Merge branch 'train-days' into integration

# Conflicts:
#	apps/train/halkyon_train_flutter/lib/src/app/train_paths.dart
#	docs/adr/0030-halkyon-train.md

apps/train/halkyon_train_flutter/test/support/fake_health_platform.dart

@@ -135,6 +135,20 @@ class FakeHealthPlatform({
   @override
   Future<List<Fix>?> route(String sessionId) async => routes[sessionId];
 
+  /// Other apps' weights (D64).
+  final otherWeights = <HealthWeight>[];
+
+  @override
+  Future<List<HealthWeight>> weights({required DateTime from}) async {
+    if (!grantedNow.contains(HealthAccess.weight)) {
+      throw HealthRefused();
+    }
+    return [
+      for (final weight in otherWeights)
+        if (!weight.at.isBefore(from)) weight,
+    ];
+  }
+
   /// How many times Health Connect's settings were opened.
   int settingsOpened = 0;
 

apps/train/halkyon_train_flutter/test/support/memory_weight_gateway.dart

@@ -0,0 +1,36 @@
+import 'dart:async';
+
+import 'package:halkyon_app/halkyon_app.dart';
+import 'package:halkyon_train_flutter/src/feature/weight/data/weight_gateway.dart';
+
+/// [WeightGateway] in memory, whose rows a test changes as an instance could.
+class MemoryWeightGateway() implements WeightGateway {
+  final rows = <String, Envelope>{};
+  final _remote = StreamController<void>.broadcast();
+
+  /// As a sync bringing others' changes.
+  void bringRemoteChanges() => _remote.add(null);
+
+  @override
+  Future<List<WeightRow>> weights() async => [
+    for (final MapEntry(:key, :value) in rows.entries)
+      (id: key, envelope: value),
+  ];
+
+  @override
+  Future<void> insert(WeightRow weight) async =>
+      rows[weight.id] = weight.envelope;
+
+  @override
+  Future<void> update(String id, Envelope envelope) async {
+    if (rows.containsKey(id)) {
+      rows[id] = envelope;
+    }
+  }
+
+  @override
+  Future<void> delete(String id) async => rows.remove(id);
+
+  @override
+  Stream<void> get remoteChanges => _remote.stream;
+}