feat(app): hint isolation distance when sowing a cross-pollinating crop

One passive line in the batch story after a 'sown today' tap — 'this
species crosses, grow it ~400 m from others' — sourced from the bundled
seed-saving guidance (family default + species override). Selfers get
nothing: the trap is recording isolation religiously for beans where it
never mattered. No input fields, no schema change.

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

@@ -737,7 +737,8 @@
   "ratedMixed": "It did so-so",
   "ratedPoor": "It did poorly",
   "outcomeTitle": "Season note",
-  "outcomeYear": "Season {year}"
+  "outcomeYear": "Season {year}",
+  "isolationHint": "This species crosses with its neighbours — grow it about {meters} m away from others to keep it true"
  },
  "sale": {
   "title": "Sales",

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

@@ -736,7 +736,8 @@
   "ratedMixed": "Se dio regular",
   "ratedPoor": "Se dio mal",
   "outcomeTitle": "Nota de temporada",
-  "outcomeYear": "Temporada {year}"
+  "outcomeYear": "Temporada {year}",
+  "isolationHint": "Esta especie se cruza con sus vecinas — cultívala a unos {meters} m de otras para que se mantenga fiel"
  },
  "sale": {
   "title": "Ventas",

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

@@ -4,9 +4,9 @@
 /// To regenerate, run: `dart run slang`
 ///
 /// Locales: 7
-/// Strings: 3564 (509 per locale)
+/// Strings: 3566 (509 per locale)
 ///
-/// Built on 2026-07-18 at 10:23 UTC
+/// Built on 2026-07-18 at 10:28 UTC
 
 // coverage:ignore-file
 // ignore_for_file: type=lint, unused_import

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

@@ -2103,6 +2103,9 @@ class Translations$history$en {
 
 	/// en: 'Season {year}'
 	String outcomeYear({required Object year}) => 'Season ${year}';
+
+	/// en: 'This species crosses with its neighbours — grow it about {meters} m away from others to keep it true'
+	String isolationHint({required Object meters}) => 'This species crosses with its neighbours — grow it about ${meters} m away from others to keep it true';
 }
 
 // Path: sale
@@ -3359,6 +3362,7 @@ extension on Translations {
 			'history.ratedPoor' => 'It did poorly',
 			'history.outcomeTitle' => 'Season note',
 			'history.outcomeYear' => ({required Object year}) => 'Season ${year}',
+			'history.isolationHint' => ({required Object meters}) => 'This species crosses with its neighbours — grow it about ${meters} m away from others to keep it true',
 			'sale.title' => 'Sales',
 			'sale.help' => 'Record seed you sold or bought — money, Ğ1, or any currency. A separate model from a gift or a Plantare. No commission is ever taken on seeds.',
 			'sale.add' => 'Record a sale',

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

@@ -1074,6 +1074,7 @@ class _Translations$history$es extends Translations$history$en {
 	@override String get ratedPoor => 'Se dio mal';
 	@override String get outcomeTitle => 'Nota de temporada';
 	@override String outcomeYear({required Object year}) => 'Temporada ${year}';
+	@override String isolationHint({required Object meters}) => 'Esta especie se cruza con sus vecinas — cultívala a unos ${meters} m de otras para que se mantenga fiel';
 }
 
 // Path: sale
@@ -2101,6 +2102,7 @@ extension on TranslationsEs {
 			'history.ratedPoor' => 'Se dio mal',
 			'history.outcomeTitle' => 'Nota de temporada',
 			'history.outcomeYear' => ({required Object year}) => 'Temporada ${year}',
+			'history.isolationHint' => ({required Object meters}) => 'Esta especie se cruza con sus vecinas — cultívala a unos ${meters} m de otras para que se mantenga fiel',
 			'sale.title' => 'Ventas',
 			'sale.help' => 'Registra semilla vendida o comprada — dinero, Ğ1 o cualquier moneda. Un modelo aparte del regalo y del Plantare. Nunca se cobra comisión por las semillas.',
 			'sale.add' => 'Registrar venta',

apps/app_seeds/lib/ui/lot_history_sheet.dart

@@ -3,6 +3,7 @@ import 'package:intl/intl.dart';
 
 import '../data/variety_repository.dart';
 import '../db/enums.dart';
+import '../domain/seed_saving.dart';
 import '../i18n/strings.g.dart';
 import 'quantity_kind_l10n.dart';
 
@@ -14,20 +15,31 @@ Future<void> showLotHistorySheet(
   BuildContext context, {
   required VarietyRepository repository,
   required VarietyLot lot,
+  SeedSavingGuide? guide,
 }) {
   return showModalBottomSheet<void>(
     context: context,
     isScrollControlled: true,
-    builder: (_) => _LotHistorySheet(repository: repository, lot: lot),
+    builder: (_) =>
+        _LotHistorySheet(repository: repository, lot: lot, guide: guide),
   );
 }
 
 class _LotHistorySheet extends StatefulWidget {
-  const _LotHistorySheet({required this.repository, required this.lot});
+  const _LotHistorySheet({
+    required this.repository,
+    required this.lot,
+    this.guide,
+  });
 
   final VarietyRepository repository;
   final VarietyLot lot;
 
+  /// Bundled species guidance, or null. Only read to drop the one-line
+  /// isolation hint when a cross-pollinating crop is sown — selfers get
+  /// nothing (the fields people record religiously where they don't matter).
+  final SeedSavingGuide? guide;
+
   @override
   State<_LotHistorySheet> createState() => _LotHistorySheetState();
 }
@@ -43,6 +55,10 @@ class _LotHistorySheetState extends State<_LotHistorySheet> {
   bool _askOutcome = false;
   final _outcomeNote = TextEditingController();
 
+  // One passive line after sowing a crosser ("this species crosses — isolate
+  // ~400 m"). Never shown for selfers, never an input.
+  bool _showSowingHint = false;
+
   @override
   void initState() {
     super.initState();
@@ -74,9 +90,14 @@ class _LotHistorySheetState extends State<_LotHistorySheet> {
         ),
       ),
     );
+    final guide = widget.guide;
     setState(() {
       _saving = false;
       _askOutcome = type == MovementType.harvested;
+      _showSowingHint =
+          type == MovementType.sown &&
+          guide?.pollination == Pollination.cross &&
+          guide?.isolationMinM != null;
       _history = widget.repository.lotHistory(widget.lot.id);
     });
   }
@@ -146,6 +167,25 @@ class _LotHistorySheetState extends State<_LotHistorySheet> {
                 ),
               ],
             ),
+            if (_showSowingHint)
+              Padding(
+                key: const Key('history.isolationHint'),
+                padding: const EdgeInsetsDirectional.only(top: 8, start: 4),
+                child: Row(
+                  children: [
+                    const Icon(Icons.lightbulb_outline, size: 16),
+                    const SizedBox(width: 6),
+                    Expanded(
+                      child: Text(
+                        context.t.history.isolationHint(
+                          meters: widget.guide!.isolationMinM!,
+                        ),
+                        style: Theme.of(context).textTheme.bodySmall,
+                      ),
+                    ),
+                  ],
+                ),
+              ),
             if (_askOutcome) ...[
               const SizedBox(height: 8),
               _OutcomeQuestion(

apps/app_seeds/lib/ui/variety_detail_screen.dart

@@ -237,6 +237,10 @@ class _DetailView extends StatelessWidget {
                 cubit: cubit,
                 lot: lot,
                 viabilityYears: detail.viabilityYears,
+                guide: SeedSavingCatalog.guideFor(
+                  scientificName: detail.scientificName,
+                  family: detail.family ?? detail.category,
+                ),
               ),
           _PlantaresSection(varietyId: detail.id),
         ],
@@ -375,6 +379,7 @@ class _LotTile extends StatelessWidget {
     required this.cubit,
     required this.lot,
     required this.viabilityYears,
+    this.guide,
   });
 
   final VarietyDetailCubit cubit;
@@ -383,6 +388,10 @@ class _LotTile extends StatelessWidget {
   /// Typical seed longevity of the variety's species (years), or null.
   final int? viabilityYears;
 
+  /// Bundled seed-saving guidance for the species, or null — lets the history
+  /// sheet drop a one-line isolation hint when a crosser is sown.
+  final SeedSavingGuide? guide;
+
   @override
   Widget build(BuildContext context) {
     final t = context.t;
@@ -443,6 +452,7 @@ class _LotTile extends StatelessWidget {
               context,
               repository: context.read<VarietyRepository>(),
               lot: lot,
+              guide: guide,
             ),
           ),
           IconButton(

apps/app_seeds/test/ui/lot_history_sheet_test.dart

@@ -1,7 +1,9 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:tane/data/seed_saving_catalog.dart';
 import 'package:tane/db/database.dart';
 import 'package:tane/db/enums.dart';
+import 'package:tane/domain/seed_saving.dart';
 
 import '../support/test_support.dart';
 
@@ -9,7 +11,10 @@ void main() {
   late AppDatabase db;
 
   setUp(() => db = newTestDatabase());
-  tearDown(() => db.close());
+  tearDown(() {
+    SeedSavingCatalog.data = null;
+    return db.close();
+  });
 
   testWidgets('the lot tile opens the batch story, closed by its origin', (
     tester,
@@ -153,6 +158,52 @@ void main() {
     await disposeTree(tester);
   });
 
+  testWidgets('sowing a crosser drops the isolation hint; a selfer gets '
+      'nothing', (tester) async {
+    SeedSavingCatalog.data = SeedSavingData(
+      families: {
+        'Cucurbitaceae': const SeedSavingGuide(
+          pollination: Pollination.cross,
+          isolationMinM: 400,
+        ),
+        'Solanaceae': const SeedSavingGuide(
+          pollination: Pollination.self,
+          isolationMinM: 3,
+        ),
+      },
+      taxa: const {},
+    );
+    final repo = newTestRepository(db);
+
+    Future<void> sowAndCheck(String category, {required bool hinted}) async {
+      final id = await repo.addQuickVariety(label: 'x-$category');
+      await repo.updateVariety(id: id, label: 'x-$category', category: category);
+      final lotId = await repo.addLot(varietyId: id);
+      await tester.pumpWidget(
+        wrapDetail(
+          repository: repo,
+          varietyId: id,
+          species: newTestSpeciesRepository(db),
+        ),
+      );
+      await tester.pumpAndSettle();
+      await tester.tap(find.byKey(Key('lot.history.$lotId')));
+      await tester.pumpAndSettle();
+      await tester.tap(find.byKey(const Key('history.sowToday')));
+      await tester.pumpAndSettle();
+      expect(
+        find.byKey(const Key('history.isolationHint')),
+        hinted ? findsOneWidget : findsNothing,
+      );
+      await disposeTree(tester);
+    }
+
+    // The family drives it: squash (crosses, 400 m) hints; tomato does not.
+    await sowAndCheck('Cucurbitaceae', hinted: true);
+    expect(find.textContaining('400'), findsNothing); // tree disposed
+    await sowAndCheck('Solanaceae', hinted: false);
+  });
+
   testWidgets('a plant lot offers harvest but not sowing', (tester) async {
     final repo = newTestRepository(db);
     final id = await repo.addQuickVariety(label: 'Rosemary');