feat(market): saved searches with in-app alerts (Wallapop-style)

Save the current market search (query + facets) and get notified when a
matching offer appears in your zone while the app is open, with a catch-up
scan on start. Adds a save affordance in the search bar, a saved-searches
list (apply/delete) with a per-search new-match badge, an AppBar entry
badged with the unseen total, and notification-tap routing to the list.
Alerts evaluate against the user's current area, dedup via seen keys, and
skip own/blocked/hidden/non-active offers. en+es strings.

apps/app_seeds/lib/ui/market_screen.dart

@@ -8,6 +8,7 @@ import '../i18n/strings.g.dart';
 import '../services/coarse_location.dart';
 import '../services/discovery_area.dart';
 import '../services/offer_outbox.dart';
+import '../services/saved_searches_store.dart';
 import '../services/social_connection.dart';
 import '../services/social_service.dart';
 import '../services/social_settings.dart';
@@ -18,6 +19,7 @@ import 'edge_fade.dart';
 import 'filter_chips.dart';
 import 'market_gate.dart';
 import 'market_widgets.dart';
+import 'saved_searches_screen.dart';
 import 'theme.dart';
 
 /// The market (redesign screens 04/05): discover seeds shared near you. Opens
@@ -31,12 +33,22 @@ class MarketScreen extends StatefulWidget {
     this.location,
     this.outbox,
     this.onboarding,
+    this.savedSearches,
+    this.initialSearch,
     super.key,
   });
 
   final SocialService social;
   final SocialSettings settings;
 
+  /// Optional store of the user's saved searches (with alerts). Null in tests /
+  /// inventory-only → the save affordance and the saved-searches action hide.
+  final SavedSearchesStore? savedSearches;
+
+  /// When set (arriving from the saved-searches list), the market opens with
+  /// this search's query and facets already applied.
+  final SavedSearch? initialSearch;
+
   /// When set, joining the market is gated on a one-time acceptance of the
   /// community rules (store UGC policies require it before content is
   /// created). Null in tests → no gate.
@@ -100,6 +112,9 @@ class _MarketScreenState extends State<MarketScreen> {
       await cubit.close();
       return;
     }
+    // Arriving from the saved-searches list: pre-apply its query and facets.
+    final initial = widget.initialSearch;
+    if (initial != null) cubit.applySavedSearch(initial);
     final previous = _cubit;
     setState(() {
       _cubit = cubit;
@@ -213,6 +228,8 @@ class _MarketScreenState extends State<MarketScreen> {
       appBar: AppBar(
         title: Text(t.market.title),
         actions: [
+          if (widget.savedSearches != null)
+            SavedSearchesAction(store: widget.savedSearches!),
           IconButton(
             key: const Key('market.config'),
             icon: const Icon(Icons.tune),
@@ -240,6 +257,7 @@ class _MarketScreenState extends State<MarketScreen> {
                 hasArea: _hasArea,
                 selfPubkey: widget.social.publicKeyHex,
                 onOfferClosed: _reloadBlocked,
+                savedSearches: widget.savedSearches,
               ),
             ),
     );
@@ -253,11 +271,15 @@ class MarketBody extends StatelessWidget {
     this.hasArea = true,
     this.selfPubkey,
     this.onOfferClosed,
+    this.savedSearches,
     super.key,
   });
 
   final VoidCallback onConfigure;
 
+  /// Store for the "save this search" affordance; null → the button hides.
+  final SavedSearchesStore? savedSearches;
+
   /// Re-opens the connection (for the "can't reach servers" retry).
   final VoidCallback? onRetry;
 
@@ -346,6 +368,20 @@ class MarketBody extends StatelessWidget {
                 decoration: InputDecoration(
                   hintText: t.market.searchHint,
                   prefixIcon: const Icon(Icons.search, color: seedMuted),
+                  // Offer to save the current search once it's worth alerting on
+                  // (some text typed or a chip active), never for the bare list.
+                  suffixIcon: savedSearches != null &&
+                          (state.query.trim().isNotEmpty ||
+                              state.hasActiveFilter)
+                      ? IconButton(
+                          key: const Key('market.saveSearch'),
+                          icon: const Icon(Icons.bookmark_add_outlined,
+                              color: seedGreen),
+                          tooltip: t.savedSearches.save,
+                          onPressed: () =>
+                              _saveCurrentSearch(context, savedSearches!, state),
+                        )
+                      : null,
                   hintStyle: const TextStyle(color: seedMuted),
                   filled: true,
                   fillColor: Colors.white,
@@ -405,6 +441,63 @@ class MarketBody extends StatelessWidget {
   }
 }
 
+/// Prompts for a name, then saves the current query + facets as a search the
+/// user will be alerted about. Offers already visible are seeded as "seen" so
+/// saving never immediately alerts about listings the user is looking at.
+Future<void> _saveCurrentSearch(
+  BuildContext context,
+  SavedSearchesStore store,
+  OffersState state,
+) async {
+  final t = context.t;
+  final messenger = ScaffoldMessenger.of(context);
+  final defaultLabel = state.query.trim();
+  final controller = TextEditingController(text: defaultLabel);
+  final label = await showDialog<String>(
+    context: context,
+    builder: (context) => AlertDialog(
+      title: Text(t.savedSearches.save),
+      content: TextField(
+        controller: controller,
+        autofocus: true,
+        decoration: InputDecoration(
+          labelText: t.savedSearches.nameLabel,
+          hintText: t.savedSearches.namePlaceholder,
+        ),
+        onSubmitted: (v) => Navigator.of(context).pop(v),
+      ),
+      actions: [
+        TextButton(
+          onPressed: () => Navigator.of(context).pop(),
+          child: Text(t.common.cancel),
+        ),
+        FilledButton(
+          onPressed: () => Navigator.of(context).pop(controller.text),
+          child: Text(t.common.save),
+        ),
+      ],
+    ),
+  );
+  if (label == null) return; // cancelled
+  final trimmed = label.trim();
+  final search = SavedSearch(
+    id: IdGen().newId(),
+    label: trimmed.isEmpty ? t.savedSearches.title : trimmed,
+    query: state.query.trim(),
+    types: state.typeFilter,
+    categories: state.categoryFilter,
+    organicOnly: state.organicOnly,
+    createdAt: DateTime.now().millisecondsSinceEpoch,
+  );
+  await store.save(
+    search,
+    seedSeenKeys: [
+      for (final o in state.visibleOffers) SavedSearchesStore.keyOf(o),
+    ],
+  );
+  messenger.showSnackBar(SnackBar(content: Text(t.savedSearches.saved)));
+}
+
 /// One discovered offer. Human words for the reciprocity mode; coarse "near you"
 /// instead of any precise location; price only when it's a sale.
 class _OfferCard extends StatelessWidget {