polish(ux): drop the checkmark on selected filter chips

The tick overlapped the leading icon on selected chips, reading as a
confusing blob. The solid fill already signals 'on', so hide the
checkmark. Also make the selected label reliably white via an explicit
per-chip style: the global ChipTheme's secondaryLabelStyle was not
applied to FilterChips, leaving dark text on green. Plain attribute/
market chips now share a PlainFilterChip widget; swatch and month chips
just drop their tick.

apps/app_seeds/lib/ui/calendar_screen.dart

@@ -157,6 +157,7 @@ class _MonthStripState extends State<_MonthStrip> {
             final selected = m == widget.month;
             return ChoiceChip(
               key: Key('calendar.month.$m'),
+              showCheckmark: false,
               labelPadding: const EdgeInsets.symmetric(horizontal: 6),
               label: Text(
                 _capitalise(fmt.format(DateTime(2000, m))),

apps/app_seeds/lib/ui/filter_chips.dart

@@ -0,0 +1,45 @@
+import 'package:flutter/material.dart';
+
+import 'theme.dart';
+
+/// A filter chip for the horizontal filter rows: light with dark ink when idle,
+/// a solid green fill with white content when selected — no checkmark, since the
+/// fill already reads as "on" and a tick over the leading icon just muddles it.
+/// White on [seedGreen] meets WCAG AA (see test/ui/theme_contrast_test.dart).
+class PlainFilterChip extends StatelessWidget {
+  const PlainFilterChip({
+    required this.label,
+    required this.selected,
+    required this.onSelected,
+    this.icon,
+    super.key,
+  });
+
+  final String label;
+  final bool selected;
+  final ValueChanged<bool> onSelected;
+
+  /// Optional leading icon (attribute chips carry one; type/category chips do
+  /// not).
+  final IconData? icon;
+
+  @override
+  Widget build(BuildContext context) {
+    final fg = selected ? Colors.white : seedOnSurface;
+    return FilterChip(
+      avatar: icon == null
+          ? null
+          : Icon(icon, size: 18, color: selected ? Colors.white : seedGreen),
+      label: Text(label),
+      selected: selected,
+      onSelected: onSelected,
+      showCheckmark: false,
+      selectedColor: seedGreen,
+      labelStyle: TextStyle(
+        color: fg,
+        fontSize: 14,
+        fontWeight: FontWeight.w500,
+      ),
+    );
+  }
+}

apps/app_seeds/lib/ui/inventory_list_screen.dart

@@ -12,6 +12,7 @@ import '../state/inventory_cubit.dart';
 import 'category_palette.dart';
 import 'draft_triage.dart';
 import 'edge_fade.dart';
+import 'filter_chips.dart';
 import 'label_print_sheet.dart';
 import 'quantity_kind_l10n.dart';
 import 'quantity_picker.dart';
@@ -303,50 +304,34 @@ class _FilterBar extends StatelessWidget {
     // stable earthy tonality). Grouping + colour makes a long row scannable.
     final attrChips = <Widget>[
       if (hasSowCalendar)
-        FilterChip(
+        PlainFilterChip(
           key: const Key('inventory.filter.sowThisMonth'),
-          avatar: Icon(
-            Icons.calendar_month,
-            size: 18,
-            color: state.sowThisMonthOnly ? Colors.white : seedGreen,
-          ),
-          label: Text(t.calendar.filterChip),
+          icon: Icons.calendar_month,
+          label: t.calendar.filterChip,
           selected: state.sowThisMonthOnly,
           onSelected: (_) => cubit.toggleSowThisMonth(),
         ),
       if (hasShared)
-        FilterChip(
+        PlainFilterChip(
           key: const Key('inventory.filter.sharing'),
-          avatar: Icon(
-            Icons.volunteer_activism_outlined,
-            size: 18,
-            color: state.sharingOnly ? Colors.white : seedGreen,
-          ),
-          label: Text(t.share.filterChip),
+          icon: Icons.volunteer_activism_outlined,
+          label: t.share.filterChip,
           selected: state.sharingOnly,
           onSelected: (_) => cubit.toggleSharingOnly(),
         ),
       if (hasOrganic)
-        FilterChip(
+        PlainFilterChip(
           key: const Key('inventory.filter.organic'),
-          avatar: Icon(
-            Icons.eco,
-            size: 18,
-            color: state.organicOnly ? Colors.white : seedGreen,
-          ),
-          label: Text(t.editVariety.organic),
+          icon: Icons.eco,
+          label: t.editVariety.organic,
           selected: state.organicOnly,
           onSelected: (_) => cubit.toggleOrganicOnly(),
         ),
       if (hasNeedsReproduction)
-        FilterChip(
+        PlainFilterChip(
           key: const Key('inventory.filter.needsReproduction'),
-          avatar: Icon(
-            Icons.autorenew,
-            size: 18,
-            color: state.needsReproductionOnly ? Colors.white : seedGreen,
-          ),
-          label: Text(t.inventory.needsReproductionFilter),
+          icon: Icons.autorenew,
+          label: t.inventory.needsReproductionFilter,
           selected: state.needsReproductionOnly,
           onSelected: (_) => cubit.toggleNeedsReproductionOnly(),
         ),
@@ -456,9 +441,9 @@ class _SwatchFilterChip extends StatelessWidget {
       avatar: icon == null ? null : Icon(icon, size: 18, color: ink),
       selected: selected,
       onSelected: (_) => onSelected(),
+      showCheckmark: false,
       backgroundColor: swatch.fill,
       selectedColor: swatch.ink,
-      checkmarkColor: Colors.white,
       side: BorderSide(
         color: swatch.ink.withValues(alpha: selected ? 0 : 0.35),
       ),

apps/app_seeds/lib/ui/market_screen.dart

@@ -13,6 +13,7 @@ import '../services/social_service.dart';
 import '../services/social_settings.dart';
 import '../state/offers_cubit.dart';
 import 'edge_fade.dart';
+import 'filter_chips.dart';
 import 'market_widgets.dart';
 import 'theme.dart';
 
@@ -488,28 +489,24 @@ class _MarketFilterBar extends StatelessWidget {
 
     final chips = <Widget>[
       if (hasOrganic)
-        FilterChip(
+        PlainFilterChip(
           key: const Key('market.filter.organic'),
-          avatar: Icon(
-            Icons.eco,
-            size: 18,
-            color: state.organicOnly ? Colors.white : seedGreen,
-          ),
-          label: Text(t.editVariety.organic),
+          icon: Icons.eco,
+          label: t.editVariety.organic,
           selected: state.organicOnly,
           onSelected: (_) => cubit.toggleOrganicOnly(),
         ),
       for (final type in types)
-        FilterChip(
+        PlainFilterChip(
           key: Key('market.filter.type.${type.name}'),
-          label: Text(offerTypeLabel(t, type)),
+          label: offerTypeLabel(t, type),
           selected: state.typeFilter.contains(type),
           onSelected: (_) => cubit.toggleType(type),
         ),
       for (final category in categories)
-        FilterChip(
+        PlainFilterChip(
           key: Key('market.filter.category.$category'),
-          label: Text(category),
+          label: category,
           selected: state.categoryFilter.contains(category),
           onSelected: (_) => cubit.toggleCategory(category),
         ),

apps/app_seeds/lib/ui/theme.dart

@@ -105,24 +105,5 @@ ThemeData buildTaneTheme() {
       thickness: 1,
       color: seedDivider,
     ),
-    // Filter/choice chips: idle chips stay light with dark ink, but a *selected*
-    // chip fills solid green with white ink so "on" reads unmistakably against
-    // the pale canvas (the soft tonal default sat too close to it). White on
-    // seedGreen meets WCAG AA — see test/ui/theme_contrast_test.dart. Chips that
-    // carry their own hue (family/form swatches) override this per-swatch.
-    chipTheme: const ChipThemeData(
-      selectedColor: seedGreen,
-      checkmarkColor: Colors.white,
-      labelStyle: TextStyle(
-        color: seedOnSurface,
-        fontSize: 14,
-        fontWeight: FontWeight.w500,
-      ),
-      secondaryLabelStyle: TextStyle(
-        color: Colors.white,
-        fontSize: 14,
-        fontWeight: FontWeight.w500,
-      ),
-    ),
   );
 }