feat(plantare): tie the propose form to a real seed

The propose sheet used a free-text seed name, unlinked from the
inventory. Now the seed is picked from your catalogued varieties so the
Plantaré is always tied to a real Variety (tap-through to its detail, and
it shows in that seed's commitments):

- Seed field is an Autocomplete over the inventory; on send the typed name
  resolves to the matching Variety, or creates a quick one if it's new —
  so varietyId is never null. Sheet takes the VarietyRepository; chat
  passes it.
- New repo one-shot `varietyLabels()` (id + label, no joins) feeds the
  picker. Deliberately a Future, not `watchInventory()` — a transient
  sheet must not hold a live Drift subscription (that hung the widget test
  ~36 min). Tests use it too and now run in ~2s with bounded pumps + a
  tall surface, no pumpAndSettle.

Tests: a new name creates & links a Variety; a matching name links the
existing one without duplicating. ui/services/data plantare suites green.

apps/app_seeds/lib/ui/chat_screen.dart

@@ -6,6 +6,7 @@ import 'package:flutter/services.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:url_launcher/url_launcher.dart';
 
+import '../data/variety_repository.dart';
 import '../di/injector.dart';
 import '../domain/chat_timeline.dart';
 import '../domain/message_rules.dart';
@@ -214,6 +215,7 @@ class _ChatScreenState extends State<ChatScreen> {
     final sent = await showProposePlantareSheet(
       context,
       service: getIt<PlantareService>(),
+      repository: getIt<VarietyRepository>(),
       peerPubkey: widget.peerPubkey,
       peerName: _peerName,
     );

apps/app_seeds/lib/ui/plantare_propose_sheet.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 
+import '../data/variety_repository.dart';
 import '../db/enums.dart';
 import '../i18n/strings.g.dart';
 import '../services/plantare_service.dart';
@@ -8,12 +9,15 @@ import 'theme.dart';
 
 /// Opens the "propose a signed Plantaré" sheet against a specific peer, whose
 /// [peerPubkey] is already in hand (the flow starts from a chat or a closed
-/// offer). Fills the terms, self-signs, and sends the proposal via
-/// [PlantareService]; the peer counter-signs to close it. Returns true if a
-/// proposal was sent.
+/// offer). The seed is picked from the inventory ([repository]) so the promise
+/// is tied to a real `Variety`; a new name creates one. Fills the terms,
+/// self-signs, and sends via [PlantareService]; the peer counter-signs to close
+/// it. When [varietyId]/[seedLabel] are given (opened from a seed) that seed is
+/// preselected. Returns true if a proposal was sent.
 Future<bool?> showProposePlantareSheet(
   BuildContext context, {
   required PlantareService service,
+  required VarietyRepository repository,
   required String peerPubkey,
   String? peerName,
   String? varietyId,
@@ -24,6 +28,7 @@ Future<bool?> showProposePlantareSheet(
     isScrollControlled: true,
     builder: (_) => _ProposeSheet(
       service: service,
+      repository: repository,
       peerPubkey: peerPubkey,
       peerName: peerName,
       varietyId: varietyId,
@@ -35,6 +40,7 @@ Future<bool?> showProposePlantareSheet(
 class _ProposeSheet extends StatefulWidget {
   const _ProposeSheet({
     required this.service,
+    required this.repository,
     required this.peerPubkey,
     this.peerName,
     this.varietyId,
@@ -42,6 +48,7 @@ class _ProposeSheet extends StatefulWidget {
   });
 
   final PlantareService service;
+  final VarietyRepository repository;
   final String peerPubkey;
   final String? peerName;
   final String? varietyId;
@@ -56,16 +63,41 @@ class _ProposeSheetState extends State<_ProposeSheet> {
   // common "I'm sharing seed" case.
   PlantareDirection _direction = PlantareDirection.owedToMe;
   PlantareReturnKind _returnKind = PlantareReturnKind.similar;
-  late final TextEditingController _seed =
-      TextEditingController(text: widget.seedLabel ?? '');
   final _owed = TextEditingController();
   final _hours = TextEditingController();
   DateTime? _dueBy;
   bool _saving = false;
 
+  /// The user's catalogued seeds (id + label), for the picker (empty until
+  /// loaded). A one-shot load, not a live stream — a transient sheet must not
+  /// hold a Drift subscription.
+  List<({String id, String label})> _varieties = [];
+
+  /// The picked seed's id — set when the typed name matches (or is chosen from)
+  /// the inventory, cleared when the text is edited to something else. Null →
+  /// the name will create a new Variety on send, so the promise is always tied
+  /// to a real seed.
+  String? _varietyId;
+
+  /// Autocomplete owns the field's controller; captured here to read on send
+  /// and to seed the initial text.
+  TextEditingController? _seedController;
+
+  @override
+  void initState() {
+    super.initState();
+    _varietyId = widget.varietyId;
+    _loadVarieties();
+  }
+
+  Future<void> _loadVarieties() async {
+    final items = await widget.repository.varietyLabels();
+    if (!mounted) return;
+    setState(() => _varieties = items);
+  }
+
   @override
   void dispose() {
-    _seed.dispose();
     _owed.dispose();
     _hours.dispose();
     super.dispose();
@@ -73,6 +105,18 @@ class _ProposeSheetState extends State<_ProposeSheet> {
 
   String? _nullIfBlank(String s) => s.trim().isEmpty ? null : s.trim();
 
+  /// Resolves the typed seed name to a real Variety id: an existing one when the
+  /// name matches the inventory, otherwise a freshly created quick variety — so
+  /// the Plantaré is always linked to a seed.
+  Future<String> _resolveVarietyId(String label) async {
+    if (_varietyId != null) return _varietyId!;
+    final match = _varieties.where(
+      (v) => v.label.trim().toLowerCase() == label.toLowerCase(),
+    );
+    if (match.isNotEmpty) return match.first.id;
+    return widget.repository.addQuickVariety(label: label);
+  }
+
   Future<void> _pickDueBy() async {
     final now = DateTime.now();
     final picked = await showDatePicker(
@@ -85,14 +129,15 @@ class _ProposeSheetState extends State<_ProposeSheet> {
   }
 
   Future<void> _send() async {
-    final label = _seed.text.trim();
+    final label = (_seedController?.text ?? widget.seedLabel ?? '').trim();
     if (label.isEmpty) return; // the seed name is the one thing we need
     setState(() => _saving = true);
+    final varietyId = await _resolveVarietyId(label);
     await widget.service.propose(
       direction: _direction,
       counterpartyKey: widget.peerPubkey,
       counterpartyName: widget.peerName,
-      varietyId: widget.varietyId,
+      varietyId: varietyId,
       label: label,
       owedDescription: _nullIfBlank(_owed.text),
       returnKind: _returnKind,
@@ -148,15 +193,39 @@ class _ProposeSheetState extends State<_ProposeSheet> {
                 onTap: () => setState(() => _direction = d),
               ),
             const SizedBox(height: 8),
-            TextField(
-              key: const Key('propose.seed'),
-              controller: _seed,
-              textCapitalization: TextCapitalization.sentences,
-              decoration: InputDecoration(
-                labelText: t.plantare.seedLabel,
-                helperText: t.plantare.seedHint,
-                border: const OutlineInputBorder(),
-              ),
+            // Pick the seed from the inventory so the promise is tied to a real
+            // Variety; typing a new name creates one on send.
+            Autocomplete<({String id, String label})>(
+              initialValue: TextEditingValue(text: widget.seedLabel ?? ''),
+              displayStringForOption: (v) => v.label,
+              optionsBuilder: (value) {
+                final q = value.text.trim().toLowerCase();
+                if (q.isEmpty) return _varieties;
+                return _varieties
+                    .where((v) => v.label.toLowerCase().contains(q));
+              },
+              onSelected: (v) => setState(() => _varietyId = v.id),
+              fieldViewBuilder:
+                  (context, controller, focusNode, onFieldSubmitted) {
+                _seedController = controller;
+                return TextField(
+                  key: const Key('propose.seed'),
+                  controller: controller,
+                  focusNode: focusNode,
+                  textCapitalization: TextCapitalization.sentences,
+                  onChanged: (_) {
+                    // Editing away from a picked seed unlinks it (a new name
+                    // will create its own Variety).
+                    if (_varietyId != null) setState(() => _varietyId = null);
+                  },
+                  onSubmitted: (_) => onFieldSubmitted(),
+                  decoration: InputDecoration(
+                    labelText: t.plantare.seedLabel,
+                    helperText: t.plantare.seedHint,
+                    border: const OutlineInputBorder(),
+                  ),
+                );
+              },
             ),
             const SizedBox(height: 16),
             Text(t.plantare.returnKindLabel,