feat(reports): controlled ReportDateFilter

Co-Authored-By: claude-flow <ruv@ruv.net>

lib/screens/reports/report_date_filter.dart

@@ -5,14 +5,47 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import '../../providers/reports_provider.dart';
 import '../../utils/app_time.dart';
 
+/// Returns a [ReportDateRange] spanning the calendar month that contains [now].
+/// start = DateTime(y, m, 1), end = DateTime(y, m+1, 1), label = 'This Month'.
+ReportDateRange thisMonthRange(DateTime now) {
+  return ReportDateRange(
+    start: DateTime(now.year, now.month, 1),
+    end: DateTime(now.year, now.month + 1, 1),
+    label: 'This Month',
+  );
+}
+
 /// A Metabase-inspired date filter with quick presets, relative offsets,
 /// and a custom date-range picker.
+///
+/// Two construction modes:
+/// - Default `ReportDateFilter({key})` — provider-bound, reads/writes
+///   [reportDateRangeProvider].
+/// - `ReportDateFilter.controlled({key, value, onChanged})` — controlled;
+///   displays [value] and calls [onChanged] on apply without touching the
+///   provider.
 class ReportDateFilter extends ConsumerWidget {
-  const ReportDateFilter({super.key});
+  /// Provider-bound mode.
+  const ReportDateFilter({super.key})
+      : _value = null,
+        _onChanged = null;
+
+  /// Controlled mode: does NOT read or write [reportDateRangeProvider].
+  const ReportDateFilter.controlled({
+    super.key,
+    required ReportDateRange value,
+    required ValueChanged<ReportDateRange> onChanged,
+  })  : _value = value,
+        _onChanged = onChanged;
+
+  final ReportDateRange? _value;
+  final ValueChanged<ReportDateRange>? _onChanged;
+
+  bool get _isControlled => _value != null;
 
   @override
   Widget build(BuildContext context, WidgetRef ref) {
-    final range = ref.watch(reportDateRangeProvider);
+    final range = _isControlled ? _value! : ref.watch(reportDateRangeProvider);
     final theme = Theme.of(context);
     final colors = theme.colorScheme;
     final text = theme.textTheme;
@@ -51,12 +84,18 @@ class ReportDateFilter extends ConsumerWidget {
   }
 
   void _showDateFilterDialog(BuildContext context, WidgetRef ref) {
+    final current =
+        _isControlled ? _value! : ref.read(reportDateRangeProvider);
     m3ShowDialog(
       context: context,
       builder: (ctx) => _DateFilterDialog(
-        current: ref.read(reportDateRangeProvider),
+        current: current,
         onApply: (newRange) {
-          ref.read(reportDateRangeProvider.notifier).state = newRange;
+          if (_isControlled) {
+            _onChanged!(newRange);
+          } else {
+            ref.read(reportDateRangeProvider.notifier).state = newRange;
+          }
         },
       ),
     );

test/report_date_filter_test.dart

@@ -0,0 +1,52 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:tasq/providers/reports_provider.dart';
+import 'package:tasq/screens/reports/report_date_filter.dart';
+import 'package:tasq/utils/app_time.dart';
+
+void main() {
+  setUpAll(() {
+    AppTime.initialize();
+  });
+
+  group('ReportDateFilter.controlled', () {
+    testWidgets(
+      'emits via onChanged and never writes provider',
+      (tester) async {
+        final now = DateTime(2025, 1, 15);
+        final captured = <ReportDateRange>[];
+        final container = ProviderContainer();
+        addTearDown(container.dispose);
+
+        await tester.pumpWidget(
+          UncontrolledProviderScope(
+            container: container,
+            child: MaterialApp(
+              home: Scaffold(
+                body: ReportDateFilter.controlled(
+                  value: thisMonthRange(now),
+                  onChanged: captured.add,
+                ),
+              ),
+            ),
+          ),
+        );
+
+        // Tap the "Change" button to open the dialog
+        await tester.tap(find.text('Change'));
+        await tester.pumpAndSettle();
+
+        // Tap the "Yesterday" preset chip
+        await tester.tap(find.text('Yesterday'));
+        await tester.pumpAndSettle();
+
+        // The onChanged callback received Yesterday
+        expect(captured.single.label, 'Yesterday');
+
+        // The provider was NOT touched — still at its default label
+        expect(container.read(reportDateRangeProvider).label, 'Last 30 Days');
+      },
+    );
+  });
+}