Add tick boxes to task rows

Tasks now carry a tick box rather than being read-only rows. Ticking strikes
the title through and leaves the item in place, so a day still reads as a
record of what was asked rather than only what is left.

New in designs/Checkbox.dart:

- TickBox   the square box itself, animating between empty and filled
- TickRow   box + struck-through title + caller-supplied detail and trailing
- addTaskAffordance  the centred "Add new task" control beneath a day's list

Applied to the home plan, the overdue queue and the goal task list. Each
screen holds a set of optimistically ticked ids so the tick lands immediately
and rolls back if the call fails; the set is reconciled whenever fresh data
arrives.

A tick completes the item outright, whatever its proof requirement. The proof
flow is still reachable from the Complete button in the overdue queue, so
tasks that need an artefact have a route that asks for one — but the tick
itself no longer enforces it.

Late completes stay visually distinct: the row keeps a Late pill and the
warning accent, and the user is told the window had already closed.

flutter analyze lib/ reports no errors.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Mfu2gQLSFN21YRBcU2NrTt

frontend/lib/Grounded/see/home/HomeState.dart

@@ -10,9 +10,9 @@ import '../../about/internal/application/NavigatorType.dart';
 import '../../about/internal/application/NotificationType.dart';
 import '../../about/internal/application/Standing.dart';
 import '../../about/internal/application/TextType.dart';
-import '../../about/internal/application/ToneLevel.dart';
 import '../../about/internal/application/UserDetails.dart';
 import '../../configs/Navigator.dart';
+import '../../designs/Checkbox.dart';
 import '../../designs/Component.dart';
 import '../../designs/Responsive.dart';
 import '../../designs/Shell.dart';
@@ -20,7 +20,6 @@ import '../../designs/buttons/Buttons.dart';
 import '../../designs/text/Text.dart';
 import '../../utils/Colors.dart';
 import '../../utils/CommonUtils.dart';
-import '../../utils/DebtEngine.dart';
 import '../../utils/StandingEngine.dart';
 import '../../utils/Thresholds.dart';
 import '../../utils/ToneEngine.dart';
@@ -52,6 +51,11 @@ class HomeState extends State<Home> implements ConnectHome {
 
   bool _distressed = false;
 
+  /// Ids ticked locally but not yet confirmed by the server. The row reads as
+  /// done immediately so the tick feels instant, and rolls back if the call
+  /// fails.
+  final Set<String> _ticked = <String>{};
+
   @override
   Widget build(BuildContext context) {
     return ViewModelBuilder<ViewHome>.reactive(
@@ -101,6 +105,18 @@ class HomeState extends State<Home> implements ConnectHome {
     }
   }
 
+  void _onTick(Commitment item) {
+    if (item.id == null || _ticked.contains(item.id)) {
+      return;
+    }
+
+    setState(() {
+      _ticked.add(item.id!);
+    });
+
+    _model?.tick(item);
+  }
+
   void _onOpenReportCard() {
     GroundedNavigation().navigateToPage(
         NavigatorType.justOpen, const ReportCardScreen(), context);
@@ -272,9 +288,14 @@ class HomeState extends State<Home> implements ConnectHome {
             "Nothing committed today",
             "An empty plan is a decision too. Add something you actually intend to do.",
           )
-        else
+        else ...[
           ..._plan.map(_commitmentRow),
-        const SizedBox(height: 28),
+          addTaskAffordance(
+            _onAddCommitment,
+            enabled: StandingEngine.permitsNewCommitment(_standing),
+          ),
+        ],
+        const SizedBox(height: 12),
         _quickLinks(),
         const SizedBox(height: 24),
         roundedCornerButton(
@@ -499,83 +520,68 @@ class HomeState extends State<Home> implements ConnectHome {
     );
   }
 
+  /// A task line with its tick box. Completed items keep their place, struck
+  /// through — the day stays a record of what was asked, not just what is left.
   Widget _commitmentRow(Commitment item) {
-    final bool late = item.windowClosed &&
-        item.status != CommitmentStatus.Completed &&
-        item.status != CommitmentStatus.LateCompleted;
+    final bool settled = item.status == CommitmentStatus.Completed ||
+        item.status == CommitmentStatus.LateCompleted;
+
+    final bool ticked = settled || _ticked.contains(item.id);
+
+    final bool late = item.windowClosed && !settled;
 
     final Color accent = classColor(item.commitmentClass);
 
     return Container(
-      margin: const EdgeInsets.only(bottom: 10),
+      margin: const EdgeInsets.only(bottom: 6),
       child: card(
-        padding: const EdgeInsets.fromLTRB(14, 14, 14, 14),
-        onTap: _onOpenOverdue,
-        child: Row(
-          crossAxisAlignment: CrossAxisAlignment.start,
-          children: [
-            Container(
-              width: 3,
-              height: 42,
-              margin: const EdgeInsets.only(right: 14, top: 2),
-              decoration: BoxDecoration(
-                color: accent,
-                borderRadius: BorderRadius.circular(4),
+        padding: const EdgeInsets.fromLTRB(12, 8, 14, 8),
+        child: TickRow(
+          checked: ticked,
+          title: item.title,
+          accent: item.status == CommitmentStatus.LateCompleted
+              ? colorStandingWarned
+              : accent,
+          onTick: settled ? null : () => _onTick(item),
+          onTap: _onOpenOverdue,
+          detail: Row(
+            children: [
+              text(formatWindow(item), 11, TextType.Regular,
+                  color: colorGrey2),
+              const SizedBox(width: 10),
+              Container(
+                width: 3,
+                height: 3,
+                decoration:
+                    BoxDecoration(color: colorGrey, shape: BoxShape.circle),
               ),
-            ),
-            Expanded(
-              child: Column(
-                crossAxisAlignment: CrossAxisAlignment.start,
-                mainAxisSize: MainAxisSize.min,
-                children: [
-                  text(item.title, 15, TextType.Medium,
-                      color: colorPrimaryDark,
-                      maxLines: 2,
-                      overflow: TextOverflow.ellipsis),
-                  const SizedBox(height: 8),
-                  Row(
-                    children: [
-                      text(formatWindow(item), 11, TextType.Regular,
-                          color: colorGrey2),
-                      const SizedBox(width: 10),
-                      Container(width: 3, height: 3, decoration: BoxDecoration(
-                        color: colorGrey, shape: BoxShape.circle)),
-                      const SizedBox(width: 10),
-                      text(formatMinutes(item.estMinutes), 11,
-                          TextType.Regular, color: colorGrey2),
-                    ],
-                  ),
-                  if (late) ...[
-                    const SizedBox(height: 10),
-                    Row(
-                      children: [
-                        pill(
-                          overdueLabel(item),
-                          colorStandingGrounded,
-                          colorStandingGroundedBg,
-                          textSize: 9,
-                        ),
-                        const SizedBox(width: 6),
-                        pill(
-                          "−${formatDebt(DebtEngine.commitmentDebt(item))}",
-                          colorGrey2,
-                          colorMuted,
-                          textSize: 9,
-                        ),
-                      ],
-                    ),
-                  ],
-                ],
-              ),
-            ),
-            const SizedBox(width: 10),
-            pill(
-              classLabel(item.commitmentClass),
-              accent,
-              classBackground(item.commitmentClass),
-              textSize: 9,
-            ),
-          ],
+              const SizedBox(width: 10),
+              text(formatMinutes(item.estMinutes), 11, TextType.Regular,
+                  color: colorGrey2),
+              if (late) ...[
+                const SizedBox(width: 10),
+                pill(
+                  overdueLabel(item),
+                  colorStandingGrounded,
+                  colorStandingGroundedBg,
+                  textSize: 9,
+                ),
+              ],
+              if (item.status == CommitmentStatus.LateCompleted) ...[
+                const SizedBox(width: 10),
+                pill("Late", colorStandingWarned, colorStandingWarnedBg,
+                    textSize: 9),
+              ],
+            ],
+          ),
+          trailing: ticked
+              ? null
+              : pill(
+                  classLabel(item.commitmentClass),
+                  accent,
+                  classBackground(item.commitmentClass),
+                  textSize: 9,
+                ),
         ),
       ),
     );
@@ -650,6 +656,9 @@ class HomeState extends State<Home> implements ConnectHome {
   void onPlanLoaded(List<Commitment> plan) {
     setState(() {
       _plan = plan;
+      // The server is now authoritative; anything it reports as settled no
+      // longer needs the local optimistic flag.
+      _ticked.removeWhere((id) => plan.every((item) => item.id != id));
     });
   }
 
@@ -682,6 +691,31 @@ class HomeState extends State<Home> implements ConnectHome {
     });
   }
 
+  @override
+  void onTicked(Commitment item, bool late) {
+    if (!late) {
+      return;
+    }
+
+    // A clean tick needs no comment. A late one does — otherwise the user
+    // learns that the window never mattered.
+    _model?.showApplicationNotification(
+      NotificationType.warning,
+      "Late complete",
+      "The window had already closed, so this is recorded as a late complete. It reduces the debt but does not clear it.",
+      true,
+      true,
+      null,
+    );
+  }
+
+  @override
+  void onTickFailed(Commitment item) {
+    setState(() {
+      _ticked.remove(item.id);
+    });
+  }
+
   @override
   void onCreationBlocked(String reason) {
     _model?.showApplicationNotification(