Add lifestyle factors screen with diet, social, stress tracking

- Split behavioral inputs into two screens (Habits + Lifestyle)
- Added 5 new modifiable factors: diet quality, processed food,
  drug use, social connection, and stress level
- Updated hazard ratios for all new factors based on meta-analyses
- Model version bumped to 1.1
- Simplified welcome screen with clearer value proposition
- Updated tests for expanded behavioral model

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/models/behavioral_inputs.dart

@@ -1,12 +1,20 @@
 import 'enums.dart';
 
 class BehavioralInputs {
+  // Screen 1: Basic behaviors
   final SmokingStatus smoking;
-  final int cigarettesPerDay; // only relevant if smoking == current
+  final int cigarettesPerDay;
   final AlcoholLevel alcohol;
   final double sleepHours;
   final bool sleepConsistent;
   final ActivityLevel activity;
+
+  // Screen 2: Lifestyle factors
+  final DietQuality diet;
+  final ProcessedFoodLevel processedFood;
+  final DrugUse drugUse;
+  final SocialConnection social;
+  final StressLevel stress;
   final DrivingExposure driving;
   final WorkHoursLevel workHours;
 
@@ -17,6 +25,11 @@ class BehavioralInputs {
     required this.sleepHours,
     required this.sleepConsistent,
     required this.activity,
+    required this.diet,
+    required this.processedFood,
+    required this.drugUse,
+    required this.social,
+    required this.stress,
     required this.driving,
     required this.workHours,
   });
@@ -28,10 +41,41 @@ class BehavioralInputs {
     sleepHours: 7.5,
     sleepConsistent: true,
     activity: ActivityLevel.high,
+    diet: DietQuality.excellent,
+    processedFood: ProcessedFoodLevel.rarely,
+    drugUse: DrugUse.none,
+    social: SocialConnection.strong,
+    stress: StressLevel.low,
     driving: DrivingExposure.low,
     workHours: WorkHoursLevel.normal,
   );
 
+  /// Create partial inputs from screen 1 (with defaults for screen 2)
+  factory BehavioralInputs.fromScreen1({
+    required SmokingStatus smoking,
+    int cigarettesPerDay = 0,
+    required AlcoholLevel alcohol,
+    required double sleepHours,
+    required bool sleepConsistent,
+    required ActivityLevel activity,
+  }) {
+    return BehavioralInputs(
+      smoking: smoking,
+      cigarettesPerDay: cigarettesPerDay,
+      alcohol: alcohol,
+      sleepHours: sleepHours,
+      sleepConsistent: sleepConsistent,
+      activity: activity,
+      diet: DietQuality.fair,
+      processedFood: ProcessedFoodLevel.frequent,
+      drugUse: DrugUse.none,
+      social: SocialConnection.moderate,
+      stress: StressLevel.moderate,
+      driving: DrivingExposure.low,
+      workHours: WorkHoursLevel.normal,
+    );
+  }
+
   Map<String, dynamic> toJson() => {
         'smoking': smoking.name,
         'cigarettesPerDay': cigarettesPerDay,
@@ -39,6 +83,11 @@ class BehavioralInputs {
         'sleepHours': sleepHours,
         'sleepConsistent': sleepConsistent,
         'activity': activity.name,
+        'diet': diet.name,
+        'processedFood': processedFood.name,
+        'drugUse': drugUse.name,
+        'social': social.name,
+        'stress': stress.name,
         'driving': driving.name,
         'workHours': workHours.name,
       };
@@ -51,6 +100,14 @@ class BehavioralInputs {
         sleepHours: (json['sleepHours'] as num).toDouble(),
         sleepConsistent: json['sleepConsistent'] as bool,
         activity: ActivityLevel.values.byName(json['activity'] as String),
+        diet: DietQuality.values.byName(json['diet'] as String? ?? 'fair'),
+        processedFood: ProcessedFoodLevel.values
+            .byName(json['processedFood'] as String? ?? 'frequent'),
+        drugUse: DrugUse.values.byName(json['drugUse'] as String? ?? 'none'),
+        social: SocialConnection.values
+            .byName(json['social'] as String? ?? 'moderate'),
+        stress:
+            StressLevel.values.byName(json['stress'] as String? ?? 'moderate'),
         driving: DrivingExposure.values.byName(json['driving'] as String),
         workHours: WorkHoursLevel.values.byName(json['workHours'] as String),
       );
@@ -62,6 +119,11 @@ class BehavioralInputs {
     double? sleepHours,
     bool? sleepConsistent,
     ActivityLevel? activity,
+    DietQuality? diet,
+    ProcessedFoodLevel? processedFood,
+    DrugUse? drugUse,
+    SocialConnection? social,
+    StressLevel? stress,
     DrivingExposure? driving,
     WorkHoursLevel? workHours,
   }) =>
@@ -72,6 +134,11 @@ class BehavioralInputs {
         sleepHours: sleepHours ?? this.sleepHours,
         sleepConsistent: sleepConsistent ?? this.sleepConsistent,
         activity: activity ?? this.activity,
+        diet: diet ?? this.diet,
+        processedFood: processedFood ?? this.processedFood,
+        drugUse: drugUse ?? this.drugUse,
+        social: social ?? this.social,
+        stress: stress ?? this.stress,
         driving: driving ?? this.driving,
         workHours: workHours ?? this.workHours,
       );

lib/models/enums.dart

@@ -13,3 +13,14 @@ enum WorkHoursLevel { normal, elevated, high, extreme }
 enum Diagnosis { cardiovascular, diabetes, cancer, copd, hypertension }
 
 enum Confidence { high, moderate, emerging }
+
+// Lifestyle factors
+enum DietQuality { poor, fair, good, excellent }
+
+enum ProcessedFoodLevel { daily, frequent, occasional, rarely }
+
+enum DrugUse { none, occasional, regular, daily }
+
+enum SocialConnection { isolated, limited, moderate, strong }
+
+enum StressLevel { low, moderate, high, chronic }

lib/risk_engine/calculator.dart

@@ -3,7 +3,7 @@ import '../models/models.dart';
 import 'hazard_ratios.dart';
 import 'mortality_tables.dart';
 
-const String modelVersion = '1.0';
+const String modelVersion = '1.1';
 
 /// Maximum combined hazard ratio (prevents unrealistic compounding).
 const double _maxCombinedHR = 4.0;
@@ -19,11 +19,19 @@ const double _highMultiplier = 1.2;
 double computeCombinedHazard(BehavioralInputs inputs, double bmi) {
   double hr = 1.0;
 
+  // Screen 1 factors
   hr *= getSmokingHR(inputs.smoking, inputs.cigarettesPerDay);
   hr *= getAlcoholHR(inputs.alcohol);
   hr *= getSleepHR(inputs.sleepHours, inputs.sleepConsistent);
   hr *= getActivityHR(inputs.activity);
   hr *= getBmiHR(bmi);
+
+  // Screen 2 factors
+  hr *= getDietHR(inputs.diet);
+  hr *= getProcessedFoodHR(inputs.processedFood);
+  hr *= getDrugUseHR(inputs.drugUse);
+  hr *= getSocialHR(inputs.social);
+  hr *= getStressHR(inputs.stress);
   hr *= getDrivingHR(inputs.driving);
   hr *= getWorkHoursHR(inputs.workHours);
 
@@ -38,7 +46,6 @@ LifespanDelta _computeDelta(
   String behaviorKey,
 ) {
   if (currentHR <= modifiedHR) {
-    // No improvement possible or already optimal
     return LifespanDelta(
       lowMonths: 0,
       highMonths: 0,
@@ -46,11 +53,9 @@ LifespanDelta _computeDelta(
     );
   }
 
-  // Delta years ≈ baselineYears × (1 - modifiedHR/currentHR) × dampingFactor
   final rawDeltaYears =
       baselineYears * (1 - modifiedHR / currentHR) * _dampingFactor;
 
-  // Convert to months with uncertainty range
   final midpointMonths = rawDeltaYears * 12;
   final lowMonths = (midpointMonths * _lowMultiplier).round();
   final highMonths = (midpointMonths * _highMultiplier).round();
@@ -76,6 +81,16 @@ BehavioralInputs _setToOptimal(BehavioralInputs inputs, String behaviorKey) {
       return inputs.copyWith(sleepHours: 7.5, sleepConsistent: true);
     case 'activity':
       return inputs.copyWith(activity: ActivityLevel.high);
+    case 'diet':
+      return inputs.copyWith(diet: DietQuality.excellent);
+    case 'processedFood':
+      return inputs.copyWith(processedFood: ProcessedFoodLevel.rarely);
+    case 'drugUse':
+      return inputs.copyWith(drugUse: DrugUse.none);
+    case 'social':
+      return inputs.copyWith(social: SocialConnection.strong);
+    case 'stress':
+      return inputs.copyWith(stress: StressLevel.low);
     case 'driving':
       return inputs.copyWith(driving: DrivingExposure.low);
     case 'workHours':
@@ -99,6 +114,16 @@ bool _isOptimal(BehavioralInputs inputs, String behaviorKey) {
           inputs.sleepConsistent;
     case 'activity':
       return inputs.activity == ActivityLevel.high;
+    case 'diet':
+      return inputs.diet == DietQuality.excellent;
+    case 'processedFood':
+      return inputs.processedFood == ProcessedFoodLevel.rarely;
+    case 'drugUse':
+      return inputs.drugUse == DrugUse.none;
+    case 'social':
+      return inputs.social == SocialConnection.strong;
+    case 'stress':
+      return inputs.stress == StressLevel.low;
     case 'driving':
       return inputs.driving == DrivingExposure.low;
     case 'workHours':
@@ -114,6 +139,11 @@ const _modifiableBehaviors = [
   'alcohol',
   'sleep',
   'activity',
+  'diet',
+  'processedFood',
+  'drugUse',
+  'social',
+  'stress',
   'driving',
   'workHours',
 ];
@@ -123,28 +153,22 @@ CalculationResult calculateRankedFactors(
   UserProfile profile,
   BehavioralInputs inputs,
 ) {
-  // Get baseline remaining life expectancy
   final baselineYears = getRemainingLifeExpectancy(
     profile.age,
     profile.sex,
     profile.country,
   );
 
-  // Apply existing condition modifiers (reduces baseline)
   final conditionHR = getDiagnosisHR(profile.diagnoses);
   final adjustedBaselineYears = baselineYears / conditionHR;
 
-  // Calculate current combined HR from behaviors
   final currentHR = computeCombinedHazard(inputs, profile.bmi);
 
-  // Calculate delta for each modifiable behavior
   final factors = <RankedFactor>[];
 
   for (final behaviorKey in _modifiableBehaviors) {
-    // Skip if already optimal
     if (_isOptimal(inputs, behaviorKey)) continue;
 
-    // Compute HR with this behavior set to optimal
     final modifiedInputs = _setToOptimal(inputs, behaviorKey);
     final modifiedHR = computeCombinedHazard(modifiedInputs, profile.bmi);
 
@@ -155,7 +179,6 @@ CalculationResult calculateRankedFactors(
       behaviorKey,
     );
 
-    // Only include if there's meaningful gain (> 1 month)
     if (delta.highMonths >= 1) {
       factors.add(RankedFactor(
         behaviorKey: behaviorKey,
@@ -165,8 +188,8 @@ CalculationResult calculateRankedFactors(
     }
   }
 
-  // Sort by midpoint delta descending
+  factors.sort(
-  factors.sort((a, b) => b.delta.midpointMonths.compareTo(a.delta.midpointMonths));
+      (a, b) => b.delta.midpointMonths.compareTo(a.delta.midpointMonths));
 
   return CalculationResult(
     rankedFactors: factors,

lib/risk_engine/hazard_ratios.dart

@@ -43,7 +43,6 @@ double getSleepHR(double hours, bool consistent) {
     hr = 1.10;
   }
 
-  // Inconsistent sleep schedule adds additional risk
   if (!consistent) {
     hr *= 1.05;
   }
@@ -70,8 +69,7 @@ double getBmiHR(double bmi) {
   if (bmi >= 30 && bmi < 35) return 1.2;
   if (bmi >= 35 && bmi < 40) return 1.4;
   if (bmi >= 40) return 1.8;
-  // Underweight
+  return 1.15; // Underweight
-  return 1.15;
 }
 
 double getDrivingHR(DrivingExposure level) {
@@ -100,6 +98,78 @@ double getWorkHoursHR(WorkHoursLevel level) {
   }
 }
 
+// --- New lifestyle factors ---
+
+/// Diet quality - based on Mediterranean diet studies
+double getDietHR(DietQuality level) {
+  switch (level) {
+    case DietQuality.excellent:
+      return 1.0;
+    case DietQuality.good:
+      return 1.05;
+    case DietQuality.fair:
+      return 1.15;
+    case DietQuality.poor:
+      return 1.3;
+  }
+}
+
+/// Processed food consumption - ultra-processed food studies
+double getProcessedFoodHR(ProcessedFoodLevel level) {
+  switch (level) {
+    case ProcessedFoodLevel.rarely:
+      return 1.0;
+    case ProcessedFoodLevel.occasional:
+      return 1.05;
+    case ProcessedFoodLevel.frequent:
+      return 1.12;
+    case ProcessedFoodLevel.daily:
+      return 1.2;
+  }
+}
+
+/// Drug use - excluding alcohol/tobacco (cannabis, recreational drugs)
+double getDrugUseHR(DrugUse level) {
+  switch (level) {
+    case DrugUse.none:
+      return 1.0;
+    case DrugUse.occasional:
+      return 1.05;
+    case DrugUse.regular:
+      return 1.15;
+    case DrugUse.daily:
+      return 1.35;
+  }
+}
+
+/// Social connection - loneliness/isolation meta-analyses
+double getSocialHR(SocialConnection level) {
+  switch (level) {
+    case SocialConnection.strong:
+      return 1.0;
+    case SocialConnection.moderate:
+      return 1.05;
+    case SocialConnection.limited:
+      return 1.2;
+    case SocialConnection.isolated:
+      return 1.45;
+  }
+}
+
+/// Chronic stress - based on allostatic load research
+double getStressHR(StressLevel level) {
+  switch (level) {
+    case StressLevel.low:
+      return 1.0;
+    case StressLevel.moderate:
+      return 1.05;
+    case StressLevel.high:
+      return 1.15;
+    case StressLevel.chronic:
+      return 1.35;
+  }
+}
+
 /// Existing conditions modify baseline mortality but are NOT modifiable.
 double getDiagnosisHR(Set<Diagnosis> diagnoses) {
   double hr = 1.0;
@@ -131,11 +201,16 @@ Confidence getConfidenceForBehavior(String behaviorKey) {
     case 'smoking':
     case 'alcohol':
     case 'activity':
+    case 'social':
       return Confidence.high;
     case 'sleep':
     case 'workHours':
+    case 'diet':
+    case 'stress':
       return Confidence.moderate;
     case 'driving':
+    case 'processedFood':
+    case 'drugUse':
       return Confidence.emerging;
     default:
       return Confidence.moderate;
@@ -157,6 +232,16 @@ String getDisplayName(String behaviorKey) {
       return 'Driving Exposure';
     case 'workHours':
       return 'Work Hours';
+    case 'diet':
+      return 'Diet Quality';
+    case 'processedFood':
+      return 'Processed Food';
+    case 'drugUse':
+      return 'Drug Use';
+    case 'social':
+      return 'Social Connection';
+    case 'stress':
+      return 'Chronic Stress';
     default:
       return behaviorKey;
   }

lib/screens/behavioral_screen.dart

@@ -3,7 +3,7 @@ import 'package:flutter/services.dart';
 import '../models/models.dart';
 import '../storage/local_storage.dart';
 import '../theme.dart';
-import 'results_screen.dart';
+import 'lifestyle_screen.dart';
 
 class BehavioralScreen extends StatefulWidget {
   final UserProfile profile;
@@ -21,8 +21,6 @@ class _BehavioralScreenState extends State<BehavioralScreen> {
   double _sleepHours = 7.5;
   bool _sleepConsistent = true;
   ActivityLevel _activity = ActivityLevel.moderate;
-  DrivingExposure _driving = DrivingExposure.low;
-  WorkHoursLevel _workHours = WorkHoursLevel.normal;
 
   @override
   void initState() {
@@ -40,8 +38,6 @@ class _BehavioralScreenState extends State<BehavioralScreen> {
         _sleepHours = behaviors.sleepHours;
         _sleepConsistent = behaviors.sleepConsistent;
         _activity = behaviors.activity;
-        _driving = behaviors.driving;
-        _workHours = behaviors.workHours;
       });
     }
   }
@@ -50,7 +46,7 @@ class _BehavioralScreenState extends State<BehavioralScreen> {
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
-        title: const Text('Behaviors'),
+        title: const Text('Habits'),
         leading: IconButton(
           icon: const Icon(Icons.arrow_back),
           onPressed: () => Navigator.pop(context),
@@ -62,12 +58,12 @@ class _BehavioralScreenState extends State<BehavioralScreen> {
           crossAxisAlignment: CrossAxisAlignment.start,
           children: [
             Text(
-              'Modifiable Factors',
+              'Daily Habits',
               style: Theme.of(context).textTheme.headlineSmall,
             ),
             const SizedBox(height: 8),
             Text(
-              'These behaviors can be changed. We\'ll identify which has the largest impact.',
+              'Substances, sleep, and activity levels.',
               style: Theme.of(context).textTheme.bodyMedium,
             ),
             const SizedBox(height: 32),
@@ -100,26 +96,14 @@ class _BehavioralScreenState extends State<BehavioralScreen> {
             _buildSectionLabel('Physical Activity'),
             const SizedBox(height: 12),
             _buildActivitySelector(),
-            const SizedBox(height: 28),
-
-            // Driving Exposure
-            _buildSectionLabel('Driving Exposure'),
-            const SizedBox(height: 12),
-            _buildDrivingSelector(),
-            const SizedBox(height: 28),
-
-            // Work Hours
-            _buildSectionLabel('Work Hours'),
-            const SizedBox(height: 12),
-            _buildWorkHoursSelector(),
             const SizedBox(height: 40),
 
-            // Calculate button
+            // Continue button
             SizedBox(
               width: double.infinity,
               child: ElevatedButton(
-                onPressed: _calculate,
+                onPressed: _continue,
-                child: const Text('Calculate'),
+                child: const Text('Continue'),
               ),
             ),
             const SizedBox(height: 16),
@@ -166,7 +150,6 @@ class _BehavioralScreenState extends State<BehavioralScreen> {
                 max: 40,
                 divisions: 39,
                 onChanged: (value) {
-                  // Haptic feedback at 20 (one pack)
                   if (value.round() == 20 && _cigarettesPerDay != 20) {
                     HapticFeedback.mediumImpact();
                   }
@@ -264,32 +247,6 @@ class _BehavioralScreenState extends State<BehavioralScreen> {
     );
   }
 
-  Widget _buildDrivingSelector() {
-    return _buildSegmentedControl<DrivingExposure>(
-      value: _driving,
-      options: [
-        (DrivingExposure.low, '<50 mi/wk'),
-        (DrivingExposure.moderate, '50-150'),
-        (DrivingExposure.high, '150-300'),
-        (DrivingExposure.veryHigh, '300+'),
-      ],
-      onChanged: (value) => setState(() => _driving = value),
-    );
-  }
-
-  Widget _buildWorkHoursSelector() {
-    return _buildSegmentedControl<WorkHoursLevel>(
-      value: _workHours,
-      options: [
-        (WorkHoursLevel.normal, '<40'),
-        (WorkHoursLevel.elevated, '40-55'),
-        (WorkHoursLevel.high, '55-70'),
-        (WorkHoursLevel.extreme, '70+'),
-      ],
-      onChanged: (value) => setState(() => _workHours = value),
-    );
-  }
-
   Widget _buildSegmentedControl<T>({
     required T value,
     required List<(T, String)> options,
@@ -329,29 +286,19 @@ class _BehavioralScreenState extends State<BehavioralScreen> {
     );
   }
 
-  void _calculate() async {
+  void _continue() {
-    final behaviors = BehavioralInputs(
+    Navigator.of(context).push(
+      MaterialPageRoute(
+        builder: (_) => LifestyleScreen(
+          profile: widget.profile,
           smoking: _smoking,
           cigarettesPerDay: _cigarettesPerDay,
           alcohol: _alcohol,
           sleepHours: _sleepHours,
           sleepConsistent: _sleepConsistent,
           activity: _activity,
-      driving: _driving,
-      workHours: _workHours,
-    );
-
-    await LocalStorage.saveBehaviors(behaviors);
-
-    if (mounted) {
-      Navigator.of(context).push(
-        MaterialPageRoute(
-          builder: (_) => ResultsScreen(
-            profile: widget.profile,
-            behaviors: behaviors,
         ),
       ),
     );
   }
-  }
 }

lib/screens/lifestyle_screen.dart

@@ -0,0 +1,323 @@
+import 'package:flutter/material.dart';
+import '../models/models.dart';
+import '../storage/local_storage.dart';
+import '../theme.dart';
+import 'results_screen.dart';
+
+class LifestyleScreen extends StatefulWidget {
+  final UserProfile profile;
+  final SmokingStatus smoking;
+  final int cigarettesPerDay;
+  final AlcoholLevel alcohol;
+  final double sleepHours;
+  final bool sleepConsistent;
+  final ActivityLevel activity;
+
+  const LifestyleScreen({
+    super.key,
+    required this.profile,
+    required this.smoking,
+    required this.cigarettesPerDay,
+    required this.alcohol,
+    required this.sleepHours,
+    required this.sleepConsistent,
+    required this.activity,
+  });
+
+  @override
+  State<LifestyleScreen> createState() => _LifestyleScreenState();
+}
+
+class _LifestyleScreenState extends State<LifestyleScreen> {
+  DietQuality _diet = DietQuality.fair;
+  ProcessedFoodLevel _processedFood = ProcessedFoodLevel.frequent;
+  DrugUse _drugUse = DrugUse.none;
+  SocialConnection _social = SocialConnection.moderate;
+  StressLevel _stress = StressLevel.moderate;
+  DrivingExposure _driving = DrivingExposure.low;
+  WorkHoursLevel _workHours = WorkHoursLevel.normal;
+
+  @override
+  void initState() {
+    super.initState();
+    _loadExistingBehaviors();
+  }
+
+  Future<void> _loadExistingBehaviors() async {
+    final behaviors = await LocalStorage.getBehaviors();
+    if (behaviors != null) {
+      setState(() {
+        _diet = behaviors.diet;
+        _processedFood = behaviors.processedFood;
+        _drugUse = behaviors.drugUse;
+        _social = behaviors.social;
+        _stress = behaviors.stress;
+        _driving = behaviors.driving;
+        _workHours = behaviors.workHours;
+      });
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: const Text('Lifestyle'),
+        leading: IconButton(
+          icon: const Icon(Icons.arrow_back),
+          onPressed: () => Navigator.pop(context),
+        ),
+      ),
+      body: SingleChildScrollView(
+        padding: const EdgeInsets.all(24),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            Text(
+              'Lifestyle Factors',
+              style: Theme.of(context).textTheme.headlineSmall,
+            ),
+            const SizedBox(height: 8),
+            Text(
+              'Diet, social life, stress, and daily exposures.',
+              style: Theme.of(context).textTheme.bodyMedium,
+            ),
+            const SizedBox(height: 32),
+
+            // Diet Quality
+            _buildSectionLabel('Diet Quality'),
+            _buildSectionHint('Vegetables, whole foods, variety'),
+            const SizedBox(height: 12),
+            _buildDietSelector(),
+            const SizedBox(height: 28),
+
+            // Processed Food
+            _buildSectionLabel('Processed Food'),
+            _buildSectionHint('Fast food, packaged snacks, sugary drinks'),
+            const SizedBox(height: 12),
+            _buildProcessedFoodSelector(),
+            const SizedBox(height: 28),
+
+            // Drug Use
+            _buildSectionLabel('Recreational Drugs'),
+            _buildSectionHint('Cannabis, stimulants, other substances'),
+            const SizedBox(height: 12),
+            _buildDrugUseSelector(),
+            const SizedBox(height: 28),
+
+            // Social Connection
+            _buildSectionLabel('Social Connection'),
+            _buildSectionHint('Time with friends, family, community'),
+            const SizedBox(height: 12),
+            _buildSocialSelector(),
+            const SizedBox(height: 28),
+
+            // Stress Level
+            _buildSectionLabel('Stress Level'),
+            _buildSectionHint('Work pressure, anxiety, life demands'),
+            const SizedBox(height: 12),
+            _buildStressSelector(),
+            const SizedBox(height: 28),
+
+            // Driving Exposure
+            _buildSectionLabel('Driving Exposure'),
+            const SizedBox(height: 12),
+            _buildDrivingSelector(),
+            const SizedBox(height: 28),
+
+            // Work Hours
+            _buildSectionLabel('Work Hours'),
+            const SizedBox(height: 12),
+            _buildWorkHoursSelector(),
+            const SizedBox(height: 40),
+
+            // Calculate button
+            SizedBox(
+              width: double.infinity,
+              child: ElevatedButton(
+                onPressed: _calculate,
+                child: const Text('Calculate'),
+              ),
+            ),
+            const SizedBox(height: 16),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Widget _buildSectionLabel(String label) {
+    return Text(
+      label,
+      style: Theme.of(context).textTheme.labelLarge,
+    );
+  }
+
+  Widget _buildSectionHint(String hint) {
+    return Text(
+      hint,
+      style: Theme.of(context).textTheme.bodySmall,
+    );
+  }
+
+  Widget _buildDietSelector() {
+    return _buildSegmentedControl<DietQuality>(
+      value: _diet,
+      options: [
+        (DietQuality.poor, 'Poor'),
+        (DietQuality.fair, 'Fair'),
+        (DietQuality.good, 'Good'),
+        (DietQuality.excellent, 'Excellent'),
+      ],
+      onChanged: (value) => setState(() => _diet = value),
+    );
+  }
+
+  Widget _buildProcessedFoodSelector() {
+    return _buildSegmentedControl<ProcessedFoodLevel>(
+      value: _processedFood,
+      options: [
+        (ProcessedFoodLevel.daily, 'Daily'),
+        (ProcessedFoodLevel.frequent, 'Often'),
+        (ProcessedFoodLevel.occasional, 'Sometimes'),
+        (ProcessedFoodLevel.rarely, 'Rarely'),
+      ],
+      onChanged: (value) => setState(() => _processedFood = value),
+    );
+  }
+
+  Widget _buildDrugUseSelector() {
+    return _buildSegmentedControl<DrugUse>(
+      value: _drugUse,
+      options: [
+        (DrugUse.none, 'None'),
+        (DrugUse.occasional, 'Occasional'),
+        (DrugUse.regular, 'Regular'),
+        (DrugUse.daily, 'Daily'),
+      ],
+      onChanged: (value) => setState(() => _drugUse = value),
+    );
+  }
+
+  Widget _buildSocialSelector() {
+    return _buildSegmentedControl<SocialConnection>(
+      value: _social,
+      options: [
+        (SocialConnection.isolated, 'Isolated'),
+        (SocialConnection.limited, 'Limited'),
+        (SocialConnection.moderate, 'Moderate'),
+        (SocialConnection.strong, 'Strong'),
+      ],
+      onChanged: (value) => setState(() => _social = value),
+    );
+  }
+
+  Widget _buildStressSelector() {
+    return _buildSegmentedControl<StressLevel>(
+      value: _stress,
+      options: [
+        (StressLevel.low, 'Low'),
+        (StressLevel.moderate, 'Moderate'),
+        (StressLevel.high, 'High'),
+        (StressLevel.chronic, 'Chronic'),
+      ],
+      onChanged: (value) => setState(() => _stress = value),
+    );
+  }
+
+  Widget _buildDrivingSelector() {
+    return _buildSegmentedControl<DrivingExposure>(
+      value: _driving,
+      options: [
+        (DrivingExposure.low, '<50 mi/wk'),
+        (DrivingExposure.moderate, '50-150'),
+        (DrivingExposure.high, '150-300'),
+        (DrivingExposure.veryHigh, '300+'),
+      ],
+      onChanged: (value) => setState(() => _driving = value),
+    );
+  }
+
+  Widget _buildWorkHoursSelector() {
+    return _buildSegmentedControl<WorkHoursLevel>(
+      value: _workHours,
+      options: [
+        (WorkHoursLevel.normal, '<40'),
+        (WorkHoursLevel.elevated, '40-55'),
+        (WorkHoursLevel.high, '55-70'),
+        (WorkHoursLevel.extreme, '70+'),
+      ],
+      onChanged: (value) => setState(() => _workHours = value),
+    );
+  }
+
+  Widget _buildSegmentedControl<T>({
+    required T value,
+    required List<(T, String)> options,
+    required ValueChanged<T> onChanged,
+  }) {
+    return Container(
+      decoration: BoxDecoration(
+        color: AppColors.surfaceVariant,
+        borderRadius: BorderRadius.circular(12),
+      ),
+      child: Row(
+        children: options.map((option) {
+          final isSelected = value == option.$1;
+          return Expanded(
+            child: GestureDetector(
+              onTap: () => onChanged(option.$1),
+              child: Container(
+                padding: const EdgeInsets.symmetric(vertical: 12),
+                decoration: BoxDecoration(
+                  color: isSelected ? AppColors.primary : Colors.transparent,
+                  borderRadius: BorderRadius.circular(12),
+                ),
+                child: Text(
+                  option.$2,
+                  textAlign: TextAlign.center,
+                  style: TextStyle(
+                    fontSize: 13,
+                    fontWeight: FontWeight.w600,
+                    color: isSelected ? Colors.white : AppColors.textSecondary,
+                  ),
+                ),
+              ),
+            ),
+          );
+        }).toList(),
+      ),
+    );
+  }
+
+  void _calculate() async {
+    final behaviors = BehavioralInputs(
+      smoking: widget.smoking,
+      cigarettesPerDay: widget.cigarettesPerDay,
+      alcohol: widget.alcohol,
+      sleepHours: widget.sleepHours,
+      sleepConsistent: widget.sleepConsistent,
+      activity: widget.activity,
+      diet: _diet,
+      processedFood: _processedFood,
+      drugUse: _drugUse,
+      social: _social,
+      stress: _stress,
+      driving: _driving,
+      workHours: _workHours,
+    );
+
+    await LocalStorage.saveBehaviors(behaviors);
+
+    if (mounted) {
+      Navigator.of(context).push(
+        MaterialPageRoute(
+          builder: (_) => ResultsScreen(
+            profile: widget.profile,
+            behaviors: behaviors,
+          ),
+        ),
+      );
+    }
+  }
+}

lib/screens/screens.dart

@@ -2,4 +2,5 @@ export 'onboarding_screen.dart';
 export 'welcome_screen.dart';
 export 'baseline_screen.dart';
 export 'behavioral_screen.dart';
+export 'lifestyle_screen.dart';
 export 'results_screen.dart';

lib/screens/welcome_screen.dart

@@ -13,60 +13,44 @@ class WelcomeScreen extends StatelessWidget {
           padding: const EdgeInsets.symmetric(horizontal: 32),
           child: Column(
             children: [
-              const Spacer(flex: 2),
+              const Spacer(flex: 1),
-              // Icon or logo area
+              // Main question - large and centered
-              Container(
-                width: 80,
-                height: 80,
-                decoration: BoxDecoration(
-                  color: AppColors.surfaceVariant,
-                  borderRadius: BorderRadius.circular(20),
-                ),
-                child: const Icon(
-                  Icons.timeline,
-                  size: 40,
-                  color: AppColors.primary,
-                ),
-              ),
-              const SizedBox(height: 32),
-              // Title
               Text(
-                'Add Months',
+                'Simple questions.\nHonest answers.',
-                style: Theme.of(context).textTheme.headlineLarge,
+                style: Theme.of(context).textTheme.headlineLarge?.copyWith(
+                      fontSize: 32,
+                      height: 1.3,
+                    ),
                 textAlign: TextAlign.center,
               ),
-              const SizedBox(height: 16),
+              const SizedBox(height: 40),
-              // Description
               Text(
-                'Identify the single change most likely to extend your lifespan.',
+                "What's the single biggest change I can make to live a longer, healthier life?",
-                style: Theme.of(context).textTheme.bodyLarge?.copyWith(
+                style: Theme.of(context).textTheme.headlineSmall?.copyWith(
+                      fontWeight: FontWeight.w400,
+                      color: AppColors.textSecondary,
+                      height: 1.4,
+                    ),
+                textAlign: TextAlign.center,
+              ),
+              const Spacer(flex: 2),
+              // Privacy note
+              Row(
+                mainAxisAlignment: MainAxisAlignment.center,
+                children: [
+                  Icon(
+                    Icons.lock_outline,
+                    size: 16,
                     color: AppColors.textSecondary,
                   ),
-                textAlign: TextAlign.center,
+                  const SizedBox(width: 8),
-              ),
+                  Text(
-              const SizedBox(height: 48),
-              // Features list
-              _buildFeatureItem(
-                context,
-                Icons.shield_outlined,
-                'Private',
                     'All data stays on your device',
+                    style: Theme.of(context).textTheme.bodySmall,
                   ),
-              const SizedBox(height: 16),
+                ],
-              _buildFeatureItem(
-                context,
-                Icons.science_outlined,
-                'Evidence-based',
-                'Hazard ratios from meta-analyses',
               ),
-              const SizedBox(height: 16),
+              const SizedBox(height: 24),
-              _buildFeatureItem(
-                context,
-                Icons.trending_up_outlined,
-                'Actionable',
-                'Focus on what matters most',
-              ),
-              const Spacer(flex: 3),
               // Start button
               SizedBox(
                 width: double.infinity,
@@ -83,43 +67,6 @@ class WelcomeScreen extends StatelessWidget {
     );
   }
 
-  Widget _buildFeatureItem(
-    BuildContext context,
-    IconData icon,
-    String title,
-    String description,
-  ) {
-    return Row(
-      children: [
-        Container(
-          width: 44,
-          height: 44,
-          decoration: BoxDecoration(
-            color: AppColors.surfaceVariant,
-            borderRadius: BorderRadius.circular(12),
-          ),
-          child: Icon(icon, color: AppColors.primary, size: 22),
-        ),
-        const SizedBox(width: 16),
-        Expanded(
-          child: Column(
-            crossAxisAlignment: CrossAxisAlignment.start,
-            children: [
-              Text(
-                title,
-                style: Theme.of(context).textTheme.labelLarge,
-              ),
-              Text(
-                description,
-                style: Theme.of(context).textTheme.bodySmall,
-              ),
-            ],
-          ),
-        ),
-      ],
-    );
-  }
-
   void _navigateToBaseline(BuildContext context) {
     Navigator.of(context).push(
       MaterialPageRoute(builder: (_) => const BaselineScreen()),

test/risk_engine/calculator_test.dart

@@ -94,6 +94,11 @@ void main() {
       sleepHours: 5.0,
       sleepConsistent: false,
       activity: ActivityLevel.sedentary,
+      diet: DietQuality.poor,
+      processedFood: ProcessedFoodLevel.daily,
+      drugUse: DrugUse.regular,
+      social: SocialConnection.isolated,
+      stress: StressLevel.chronic,
       driving: DrivingExposure.veryHigh,
       workHours: WorkHoursLevel.extreme,
     );
@@ -121,6 +126,11 @@ void main() {
         sleepHours: 7.5,
         sleepConsistent: true,
         activity: ActivityLevel.high,
+        diet: DietQuality.excellent,
+        processedFood: ProcessedFoodLevel.rarely,
+        drugUse: DrugUse.none,
+        social: SocialConnection.strong,
+        stress: StressLevel.low,
         driving: DrivingExposure.veryHigh,
         workHours: WorkHoursLevel.normal,
       );
@@ -138,7 +148,7 @@ void main() {
 
     test('result includes model version', () {
       final result = calculateRankedFactors(healthyProfile, unhealthyInputs);
-      expect(result.modelVersion, equals('1.0'));
+      expect(result.modelVersion, equals('1.1'));
     });
 
     test('sedentary person sees activity as factor', () {
@@ -149,6 +159,11 @@ void main() {
         sleepHours: 7.5,
         sleepConsistent: true,
         activity: ActivityLevel.sedentary,
+        diet: DietQuality.excellent,
+        processedFood: ProcessedFoodLevel.rarely,
+        drugUse: DrugUse.none,
+        social: SocialConnection.strong,
+        stress: StressLevel.low,
         driving: DrivingExposure.low,
         workHours: WorkHoursLevel.normal,
       );
@@ -205,6 +220,11 @@ void main() {
         sleepHours: 7.5,
         sleepConsistent: true,
         activity: ActivityLevel.sedentary,
+        diet: DietQuality.excellent,
+        processedFood: ProcessedFoodLevel.rarely,
+        drugUse: DrugUse.none,
+        social: SocialConnection.strong,
+        stress: StressLevel.low,
         driving: DrivingExposure.low,
         workHours: WorkHoursLevel.normal,
       );