Gym mode UI Updates

lib/core/widgets/datetime_input.dart

@@ -67,18 +67,30 @@ class _TimeInputWidgetState extends State<TimeInputWidget> {
     _value = widget.value;
   }
 
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    // Format depends on MaterialLocalizations, so (re)sync once dependencies
+    // are available rather than during build (which would notify the parent
+    // Form mid-build and trigger setState-during-build).
+    _syncText();
+  }
+
   @override
   void didUpdateWidget(TimeInputWidget oldWidget) {
     super.didUpdateWidget(oldWidget);
     if (widget.value != oldWidget.value) {
       _value = widget.value;
+      _syncText();
     }
   }
 
+  /// Rewrites the read-only display text to match [_value]. Must be called
+  /// outside of [build] because it notifies the controller's listeners.
+  void _syncText() {}
+
   @override
   Widget build(BuildContext context) {
-    // Keyed initialValue, not a controller: a controller notifies the enclosing
-    // Form on assignment, which crashes if that happens during a build.
     return TextFormField(
       key: ValueKey(_value),
       readOnly: true,
@@ -92,6 +104,7 @@ class _TimeInputWidgetState extends State<TimeInputWidget> {
                 icon: const Icon(Icons.clear),
                 onPressed: () {
                   setState(() => _value = null);
+                  _syncText();
                   widget.onCleared!();
                 },
               )
@@ -107,6 +120,7 @@ class _TimeInputWidgetState extends State<TimeInputWidget> {
         );
         if (picked != null && context.mounted) {
           setState(() => _value = picked);
+          _syncText();
           widget.onChanged(picked);
         }
       },
@@ -172,19 +186,31 @@ class _DateInputWidgetState extends State<DateInputWidget> {
     _value = widget.value;
   }
 
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    // Format depends on the locale, so (re)sync once dependencies are
+    // available rather than during build (which would notify the parent Form
+    // mid-build and trigger setState-during-build).
+    _syncText();
+  }
+
   @override
   void didUpdateWidget(DateInputWidget oldWidget) {
     super.didUpdateWidget(oldWidget);
     if (widget.value != oldWidget.value) {
       _value = widget.value;
+      _syncText();
     }
   }
 
+  /// Rewrites the read-only display text to match [_value]. Must be called
+  /// outside of [build] because it notifies the controller's listeners.
+  void _syncText() {}
+
   @override
   Widget build(BuildContext context) {
     final dateFormat = localizedDate(context);
-    // Keyed initialValue, not a controller: a controller notifies the enclosing
-    // Form on assignment, which crashes if that happens during a build.
     return TextFormField(
       key: ValueKey(_value),
       readOnly: true,
@@ -199,6 +225,7 @@ class _DateInputWidgetState extends State<DateInputWidget> {
                 icon: const Icon(Icons.clear),
                 onPressed: () {
                   setState(() => _value = null);
+                  _syncText();
                   widget.onCleared!();
                 },
               )
@@ -216,6 +243,7 @@ class _DateInputWidgetState extends State<DateInputWidget> {
         );
         if (picked != null && context.mounted) {
           setState(() => _value = picked);
+          _syncText();
           widget.onChanged(picked);
         }
       },

lib/features/routines/models/log.dart

@@ -100,7 +100,13 @@ class Log {
     sessionId = null;
 
     slotEntryId = setConfig.slotEntryId;
-    exercise = setConfig.exercise;
+    // The exercise may not be hydrated yet; keep the id so the log is still
+    // valid to submit rather than throwing and taking the gym page down.
+    exerciseId = setConfig.exerciseId;
+    final configExercise = setConfig.exerciseOrNull;
+    if (configExercise != null) {
+      exerciseObj = configExercise;
+    }
 
     weight = setConfig.weight;
     weightTarget = setConfig.weight;
@@ -228,18 +234,21 @@ class Log {
       // is no weight defined so that we don't just output something like "8" but
       // rather "8 repetitions". If there is weight we want to output "8 x 50kg",
       // since the repetitions are implied. If other units are used, we always
-      // print them
-      if (repetitionsUnitObj != null && repetitionsUnitObj!.id != REP_UNIT_REPETITIONS_ID ||
-          weight == 0 ||
-          weight == null) {
-        out.add(getServerStringTranslation(repetitionsUnitObj!.name, context));
+      // print them. The unit object may be missing (not yet hydrated), in which
+      // case we simply omit the label rather than crash.
+      final repUnit = repetitionsUnitObj;
+      final isNonDefaultRepUnit = repUnit != null && repUnit.id != REP_UNIT_REPETITIONS_ID;
+      if ((isNonDefaultRepUnit || weight == 0 || weight == null) && repUnit != null) {
+        out.add(getServerStringTranslation(repUnit.name, context));
       }
     }
 
     if (weight != null && weight != 0) {
       out.add('×');
       out.add(formatNum(weight!).toString());
-      out.add(weightUnitObj!.name);
+      if (weightUnitObj != null) {
+        out.add(weightUnitObj!.name);
+      }
     }
 
     if (rir != null) {

lib/features/routines/models/set_config_data.dart

@@ -31,8 +31,25 @@ class SetConfigData {
   @JsonKey(required: true, name: 'exercise')
   late int exerciseId;
 
+  /// The hydrated exercise. Only set once `hydrateSetConfigs` has found it, so
+  /// it stays null for configs whose exercise is missing locally. Read it
+  /// through [exerciseOrNull] anywhere a missing exercise must not take the
+  /// whole screen down — an unguarded [exercise] read throws and Flutter
+  /// replaces the surrounding widget with a blank ErrorWidget.
+  Exercise? _exercise;
+
   @JsonKey(includeFromJson: false, includeToJson: false)
-  late Exercise exercise;
+  Exercise get exercise {
+    if (_exercise == null) {
+      throw StateError('SetConfigData has no hydrated exercise (exercise ID $exerciseId)');
+    }
+    return _exercise!;
+  }
+
+  set exercise(Exercise value) => _exercise = value;
+
+  /// Like [exercise] but returns null instead of throwing
+  Exercise? get exerciseOrNull => _exercise;
 
   @JsonKey(required: true, name: 'slot_entry_id')
   late int slotEntryId;
@@ -181,7 +198,7 @@ class SetConfigData {
       restTime: restTime ?? this.restTime,
       maxRestTime: maxRestTime ?? this.maxRestTime,
       comment: comment ?? this.comment,
-      exercise: exercise ?? this.exercise,
+      exercise: exercise ?? _exercise,
       weightUnit: weightUnit ?? this.weightUnit,
       repetitionsUnit: repetitionsUnit ?? this.repetitionsUnit,
     );

lib/features/routines/models/weight_unit.dart

@@ -17,6 +17,35 @@
  */
 
 import 'package:flutter/foundation.dart';
+import 'package:wger/core/consts.dart';
+
+const _KG_PER_LB = 0.45359237;
+
+/// Converts [value] between [WEIGHT_UNIT_KG] and [WEIGHT_UNIT_LB].
+///
+/// Anything else (the server also knows custom units such as plates) is
+/// returned untouched — there is no sensible factor for those.
+///
+/// The result is snapped to [rounding] when given (the routine's
+/// `weightRounding`), otherwise to the nearest half unit, so switching units
+/// mid-session yields a number that exists on a rack rather than 176.3696.
+num convertWeight(num value, {required int from, required int to, num? rounding}) {
+  if (from == to) {
+    return value;
+  }
+
+  final num converted;
+  if (from == WEIGHT_UNIT_KG && to == WEIGHT_UNIT_LB) {
+    converted = value / _KG_PER_LB;
+  } else if (from == WEIGHT_UNIT_LB && to == WEIGHT_UNIT_KG) {
+    converted = value * _KG_PER_LB;
+  } else {
+    return value;
+  }
+
+  final step = (rounding == null || rounding <= 0) ? 0.5 : rounding;
+  return (converted / step).round() * step;
+}
 
 @immutable
 class WeightUnit {