feat(block2): 'use my location' — set the sharing area without typing a code

Makes the coarse area human, per feedback that a typed code is jargon.
- CoarseLocationProvider interface + geolocator-backed impl (BSD-3): low
  accuracy only, returns null on any denial/error (degrades quietly). Behind an
  interface so it's fakeable and the plugin stays at the composition root.
- Config sheet: a 'Use my approximate location' button (shown only when a
  provider is wired) fills the area from the device position, reduced to a
  5-char geohash via commons_core's Geohash — a precise fix never leaves the
  device. 'Couldn't get your location' on failure.
- Threaded via TaneApp(location); main wires GeolocatorCoarseLocation.
- Platform: ACCESS_COARSE_LOCATION (Android) + NSLocationWhenInUseUsageDescription
  (iOS), both scoped to the coarse-area use.
- i18n en/es/pt. Widget test fills the area from a fake location. 8 tests green.

apps/app_seeds/android/app/src/main/AndroidManifest.xml

@@ -1,4 +1,7 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- Coarse location only, for the optional "use my location" sharing area
+         (reduced to a low-precision geohash; never a precise fix). -->
+    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
     <application
         android:label="tane"
         android:name="${applicationName}"

apps/app_seeds/ios/Runner/Info.plist

@@ -68,5 +68,7 @@
 		</array>
 		<key>UIStatusBarHidden</key>
 		<false/>
+		<key>NSLocationWhenInUseUsageDescription</key>
+		<string>Used only to set your approximate sharing area — reduced to a coarse zone, never your exact location.</string>
 	</dict>
 </plist>

apps/app_seeds/lib/app.dart

@@ -7,6 +7,7 @@ import 'package:go_router/go_router.dart';
 import 'data/species_repository.dart';
 import 'data/variety_repository.dart';
 import 'i18n/strings.g.dart';
+import 'services/coarse_location.dart';
 import 'services/onboarding_store.dart';
 import 'services/social_service.dart';
 import 'services/social_settings.dart';
@@ -31,6 +32,7 @@ class TaneApp extends StatelessWidget {
     required this.onboarding,
     this.social,
     this.socialSettings,
+    this.location,
     this.showIntro = false,
     super.key,
   }) : _router = _buildRouter(
@@ -39,6 +41,7 @@ class TaneApp extends StatelessWidget {
           showIntro,
           social,
           socialSettings,
+          location,
         );
 
   final VarietyRepository repository;
@@ -49,6 +52,9 @@ class TaneApp extends StatelessWidget {
   /// null the market stays a "coming soon" card and `/market` is not routed.
   final SocialService? social;
   final SocialSettings? socialSettings;
+
+  /// Optional device-location source for the market's "use my location".
+  final CoarseLocationProvider? location;
   final bool showIntro;
   final GoRouter _router;
 
@@ -58,6 +64,7 @@ class TaneApp extends StatelessWidget {
     bool showIntro,
     SocialService? social,
     SocialSettings? socialSettings,
+    CoarseLocationProvider? location,
   ) {
     return GoRouter(
       initialLocation: showIntro ? '/intro' : '/',
@@ -70,8 +77,11 @@ class TaneApp extends StatelessWidget {
         if (social != null && socialSettings != null)
           GoRoute(
             path: '/market',
-            builder: (context, state) =>
+            builder: (context, state) => MarketScreen(
-                MarketScreen(social: social, settings: socialSettings),
+              social: social,
+              settings: socialSettings,
+              location: location,
+            ),
           ),
         GoRoute(
           path: '/intro',

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

@@ -351,6 +351,8 @@
     "wanted": "Wanted",
     "shareMine": "Share my seeds",
     "sharedCount": "Shared {n} seeds nearby",
-    "nothingToShare": "Mark some seeds to give, swap or sell first"
+    "nothingToShare": "Mark some seeds to give, swap or sell first",
+    "useLocation": "Use my approximate location",
+    "locationFailed": "Couldn't get your location"
   }
 }

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

@@ -351,6 +351,8 @@
     "wanted": "Busco",
     "shareMine": "Compartir mis semillas",
     "sharedCount": "Compartidas {n} semillas",
-    "nothingToShare": "Marca antes algunas semillas para regalar, cambiar o vender"
+    "nothingToShare": "Marca antes algunas semillas para regalar, cambiar o vender",
+    "useLocation": "Usar mi ubicación aproximada",
+    "locationFailed": "No se pudo obtener tu ubicación"
   }
 }

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

@@ -347,6 +347,8 @@
     "wanted": "Procuro",
     "shareMine": "Partilhar as minhas sementes",
     "sharedCount": "Partilhadas {n} sementes",
-    "nothingToShare": "Marca primeiro algumas sementes para dar, trocar ou vender"
+    "nothingToShare": "Marca primeiro algumas sementes para dar, trocar ou vender",
+    "useLocation": "Usar a minha localização aproximada",
+    "locationFailed": "Não foi possível obter a tua localização"
   }
 }

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

@@ -4,9 +4,9 @@
 /// To regenerate, run: `dart run slang`
 ///
 /// Locales: 3
-/// Strings: 938 (312 per locale)
+/// Strings: 944 (314 per locale)
 ///
-/// Built on 2026-07-10 at 08:17 UTC
+/// Built on 2026-07-10 at 08:25 UTC
 
 // coverage:ignore-file
 // ignore_for_file: type=lint, unused_import

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

@@ -1114,6 +1114,12 @@ class Translations$market$en {
 
 	/// en: 'Mark some seeds to give, swap or sell first'
 	String get nothingToShare => 'Mark some seeds to give, swap or sell first';
+
+	/// en: 'Use my approximate location'
+	String get useLocation => 'Use my approximate location';
+
+	/// en: 'Couldn't get your location'
+	String get locationFailed => 'Couldn\'t get your location';
 }
 
 // Path: intro.slides
@@ -1887,6 +1893,8 @@ extension on Translations {
 			'market.shareMine' => 'Share my seeds',
 			'market.sharedCount' => ({required Object n}) => 'Shared ${n} seeds nearby',
 			'market.nothingToShare' => 'Mark some seeds to give, swap or sell first',
+			'market.useLocation' => 'Use my approximate location',
+			'market.locationFailed' => 'Couldn\'t get your location',
 			_ => null,
 		};
 	}

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

@@ -622,6 +622,8 @@ class _Translations$market$es extends Translations$market$en {
 	@override String get shareMine => 'Compartir mis semillas';
 	@override String sharedCount({required Object n}) => 'Compartidas ${n} semillas';
 	@override String get nothingToShare => 'Marca antes algunas semillas para regalar, cambiar o vender';
+	@override String get useLocation => 'Usar mi ubicación aproximada';
+	@override String get locationFailed => 'No se pudo obtener tu ubicación';
 }
 
 // Path: intro.slides
@@ -1279,6 +1281,8 @@ extension on TranslationsEs {
 			'market.shareMine' => 'Compartir mis semillas',
 			'market.sharedCount' => ({required Object n}) => 'Compartidas ${n} semillas',
 			'market.nothingToShare' => 'Marca antes algunas semillas para regalar, cambiar o vender',
+			'market.useLocation' => 'Usar mi ubicación aproximada',
+			'market.locationFailed' => 'No se pudo obtener tu ubicación',
 			_ => null,
 		};
 	}

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

@@ -618,6 +618,8 @@ class _Translations$market$pt extends Translations$market$en {
 	@override String get shareMine => 'Partilhar as minhas sementes';
 	@override String sharedCount({required Object n}) => 'Partilhadas ${n} sementes';
 	@override String get nothingToShare => 'Marca primeiro algumas sementes para dar, trocar ou vender';
+	@override String get useLocation => 'Usar a minha localização aproximada';
+	@override String get locationFailed => 'Não foi possível obter a tua localização';
 }
 
 // Path: intro.slides
@@ -1271,6 +1273,8 @@ extension on TranslationsPt {
 			'market.shareMine' => 'Partilhar as minhas sementes',
 			'market.sharedCount' => ({required Object n}) => 'Partilhadas ${n} sementes',
 			'market.nothingToShare' => 'Marca primeiro algumas sementes para dar, trocar ou vender',
+			'market.useLocation' => 'Usar a minha localização aproximada',
+			'market.locationFailed' => 'Não foi possível obter a tua localização',
 			_ => null,
 		};
 	}

apps/app_seeds/lib/main.dart

@@ -5,6 +5,7 @@ import 'data/species_repository.dart';
 import 'data/variety_repository.dart';
 import 'di/injector.dart';
 import 'i18n/strings.g.dart';
+import 'services/coarse_location.dart';
 import 'services/onboarding_store.dart';
 import 'services/social_service.dart';
 import 'services/social_settings.dart';
@@ -22,6 +23,7 @@ Future<void> main() async {
         onboarding: onboarding,
         social: getIt<SocialService>(),
         socialSettings: getIt<SocialSettings>(),
+        location: const GeolocatorCoarseLocation(),
         showIntro: !await onboarding.introSeen(),
       ),
     ),

apps/app_seeds/lib/services/coarse_location.dart

@@ -0,0 +1,38 @@
+import 'package:geolocator/geolocator.dart';
+
+/// Supplies the device's *approximate* location (or null when unavailable or
+/// denied). Behind an interface so the UI is fakeable in tests and the concrete
+/// platform plugin stays at the composition root. The caller immediately reduces
+/// the result to a low-precision geohash — a precise fix never leaves the device.
+abstract interface class CoarseLocationProvider {
+  Future<({double lat, double lon})?> currentCoarseLatLon();
+}
+
+/// [geolocator]-backed implementation. Requests low accuracy only, and returns
+/// null on any denial/error rather than throwing, so the UI can degrade quietly.
+class GeolocatorCoarseLocation implements CoarseLocationProvider {
+  const GeolocatorCoarseLocation();
+
+  @override
+  Future<({double lat, double lon})?> currentCoarseLatLon() async {
+    try {
+      if (!await Geolocator.isLocationServiceEnabled()) return null;
+      var permission = await Geolocator.checkPermission();
+      if (permission == LocationPermission.denied) {
+        permission = await Geolocator.requestPermission();
+      }
+      if (permission == LocationPermission.denied ||
+          permission == LocationPermission.deniedForever) {
+        return null;
+      }
+      final position = await Geolocator.getCurrentPosition(
+        locationSettings: const LocationSettings(
+          accuracy: LocationAccuracy.low,
+        ),
+      );
+      return (lat: position.latitude, lon: position.longitude);
+    } catch (_) {
+      return null; // service off, plugin unsupported (desktop), timeout, …
+    }
+  }
+}

apps/app_seeds/lib/ui/market_screen.dart

@@ -4,6 +4,7 @@ import 'package:flutter_bloc/flutter_bloc.dart';
 
 import '../data/variety_repository.dart';
 import '../i18n/strings.g.dart';
+import '../services/coarse_location.dart';
 import '../services/social_service.dart';
 import '../services/social_settings.dart';
 import '../state/offers_cubit.dart';
@@ -13,11 +14,20 @@ import 'theme.dart';
 /// an offer transport lazily; local-first, so it degrades to a "set up sharing"
 /// prompt when no relay/area is configured or the network is unreachable.
 class MarketScreen extends StatefulWidget {
-  const MarketScreen({required this.social, required this.settings, super.key});
+  const MarketScreen({
+    required this.social,
+    required this.settings,
+    this.location,
+    super.key,
+  });
 
   final SocialService social;
   final SocialSettings settings;
 
+  /// Optional device-location source for the "use my location" shortcut; when
+  /// null (tests, or a platform without it) the shortcut is hidden.
+  final CoarseLocationProvider? location;
+
   @override
   State<MarketScreen> createState() => _MarketScreenState();
 }
@@ -53,7 +63,8 @@ class _MarketScreenState extends State<MarketScreen> {
     final changed = await showModalBottomSheet<bool>(
       context: context,
       isScrollControlled: true,
-      builder: (_) => _ConfigSheet(settings: widget.settings),
+      builder: (_) =>
+          _ConfigSheet(settings: widget.settings, location: widget.location),
     );
     if (changed == true) await _init();
   }
@@ -325,9 +336,10 @@ class _EmptyState extends StatelessWidget {
 /// Coarse-area + community-server setup. Kept behind progressive disclosure — a
 /// power-user surface — with human-worded labels.
 class _ConfigSheet extends StatefulWidget {
-  const _ConfigSheet({required this.settings});
+  const _ConfigSheet({required this.settings, this.location});
 
   final SocialSettings settings;
+  final CoarseLocationProvider? location;
 
   @override
   State<_ConfigSheet> createState() => _ConfigSheetState();
@@ -356,6 +368,22 @@ class _ConfigSheetState extends State<_ConfigSheet> {
     if (mounted) Navigator.of(context).pop(true);
   }
 
+  /// Fills the area from the device's approximate location, reduced to a coarse
+  /// geohash so no precise fix is stored.
+  Future<void> _useLocation() async {
+    final provider = widget.location;
+    if (provider == null) return;
+    final messenger = ScaffoldMessenger.of(context);
+    final t = context.t;
+    final loc = await provider.currentCoarseLatLon();
+    if (!mounted) return;
+    if (loc == null) {
+      messenger.showSnackBar(SnackBar(content: Text(t.market.locationFailed)));
+      return;
+    }
+    setState(() => _area.text = Geohash.encode(loc.lat, loc.lon, precision: 5));
+  }
+
   @override
   void dispose() {
     _area.dispose();
@@ -402,6 +430,16 @@ class _ConfigSheetState extends State<_ConfigSheet> {
                     helperMaxLines: 3,
                   ),
                 ),
+                if (widget.location != null)
+                  Align(
+                    alignment: AlignmentDirectional.centerStart,
+                    child: TextButton.icon(
+                      key: const Key('market.useLocation'),
+                      icon: const Icon(Icons.my_location, size: 18),
+                      label: Text(t.market.useLocation),
+                      onPressed: _useLocation,
+                    ),
+                  ),
                 const SizedBox(height: 8),
                 // The technical web address lives under progressive disclosure —
                 // most people won't have one, and jargon shouldn't greet them.

apps/app_seeds/pubspec.yaml

@@ -62,6 +62,10 @@ dependencies:
   material_symbols_icons: ^4.2951.0
   url_launcher: ^6.3.2
   package_info_plus: ^9.0.1
+  # Optional coarse device location (BSD-3) to set the sharing area without
+  # typing a code. Low accuracy only; the value is immediately reduced to a
+  # low-precision geohash. Behind an interface so it's fakeable and pluggable.
+  geolocator: ^13.0.1
 
 dev_dependencies:
   flutter_test:

apps/app_seeds/test/ui/market_screen_test.dart

@@ -6,6 +6,7 @@ import 'package:flutter_bloc/flutter_bloc.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/coarse_location.dart';
 import 'package:tane/services/social_service.dart';
 import 'package:tane/services/social_settings.dart';
 import 'package:tane/state/offers_cubit.dart';
@@ -13,6 +14,16 @@ import 'package:tane/ui/market_screen.dart';
 
 import '../support/test_support.dart';
 
+/// A location provider returning a fixed coarse position.
+class FakeLocation implements CoarseLocationProvider {
+  FakeLocation(this.lat, this.lon);
+  final double lat;
+  final double lon;
+  @override
+  Future<({double lat, double lon})?> currentCoarseLatLon() async =>
+      (lat: lat, lon: lon);
+}
+
 /// In-memory offer transport: discover matches by geohash prefix.
 class FakeOfferTransport implements OfferTransport {
   final List<Offer> offers;
@@ -120,4 +131,40 @@ void main() {
     expect(find.text('Seeds near you'), findsOneWidget); // app bar title
     expect(find.text('Set up sharing'), findsOneWidget); // offline prompt
   });
+
+  testWidgets('"use my location" fills the area with a coarse geohash',
+      (tester) async {
+    final social = await SocialService.fromRootSeedHex('00' * 32);
+    final settings = SocialSettings(InMemorySecretStore());
+    LocaleSettings.setLocaleSync(AppLocale.en);
+
+    await tester.pumpWidget(
+      TranslationProvider(
+        child: MaterialApp(
+          locale: AppLocale.en.flutterLocale,
+          supportedLocales: AppLocaleUtils.supportedLocales,
+          localizationsDelegates: const [
+            GlobalMaterialLocalizations.delegate,
+            GlobalWidgetsLocalizations.delegate,
+            GlobalCupertinoLocalizations.delegate,
+          ],
+          home: MarketScreen(
+            social: social,
+            settings: settings,
+            location: FakeLocation(41.39, 2.16), // Barcelona-ish
+          ),
+        ),
+      ),
+    );
+    await tester.pumpAndSettle();
+
+    await tester.tap(find.byKey(const Key('market.config')));
+    await tester.pumpAndSettle();
+    await tester.tap(find.byKey(const Key('market.useLocation')));
+    await tester.pumpAndSettle();
+
+    final area = tester.widget<TextField>(find.byKey(const Key('market.area')));
+    expect(area.controller!.text, hasLength(5));
+    expect(area.controller!.text, matches(RegExp(r'^[0-9a-z]+$')));
+  });
 }