'active'),
+    category: e['category'] as String?,
+    approxGeohash: e['geohash'] as String? ?? '',
+    radiusKm: e['radiusKm'] as int?,
+    priceAmount: e['priceAmount'] as num?,
+    priceCurrency: e['priceCurrency'] as String?,
+    exchangeTerms: e['exchangeTerms'] as String?,
+    imageUrl: e['imageUrl'] as String?,
+    expiresAt: e['expiresAt'] == null
+        ? null
+        : DateTime.fromMillisecondsSinceEpoch(e['expiresAt'] as int),
+    isOrganic: e['isOrganic'] as bool? ?? false,
+  );
+
+  Future<void> close() async {
+    await _changes.close();
+  }
+}

apps/app_seeds/lib/ui/app_drawer.dart

@@ -103,6 +103,12 @@ class AppDrawer extends StatelessWidget {
                   _DrawerItem(
                     icon: const Icon(Icons.favorite),
                     label: t.menu.wishlist,
+                    onTap: marketEnabled
+                        ? () {
+                            Navigator.of(context).pop();
+                            context.push('/favorites');
+                          }
+                        : null,
                   ),
                   // The ego-centric web of trust ("your people") — live once the
                   // social layer is on.

apps/app_seeds/lib/ui/favorites_screen.dart

@@ -0,0 +1,257 @@
+import 'dart:async';
+
+import 'package:commons_core/commons_core.dart';
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+import '../i18n/strings.g.dart';
+import '../services/saved_offers_store.dart';
+import '../services/social_connection.dart';
+import 'market_widgets.dart';
+import 'theme.dart';
+
+/// The Wallapop-style "Favorites": offers from other people the user saved.
+/// Shows the saved snapshots offline-first; when a relay is reachable it checks
+/// which ones are still published and flags the rest as no longer available
+/// (they may have been withdrawn or expired). Tapping opens the offer detail.
+class FavoritesScreen extends StatefulWidget {
+  const FavoritesScreen({
+    required this.savedOffers,
+    this.connection,
+    super.key,
+  });
+
+  final SavedOffersStore savedOffers;
+
+  /// The shared relay connection, used to check whether saved offers still
+  /// exist. Null (tests / no social layer) → no check, snapshots shown as-is.
+  final SocialConnection? connection;
+
+  @override
+  State<FavoritesScreen> createState() => _FavoritesScreenState();
+}
+
+class _FavoritesScreenState extends State<FavoritesScreen> {
+  List<Offer>? _offers;
+  var _liveKeys = <String>{};
+  var _checked = false;
+  StreamSubscription<void>? _changesSub;
+
+  @override
+  void initState() {
+    super.initState();
+    _changesSub = widget.savedOffers.changes.listen((_) => _load());
+    _load();
+  }
+
+  @override
+  void dispose() {
+    _changesSub?.cancel();
+    super.dispose();
+  }
+
+  Future<void> _load() async {
+    final offers = await widget.savedOffers.list();
+    if (!mounted) return;
+    setState(() => _offers = offers);
+    unawaited(_check(offers));
+  }
+
+  /// Asks the relay which saved offers are still out there. Offline (no session)
+  /// leaves [_checked] false, so nothing is wrongly flagged as gone.
+  Future<void> _check(List<Offer> offers) async {
+    final connection = widget.connection;
+    if (connection == null || offers.isEmpty) return;
+    final session = await connection.session();
+    if (session == null || !mounted) return;
+
+    final live = <String>{};
+    final geohashes = {
+      for (final o in offers)
+        if (o.approxGeohash.isNotEmpty) o.approxGeohash,
+    };
+    final subs = <StreamSubscription<Offer>>[];
+    for (final geohash in geohashes) {
+      subs.add(
+        session.offers
+            .discover(DiscoveryQuery(geohashPrefix: geohash))
+            .listen((o) => live.add(SavedOffersStore.keyOf(o)), onError: (_) {}),
+      );
+    }
+    // The discover streams stay open for live offers and never signal "done";
+    // give them a beat to deliver what's stored, then take stock.
+    await Future<void>.delayed(const Duration(seconds: 5));
+    for (final s in subs) {
+      unawaited(s.cancel());
+    }
+    if (!mounted) return;
+    setState(() {
+      _liveKeys = live;
+      _checked = true;
+    });
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final t = context.t;
+    final offers = _offers;
+    return Scaffold(
+      appBar: AppBar(title: Text(t.favorites.title)),
+      body: offers == null
+          ? const Center(child: CircularProgressIndicator())
+          : offers.isEmpty
+          ? _Empty(text: t.favorites.empty)
+          : ListView.separated(
+              padding: const EdgeInsets.all(12),
+              itemCount: offers.length,
+              separatorBuilder: (_, _) => const SizedBox(height: 10),
+              itemBuilder: (context, i) {
+                final offer = offers[i];
+                final key = SavedOffersStore.keyOf(offer);
+                // Only call something gone once a check actually ran and didn't
+                // see it — never while offline (checked == false).
+                final gone = _checked && !_liveKeys.contains(key);
+                return _FavoriteCard(
+                  offer: offer,
+                  unavailable: gone,
+                  onOpen: () => context.push('/market/offer', extra: offer),
+                  onRemove: () => widget.savedOffers.remove(key),
+                );
+              },
+            ),
+    );
+  }
+}
+
+class _FavoriteCard extends StatelessWidget {
+  const _FavoriteCard({
+    required this.offer,
+    required this.unavailable,
+    required this.onOpen,
+    required this.onRemove,
+  });
+
+  final Offer offer;
+  final bool unavailable;
+  final VoidCallback onOpen;
+  final VoidCallback onRemove;
+
+  @override
+  Widget build(BuildContext context) {
+    final t = context.t;
+    final radius = BorderRadius.circular(14);
+    return Material(
+      color: Colors.white,
+      borderRadius: radius,
+      child: InkWell(
+        key: Key('favorites.offer.${offer.authorPubkeyHex}.${offer.id}'),
+        onTap: onOpen,
+        borderRadius: radius,
+        child: Container(
+          decoration: BoxDecoration(
+            borderRadius: radius,
+            border: Border.all(color: seedOutline),
+          ),
+          padding: const EdgeInsets.all(16),
+          child: Opacity(
+            opacity: unavailable ? 0.55 : 1,
+            child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: [
+                Row(
+                  children: [
+                    if (offer.imageUrl != null) ...[
+                      OfferThumbnail(
+                        url: offer.imageUrl!,
+                        semanticLabel: t.market.photo,
+                      ),
+                      const SizedBox(width: 12),
+                    ],
+                    Expanded(
+                      child: Text(
+                        offer.summary,
+                        style: const TextStyle(
+                          fontSize: 17,
+                          fontWeight: FontWeight.w500,
+                          color: seedOnSurface,
+                        ),
+                      ),
+                    ),
+                    IconButton(
+                      key: Key('favorites.remove.${offer.authorPubkeyHex}'
+                          '.${offer.id}'),
+                      icon: const Icon(Icons.favorite, color: seedGreen),
+                      tooltip: t.favorites.remove,
+                      onPressed: onRemove,
+                    ),
+                  ],
+                ),
+                const SizedBox(height: 4),
+                Row(
+                  children: [
+                    if (unavailable)
+                      Row(
+                        children: [
+                          const Icon(Icons.cloud_off,
+                              size: 15, color: seedMuted),
+                          const SizedBox(width: 4),
+                          Text(
+                            t.favorites.unavailable,
+                            style:
+                                const TextStyle(color: seedMuted, fontSize: 13),
+                          ),
+                        ],
+                      )
+                    else
+                      OfferTypeChip(label: offerTypeLabel(t, offer.type)),
+                    const Spacer(),
+                    if (offer.type == OfferType.sale && offer.priceAmount != null)
+                      Text(
+                        '${offer.priceAmount} ${offer.priceCurrency ?? ''}'
+                            .trim(),
+                        style: const TextStyle(
+                          color: seedOnSurface,
+                          fontWeight: FontWeight.w600,
+                        ),
+                      ),
+                  ],
+                ),
+              ],
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}
+
+class _Empty extends StatelessWidget {
+  const _Empty({required this.text});
+
+  final String text;
+
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: Padding(
+        padding: const EdgeInsets.all(24),
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          children: [
+            Icon(
+              Icons.favorite_border,
+              size: 64,
+              color: seedGreen.withValues(alpha: 0.5),
+            ),
+            const SizedBox(height: 16),
+            Text(
+              text,
+              textAlign: TextAlign.center,
+              style: Theme.of(context).textTheme.bodyLarge,
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

apps/app_seeds/lib/ui/market_offer_detail_screen.dart

@@ -7,6 +7,7 @@ import 'package:go_router/go_router.dart';
 
 import '../i18n/strings.g.dart';
 import '../services/profile_cache.dart';
+import '../services/saved_offers_store.dart';
 import '../services/social_connection.dart';
 import '../services/social_service.dart';
 import '../state/peer_rating_cubit.dart';
@@ -27,6 +28,7 @@ class MarketOfferDetailScreen extends StatefulWidget {
     this.mine = false,
     this.profileCache,
     this.selfPubkey,
+    this.savedOffers,
     super.key,
   });
 
@@ -38,6 +40,10 @@ class MarketOfferDetailScreen extends StatefulWidget {
   /// Whether this is the current user's own listing (hide the message button).
   final bool mine;
 
+  /// Store of the user's saved ("favorite") offers, for the save toggle. Null in
+  /// tests / when there's no social layer → the heart action is hidden.
+  final SavedOffersStore? savedOffers;
+
   /// Optional cache of peers' published display names; null in tests.
   final ProfileCache? profileCache;
 
@@ -58,10 +64,32 @@ class _MarketOfferDetailScreenState extends State<MarketOfferDetailScreen> {
   bool _profileLoading = true;
   PeerRatingState? _sellerRating;
 
+  /// Whether this offer is in the user's favorites; null while loading (the
+  /// heart action stays hidden until we know, to avoid a flicker).
+  bool? _saved;
+
   @override
   void initState() {
     super.initState();
     _loadSeller();
+    _loadSaved();
+  }
+
+  Future<void> _loadSaved() async {
+    final store = widget.savedOffers;
+    if (store == null) return;
+    final saved = await store.isSaved(SavedOffersStore.keyOf(widget.offer));
+    if (mounted) setState(() => _saved = saved);
+  }
+
+  Future<void> _toggleSaved() async {
+    final store = widget.savedOffers;
+    if (store == null) return;
+    final nowSaved = await store.toggle(
+      widget.offer,
+      savedAt: DateTime.now().millisecondsSinceEpoch,
+    );
+    if (mounted) setState(() => _saved = nowSaved);
   }
 
   /// Best-effort fetch of the author's published profile (name/about/Ğ1), the
@@ -145,8 +173,23 @@ class _MarketOfferDetailScreenState extends State<MarketOfferDetailScreen> {
   Widget build(BuildContext context) {
     final t = context.t;
     final o = widget.offer;
+    final saved = _saved;
     return Scaffold(
-      appBar: AppBar(title: Text(o.summary)),
+      appBar: AppBar(
+        title: Text(o.summary),
+        actions: [
+          // Save other people's offers (Wallapop-style). Hidden on your own
+          // listing and until the saved state is known.
+          if (!widget.mine && widget.savedOffers != null && saved != null)
+            IconButton(
+              key: const Key('offerDetail.save'),
+              icon: Icon(saved ? Icons.favorite : Icons.favorite_border),
+              color: saved ? seedGreen : null,
+              tooltip: saved ? t.favorites.remove : t.favorites.save,
+              onPressed: _toggleSaved,
+            ),
+        ],
+      ),
       body: ListView(
         padding: const EdgeInsets.all(16),
         children: [

apps/app_seeds/test/services/saved_offers_store_test.dart

@@ -0,0 +1,100 @@
+import 'package:commons_core/commons_core.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:tane/services/saved_offers_store.dart';
+
+import '../support/test_support.dart';
+
+Offer _offer(
+  String id, {
+  String author = 'aa',
+  OfferType type = OfferType.gift,
+  num? price,
+  String? currency,
+  String geohash = 'u09',
+}) => Offer(
+  id: id,
+  authorPubkeyHex: author,
+  summary: 'Tomate $id',
+  type: type,
+  approxGeohash: geohash,
+  priceAmount: price,
+  priceCurrency: currency,
+  isOrganic: true,
+);
+
+void main() {
+  late SavedOffersStore store;
+
+  setUp(() => store = SavedOffersStore(InMemorySecretStore()));
+
+  test('keyOf is the author:id coordinate', () {
+    expect(SavedOffersStore.keyOf(_offer('x', author: 'bb')), 'bb:x');
+  });
+
+  test('starts empty', () async {
+    expect(await store.list(), isEmpty);
+    expect(await store.isSaved('aa:x'), isFalse);
+  });
+
+  test('save then list round-trips every field', () async {
+    await store.save(
+      _offer('1', type: OfferType.sale, price: 3, currency: 'Ğ1'),
+      savedAt: 100,
+    );
+    final saved = await store.list();
+    expect(saved, hasLength(1));
+    final o = saved.single;
+    expect(o.id, '1');
+    expect(o.authorPubkeyHex, 'aa');
+    expect(o.type, OfferType.sale);
+    expect(o.priceAmount, 3);
+    expect(o.priceCurrency, 'Ğ1');
+    expect(o.isOrganic, isTrue);
+    expect(await store.isSaved('aa:1'), isTrue);
+  });
+
+  test('list is newest-first by savedAt', () async {
+    await store.save(_offer('old'), savedAt: 100);
+    await store.save(_offer('new'), savedAt: 200);
+    expect([for (final o in await store.list()) o.id], ['new', 'old']);
+  });
+
+  test('saving the same coordinate again de-duplicates', () async {
+    await store.save(_offer('1'), savedAt: 100);
+    await store.save(_offer('1'), savedAt: 200); // same author:id
+    expect(await store.list(), hasLength(1));
+  });
+
+  test('remove drops it', () async {
+    await store.save(_offer('1'), savedAt: 100);
+    await store.remove('aa:1');
+    expect(await store.list(), isEmpty);
+    expect(await store.isSaved('aa:1'), isFalse);
+  });
+
+  test('toggle saves then removes and reports the new state', () async {
+    expect(await store.toggle(_offer('1'), savedAt: 100), isTrue);
+    expect(await store.isSaved('aa:1'), isTrue);
+    expect(await store.toggle(_offer('1'), savedAt: 200), isFalse);
+    expect(await store.isSaved('aa:1'), isFalse);
+  });
+
+  test('scopes are isolated by account', () async {
+    final secret = InMemorySecretStore();
+    final a = SavedOffersStore(secret, accountScope: 'acct1');
+    final b = SavedOffersStore(secret, accountScope: 'acct2');
+    await a.save(_offer('1'), savedAt: 100);
+    expect(await a.list(), hasLength(1));
+    expect(await b.list(), isEmpty);
+  });
+
+  test('changes stream fires on save and remove', () async {
+    final events = <void>[];
+    final sub = store.changes.listen(events.add);
+    await store.save(_offer('1'), savedAt: 100);
+    await store.remove('aa:1');
+    await Future<void>.delayed(Duration.zero);
+    expect(events, hasLength(2));
+    await sub.cancel();
+  });
+}

apps/app_seeds/test/ui/favorites_screen_test.dart

@@ -0,0 +1,77 @@
+import 'package:commons_core/commons_core.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_localizations/flutter_localizations.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:tane/i18n/strings.g.dart';
+import 'package:tane/services/saved_offers_store.dart';
+import 'package:tane/ui/favorites_screen.dart';
+
+import '../support/test_support.dart';
+
+Widget _wrap(Widget child) {
+  LocaleSettings.setLocaleSync(AppLocale.en);
+  return TranslationProvider(
+    child: MaterialApp(
+      locale: AppLocale.en.flutterLocale,
+      supportedLocales: AppLocaleUtils.supportedLocales,
+      localizationsDelegates: const [
+        GlobalMaterialLocalizations.delegate,
+        GlobalWidgetsLocalizations.delegate,
+        GlobalCupertinoLocalizations.delegate,
+      ],
+      home: child,
+    ),
+  );
+}
+
+Offer _offer(String id) => Offer(
+  id: id,
+  authorPubkeyHex: 'ab',
+  summary: 'Tomate $id',
+  type: OfferType.gift,
+  approxGeohash: 'u09',
+);
+
+void main() {
+  testWidgets('shows the empty state when nothing is saved', (tester) async {
+    final store = SavedOffersStore(InMemorySecretStore());
+    // No connection → no relay check, just the local snapshots.
+    await tester.pumpWidget(_wrap(FavoritesScreen(savedOffers: store)));
+    await tester.pumpAndSettle();
+
+    expect(
+      find.text('No favorites yet. Save offers you like from the market.'),
+      findsOneWidget,
+    );
+  });
+
+  testWidgets('lists saved offers newest-first', (tester) async {
+    final store = SavedOffersStore(InMemorySecretStore());
+    await store.save(_offer('old'), savedAt: 100);
+    await store.save(_offer('new'), savedAt: 200);
+
+    await tester.pumpWidget(_wrap(FavoritesScreen(savedOffers: store)));
+    await tester.pumpAndSettle();
+
+    expect(find.text('Tomate new'), findsOneWidget);
+    expect(find.text('Tomate old'), findsOneWidget);
+    final newY = tester.getTopLeft(find.text('Tomate new')).dy;
+    final oldY = tester.getTopLeft(find.text('Tomate old')).dy;
+    expect(newY, lessThan(oldY)); // newest on top
+  });
+
+  testWidgets('the heart removes a favorite', (tester) async {
+    final store = SavedOffersStore(InMemorySecretStore());
+    await store.save(_offer('1'), savedAt: 100);
+
+    await tester.pumpWidget(_wrap(FavoritesScreen(savedOffers: store)));
+    await tester.pumpAndSettle();
+    expect(find.text('Tomate 1'), findsOneWidget);
+
+    await tester.tap(find.byKey(const Key('favorites.remove.ab.1')));
+    await tester.pumpAndSettle();
+
+    expect(find.text('Tomate 1'), findsNothing);
+    expect(await store.isSaved('ab:1'), isFalse);
+  });
+}

apps/app_seeds/test/ui/market_offer_detail_screen_test.dart

@@ -3,6 +3,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_localizations/flutter_localizations.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:tane/i18n/strings.g.dart';
+import 'package:tane/services/saved_offers_store.dart';
 import 'package:tane/services/social_connection.dart';
 import 'package:tane/services/social_service.dart';
 import 'package:tane/services/social_settings.dart';
@@ -103,4 +104,50 @@ void main() {
 
     expect(find.byType(OfferHeroImage), findsNothing);
   });
+
+  testWidgets('the heart saves and unsaves a stranger\'s offer',
+      (tester) async {
+    final social = await SocialService.fromRootSeedHex('00' * 32);
+    final settings = SocialSettings(InMemorySecretStore());
+    await settings.setRelayUrls(const []);
+    final connection = SocialConnection(social: social, settings: settings);
+    final saved = SavedOffersStore(InMemorySecretStore());
+
+    await tester.pumpWidget(_wrap(MarketOfferDetailScreen(
+      offer: _offer(),
+      connection: connection,
+      savedOffers: saved,
+    )));
+    await tester.pumpAndSettle();
+
+    final heart = find.byKey(const Key('offerDetail.save'));
+    expect(heart, findsOneWidget);
+    expect(await saved.isSaved('${'ab' * 32}:lot-1'), isFalse);
+
+    await tester.tap(heart);
+    await tester.pumpAndSettle();
+    expect(await saved.isSaved('${'ab' * 32}:lot-1'), isTrue);
+
+    await tester.tap(heart);
+    await tester.pumpAndSettle();
+    expect(await saved.isSaved('${'ab' * 32}:lot-1'), isFalse);
+  });
+
+  testWidgets('no heart on my own listing', (tester) async {
+    final social = await SocialService.fromRootSeedHex('00' * 32);
+    final settings = SocialSettings(InMemorySecretStore());
+    await settings.setRelayUrls(const []);
+    final connection = SocialConnection(social: social, settings: settings);
+    final saved = SavedOffersStore(InMemorySecretStore());
+
+    await tester.pumpWidget(_wrap(MarketOfferDetailScreen(
+      offer: _offer(),
+      connection: connection,
+      mine: true,
+      savedOffers: saved,
+    )));
+    await tester.pumpAndSettle();
+
+    expect(find.byKey(const Key('offerDetail.save')), findsNothing);
+  });
 }