diff --git a/workout-logger/lib/main.dart b/workout-logger/lib/main.dart
index f1b6cd1..91aa03a 100644
--- a/workout-logger/lib/main.dart
+++ b/workout-logger/lib/main.dart
@@ -9,7 +9,8 @@ import 'package:provider/provider.dart';
 
 import 'services/storage_service.dart';
 import 'services/ml_service.dart';
-import 'services/gemini_service.dart';
+import 'services/ai/gemini_ai_service.dart';
+import 'services/ai/coach_tool_service.dart';
 import 'services/health_connect_service.dart';
 import 'services/interfaces/storage_service_interface.dart';
 import 'services/interfaces/ml_service_interface.dart';
@@ -21,6 +22,7 @@ import 'services/managers/program_manager.dart';
 import 'services/managers/history_manager.dart';
 import 'services/managers/health_sync_manager.dart';
 import 'services/managers/pr_manager.dart';
+import 'services/managers/conversation_manager.dart';
 import 'theme/app_theme.dart';
 import 'screens/home_screen.dart';
 import 'screens/onboarding_screen.dart';
@@ -62,7 +64,10 @@ class WorkoutLoggerApp extends StatelessWidget {
   static final HistoryManager _historyManager =
       HistoryManager(_storageService, healthSyncManager: _healthSyncManager);
   static final PRManager _prManager = PRManager(_storageService);
-  static final GeminiService _geminiService = GeminiService();
+  static final GeminiAiService _geminiService =
+      GeminiAiService(storage: _storageService);
+  static final ConversationManager _conversationManager =
+      ConversationManager(_storageService);
 
   const WorkoutLoggerApp({super.key});
 
@@ -89,7 +94,15 @@ class WorkoutLoggerApp extends StatelessWidget {
         // Provided as ChangeNotifier so HistoryScreen rebuilds on sync badge changes.
         ChangeNotifierProvider<HistoryManager>.value(value: _historyManager),
         ChangeNotifierProvider<PRManager>.value(value: _prManager),
-        ChangeNotifierProvider<GeminiService>.value(value: _geminiService),
+        // GeminiAiService is the single AI backend instance. It's a ChangeNotifier
+        // (settings UI watches isConfigured/model), so it's provided as such.
+        // Consumers that should depend on the abstraction (the coach ViewModel,
+        // program generator) receive it typed as IAiService at construction —
+        // the future firebase_ai swap point — without a separate provider.
+        ChangeNotifierProvider<GeminiAiService>.value(value: _geminiService),
+        ChangeNotifierProvider<ConversationManager>.value(
+          value: _conversationManager,
+        ),
         // WorkoutProvider receives dependencies via constructor injection
         ChangeNotifierProvider(
           create: (_) => WorkoutProvider(
@@ -99,6 +112,13 @@ class WorkoutLoggerApp extends StatelessWidget {
             programManager: _programManager,
           ),
         ),
+        // CoachToolService backs AI tool calls; reads from WorkoutProvider + PRManager.
+        Provider<CoachToolService>(
+          create: (ctx) => CoachToolService(
+            ctx.read<WorkoutProvider>(),
+            ctx.read<PRManager>(),
+          ),
+        ),
       ],
       child: MaterialApp(
         title: 'Workout Logger',
@@ -135,12 +155,17 @@ class _AppInitializerState extends State<AppInitializer> {
     final historyManager = context.read<HistoryManager>();
     final prManager = context.read<PRManager>();
     final api = context.read<ApiService>();
-    final gemini = context.read<GeminiService>();
+    final gemini = context.read<GeminiAiService>();
 
     try {
       await provider.init();
       await settings.init();
       gemini.init(settings.geminiApiKey, model: settings.geminiModel);
+      try {
+        await gemini.loadUsage();
+      } catch (e, st) {
+        debugPrint('gemini.loadUsage failed: $e\n$st');
+      }
       await historyManager.loadSessions();
       await prManager.load();
       await prManager.backfillFromSessions(historyManager.sessions);
diff --git a/workout-logger/lib/models/models.dart b/workout-logger/lib/models/models.dart
index 2a5b643..ecf7551 100644
--- a/workout-logger/lib/models/models.dart
+++ b/workout-logger/lib/models/models.dart
@@ -812,3 +812,101 @@ class TrainingProgram {
         createdAt == _sentinel ? this.createdAt : createdAt as DateTime,
   );
 }
+
+// ==================== AI Coach Chat ====================
+
+/// A single message in an AI coach conversation.
+class ChatMessage {
+  final String id;
+  final String role; // 'user' | 'model'
+  final String text;
+  final DateTime timestamp;
+
+  ChatMessage({
+    String? id,
+    required this.role,
+    required this.text,
+    DateTime? timestamp,
+  })  : id = id ?? _uuid.v4(),
+        timestamp = timestamp ?? DateTime.now();
+
+  Map<String, dynamic> toJson() => {
+    'id': id,
+    'role': role,
+    'text': text,
+    'timestamp': timestamp.toIso8601String(),
+  };
+
+  factory ChatMessage.fromJson(Map<String, dynamic> json) => ChatMessage(
+    id: json['id'] as String?,
+    role: json['role'] as String,
+    text: json['text'] as String,
+    timestamp: DateTime.parse(json['timestamp'] as String),
+  );
+
+  ChatMessage copyWith({
+    Object? role = _sentinel,
+    Object? text = _sentinel,
+    Object? timestamp = _sentinel,
+  }) => ChatMessage(
+    id: id,
+    role: role == _sentinel ? this.role : role as String,
+    text: text == _sentinel ? this.text : text as String,
+    timestamp: timestamp == _sentinel ? this.timestamp : timestamp as DateTime,
+  );
+}
+
+/// A persisted AI coach conversation: an ordered list of [ChatMessage]s.
+class Conversation {
+  final String id;
+  final String title;
+  final DateTime createdAt;
+  final DateTime updatedAt;
+  final List<ChatMessage> messages;
+
+  Conversation({
+    String? id,
+    required this.title,
+    DateTime? createdAt,
+    DateTime? updatedAt,
+    List<ChatMessage>? messages,
+  })  : id = id ?? _uuid.v4(),
+        createdAt = createdAt ?? DateTime.now(),
+        updatedAt = updatedAt ?? createdAt ?? DateTime.now(),
+        messages = messages ?? const [];
+
+  Map<String, dynamic> toJson() => {
+    'id': id,
+    'title': title,
+    'createdAt': createdAt.toIso8601String(),
+    'updatedAt': updatedAt.toIso8601String(),
+    'messages': messages.map((m) => m.toJson()).toList(),
+  };
+
+  factory Conversation.fromJson(Map<String, dynamic> json) => Conversation(
+    id: json['id'] as String?,
+    title: json['title'] as String,
+    createdAt: DateTime.parse(json['createdAt'] as String),
+    updatedAt: json['updatedAt'] != null
+        ? DateTime.parse(json['updatedAt'] as String)
+        : DateTime.parse(json['createdAt'] as String),
+    messages: (json['messages'] as List)
+        .map((m) => ChatMessage.fromJson(m as Map<String, dynamic>))
+        .toList(),
+  );
+
+  Conversation copyWith({
+    Object? title = _sentinel,
+    Object? createdAt = _sentinel,
+    Object? updatedAt = _sentinel,
+    Object? messages = _sentinel,
+  }) => Conversation(
+    id: id,
+    title: title == _sentinel ? this.title : title as String,
+    createdAt: createdAt == _sentinel ? this.createdAt : createdAt as DateTime,
+    updatedAt: updatedAt == _sentinel ? this.updatedAt : updatedAt as DateTime,
+    messages: messages == _sentinel
+        ? this.messages
+        : messages as List<ChatMessage>,
+  );
+}
diff --git a/workout-logger/lib/screens/ai_coach_screen.dart b/workout-logger/lib/screens/ai_coach_screen.dart
index 9a57341..79f8145 100644
--- a/workout-logger/lib/screens/ai_coach_screen.dart
+++ b/workout-logger/lib/screens/ai_coach_screen.dart
@@ -1,48 +1,58 @@
-// ai_coach_screen.dart — Conversational AI workout coach powered by Gemini
+// ai_coach_screen.dart — Conversational AI workout coach (View).
+//
+// This is a lean View: all orchestration (streaming, tool calls, persistence,
+// system-prompt building) lives in AiCoachViewModel. The widget only renders
+// state, forwards user intents, and holds UI-local controllers.
 
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
-import 'package:google_generative_ai/google_generative_ai.dart';
 import 'package:provider/provider.dart';
 import 'package:google_fonts/google_fonts.dart';
+import 'package:gpt_markdown/gpt_markdown.dart';
 
-import '../services/gemini_service.dart';
-import '../services/gemini_context_builder.dart';
-import '../services/workout_provider.dart';
+import '../models/models.dart';
+import '../viewmodels/ai_coach_view_model.dart';
+import '../services/ai/gemini_ai_service.dart';
+import '../services/ai/coach_tool_service.dart';
+import '../services/managers/conversation_manager.dart';
 import '../services/settings_provider.dart';
-import '../services/interfaces/ml_service_interface.dart';
 import '../theme/app_theme.dart';
 import 'widgets/rf_widgets.dart';
 import 'profile_screen.dart';
 
-// ── Data ──────────────────────────────────────────────────────────────────────
-
-class _ChatMessage {
-  const _ChatMessage({required this.role, required this.text});
-  final String role; // 'user' | 'model'
-  final String text;
-}
-
-// ── Screen ────────────────────────────────────────────────────────────────────
-
-class AiCoachScreen extends StatefulWidget {
+/// Public entry point. Owns the screen-scoped [AiCoachViewModel].
+class AiCoachScreen extends StatelessWidget {
   const AiCoachScreen({super.key, this.seedPrompt});
 
   /// Optional question to auto-send on open (e.g. deep-linked from analytics).
-  /// The coach system prompt already carries the user's data, so a seed needs
-  /// no extra context.
   final String? seedPrompt;
 
   @override
-  State<AiCoachScreen> createState() => _AiCoachScreenState();
+  Widget build(BuildContext context) {
+    return ChangeNotifierProvider<AiCoachViewModel>(
+      create: (ctx) => AiCoachViewModel(
+        ai: ctx.read<GeminiAiService>(),
+        coachTools: ctx.read<CoachToolService>(),
+        conversations: ctx.read<ConversationManager>(),
+        settings: ctx.read<SettingsProvider>(),
+      )..loadConversations(),
+      child: _AiCoachView(seedPrompt: seedPrompt),
+    );
+  }
 }
 
-class _AiCoachScreenState extends State<AiCoachScreen> {
+class _AiCoachView extends StatefulWidget {
+  const _AiCoachView({this.seedPrompt});
+  final String? seedPrompt;
+
+  @override
+  State<_AiCoachView> createState() => _AiCoachViewState();
+}
+
+class _AiCoachViewState extends State<_AiCoachView> {
   final _controller = TextEditingController();
   final _scrollCtrl = ScrollController();
-  final _messages = <_ChatMessage>[];
-  bool _loading = false;
-  String _streamingText = '';
+  AiCoachViewModel? _vm;
 
   @override
   void initState() {
@@ -51,92 +61,41 @@ class _AiCoachScreenState extends State<AiCoachScreen> {
     if (seed != null && seed.isNotEmpty) {
       WidgetsBinding.instance.addPostFrameCallback((_) {
         if (!mounted) return;
-        if (!context.read<GeminiService>().isConfigured) return;
-        _controller.text = seed;
-        _send();
+        final vm = context.read<AiCoachViewModel>();
+        if (!vm.isConfigured) return;
+        _controller.clear();
+        vm.sendMessage(seed);
       });
     }
   }
 
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    // Attach a scroll-follow listener once.
+    final vm = context.read<AiCoachViewModel>();
+    if (!identical(vm, _vm)) {
+      _vm?.removeListener(_onVmChanged);
+      _vm = vm..addListener(_onVmChanged);
+    }
+  }
+
+  void _onVmChanged() => _scrollToBottom();
+
   @override
   void dispose() {
+    _vm?.removeListener(_onVmChanged);
     _controller.dispose();
     _scrollCtrl.dispose();
     super.dispose();
   }
 
-  String _buildSystemPrompt() {
-    final wp = context.read<WorkoutProvider>();
-    final settings = context.read<SettingsProvider>();
-    final mlService = context.read<IMLService>();
-
-    final exerciseMap = {for (final e in wp.allExercises) e.id: e};
-    final allSessions = wp.sessions;
-    final recoveryScores = mlService.computeMuscleRecoveryScores(
-      allSessions,
-      exerciseMap,
-    );
-    final activeTargets = wp.targets.where((t) => !t.isCompleted).toList();
-
-    return GeminiContextBuilder.buildCoachSystemPrompt(
-      recentSessions: allSessions,
-      exerciseMap: exerciseMap,
-      recoveryScores: recoveryScores,
-      activeTargets: activeTargets,
-      userName: settings.userName,
-      unitLabel: settings.unitLabel,
-    );
-  }
-
-  List<Content> _buildHistory() => _messages
-      .map((m) => Content(m.role, [TextPart(m.text)]))
-      .toList();
-
-  Future<void> _send() async {
+  void _send() {
     final text = _controller.text.trim();
-    if (text.isEmpty || _loading) return;
-
+    if (text.isEmpty) return;
     HapticFeedback.lightImpact();
     _controller.clear();
-
-    setState(() {
-      _messages.add(_ChatMessage(role: 'user', text: text));
-      _loading = true;
-      _streamingText = '';
-    });
-    _scrollToBottom();
-
-    final gemini = context.read<GeminiService>();
-    final systemPrompt = _buildSystemPrompt();
-    // Build history from all messages except the one we just added.
-    final history = _messages.length > 1
-        ? _buildHistory().sublist(0, _messages.length - 1)
-        : <Content>[];
-
-    final buffer = StringBuffer();
-    try {
-      await for (final chunk in gemini.streamCoachReply(
-        userMessage: text,
-        systemPrompt: systemPrompt,
-        history: history,
-      )) {
-        buffer.write(chunk);
-        if (mounted) {
-          setState(() => _streamingText = buffer.toString());
-          _scrollToBottom();
-        }
-      }
-      if (mounted) {
-        setState(() {
-          _messages.add(_ChatMessage(role: 'model', text: buffer.toString()));
-          _streamingText = '';
-          _loading = false;
-        });
-        _scrollToBottom();
-      }
-    } catch (_) {
-      if (mounted) setState(() { _streamingText = ''; _loading = false; });
-    }
+    context.read<AiCoachViewModel>().sendMessage(text);
   }
 
   void _scrollToBottom() {
@@ -153,7 +112,7 @@ class _AiCoachScreenState extends State<AiCoachScreen> {
 
   @override
   Widget build(BuildContext context) {
-    final gemini = context.watch<GeminiService>();
+    final vm = context.watch<AiCoachViewModel>();
 
     return Scaffold(
       backgroundColor: AppColors.background,
@@ -163,13 +122,13 @@ class _AiCoachScreenState extends State<AiCoachScreen> {
           SafeArea(
             child: Column(
               children: [
-                _buildHeader(context),
+                _buildHeader(context, vm),
                 Expanded(
-                  child: gemini.isConfigured
-                      ? _buildChatArea()
+                  child: vm.isConfigured
+                      ? _buildChatArea(vm)
                       : _buildNoKeyState(context),
                 ),
-                if (gemini.isConfigured) _buildInputBar(),
+                if (vm.isConfigured) _buildInputBar(vm),
               ],
             ),
           ),
@@ -178,7 +137,7 @@ class _AiCoachScreenState extends State<AiCoachScreen> {
     );
   }
 
-  Widget _buildHeader(BuildContext context) {
+  Widget _buildHeader(BuildContext context, AiCoachViewModel vm) {
     return Padding(
       padding: const EdgeInsets.fromLTRB(
         AppSpacing.md,
@@ -248,34 +207,42 @@ class _AiCoachScreenState extends State<AiCoachScreen> {
               ],
             ),
           ),
-          if (_messages.isNotEmpty)
-            GestureDetector(
-              onTap: () => setState(() => _messages.clear()),
-              child: Container(
-                padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 5),
-                decoration: BoxDecoration(
-                  color: AppColors.glass,
-                  borderRadius: BorderRadius.circular(AppRadius.full),
-                  border: Border.all(color: AppColors.glassBorder),
-                ),
-                child: Text(
-                  'Clear',
-                  style: GoogleFonts.geist(
-                    color: AppColors.textMuted,
-                    fontSize: 11,
-                  ),
-                ),
-              ),
+          if (vm.isConfigured) ...[
+            _HeaderIconButton(
+              icon: Icons.history_rounded,
+              onTap: () => _openHistory(context, vm),
             ),
+            const SizedBox(width: AppSpacing.sm),
+            _HeaderIconButton(
+              icon: Icons.add_rounded,
+              onTap: () {
+                HapticFeedback.lightImpact();
+                vm.newConversation();
+              },
+            ),
+          ],
         ],
       ),
     );
   }
 
-  Widget _buildChatArea() {
-    final hasMessages = _messages.isNotEmpty || _loading;
+  Future<void> _openHistory(BuildContext context, AiCoachViewModel vm) async {
+    HapticFeedback.lightImpact();
+    await showModalBottomSheet<void>(
+      context: context,
+      backgroundColor: AppColors.surface,
+      isScrollControlled: true,
+      shape: const RoundedRectangleBorder(
+        borderRadius: BorderRadius.vertical(top: Radius.circular(AppRadius.lg)),
+      ),
+      builder: (_) => _ConversationsSheet(vm: vm),
+    );
+  }
 
-    if (!hasMessages) return _buildWelcome();
+  Widget _buildChatArea(AiCoachViewModel vm) {
+    final messages = vm.messages;
+    final hasContent = messages.isNotEmpty || vm.isLoading;
+    if (!hasContent) return _buildWelcome();
 
     return ListView.builder(
       controller: _scrollCtrl,
@@ -285,20 +252,18 @@ class _AiCoachScreenState extends State<AiCoachScreen> {
         AppSpacing.md,
         AppSpacing.sm,
       ),
-      itemCount: _messages.length + (_loading ? 1 : 0),
+      itemCount: messages.length + (vm.isLoading ? 1 : 0),
       itemBuilder: (_, i) {
-        if (i == _messages.length) {
-          // Streaming bubble
-          return _StreamingBubble(text: _streamingText);
+        if (i == messages.length) {
+          return _StreamingBubble(text: vm.streamingText);
         }
-        return _MessageBubble(message: _messages[i]);
+        return _MessageBubble(message: messages[i]);
       },
     );
   }
 
   Widget _buildWelcome() {
-    final settings = context.read<SettingsProvider>();
-    final name = settings.userName;
+    final name = context.read<SettingsProvider>().userName;
     return Center(
       child: Padding(
         padding: const EdgeInsets.all(AppSpacing.xl),
@@ -331,9 +296,7 @@ class _AiCoachScreenState extends State<AiCoachScreen> {
             ),
             const SizedBox(height: AppSpacing.lg),
             Text(
-              name != null && name.isNotEmpty
-                  ? 'Hey $name 👋'
-                  : 'Your AI Coach',
+              name != null && name.isNotEmpty ? 'Hey $name 👋' : 'Your AI Coach',
               style: GoogleFonts.geist(
                 color: AppColors.textPrimary,
                 fontSize: 22,
@@ -356,11 +319,20 @@ class _AiCoachScreenState extends State<AiCoachScreen> {
               spacing: AppSpacing.sm,
               runSpacing: AppSpacing.sm,
               alignment: WrapAlignment.center,
-              children: const [
-                _SuggestionChip('What should I train today?'),
-                _SuggestionChip('How\'s my recovery?'),
-                _SuggestionChip('Am I progressing on bench?'),
-                _SuggestionChip('Suggest a deload week'),
+              children: [
+                for (final s in const [
+                  'What should I train today?',
+                  'How\'s my recovery?',
+                  'Am I progressing on bench?',
+                  'Suggest a deload week',
+                ])
+                  _SuggestionChip(
+                    label: s,
+                    onTap: () {
+                      _controller.text = s;
+                      _send();
+                    },
+                  ),
               ],
             ),
           ],
@@ -397,7 +369,8 @@ class _AiCoachScreenState extends State<AiCoachScreen> {
     );
   }
 
-  Widget _buildInputBar() {
+  Widget _buildInputBar(AiCoachViewModel vm) {
+    final loading = vm.isLoading;
     return Container(
       padding: EdgeInsets.fromLTRB(
         AppSpacing.md,
@@ -445,22 +418,22 @@ class _AiCoachScreenState extends State<AiCoachScreen> {
           ),
           const SizedBox(width: AppSpacing.sm),
           GestureDetector(
-            onTap: _loading ? null : _send,
+            onTap: loading ? null : _send,
             child: AnimatedContainer(
               duration: const Duration(milliseconds: 150),
               width: 44,
               height: 44,
               decoration: BoxDecoration(
-                gradient: _loading
+                gradient: loading
                     ? null
                     : const LinearGradient(
                         colors: [AppColors.primary, Color(0xFF5B21B6)],
                         begin: Alignment.topLeft,
                         end: Alignment.bottomRight,
                       ),
-                color: _loading ? AppColors.glass3 : null,
+                color: loading ? AppColors.glass3 : null,
                 borderRadius: BorderRadius.circular(AppRadius.xl),
-                boxShadow: _loading
+                boxShadow: loading
                     ? null
                     : [
                         BoxShadow(
@@ -470,7 +443,7 @@ class _AiCoachScreenState extends State<AiCoachScreen> {
                         ),
                       ],
               ),
-              child: _loading
+              child: loading
                   ? const Center(
                       child: SizedBox(
                         width: 18,
@@ -494,21 +467,202 @@ class _AiCoachScreenState extends State<AiCoachScreen> {
   }
 }
 
+// ── Header icon button ──────────────────────────────────────────────────────
+
+class _HeaderIconButton extends StatelessWidget {
+  const _HeaderIconButton({required this.icon, required this.onTap});
+  final IconData icon;
+  final VoidCallback onTap;
+
+  @override
+  Widget build(BuildContext context) {
+    return GestureDetector(
+      onTap: onTap,
+      child: Container(
+        padding: const EdgeInsets.all(8),
+        decoration: BoxDecoration(
+          color: AppColors.glass,
+          borderRadius: BorderRadius.circular(AppRadius.sm),
+          border: Border.all(color: AppColors.glassBorder),
+        ),
+        child: Icon(icon, color: AppColors.textSoft, size: 18),
+      ),
+    );
+  }
+}
+
+// ── Conversations history sheet ───────────────────────────────────────────────
+
+class _ConversationsSheet extends StatelessWidget {
+  const _ConversationsSheet({required this.vm});
+  final AiCoachViewModel vm;
+
+  @override
+  Widget build(BuildContext context) {
+    // Rebuild when the conversation list changes (delete, new message).
+    return AnimatedBuilder(
+      animation: vm,
+      builder: (context, _) {
+        final conversations = vm.conversations;
+        return SafeArea(
+          child: Padding(
+            padding: const EdgeInsets.all(AppSpacing.md),
+            child: Column(
+              mainAxisSize: MainAxisSize.min,
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: [
+                Row(
+                  children: [
+                    Text(
+                      'Conversations',
+                      style: GoogleFonts.geist(
+                        color: AppColors.textPrimary,
+                        fontSize: 16,
+                        fontWeight: FontWeight.w700,
+                      ),
+                    ),
+                    const Spacer(),
+                    GestureDetector(
+                      onTap: () {
+                        vm.newConversation();
+                        Navigator.pop(context);
+                      },
+                      child: Row(
+                        children: [
+                          const Icon(Icons.add_rounded,
+                              color: AppColors.primary, size: 18),
+                          const SizedBox(width: 4),
+                          Text(
+                            'New chat',
+                            style: GoogleFonts.geist(
+                              color: AppColors.primary,
+                              fontSize: 13,
+                              fontWeight: FontWeight.w600,
+                            ),
+                          ),
+                        ],
+                      ),
+                    ),
+                  ],
+                ),
+                const SizedBox(height: AppSpacing.md),
+                if (conversations.isEmpty)
+                  Padding(
+                    padding: const EdgeInsets.symmetric(vertical: AppSpacing.lg),
+                    child: Text(
+                      'No saved conversations yet.',
+                      style: GoogleFonts.geist(
+                        color: AppColors.textMuted,
+                        fontSize: 13,
+                      ),
+                    ),
+                  )
+                else
+                  ConstrainedBox(
+                    constraints: BoxConstraints(
+                      maxHeight: MediaQuery.of(context).size.height * 0.5,
+                    ),
+                    child: ListView.separated(
+                      shrinkWrap: true,
+                      itemCount: conversations.length,
+                      separatorBuilder: (_, __) =>
+                          const SizedBox(height: AppSpacing.sm),
+                      itemBuilder: (_, i) {
+                        final c = conversations[i];
+                        final isActive = c.id == vm.activeConversationId;
+                        return _ConversationTile(
+                          conversation: c,
+                          isActive: isActive,
+                          onTap: () {
+                            vm.selectConversation(c.id);
+                            Navigator.pop(context);
+                          },
+                          onDelete: () => vm.deleteConversation(c.id),
+                        );
+                      },
+                    ),
+                  ),
+              ],
+            ),
+          ),
+        );
+      },
+    );
+  }
+}
+
+class _ConversationTile extends StatelessWidget {
+  const _ConversationTile({
+    required this.conversation,
+    required this.isActive,
+    required this.onTap,
+    required this.onDelete,
+  });
+
+  final Conversation conversation;
+  final bool isActive;
+  final VoidCallback onTap;
+  final VoidCallback onDelete;
+
+  @override
+  Widget build(BuildContext context) {
+    return GestureDetector(
+      onTap: onTap,
+      child: Container(
+        padding: const EdgeInsets.symmetric(
+          horizontal: AppSpacing.md,
+          vertical: AppSpacing.sm + 2,
+        ),
+        decoration: BoxDecoration(
+          color: isActive ? AppColors.primary.withValues(alpha: 0.12) : AppColors.glass3,
+          borderRadius: BorderRadius.circular(AppRadius.md),
+          border: Border.all(
+            color: isActive ? AppColors.primary.withValues(alpha: 0.4) : AppColors.glassBorder,
+          ),
+        ),
+        child: Row(
+          children: [
+            const Icon(Icons.chat_bubble_outline_rounded,
+                color: AppColors.textMuted, size: 16),
+            const SizedBox(width: AppSpacing.sm),
+            Expanded(
+              child: Text(
+                conversation.title.isEmpty ? 'New chat' : conversation.title,
+                maxLines: 1,
+                overflow: TextOverflow.ellipsis,
+                style: GoogleFonts.geist(
+                  color: AppColors.textPrimary,
+                  fontSize: 13,
+                  fontWeight: FontWeight.w500,
+                ),
+              ),
+            ),
+            GestureDetector(
+              onTap: onDelete,
+              child: const Padding(
+                padding: EdgeInsets.only(left: AppSpacing.sm),
+                child: Icon(Icons.delete_outline_rounded,
+                    color: AppColors.textFaint, size: 18),
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
 // ── Suggestion chip ───────────────────────────────────────────────────────────
 
 class _SuggestionChip extends StatelessWidget {
-  const _SuggestionChip(this.label);
+  const _SuggestionChip({required this.label, required this.onTap});
   final String label;
+  final VoidCallback onTap;
 
   @override
   Widget build(BuildContext context) {
     return GestureDetector(
-      onTap: () {
-        final state = context.findAncestorStateOfType<_AiCoachScreenState>();
-        if (state == null) return;
-        state._controller.text = label;
-        state._send();
-      },
+      onTap: onTap,
       child: Container(
         padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 8),
         decoration: BoxDecoration(
@@ -533,7 +687,7 @@ class _SuggestionChip extends StatelessWidget {
 
 class _MessageBubble extends StatelessWidget {
   const _MessageBubble({required this.message});
-  final _ChatMessage message;
+  final ChatMessage message;
 
   @override
   Widget build(BuildContext context) {
@@ -583,14 +737,16 @@ class _MessageBubble extends StatelessWidget {
                       ]
                     : null,
               ),
-              child: Text(
-                message.text,
-                style: GoogleFonts.geist(
-                  color: AppColors.textPrimary,
-                  fontSize: 14,
-                  height: 1.55,
-                ),
-              ),
+              child: isUser
+                  ? Text(
+                      message.text,
+                      style: GoogleFonts.geist(
+                        color: AppColors.textPrimary,
+                        fontSize: 14,
+                        height: 1.55,
+                      ),
+                    )
+                  : _CoachMarkdown(text: message.text),
             ),
           ),
         ],
@@ -630,14 +786,7 @@ class _StreamingBubble extends StatelessWidget {
               ),
               child: text.isEmpty
                   ? const RFLoadingDots()
-                  : Text(
-                      text,
-                      style: GoogleFonts.geist(
-                        color: AppColors.textPrimary,
-                        fontSize: 14,
-                        height: 1.55,
-                      ),
-                    ),
+                  : _CoachMarkdown(text: text),
             ),
           ),
         ],
@@ -646,6 +795,24 @@ class _StreamingBubble extends StatelessWidget {
   }
 }
 
+/// Markdown renderer for coach replies, styled to the app theme.
+class _CoachMarkdown extends StatelessWidget {
+  const _CoachMarkdown({required this.text});
+  final String text;
+
+  @override
+  Widget build(BuildContext context) {
+    return GptMarkdown(
+      text,
+      style: GoogleFonts.geist(
+        color: AppColors.textPrimary,
+        fontSize: 14,
+        height: 1.55,
+      ),
+    );
+  }
+}
+
 class _AiAvatar extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
diff --git a/workout-logger/lib/screens/ai_program_generator_screen.dart b/workout-logger/lib/screens/ai_program_generator_screen.dart
index da7cc5e..ded3dc5 100644
--- a/workout-logger/lib/screens/ai_program_generator_screen.dart
+++ b/workout-logger/lib/screens/ai_program_generator_screen.dart
@@ -6,7 +6,7 @@ import 'package:provider/provider.dart';
 import 'package:google_fonts/google_fonts.dart';
 
 import '../models/models.dart';
-import '../services/gemini_service.dart';
+import '../services/ai/gemini_ai_service.dart';
 import '../services/workout_provider.dart';
 import '../services/managers/program_manager.dart';
 import '../theme/app_theme.dart';
@@ -45,7 +45,7 @@ class _AiProgramGeneratorScreenState extends State<AiProgramGeneratorScreen> {
     final prompt = _promptCtrl.text.trim();
     if (prompt.isEmpty) return;
 
-    final gemini = context.read<GeminiService>();
+    final gemini = context.read<GeminiAiService>();
     if (!gemini.isConfigured) {
       setState(() { _error = 'Add your Gemini API key in Profile → AI Features first.'; });
       return;
diff --git a/workout-logger/lib/screens/home_screen.dart b/workout-logger/lib/screens/home_screen.dart
index e57ab32..b55a3e9 100644
--- a/workout-logger/lib/screens/home_screen.dart
+++ b/workout-logger/lib/screens/home_screen.dart
@@ -9,7 +9,7 @@ import 'package:google_fonts/google_fonts.dart';
 import '../models/models.dart';
 import '../services/workout_provider.dart';
 import '../services/settings_provider.dart';
-import '../services/gemini_service.dart';
+import '../services/ai/gemini_ai_service.dart';
 import '../services/gemini_context_builder.dart';
 import '../theme/app_theme.dart';
 import 'workout_flow_screen.dart';
@@ -1207,7 +1207,7 @@ class _WeeklyInsightsCardState extends State<_WeeklyInsightsCard> {
   bool _loading = false;
 
   Future<void> _refresh() async {
-    final gemini = context.read<GeminiService>();
+    final gemini = context.read<GeminiAiService>();
     if (!gemini.isConfigured) return;
 
     setState(() => _loading = true);
@@ -1250,7 +1250,7 @@ class _WeeklyInsightsCardState extends State<_WeeklyInsightsCard> {
 
   @override
   Widget build(BuildContext context) {
-    final gemini = context.watch<GeminiService>();
+    final gemini = context.watch<GeminiAiService>();
     final settings = context.watch<SettingsProvider>();
 
     if (!gemini.isConfigured) return const SizedBox.shrink();
diff --git a/workout-logger/lib/screens/widgets/exercise_progress_view.dart b/workout-logger/lib/screens/widgets/exercise_progress_view.dart
index d7283c6..640a664 100644
--- a/workout-logger/lib/screens/widgets/exercise_progress_view.dart
+++ b/workout-logger/lib/screens/widgets/exercise_progress_view.dart
@@ -11,7 +11,7 @@ import 'package:google_fonts/google_fonts.dart';
 import '../../models/models.dart';
 import '../../services/workout_provider.dart';
 import '../../services/settings_provider.dart';
-import '../../services/gemini_service.dart';
+import '../../services/ai/gemini_ai_service.dart';
 import '../../theme/app_theme.dart';
 import 'rf_widgets.dart';
 import '../ai_coach_screen.dart';
@@ -1489,7 +1489,7 @@ class _AskCoachButton extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final gemini = context.watch<GeminiService>();
+    final gemini = context.watch<GeminiAiService>();
     if (!gemini.isConfigured) return const SizedBox.shrink();
 
     final isPlateauing =
diff --git a/workout-logger/lib/screens/widgets/muscle_detail_sheet.dart b/workout-logger/lib/screens/widgets/muscle_detail_sheet.dart
index e66011d..5fa8f97 100644
--- a/workout-logger/lib/screens/widgets/muscle_detail_sheet.dart
+++ b/workout-logger/lib/screens/widgets/muscle_detail_sheet.dart
@@ -8,7 +8,7 @@ import 'package:google_fonts/google_fonts.dart';
 
 import '../../services/workout_provider.dart';
 import '../../services/settings_provider.dart';
-import '../../services/gemini_service.dart';
+import '../../services/ai/gemini_ai_service.dart';
 import '../../services/interfaces/ml_service_interface.dart';
 import '../../data/exercise_database.dart';
 import '../../theme/app_theme.dart';
@@ -252,7 +252,7 @@ class _AiInsightSectionState extends State<_AiInsightSection> {
 
   Future<void> _fetchInsight() async {
     setState(() => _loading = true);
-    final gemini = context.read<GeminiService>();
+    final gemini = context.read<GeminiAiService>();
     final settings = context.read<SettingsProvider>();
     final mlService = context.read<IMLService>();
     final provider = widget.provider;
@@ -298,7 +298,7 @@ class _AiInsightSectionState extends State<_AiInsightSection> {
 
   @override
   Widget build(BuildContext context) {
-    final gemini = context.watch<GeminiService>();
+    final gemini = context.watch<GeminiAiService>();
     if (!gemini.isConfigured) return const SizedBox.shrink();
 
     return Column(
diff --git a/workout-logger/lib/screens/widgets/profile_sections.dart b/workout-logger/lib/screens/widgets/profile_sections.dart
index cbeb430..d86bfd0 100644
--- a/workout-logger/lib/screens/widgets/profile_sections.dart
+++ b/workout-logger/lib/screens/widgets/profile_sections.dart
@@ -6,7 +6,7 @@ import 'package:google_fonts/google_fonts.dart';
 import 'package:provider/provider.dart';
 
 import '../../services/settings_provider.dart';
-import '../../services/gemini_service.dart';
+import '../../services/ai/gemini_ai_service.dart';
 import '../../theme/app_theme.dart';
 import 'rf_widgets.dart';
 
@@ -719,7 +719,7 @@ class _AiSettingsSectionState extends State<AiSettingsSection> {
     setState(() => _saving = true);
     final key = _ctrl.text.trim();
     final settings = context.read<SettingsProvider>();
-    final gemini = context.read<GeminiService>();
+    final gemini = context.read<GeminiAiService>();
     try {
       await settings.setGeminiApiKey(key);
       gemini.updateApiKey(key);
@@ -730,14 +730,14 @@ class _AiSettingsSectionState extends State<AiSettingsSection> {
 
   Future<void> _selectModel(String modelId) async {
     final settings = context.read<SettingsProvider>();
-    final gemini = context.read<GeminiService>();
+    final gemini = context.read<GeminiAiService>();
     await settings.setGeminiModel(modelId);
     gemini.updateModel(modelId);
   }
 
   @override
   Widget build(BuildContext context) {
-    final gemini = context.watch<GeminiService>();
+    final gemini = context.watch<GeminiAiService>();
     final settings = context.watch<SettingsProvider>();
     return _ProfileSection(
       icon: Icons.auto_awesome_rounded,
@@ -899,12 +899,99 @@ class _AiSettingsSectionState extends State<AiSettingsSection> {
               ),
             ),
           ),
+          const SizedBox(height: AppSpacing.md),
+          Row(
+            children: [
+              const _SectionLabel('TOKEN USAGE'),
+              const Spacer(),
+              if (gemini.aiRequestCount > 0)
+                GestureDetector(
+                  onTap: () => context.read<GeminiAiService>().resetUsage(),
+                  child: Text(
+                    'Reset',
+                    style: GoogleFonts.geist(
+                      color: AppColors.accent,
+                      fontSize: 11,
+                      fontWeight: FontWeight.w600,
+                    ),
+                  ),
+                ),
+            ],
+          ),
+          const SizedBox(height: AppSpacing.sm),
+          Container(
+            padding: const EdgeInsets.all(AppSpacing.md),
+            decoration: BoxDecoration(
+              color: AppColors.glass,
+              borderRadius: BorderRadius.circular(AppRadius.sm),
+              border: Border.all(color: AppColors.glassBorder),
+            ),
+            child: Column(
+              children: [
+                _UsageRow(label: 'Total tokens', value: _formatInt(gemini.totalTokensUsed)),
+                const SizedBox(height: 6),
+                _UsageRow(label: 'Input (prompt)', value: _formatInt(gemini.promptTokensUsed)),
+                const SizedBox(height: 6),
+                _UsageRow(label: 'Output (response)', value: _formatInt(gemini.responseTokensUsed)),
+                const SizedBox(height: 6),
+                _UsageRow(label: 'Requests', value: _formatInt(gemini.aiRequestCount)),
+              ],
+            ),
+          ),
+          const SizedBox(height: AppSpacing.sm),
+          Text(
+            'Cumulative billable tokens across coach, program builder & insights.',
+            style: GoogleFonts.geist(
+              color: AppColors.textFaint,
+              fontSize: 11,
+              fontStyle: FontStyle.italic,
+            ),
+          ),
         ],
       ),
     );
   }
 }
 
+/// One label/value line in the token-usage card.
+class _UsageRow extends StatelessWidget {
+  const _UsageRow({required this.label, required this.value});
+  final String label;
+  final String value;
+
+  @override
+  Widget build(BuildContext context) {
+    return Row(
+      mainAxisAlignment: MainAxisAlignment.spaceBetween,
+      children: [
+        Text(
+          label,
+          style: GoogleFonts.geist(color: AppColors.textMuted, fontSize: 12),
+        ),
+        Text(
+          value,
+          style: GoogleFonts.geistMono(
+            color: AppColors.textPrimary,
+            fontSize: 12,
+            fontWeight: FontWeight.w600,
+          ),
+        ),
+      ],
+    );
+  }
+}
+
+/// Format an int with thousands separators (e.g. 12345 → "12,345").
+String _formatInt(int n) {
+  final s = n.toString();
+  final buf = StringBuffer();
+  for (var i = 0; i < s.length; i++) {
+    if (i > 0 && (s.length - i) % 3 == 0) buf.write(',');
+    buf.write(s[i]);
+  }
+  return buf.toString();
+}
+
 class _ComingSoonBadge extends StatelessWidget {
   const _ComingSoonBadge();
 
diff --git a/workout-logger/lib/screens/widgets/targets_tab.dart b/workout-logger/lib/screens/widgets/targets_tab.dart
index 1865d4b..5cc1744 100644
--- a/workout-logger/lib/screens/widgets/targets_tab.dart
+++ b/workout-logger/lib/screens/widgets/targets_tab.dart
@@ -9,7 +9,7 @@ import 'package:intl/intl.dart';
 import '../../models/models.dart';
 import '../../services/workout_provider.dart';
 import '../../services/settings_provider.dart';
-import '../../services/gemini_service.dart';
+import '../../services/ai/gemini_ai_service.dart';
 import '../../theme/app_theme.dart';
 import '../../data/exercise_database.dart';
 import 'rf_widgets.dart';
@@ -224,7 +224,7 @@ class _TargetCardWithAiState extends State<_TargetCardWithAi> {
 
   Future<void> _fetchNudge() async {
     setState(() => _loadingNudge = true);
-    final gemini = context.read<GeminiService>();
+    final gemini = context.read<GeminiAiService>();
     final settings = context.read<SettingsProvider>();
     final t = widget.target;
 
@@ -257,7 +257,7 @@ class _TargetCardWithAiState extends State<_TargetCardWithAi> {
   @override
   Widget build(BuildContext context) {
     final settings = context.watch<SettingsProvider>();
-    final gemini = context.watch<GeminiService>();
+    final gemini = context.watch<GeminiAiService>();
     final t = widget.target;
     final pct = t.progressPercentage.clamp(0.0, 100.0);
     final etaStr = t.estimatedCompletionDate != null
@@ -486,7 +486,7 @@ class _CreateTargetSheetState extends State<_CreateTargetSheet> {
 
     final provider = context.read<WorkoutProvider>();
     final settings = context.read<SettingsProvider>();
-    final gemini = context.read<GeminiService>();
+    final gemini = context.read<GeminiAiService>();
     final exerciseName = provider.getExerciseName(_selectedExerciseId!);
     final growth = provider.getGrowthModel(_selectedExerciseId!);
     final oneRM = provider.getBestOneRM(_selectedExerciseId!);
@@ -520,7 +520,7 @@ class _CreateTargetSheetState extends State<_CreateTargetSheet> {
   Widget build(BuildContext context) {
     final exercises = ExerciseDatabase.getAll();
     final bottom = MediaQuery.of(context).viewInsets.bottom;
-    final gemini = context.watch<GeminiService>();
+    final gemini = context.watch<GeminiAiService>();
 
     return Padding(
       padding: EdgeInsets.fromLTRB(
diff --git a/workout-logger/lib/services/ai/coach_tool_service.dart b/workout-logger/lib/services/ai/coach_tool_service.dart
new file mode 100644
index 0000000..846c3c9
--- /dev/null
+++ b/workout-logger/lib/services/ai/coach_tool_service.dart
@@ -0,0 +1,458 @@
+// coach_tool_service.dart — DB-backed function-calling tools for the AI coach.
+//
+// Exposes a set of read-only query functions the model can call to ground its
+// answers in the user's real data. Every tool reuses existing parameterized
+// query methods on WorkoutProvider / PRManager — no new analytics logic lives
+// here, only the schema + arg parsing + JSON shaping.
+
+import 'package:google_generative_ai/google_generative_ai.dart';
+
+import '../../models/models.dart';
+import '../workout_provider.dart';
+import '../managers/pr_manager.dart';
+
+class AmbiguousMatchException implements Exception {
+  const AmbiguousMatchException(this.candidates);
+  final List<String> candidates;
+}
+
+class CoachToolService {
+  final WorkoutProvider _wp;
+  final PRManager _pr;
+
+  CoachToolService(this._wp, this._pr);
+
+  /// Tool declarations advertised to the model.
+  List<Tool> buildTools() => [
+        Tool(functionDeclarations: [
+          FunctionDeclaration(
+            'get_exercise_performance',
+            'Get how a specific exercise has progressed: per-session volume '
+                'trend, growth slope, best estimated 1RM, last logged sets, and '
+                'personal record. Use for questions like "how is my bench press '
+                'progressing".',
+            Schema.object(
+              properties: {
+                'exercise_name': Schema.string(
+                  description:
+                      'Name of the exercise, e.g. "Bench Press" or "Squat".',
+                ),
+                'days': Schema.integer(
+                  description:
+                      'Optional. Only consider sessions from the last N days.',
+                  nullable: true,
+                ),
+              },
+              requiredProperties: ['exercise_name'],
+            ),
+          ),
+          FunctionDeclaration(
+            'get_workouts_in_range',
+            'Summarize workouts in a date range: session count, total volume, '
+                'and a per-session breakdown. Use for "what did I do last week" '
+                'or "how many workouts in the last 3 months".',
+            Schema.object(
+              properties: {
+                'start_date': Schema.string(
+                  description: 'Optional ISO date (YYYY-MM-DD) range start.',
+                  nullable: true,
+                ),
+                'end_date': Schema.string(
+                  description: 'Optional ISO date (YYYY-MM-DD) range end.',
+                  nullable: true,
+                ),
+                'days': Schema.integer(
+                  description:
+                      'Optional. Last N days; overrides start/end when set. '
+                      'Defaults to 30 if no dates are provided.',
+                  nullable: true,
+                ),
+              },
+            ),
+          ),
+          FunctionDeclaration(
+            'get_routine_performance',
+            'Get how a named routine is performing: number of sessions logged '
+                'against it, total volume, volume trend over time, and the '
+                'exercises it contains.',
+            Schema.object(
+              properties: {
+                'routine_name': Schema.string(
+                  description: 'Name of the routine, e.g. "Push Day".',
+                ),
+                'days': Schema.integer(
+                  description:
+                      'Optional. Only consider sessions from the last N days.',
+                  nullable: true,
+                ),
+              },
+              requiredProperties: ['routine_name'],
+            ),
+          ),
+          FunctionDeclaration(
+            'get_personal_records',
+            'Get personal records (best weight, reps, and single-set volume). '
+                'Pass an exercise name for one exercise, or omit for all PRs.',
+            Schema.object(
+              properties: {
+                'exercise_name': Schema.string(
+                  description: 'Optional exercise name to filter to.',
+                  nullable: true,
+                ),
+              },
+            ),
+          ),
+          FunctionDeclaration(
+            'get_goal_progress',
+            'Get progress toward training goals/targets: current vs target '
+                'value, percent complete, and estimated completion date.',
+            Schema.object(
+              properties: {
+                'exercise_name': Schema.string(
+                  description: 'Optional exercise name to filter goals to.',
+                  nullable: true,
+                ),
+              },
+            ),
+          ),
+          FunctionDeclaration(
+            'get_muscle_recovery',
+            'Get current per-muscle-group recovery status (percent recovered '
+                'and whether each is ready, recovering, or fatigued). Use for '
+                '"what can I train today".',
+            Schema.object(properties: {}),
+          ),
+        ]),
+      ];
+
+  /// Dispatch a model function call to the matching query and return a
+  /// JSON-serializable result map.
+  Future<Map<String, Object?>> handleCall(FunctionCall call) async {
+    switch (call.name) {
+      case 'get_exercise_performance':
+        return _exercisePerformance(call.args);
+      case 'get_workouts_in_range':
+        return _workoutsInRange(call.args);
+      case 'get_routine_performance':
+        return _routinePerformance(call.args);
+      case 'get_personal_records':
+        return _personalRecords(call.args);
+      case 'get_goal_progress':
+        return _goalProgress(call.args);
+      case 'get_muscle_recovery':
+        return _muscleRecovery();
+      default:
+        return {'error': 'Unknown tool: ${call.name}'};
+    }
+  }
+
+  // ── Tool implementations ───────────────────────────────────────────────────
+
+  Map<String, Object?> _exercisePerformance(Map<String, Object?> args) {
+    final name = (args['exercise_name'] as String?)?.trim() ?? '';
+    final Exercise exercise;
+    try {
+      final resolved = _resolveExercise(name);
+      if (resolved == null) {
+        return {
+          'error': 'No exercise found matching "$name".',
+          'available_examples': _exampleExerciseNames(),
+        };
+      }
+      exercise = resolved;
+    } on AmbiguousMatchException catch (e) {
+      return {
+        'error': 'Multiple exercises match "$name". Did you mean one of:',
+        'ambiguous_matches': e.candidates,
+      };
+    }
+
+    final days = (args['days'] as num?)?.toInt();
+    final cutoff =
+        days != null ? DateTime.now().subtract(Duration(days: days)) : null;
+
+    final progression = _wp
+        .getVolumeProgression(exercise.id)
+        .where((p) => cutoff == null || !p.date.isBefore(cutoff))
+        .toList();
+
+    final growth = _wp.getGrowthModel(exercise.id);
+    final lastLog = _wp.getLastSessionForExercise(exercise.id);
+    final pr = _pr.getRecord(exercise.id);
+
+    return {
+      'exercise': exercise.name,
+      'session_count': progression.length,
+      if (days != null) 'window_days': days,
+      'volume_trend': [
+        for (final p in progression.length > 40
+            ? progression.sublist(progression.length - 40)
+            : progression)
+          {'date': _d(p.date), 'volume': _round(p.volume)},
+      ],
+      'growth': growth == null
+          ? null
+          : {
+              'slope_per_session': _round(growth.slope),
+              'r2': _round(growth.r2),
+              'trend': growth.slope > 0
+                  ? 'improving'
+                  : growth.slope < 0
+                      ? 'declining'
+                      : 'flat',
+            },
+      'best_estimated_1rm': _roundOrNull(_wp.getBestOneRM(exercise.id)),
+      'last_session': lastLog == null
+          ? null
+          : [
+              for (final s in lastLog.sets)
+                {'weight': _round(s.weight), 'reps': s.reps},
+            ],
+      'personal_record': pr == null
+          ? null
+          : {
+              'best_weight': _round(pr.bestWeight),
+              'best_reps': pr.bestReps,
+              'best_volume': _round(pr.bestVolume),
+              'achieved_at': _d(pr.achievedAt),
+            },
+    };
+  }
+
+  Map<String, Object?> _workoutsInRange(Map<String, Object?> args) {
+    final now = DateTime.now();
+    final days = (args['days'] as num?)?.toInt();
+    final startArg = DateTime.tryParse((args['start_date'] as String?) ?? '');
+    final endArg = DateTime.tryParse((args['end_date'] as String?) ?? '');
+
+    final DateTime start;
+    final DateTime end;
+    if (days != null) {
+      start = now.subtract(Duration(days: days));
+      end = now;
+    } else if (startArg != null || endArg != null) {
+      start = startArg ?? now.subtract(const Duration(days: 30));
+      end = endArg ?? now;
+    } else {
+      start = now.subtract(const Duration(days: 30));
+      end = now;
+    }
+
+    final sessions = _wp.sessions
+        .where((s) => !s.date.isBefore(start) && !s.date.isAfter(end))
+        .toList()
+      ..sort((a, b) => b.date.compareTo(a.date));
+
+    final totalVolume =
+        sessions.fold<double>(0, (sum, s) => sum + s.totalVolume);
+
+    return {
+      'start_date': _d(start),
+      'end_date': _d(end),
+      'session_count': sessions.length,
+      'total_volume': _round(totalVolume),
+      'sessions': [
+        for (final s in sessions.take(40))
+          {
+            'date': _d(s.date),
+            'duration_min': s.duration,
+            'exercise_count': s.exercises.length,
+            'volume': _round(s.totalVolume),
+            'exercises': [
+              for (final e in s.exercises) _wp.getExerciseName(e.exerciseId),
+            ],
+          },
+      ],
+    };
+  }
+
+  Map<String, Object?> _routinePerformance(Map<String, Object?> args) {
+    final name = (args['routine_name'] as String?)?.trim() ?? '';
+    final Routine routine;
+    try {
+      final resolved = _resolveRoutine(name);
+      if (resolved == null) {
+        return {
+          'error': 'No routine found matching "$name".',
+          'available_routines': [for (final r in _wp.routines) r.name],
+        };
+      }
+      routine = resolved;
+    } on AmbiguousMatchException catch (e) {
+      return {
+        'error': 'Multiple routines match "$name". Did you mean one of:',
+        'ambiguous_matches': e.candidates,
+      };
+    }
+
+    final days = (args['days'] as num?)?.toInt();
+    final cutoff =
+        days != null ? DateTime.now().subtract(Duration(days: days)) : null;
+
+    final sessions = _wp.sessions
+        .where((s) => s.routineId == routine.id)
+        .where((s) => cutoff == null || !s.date.isBefore(cutoff))
+        .toList()
+      ..sort((a, b) => a.date.compareTo(b.date));
+
+    final totalVolume =
+        sessions.fold<double>(0, (sum, s) => sum + s.totalVolume);
+
+    return {
+      'routine': routine.name,
+      'exercises': [for (final id in routine.exerciseIds) _wp.getExerciseName(id)],
+      'session_count': sessions.length,
+      if (days != null) 'window_days': days,
+      'total_volume': _round(totalVolume),
+      'volume_over_time': [
+        for (final s in sessions.length > 40
+            ? sessions.sublist(sessions.length - 40)
+            : sessions)
+          {'date': _d(s.date), 'volume': _round(s.totalVolume)},
+      ],
+    };
+  }
+
+  Map<String, Object?> _personalRecords(Map<String, Object?> args) {
+    final name = (args['exercise_name'] as String?)?.trim();
+    if (name != null && name.isNotEmpty) {
+      final Exercise exercise;
+      try {
+        final resolved = _resolveExercise(name);
+        if (resolved == null) {
+          return {'error': 'No exercise found matching "$name".'};
+        }
+        exercise = resolved;
+      } on AmbiguousMatchException catch (e) {
+        return {
+          'error': 'Multiple exercises match "$name". Did you mean one of:',
+          'ambiguous_matches': e.candidates,
+        };
+      }
+      final pr = _pr.getRecord(exercise.id);
+      return {
+        'exercise': exercise.name,
+        'personal_record': pr == null
+            ? null
+            : {
+                'best_weight': _round(pr.bestWeight),
+                'best_reps': pr.bestReps,
+                'best_volume': _round(pr.bestVolume),
+                'achieved_at': _d(pr.achievedAt),
+              },
+      };
+    }
+
+    return {
+      'records': [
+        for (final pr in _pr.allRecords)
+          {
+            'exercise': _wp.getExerciseName(pr.exerciseId),
+            'best_weight': _round(pr.bestWeight),
+            'best_reps': pr.bestReps,
+            'best_volume': _round(pr.bestVolume),
+            'achieved_at': _d(pr.achievedAt),
+          },
+      ],
+    };
+  }
+
+  Map<String, Object?> _goalProgress(Map<String, Object?> args) {
+    final name = (args['exercise_name'] as String?)?.trim();
+    Iterable<Target> targets = _wp.targets;
+    if (name != null && name.isNotEmpty) {
+      final Exercise exercise;
+      try {
+        final resolved = _resolveExercise(name);
+        if (resolved == null) {
+          return {'error': 'No exercise found matching "$name".'};
+        }
+        exercise = resolved;
+      } on AmbiguousMatchException catch (e) {
+        return {
+          'error': 'Multiple exercises match "$name". Did you mean one of:',
+          'ambiguous_matches': e.candidates,
+        };
+      }
+      targets = targets.where((t) => t.exerciseId == exercise.id);
+    }
+
+    return {
+      'goals': [
+        for (final t in targets)
+          {
+            'exercise': _wp.getExerciseName(t.exerciseId),
+            'type': t.targetType,
+            'current_value': _round(t.currentValue),
+            'target_value': _round(t.targetValue),
+            'progress_percent': _round(t.progressPercentage),
+            'completed': t.isCompleted,
+            'estimated_completion': t.estimatedCompletionDate == null
+                ? null
+                : _d(t.estimatedCompletionDate!),
+          },
+      ],
+    };
+  }
+
+  Map<String, Object?> _muscleRecovery() {
+    final scores = _wp.getMuscleRecoveryScores();
+    final entries = scores.entries.toList()
+      ..sort((a, b) => a.value.recoveryPercent.compareTo(b.value.recoveryPercent));
+    return {
+      'muscles': [
+        for (final e in entries)
+          {
+            'muscle': _wp.getMuscleGroupName(e.key),
+            'recovery_percent': e.value.recoveryPercent,
+            'status': e.value.isRecovered
+                ? 'ready'
+                : e.value.isUnderRecovered
+                    ? 'fatigued'
+                    : 'recovering',
+          },
+      ],
+    };
+  }
+
+  // ── Helpers ────────────────────────────────────────────────────────────────
+
+  Exercise? _resolveExercise(String query) {
+    final q = query.toLowerCase().trim();
+    if (q.isEmpty) return null;
+    final all = _wp.allExercises;
+    for (final e in all) {
+      if (e.name.toLowerCase() == q) return e;
+    }
+    final partials = [for (final e in all) if (e.name.toLowerCase().contains(q)) e];
+    if (partials.isEmpty) return null;
+    if (partials.length == 1) return partials.first;
+    throw AmbiguousMatchException([for (final e in partials) e.name]);
+  }
+
+  Routine? _resolveRoutine(String query) {
+    final q = query.toLowerCase().trim();
+    if (q.isEmpty) return null;
+    for (final r in _wp.routines) {
+      if (r.name.toLowerCase() == q) return r;
+    }
+    final partials = [
+      for (final r in _wp.routines) if (r.name.toLowerCase().contains(q)) r
+    ];
+    if (partials.isEmpty) return null;
+    if (partials.length == 1) return partials.first;
+    throw AmbiguousMatchException([for (final r in partials) r.name]);
+  }
+
+  List<String> _exampleExerciseNames() =>
+      _wp.allExercises.take(8).map((e) => e.name).toList();
+
+  String _d(DateTime dt) {
+    final m = dt.month.toString().padLeft(2, '0');
+    final d = dt.day.toString().padLeft(2, '0');
+    return '${dt.year}-$m-$d';
+  }
+
+  double _round(double v) => (v * 10).round() / 10;
+  double? _roundOrNull(double? v) => v == null ? null : _round(v);
+}
diff --git a/workout-logger/lib/services/gemini_service.dart b/workout-logger/lib/services/ai/gemini_ai_service.dart
similarity index 51%
rename from workout-logger/lib/services/gemini_service.dart
rename to workout-logger/lib/services/ai/gemini_ai_service.dart
index e87be84..08f811c 100644
--- a/workout-logger/lib/services/gemini_service.dart
+++ b/workout-logger/lib/services/ai/gemini_ai_service.dart
@@ -1,11 +1,18 @@
-// gemini_service.dart — Gemini AI integration (coach chat, program gen, insights)
+// gemini_ai_service.dart — google_generative_ai implementation of IAiService.
+//
+// Backs the AI coach chat (streaming + tool calling), program generation, and
+// insights. Uses a user-supplied Google AI Studio API key (free-tier friendly).
+// Implements [IAiService] so the backend can be swapped (e.g. firebase_ai)
+// without touching consumers.
 
 import 'dart:convert';
 import 'package:flutter/foundation.dart';
 import 'package:google_generative_ai/google_generative_ai.dart';
 import 'package:uuid/uuid.dart';
 
-import '../models/models.dart';
+import '../../models/models.dart';
+import '../interfaces/ai_service_interface.dart';
+import '../interfaces/storage_service_interface.dart';
 
 // Ordered list of available Gemini models shown in the picker.
 const kGeminiModels = [
@@ -15,20 +22,116 @@ const kGeminiModels = [
   ('gemini-3.5-flash',      'Gemini 3.5 Flash'),
 ];
 
-const kDefaultGeminiModel = 'gemini-2.5-flash';
+// Default to a fast, free-tier 3.x model. gemini-3.5-flash is selectable and
+// preferable when heavy tool-calling reliability matters.
+const kDefaultGeminiModel = 'gemini-3.1-flash-lite';
+
+// Upper bound on tool-resolution rounds per user turn, to bound runaway loops.
+const int _kMaxToolRounds = 5;
+
+class GeminiAiService extends ChangeNotifier implements IAiService {
+  // Optional storage so cumulative token usage survives restarts.
+  final IStorageService? _storage;
+
+  GeminiAiService({IStorageService? storage}) : _storage = storage;
+
+  static const String _usageKey = 'aiTokenUsage';
 
-class GeminiService extends ChangeNotifier {
   String _apiKey = '';
   String _model = kDefaultGeminiModel;
 
+  // Cumulative token usage across all AI calls (persisted).
+  int _promptTokens = 0;
+  int _responseTokens = 0;
+  int _totalTokens = 0;
+  int _requestCount = 0;
+
+  @override
   bool get isConfigured => _apiKey.isNotEmpty;
+
+  @override
   String get currentModel => _model;
 
+  /// Cumulative input (prompt) tokens billed across all AI calls.
+  int get promptTokensUsed => _promptTokens;
+
+  /// Cumulative output (response) tokens across all AI calls.
+  int get responseTokensUsed => _responseTokens;
+
+  /// Cumulative total tokens (prompt + response) across all AI calls.
+  int get totalTokensUsed => _totalTokens;
+
+  /// Number of AI requests recorded.
+  int get aiRequestCount => _requestCount;
+
   void init(String apiKey, {String model = kDefaultGeminiModel}) {
     _apiKey = apiKey.trim();
     _model = model;
   }
 
+  /// Load persisted cumulative token usage (call once at startup).
+  Future<void> loadUsage() async {
+    final raw = await _storage?.getSetting(_usageKey);
+    if (raw == null || raw.isEmpty) return;
+    try {
+      final m = jsonDecode(raw) as Map<String, dynamic>;
+      _promptTokens = (m['prompt'] as num?)?.toInt() ?? 0;
+      _responseTokens = (m['response'] as num?)?.toInt() ?? 0;
+      _totalTokens = (m['total'] as num?)?.toInt() ?? 0;
+      _requestCount = (m['requests'] as num?)?.toInt() ?? 0;
+      notifyListeners();
+    } catch (_) {
+      // Ignore corrupt usage data.
+    }
+  }
+
+  /// Reset cumulative token usage to zero.
+  Future<void> resetUsage() async {
+    _promptTokens = 0;
+    _responseTokens = 0;
+    _totalTokens = 0;
+    _requestCount = 0;
+    await _persistUsage();
+    notifyListeners();
+  }
+
+  /// Accumulate one request's token counts. Exposed for testing; normally
+  /// fed from a response's [UsageMetadata] via [_recordUsage].
+  @visibleForTesting
+  Future<void> recordUsage({
+    required int prompt,
+    required int response,
+    required int total,
+  }) async {
+    _promptTokens += prompt;
+    _responseTokens += response;
+    _totalTokens += total;
+    _requestCount += 1;
+    await _persistUsage();
+    notifyListeners();
+  }
+
+  void _recordUsage(UsageMetadata? m) {
+    if (m == null) return;
+    final p = m.promptTokenCount ?? 0;
+    final r = m.candidatesTokenCount ?? 0;
+    recordUsage(prompt: p, response: r, total: m.totalTokenCount ?? (p + r));
+  }
+
+  Future<void> _persistUsage() async {
+    final storage = _storage;
+    if (storage == null) return;
+    await storage.saveSetting(
+      _usageKey,
+      jsonEncode({
+        'prompt': _promptTokens,
+        'response': _responseTokens,
+        'total': _totalTokens,
+        'requests': _requestCount,
+      }),
+    );
+  }
+
   void updateApiKey(String key) {
     _apiKey = key.trim();
     notifyListeners();
@@ -39,35 +142,73 @@ class GeminiService extends ChangeNotifier {
     notifyListeners();
   }
 
-  GenerativeModel _makeModel({bool jsonMode = false, String? system}) {
+  GenerativeModel _makeModel({
+    bool jsonMode = false,
+    String? system,
+    List<Tool>? tools,
+  }) {
     return GenerativeModel(
       model: _model,
       apiKey: _apiKey,
       systemInstruction: system != null ? Content.system(system) : null,
+      tools: tools,
       generationConfig: jsonMode
           ? GenerationConfig(responseMimeType: 'application/json')
           : null,
     );
   }
 
-  // ── Coach chat (streaming) ─────────────────────────────────────────────────
-  // [history] is the prior conversation as alternating user/model Content objects.
+  // ── Coach chat (streaming + optional tool-call loop) ───────────────────────
+  // [history] is the prior conversation as alternating user/model Content.
+  // When [tools] + [onToolCall] are supplied, function calls the model emits
+  // are dispatched and their results fed back until a text answer is produced.
+  @override
   Stream<String> streamCoachReply({
     required String userMessage,
     required String systemPrompt,
     required List<Content> history,
+    List<Tool>? tools,
+    Future<Map<String, Object?>> Function(FunctionCall call)? onToolCall,
   }) async* {
     if (!isConfigured) {
       yield 'Please add your Gemini API key in Profile → AI Features to get started.';
       return;
     }
     try {
-      final session = _makeModel(system: systemPrompt).startChat(history: history);
-      await for (final chunk
-          in session.sendMessageStream(Content.text(userMessage))) {
-        final t = chunk.text;
-        if (t != null && t.isNotEmpty) yield t;
+      final chat = _makeModel(system: systemPrompt, tools: tools)
+          .startChat(history: history);
+
+      Content next = Content.text(userMessage);
+
+      for (var round = 0; round < _kMaxToolRounds; round++) {
+        final calls = <FunctionCall>[];
+        UsageMetadata? roundUsage;
+        await for (final chunk in chat.sendMessageStream(next)) {
+          final t = chunk.text;
+          if (t != null && t.isNotEmpty) yield t;
+          calls.addAll(chunk.functionCalls);
+          if (chunk.usageMetadata != null) roundUsage = chunk.usageMetadata;
+        }
+        // The final chunk of each round carries that round's cumulative usage.
+        _recordUsage(roundUsage);
+
+        // No tools requested (or no handler) → the streamed text is the answer.
+        if (calls.isEmpty || onToolCall == null) return;
+
+        // Resolve every requested call and feed the results back as one turn.
+        final responses = <FunctionResponse>[];
+        for (final call in calls) {
+          try {
+            final result = await onToolCall(call);
+            responses.add(FunctionResponse(call.name, result));
+          } catch (e) {
+            responses.add(FunctionResponse(call.name, {'error': '$e'}));
+          }
+        }
+        next = Content.functionResponses(responses);
       }
+      // Exhausted the tool-round budget without a final text answer.
+      yield '\n\n_(Stopped after $_kMaxToolRounds tool steps — try rephrasing.)_';
     } on GenerativeAIException catch (e) {
       yield 'AI error: ${e.message}';
     } catch (e) {
@@ -76,6 +217,7 @@ class GeminiService extends ChangeNotifier {
   }
 
   // ── Program generator (structured JSON output) ────────────────────────────
+  @override
   Future<TrainingProgram> generateProgram({
     required String userPrompt,
     required List<Exercise> allExercises,
@@ -143,8 +285,9 @@ Required JSON schema (follow exactly):
     try {
       final response = await _makeModel(jsonMode: true, system: systemPrompt)
           .generateContent([Content.text(prompt)]);
+      _recordUsage(response.usageMetadata);
       final raw = response.text ?? '';
-      if (raw.isEmpty) throw FormatException('Empty response from Gemini.');
+      if (raw.isEmpty) throw const FormatException('Empty response from Gemini.');
 
       final data = jsonDecode(raw) as Map<String, dynamic>;
       // Ensure a fresh UUID so it never collides with an existing program.
@@ -160,6 +303,7 @@ Required JSON schema (follow exactly):
   }
 
   // ── Weekly insights (single-shot text) ────────────────────────────────────
+  @override
   Future<String> generateWeeklyInsights(String contextText) async {
     if (!isConfigured) {
       return 'Add your Gemini API key in Profile → AI Features to unlock insights.';
@@ -173,6 +317,7 @@ Required JSON schema (follow exactly):
     try {
       final response = await _makeModel(system: systemPrompt)
           .generateContent([Content.text(contextText)]);
+      _recordUsage(response.usageMetadata);
       return response.text?.trim() ?? 'No insights generated.';
     } on GenerativeAIException catch (e) {
       return 'AI error: ${e.message}';
@@ -182,9 +327,7 @@ Required JSON schema (follow exactly):
   }
 
   // ── Generic one-shot insight (contextual) ─────────────────────────────────
-  // Thin, tool-agnostic helper for on-demand contextual insights (muscle
-  // drill-down, target suggestions, stalled-target nudges). Kept generic so a
-  // future function-calling path can be added additively over [_makeModel].
+  @override
   Future<String> generateInsight(String system, String context) async {
     if (!isConfigured) {
       return 'Add your Gemini API key in Profile → AI Features to unlock insights.';
@@ -192,6 +335,7 @@ Required JSON schema (follow exactly):
     try {
       final response = await _makeModel(system: system)
           .generateContent([Content.text(context)]);
+      _recordUsage(response.usageMetadata);
       return response.text?.trim() ?? 'No insight generated.';
     } on GenerativeAIException catch (e) {
       return 'AI error: ${e.message}';
diff --git a/workout-logger/lib/services/gemini_context_builder.dart b/workout-logger/lib/services/gemini_context_builder.dart
index 362af1e..a017bb6 100644
--- a/workout-logger/lib/services/gemini_context_builder.dart
+++ b/workout-logger/lib/services/gemini_context_builder.dart
@@ -1,88 +1,49 @@
 // gemini_context_builder.dart — Builds rich context strings from app data for Gemini prompts.
 
 import '../models/models.dart';
-import 'interfaces/ml_service_interface.dart';
 
 class GeminiContextBuilder {
   const GeminiContextBuilder._();
 
   // ── Coach system prompt ────────────────────────────────────────────────────
+  //
+  // Deliberately STATIC (no per-turn workout data) so the prefix stays
+  // byte-identical across a conversation and Gemini's implicit prompt caching
+  // can engage. All live data is fetched on demand via the coach tools
+  // (see CoachToolService), not embedded here.
   static String buildCoachSystemPrompt({
-    required List<WorkoutSession> recentSessions,
-    required Map<String, Exercise> exerciseMap,
-    required Map<String, MuscleRecoveryStatus> recoveryScores,
-    required List<Target> activeTargets,
     String? userName,
     String unitLabel = 'kg',
+    DateTime? now,
   }) {
+    final n = now ?? DateTime.now();
+    final today = '${n.year}-${n.month.toString().padLeft(2, '0')}-'
+        '${n.day.toString().padLeft(2, '0')}';
+
     final buf = StringBuffer()
       ..writeln(
         'You are an expert personal trainer embedded in RepForge, a workout tracking app.',
       )
       ..writeln(
         'Answer concisely (under 180 words unless a plan is requested). '
-        'Be encouraging and specific — always reference the user\'s actual data.',
+        'Be encouraging and specific.',
+      )
+      ..writeln('Today is $today. Use this when interpreting relative dates '
+          '("last week", "3 months ago").')
+      ..writeln(
+        'This prompt contains NO workout data. To answer anything about the '
+        'user\'s training — exercise progression, workouts in a date range, '
+        'routine performance, personal records, goal progress, or muscle '
+        'recovery — CALL THE PROVIDED TOOLS rather than guessing or inventing '
+        'numbers. Pass ISO dates (YYYY-MM-DD) or a day count to the tools.',
+      )
+      ..writeln(
+        'Weights are in $unitLabel. Format replies with Markdown (lists, bold, '
+        'tables) where it aids clarity.',
       );
 
     if (userName != null && userName.isNotEmpty) {
-      buf.writeln('\nUser: $userName');
-    }
-
-    // Recent sessions
-    buf.writeln('\n--- RECENT SESSIONS (last 14 days) ---');
-    final cutoff = DateTime.now().subtract(const Duration(days: 14));
-    final recent = recentSessions
-        .where((s) => s.date.isAfter(cutoff))
-        .toList()
-      ..sort((a, b) => b.date.compareTo(a.date));
-
-    if (recent.isEmpty) {
-      buf.writeln('No sessions in the last 14 days.');
-    } else {
-      for (final s in recent.take(8)) {
-        final date = '${_weekday(s.date.weekday)} ${s.date.day}/${s.date.month}';
-        final exParts = s.exercises.map((e) {
-          final name = exerciseMap[e.exerciseId]?.name ?? e.exerciseId;
-          final sets = e.sets
-              .map((ws) => '${ws.weight}$unitLabel×${ws.reps}')
-              .join(', ');
-          return '$name [$sets]';
-        });
-        buf.writeln('$date: ${exParts.join(' | ')}');
-      }
-    }
-
-    // Muscle recovery
-    buf.writeln('\n--- MUSCLE RECOVERY ---');
-    if (recoveryScores.isEmpty) {
-      buf.writeln('No recovery data yet.');
-    } else {
-      final sorted = recoveryScores.entries.toList()
-        ..sort((a, b) => a.value.recoveryPercent.compareTo(b.value.recoveryPercent));
-      for (final e in sorted) {
-        final name = e.key.replaceAll('_', ' ');
-        final pct = e.value.recoveryPercent;
-        final tag = e.value.isRecovered
-            ? 'ready'
-            : e.value.isUnderRecovered
-                ? 'fatigued'
-                : 'recovering';
-        buf.writeln('$name: $pct% ($tag)');
-      }
-    }
-
-    // Active goals
-    buf.writeln('\n--- ACTIVE GOALS ---');
-    if (activeTargets.isEmpty) {
-      buf.writeln('No active goals set.');
-    } else {
-      for (final t in activeTargets) {
-        final name = exerciseMap[t.exerciseId]?.name ?? t.exerciseId;
-        final progress = t.progressPercentage.toStringAsFixed(0);
-        buf.writeln(
-          '$name: ${t.currentValue}$unitLabel → ${t.targetValue}$unitLabel ($progress%)',
-        );
-      }
+      buf.writeln('\nThe user\'s name is $userName.');
     }
 
     return buf.toString();
diff --git a/workout-logger/lib/services/interfaces/ai_service_interface.dart b/workout-logger/lib/services/interfaces/ai_service_interface.dart
new file mode 100644
index 0000000..6f0d2d1
--- /dev/null
+++ b/workout-logger/lib/services/interfaces/ai_service_interface.dart
@@ -0,0 +1,52 @@
+// Abstract AI Service Interface (Dependency Inversion Principle)
+//
+// Defines the contract for the conversational AI / generation backend.
+// High-level modules (the coach ViewModel, program generator) depend on this
+// abstraction rather than a concrete SDK, so the backend can be swapped (e.g.
+// google_generative_ai today → firebase_ai later) without touching consumers.
+//
+// The signatures intentionally use the google_generative_ai content model
+// (Content / Tool / FunctionCall). firebase_ai exposes an almost identical
+// shape, so a future backend swap is a mechanical adapter rather than a rewrite.
+
+import 'package:google_generative_ai/google_generative_ai.dart';
+
+import '../../models/models.dart';
+
+/// Contract for the AI backend used across RepForge (coach chat, program
+/// generation, insights). Implemented by [GeminiAiService] today.
+abstract class IAiService {
+  /// True once an API key (or equivalent credential) has been supplied.
+  bool get isConfigured;
+
+  /// The model identifier currently in use (e.g. `gemini-3.1-flash-lite`).
+  String get currentModel;
+
+  /// Stream a coach reply token-by-token.
+  ///
+  /// When [tools] and [onToolCall] are provided, the implementation runs a
+  /// tool-call loop: any function calls the model emits are dispatched through
+  /// [onToolCall] and their results fed back, until the model produces a final
+  /// natural-language answer. Only text is yielded to the caller.
+  Stream<String> streamCoachReply({
+    required String userMessage,
+    required String systemPrompt,
+    required List<Content> history,
+    List<Tool>? tools,
+    Future<Map<String, Object?>> Function(FunctionCall call)? onToolCall,
+  });
+
+  /// Generate a structured multi-week training program from a natural-language
+  /// prompt, constrained to the provided exercise catalogue.
+  Future<TrainingProgram> generateProgram({
+    required String userPrompt,
+    required List<Exercise> allExercises,
+  });
+
+  /// One-shot weekly training summary in conversational prose.
+  Future<String> generateWeeklyInsights(String contextText);
+
+  /// Generic one-shot contextual insight given a [system] instruction and
+  /// [context] payload.
+  Future<String> generateInsight(String system, String context);
+}
diff --git a/workout-logger/lib/services/interfaces/storage_service_interface.dart b/workout-logger/lib/services/interfaces/storage_service_interface.dart
index 9274ea1..34132f6 100644
--- a/workout-logger/lib/services/interfaces/storage_service_interface.dart
+++ b/workout-logger/lib/services/interfaces/storage_service_interface.dart
@@ -73,6 +73,13 @@ abstract class IStorageService {
   Future<PersonalRecord?> getPersonalRecord(String exerciseId);
   Future<List<PersonalRecord>> getAllPersonalRecords();
 
+  // ==================== AI CONVERSATIONS ====================
+
+  Future<void> saveConversation(Conversation conversation);
+  Future<List<Conversation>> getAllConversations();
+  Future<Conversation?> getConversation(String id);
+  Future<void> deleteConversation(String id);
+
   // ==================== EXPORT / IMPORT ====================
 
   Future<String> exportAllData();
diff --git a/workout-logger/lib/services/managers/conversation_manager.dart b/workout-logger/lib/services/managers/conversation_manager.dart
new file mode 100644
index 0000000..ed39a52
--- /dev/null
+++ b/workout-logger/lib/services/managers/conversation_manager.dart
@@ -0,0 +1,118 @@
+// Conversation Manager (Single Responsibility Principle)
+//
+// Single source of truth for persisted AI coach conversations. Owns the
+// in-memory list + the currently active conversation, and mirrors every
+// mutation to storage. Does NOT talk to the AI backend — that's the
+// AiCoachViewModel's job.
+
+import 'package:flutter/foundation.dart';
+import '../../models/models.dart';
+import '../interfaces/storage_service_interface.dart';
+
+/// Manages the lifecycle of AI coach [Conversation]s (load, create, append,
+/// rename, delete) backed by [IStorageService].
+class ConversationManager extends ChangeNotifier {
+  final IStorageService _storage;
+
+  List<Conversation> _conversations = [];
+  Conversation? _active;
+
+  ConversationManager(this._storage);
+
+  /// All conversations, most-recently-updated first.
+  List<Conversation> get conversations => List.unmodifiable(_conversations);
+
+  /// The conversation currently shown in the coach screen, or null for a
+  /// fresh (unsaved) chat.
+  Conversation? get active => _active;
+
+  /// Messages of the active conversation (empty for a fresh chat).
+  List<ChatMessage> get activeMessages => _active?.messages ?? const [];
+
+  /// Load all conversations from storage. Does not change the active one.
+  Future<void> loadConversations() async {
+    _conversations = await _storage.getAllConversations();
+    notifyListeners();
+  }
+
+  /// Begin a fresh conversation. Nothing is persisted until the first message
+  /// is appended (avoids littering storage with empty chats).
+  void startNewConversation() {
+    _active = null;
+    notifyListeners();
+  }
+
+  /// Make [id] the active conversation, if it exists.
+  void selectConversation(String id) {
+    final idx = _conversations.indexWhere((c) => c.id == id);
+    if (idx < 0) return;
+    _active = _conversations[idx];
+    notifyListeners();
+  }
+
+  /// Append [message] to the active conversation, creating one if needed,
+  /// then persist. The conversation title is derived from the first user
+  /// message. Bumps `updatedAt` and re-sorts the list newest-first.
+  Future<void> appendMessage(ChatMessage message) async {
+    final current = _active;
+    final Conversation updated;
+
+    if (current == null) {
+      updated = Conversation(
+        title: _deriveTitle(message),
+        messages: [message],
+      );
+    } else {
+      final title = current.title.isEmpty && message.role == 'user'
+          ? _deriveTitle(message)
+          : current.title;
+      updated = current.copyWith(
+        title: title,
+        updatedAt: DateTime.now(),
+        messages: [...current.messages, message],
+      );
+    }
+
+    _active = updated;
+    _upsert(updated);
+    await _storage.saveConversation(updated);
+    notifyListeners();
+  }
+
+  /// Rename a conversation.
+  Future<void> renameConversation(String id, String title) async {
+    final idx = _conversations.indexWhere((c) => c.id == id);
+    if (idx < 0) return;
+    final updated = _conversations[idx].copyWith(
+      title: title.trim(),
+      updatedAt: DateTime.now(),
+    );
+    if (_active?.id == id) _active = updated;
+    _upsert(updated);
+    await _storage.saveConversation(updated);
+    notifyListeners();
+  }
+
+  /// Delete a conversation. Clears the active one if it was deleted.
+  Future<void> deleteConversation(String id) async {
+    _conversations = _conversations.where((c) => c.id != id).toList();
+    if (_active?.id == id) _active = null;
+    await _storage.deleteConversation(id);
+    notifyListeners();
+  }
+
+  // ── Helpers ────────────────────────────────────────────────────────────────
+
+  void _upsert(Conversation conversation) {
+    final next = _conversations.where((c) => c.id != conversation.id).toList()
+      ..add(conversation)
+      ..sort((a, b) => b.updatedAt.compareTo(a.updatedAt));
+    _conversations = next;
+  }
+
+  String _deriveTitle(ChatMessage message) {
+    final text = message.text.trim().replaceAll(RegExp(r'\s+'), ' ');
+    if (text.isEmpty) return 'New chat';
+    return text.length <= 40 ? text : '${text.substring(0, 40).trim()}…';
+  }
+}
diff --git a/workout-logger/lib/services/storage_service.dart b/workout-logger/lib/services/storage_service.dart
index 40cdc39..873de63 100644
--- a/workout-logger/lib/services/storage_service.dart
+++ b/workout-logger/lib/services/storage_service.dart
@@ -25,6 +25,7 @@ class StorageService implements IStorageService {
   static const String _settingsBox = 'settings';
   static const String _trainingProgramsBox = 'training_programs';
   static const String _personalRecordsBox = 'personal_records';
+  static const String _aiConversationsBox = 'ai_conversations';
 
   late Box<String> _sessionsBox;
   late Box<String> _routinesBoxInstance;
@@ -34,6 +35,7 @@ class StorageService implements IStorageService {
   late Box<String> _settingsBoxInstance;
   late Box<String> _trainingProgramsBoxInstance;
   late Box<String> _personalRecordsBoxInstance;
+  late Box<String> _aiConversationsBoxInstance;
 
   String _appVersion = const String.fromEnvironment(
     'APP_VERSION',
@@ -73,6 +75,9 @@ class StorageService implements IStorageService {
     _personalRecordsBoxInstance = await Hive.openBox<String>(
       _personalRecordsBox,
     );
+    _aiConversationsBoxInstance = await Hive.openBox<String>(
+      _aiConversationsBox,
+    );
 
     // Initialize default muscle groups if empty
     if (_muscleGroupsBoxInstance.isEmpty) {
@@ -364,6 +369,9 @@ class StorageService implements IStorageService {
       'customExercises': _customExercisesBoxInstance.values
           .map(_normalizeExportValue)
           .toList(growable: false),
+      'conversations': _aiConversationsBoxInstance.values
+          .map(_normalizeExportValue)
+          .toList(growable: false),
       'settings': settingsMap,
       'exportDate': DateTime.now().toIso8601String(),
       'appVersion': _appVersion,
@@ -455,6 +463,20 @@ class StorageService implements IStorageService {
         }
       }
     }
+
+    // Import AI conversations (merge: skip if id already exists)
+    final conversations = data['conversations'];
+    if (conversations is List) {
+      for (var item in conversations) {
+        final map = _normalizeImportItem(item);
+        if (map == null) continue;
+        final conversation = Conversation.fromJson(map);
+        final existing = await getConversation(conversation.id);
+        if (existing == null) {
+          await saveConversation(conversation);
+        }
+      }
+    }
   }
 
   // ==================== TRAINING PROGRAMS ====================
@@ -515,6 +537,39 @@ class StorageService implements IStorageService {
     return records;
   }
 
+  // ==================== AI CONVERSATIONS ====================
+
+  @override
+  Future<void> saveConversation(Conversation conversation) async {
+    await _aiConversationsBoxInstance.put(
+      conversation.id,
+      jsonEncode(conversation.toJson()),
+    );
+  }
+
+  @override
+  Future<List<Conversation>> getAllConversations() async {
+    final conversations = <Conversation>[];
+    for (final json in _aiConversationsBoxInstance.values) {
+      conversations.add(Conversation.fromJson(jsonDecode(json)));
+    }
+    // Most recently updated first.
+    conversations.sort((a, b) => b.updatedAt.compareTo(a.updatedAt));
+    return conversations;
+  }
+
+  @override
+  Future<Conversation?> getConversation(String id) async {
+    final json = _aiConversationsBoxInstance.get(id);
+    if (json == null) return null;
+    return Conversation.fromJson(jsonDecode(json));
+  }
+
+  @override
+  Future<void> deleteConversation(String id) async {
+    await _aiConversationsBoxInstance.delete(id);
+  }
+
   // ==================== STATS ====================
 
   @override
diff --git a/workout-logger/lib/viewmodels/ai_coach_view_model.dart b/workout-logger/lib/viewmodels/ai_coach_view_model.dart
new file mode 100644
index 0000000..036154c
--- /dev/null
+++ b/workout-logger/lib/viewmodels/ai_coach_view_model.dart
@@ -0,0 +1,143 @@
+// ai_coach_view_model.dart — orchestration for the AI coach screen.
+//
+// Owns all coach logic so the View stays dumb: builds the system prompt,
+// drives the streaming tool-call loop via IAiService + CoachToolService, and
+// persists each turn through ConversationManager. Exposes immutable state.
+
+import 'package:flutter/foundation.dart';
+import 'package:google_generative_ai/google_generative_ai.dart' show Content, TextPart;
+
+import '../models/models.dart';
+import '../services/interfaces/ai_service_interface.dart';
+import '../services/ai/coach_tool_service.dart';
+import '../services/managers/conversation_manager.dart';
+import '../services/settings_provider.dart';
+import '../services/gemini_context_builder.dart';
+
+class AiCoachViewModel extends ChangeNotifier {
+  final IAiService _ai;
+  final CoachToolService _coachTools;
+  final ConversationManager _conversations;
+  final SettingsProvider _settings;
+
+  bool _loading = false;
+  String _streamingText = '';
+
+  AiCoachViewModel({
+    required IAiService ai,
+    required CoachToolService coachTools,
+    required ConversationManager conversations,
+    required SettingsProvider settings,
+  })  : _ai = ai,
+        _coachTools = coachTools,
+        _conversations = conversations,
+        _settings = settings {
+    // Forward conversation-store changes so the View only watches the VM.
+    _conversations.addListener(notifyListeners);
+  }
+
+  @override
+  void dispose() {
+    _conversations.removeListener(notifyListeners);
+    super.dispose();
+  }
+
+  // ── Exposed state (immutable snapshots) ────────────────────────────────────
+
+  bool get isConfigured => _ai.isConfigured;
+  bool get isLoading => _loading;
+  String get streamingText => _streamingText;
+  List<ChatMessage> get messages => _conversations.activeMessages;
+  List<Conversation> get conversations => _conversations.conversations;
+  String? get activeConversationId => _conversations.active?.id;
+
+  // ── Commands ───────────────────────────────────────────────────────────────
+
+  /// Load the persisted conversation list (call when the screen opens).
+  Future<void> loadConversations() => _conversations.loadConversations();
+
+  /// Start a fresh, unsaved conversation.
+  void newConversation() {
+    if (_loading) return;
+    _conversations.startNewConversation();
+  }
+
+  /// Switch to an existing conversation.
+  void selectConversation(String id) {
+    if (_loading) return;
+    _conversations.selectConversation(id);
+  }
+
+  /// Delete a conversation.
+  Future<void> deleteConversation(String id) =>
+      _conversations.deleteConversation(id);
+
+  /// Send a user message and stream the coach's reply (running the tool-call
+  /// loop). Both the user message and the final reply are persisted.
+  Future<void> sendMessage(String text) async {
+    final trimmed = text.trim();
+    if (trimmed.isEmpty || _loading) return;
+
+    _loading = true;
+    _streamingText = '';
+    notifyListeners();
+
+    // Persist the user message first; history is derived from the store.
+    await _conversations.appendMessage(
+      ChatMessage(role: 'user', text: trimmed),
+    );
+
+    final systemPrompt = _buildSystemPrompt();
+    final history = _buildHistory();
+
+    final buffer = StringBuffer();
+    try {
+      await for (final chunk in _ai.streamCoachReply(
+        userMessage: trimmed,
+        systemPrompt: systemPrompt,
+        history: history,
+        tools: _coachTools.buildTools(),
+        onToolCall: _coachTools.handleCall,
+      )) {
+        buffer.write(chunk);
+        _streamingText = buffer.toString();
+        notifyListeners();
+      }
+      final reply = buffer.toString().trim();
+      if (reply.isNotEmpty) {
+        await _conversations.appendMessage(
+          ChatMessage(role: 'model', text: reply),
+        );
+      }
+    } catch (e) {
+      buffer.write('\n\n_Error: ${e}_');
+      final errText = buffer.toString().trim();
+      if (errText.isNotEmpty) {
+        await _conversations.appendMessage(
+          ChatMessage(role: 'model', text: errText),
+        );
+      }
+    } finally {
+      _streamingText = '';
+      _loading = false;
+      notifyListeners();
+    }
+  }
+
+  // ── Internals ──────────────────────────────────────────────────────────────
+
+  // Static prompt — live data is fetched by the model via the coach tools,
+  // keeping the prefix stable for implicit prompt caching.
+  String _buildSystemPrompt() => GeminiContextBuilder.buildCoachSystemPrompt(
+        userName: _settings.userName,
+        unitLabel: _settings.unitLabel,
+      );
+
+  /// Prior turns (everything before the user message just appended).
+  List<Content> _buildHistory() {
+    final msgs = _conversations.activeMessages;
+    final prior =
+        msgs.length > 1 ? msgs.sublist(0, msgs.length - 1) : <ChatMessage>[];
+    return prior.map((m) => Content(m.role, [TextPart(m.text)])).toList();
+  }
+}
diff --git a/workout-logger/pubspec.yaml b/workout-logger/pubspec.yaml
index 65ed2c6..d4a544d 100644
--- a/workout-logger/pubspec.yaml
+++ b/workout-logger/pubspec.yaml
@@ -65,6 +65,7 @@ dependencies:
   file_picker: ^10.3.10
   path_provider: ^2.1.5
   share_plus: ^12.0.1
+  gpt_markdown: ^1.1.7
 
 dev_dependencies:
   flutter_test:
diff --git a/workout-logger/test/ai_coach_view_model_test.dart b/workout-logger/test/ai_coach_view_model_test.dart
new file mode 100644
index 0000000..2832a2a
--- /dev/null
+++ b/workout-logger/test/ai_coach_view_model_test.dart
@@ -0,0 +1,148 @@
+// Unit tests for AiCoachViewModel — verifies orchestration (send → stream →
+// persist) using a fake IAiService, so the View has no logic left to test.
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:google_generative_ai/google_generative_ai.dart'
+    show Content, Tool, FunctionCall;
+import 'package:repforge/models/models.dart';
+import 'package:repforge/services/interfaces/ai_service_interface.dart';
+import 'package:repforge/services/ai/coach_tool_service.dart';
+import 'package:repforge/services/managers/conversation_manager.dart';
+import 'package:repforge/services/managers/program_manager.dart';
+import 'package:repforge/services/managers/pr_manager.dart';
+import 'package:repforge/services/workout_provider.dart';
+import 'package:repforge/services/settings_provider.dart';
+import 'package:repforge/viewmodels/ai_coach_view_model.dart';
+import 'test_utils/mock_storage_service.dart';
+
+/// Scripted IAiService: yields fixed chunks; optionally invokes a tool first.
+class _FakeAiService implements IAiService {
+  _FakeAiService({this.chunks = const ['Hello ', 'world'], this.invokeTool = false});
+
+  final List<String> chunks;
+  final bool invokeTool;
+  int toolCallsMade = 0;
+
+  @override
+  bool get isConfigured => true;
+
+  @override
+  String get currentModel => 'fake-model';
+
+  @override
+  Stream<String> streamCoachReply({
+    required String userMessage,
+    required String systemPrompt,
+    required List<Content> history,
+    List<Tool>? tools,
+    Future<Map<String, Object?>> Function(FunctionCall call)? onToolCall,
+  }) async* {
+    if (invokeTool && onToolCall != null) {
+      await onToolCall(FunctionCall('get_muscle_recovery', {}));
+      toolCallsMade++;
+    }
+    for (final c in chunks) {
+      yield c;
+    }
+  }
+
+  @override
+  Future<TrainingProgram> generateProgram({
+    required String userPrompt,
+    required List<Exercise> allExercises,
+  }) =>
+      throw UnimplementedError();
+
+  @override
+  Future<String> generateWeeklyInsights(String contextText) async => '';
+
+  @override
+  Future<String> generateInsight(String system, String context) async => '';
+}
+
+void main() {
+  group('AiCoachViewModel', () {
+    late MockStorageService storage;
+    late WorkoutProvider provider;
+    late ConversationManager conversations;
+    late SettingsProvider settings;
+    late PRManager pr;
+
+    Future<AiCoachViewModel> buildVm(_FakeAiService ai) async {
+      provider = WorkoutProvider(
+        storage,
+        programManager: ProgramManager(storage),
+      );
+      await provider.init();
+      pr = PRManager(storage);
+      settings = SettingsProvider(storage);
+      conversations = ConversationManager(storage);
+      return AiCoachViewModel(
+        ai: ai,
+        coachTools: CoachToolService(provider, pr),
+        conversations: conversations,
+        settings: settings,
+      );
+    }
+
+    setUp(() {
+      storage = MockStorageService();
+    });
+
+    test('sendMessage appends user + model messages and persists', () async {
+      final vm = await buildVm(_FakeAiService());
+
+      await vm.sendMessage('How am I doing?');
+
+      expect(vm.messages, hasLength(2));
+      expect(vm.messages[0].role, 'user');
+      expect(vm.messages[0].text, 'How am I doing?');
+      expect(vm.messages[1].role, 'model');
+      expect(vm.messages[1].text, 'Hello world');
+      expect(vm.isLoading, isFalse);
+      expect(vm.streamingText, isEmpty);
+
+      // Persisted.
+      final stored = await storage.getAllConversations();
+      expect(stored, hasLength(1));
+      expect(stored.first.messages, hasLength(2));
+    });
+
+    test('blank or whitespace messages are ignored', () async {
+      final vm = await buildVm(_FakeAiService());
+      await vm.sendMessage('   ');
+      expect(vm.messages, isEmpty);
+    });
+
+    test('runs the tool-call loop via CoachToolService', () async {
+      final ai = _FakeAiService(invokeTool: true, chunks: const ['done']);
+      final vm = await buildVm(ai);
+
+      await vm.sendMessage('what can I train?');
+
+      expect(ai.toolCallsMade, 1);
+      expect(vm.messages.last.text, 'done');
+    });
+
+    test('newConversation then selectConversation swaps active state',
+        () async {
+      final vm = await buildVm(_FakeAiService());
+
+      await vm.sendMessage('first chat');
+      final firstId = vm.activeConversationId;
+      expect(firstId, isNotNull);
+
+      vm.newConversation();
+      expect(vm.messages, isEmpty);
+
+      await vm.sendMessage('second chat');
+      final secondId = vm.activeConversationId;
+      expect(secondId, isNot(firstId));
+      expect(vm.conversations, hasLength(2));
+
+      vm.selectConversation(firstId!);
+      expect(vm.activeConversationId, firstId);
+      expect(vm.messages.first.text, 'first chat');
+    });
+  });
+}
diff --git a/workout-logger/test/analytics_screen_test.dart b/workout-logger/test/analytics_screen_test.dart
index 038c2a9..fbfb123 100644
--- a/workout-logger/test/analytics_screen_test.dart
+++ b/workout-logger/test/analytics_screen_test.dart
@@ -11,7 +11,7 @@ import 'package:repforge/models/models.dart';
 import 'package:repforge/screens/analytics_screen.dart';
 import 'package:repforge/services/workout_provider.dart';
 import 'package:repforge/services/settings_provider.dart';
-import 'package:repforge/services/gemini_service.dart';
+import 'package:repforge/services/ai/gemini_ai_service.dart';
 import 'package:repforge/services/managers/program_manager.dart';
 import 'package:repforge/services/managers/pr_manager.dart';
 import 'package:repforge/services/interfaces/ml_service_interface.dart';
@@ -31,7 +31,7 @@ Widget _wrap({
       ChangeNotifierProvider<WorkoutProvider>.value(value: workoutProvider),
       ChangeNotifierProvider<SettingsProvider>.value(value: sp),
       ChangeNotifierProvider<PRManager>.value(value: prManager),
-      ChangeNotifierProvider<GeminiService>.value(value: GeminiService()),
+      ChangeNotifierProvider<GeminiAiService>.value(value: GeminiAiService()),
       Provider<IMLService>.value(value: MockMLService()),
     ],
     child: const MaterialApp(home: AnalyticsScreen()),
diff --git a/workout-logger/test/coach_tool_service_test.dart b/workout-logger/test/coach_tool_service_test.dart
new file mode 100644
index 0000000..4cecf55
--- /dev/null
+++ b/workout-logger/test/coach_tool_service_test.dart
@@ -0,0 +1,170 @@
+// Unit tests for CoachToolService — each tool returns expected JSON shapes,
+// backed by a seeded WorkoutProvider + PRManager.
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:google_generative_ai/google_generative_ai.dart' show FunctionCall;
+import 'package:repforge/models/models.dart';
+import 'package:repforge/services/workout_provider.dart';
+import 'package:repforge/services/managers/program_manager.dart';
+import 'package:repforge/services/managers/pr_manager.dart';
+import 'package:repforge/services/ai/coach_tool_service.dart';
+import 'test_utils/mock_storage_service.dart';
+
+void main() {
+  group('CoachToolService', () {
+    late MockStorageService storage;
+    late WorkoutProvider provider;
+    late PRManager pr;
+    late CoachToolService tools;
+
+    WorkoutSession benchSession(DateTime date, double weight, {String? routineId}) {
+      return WorkoutSession(
+        id: 'sess-${date.millisecondsSinceEpoch}',
+        date: date,
+        routineId: routineId,
+        duration: 45,
+        exercises: [
+          ExerciseLog(
+            exerciseId: 'bench_press',
+            sets: [
+              WorkoutSet(weight: weight, reps: 8),
+              WorkoutSet(weight: weight, reps: 8),
+            ],
+          ),
+        ],
+      );
+    }
+
+    setUp(() async {
+      storage = MockStorageService();
+
+      // Two bench sessions on different days → enough for a growth model.
+      final now = DateTime.now();
+      storage.addMockRoutine(
+        Routine(id: 'r1', name: 'Push Day', exerciseIds: ['bench_press']),
+      );
+      storage.addMockSession(
+        benchSession(now.subtract(const Duration(days: 10)), 60, routineId: 'r1'),
+      );
+      storage.addMockSession(
+        benchSession(now.subtract(const Duration(days: 3)), 65, routineId: 'r1'),
+      );
+
+      provider = WorkoutProvider(
+        storage,
+        programManager: ProgramManager(storage),
+      );
+      await provider.init();
+
+      pr = PRManager(storage);
+      await pr.backfillFromSessions(provider.sessions);
+
+      tools = CoachToolService(provider, pr);
+    });
+
+    test('exposes the expected tool declarations', () {
+      final declared = tools
+          .buildTools()
+          .expand((t) => t.functionDeclarations ?? [])
+          .map((f) => f.name)
+          .toSet();
+      expect(
+        declared,
+        containsAll([
+          'get_exercise_performance',
+          'get_workouts_in_range',
+          'get_routine_performance',
+          'get_personal_records',
+          'get_goal_progress',
+          'get_muscle_recovery',
+        ]),
+      );
+    });
+
+    test('get_exercise_performance returns trend + PR for a known exercise',
+        () async {
+      final result = await tools.handleCall(
+        FunctionCall('get_exercise_performance', {'exercise_name': 'Bench Press'}),
+      );
+
+      expect(result['exercise'], 'Bench Press');
+      expect(result['session_count'], 2);
+      expect(result['volume_trend'], isA<List<dynamic>>());
+      expect((result['volume_trend'] as List), isNotEmpty);
+      expect(result['personal_record'], isNotNull);
+    });
+
+    test('get_exercise_performance returns an error for an unknown exercise',
+        () async {
+      final result = await tools.handleCall(
+        FunctionCall('get_exercise_performance', {'exercise_name': 'Nonexistent'}),
+      );
+      expect(result['error'], isNotNull);
+      expect(result['available_examples'], isA<List<dynamic>>());
+    });
+
+    test('get_workouts_in_range summarizes sessions in the window', () async {
+      final result = await tools.handleCall(
+        FunctionCall('get_workouts_in_range', {'days': 30}),
+      );
+      expect(result['session_count'], 2);
+      expect(result['total_volume'], isA<num>());
+      expect((result['total_volume'] as num) > 0, isTrue);
+    });
+
+    test('get_routine_performance returns sessions logged against the routine',
+        () async {
+      final result = await tools.handleCall(
+        FunctionCall('get_routine_performance', {'routine_name': 'Push Day'}),
+      );
+      expect(result['routine'], 'Push Day');
+      expect(result['session_count'], 2);
+      expect(result['exercises'], contains('Bench Press'));
+    });
+
+    test('get_routine_performance errors for an unknown routine', () async {
+      final result = await tools.handleCall(
+        FunctionCall('get_routine_performance', {'routine_name': 'Leg Day'}),
+      );
+      expect(result['error'], isNotNull);
+      expect(result['available_routines'], contains('Push Day'));
+    });
+
+    test('get_personal_records returns all records when unfiltered', () async {
+      final result = await tools.handleCall(
+        FunctionCall('get_personal_records', {}),
+      );
+      final records = result['records'] as List;
+      expect(records, isNotEmpty);
+      expect((records.first as Map)['exercise'], 'Bench Press');
+    });
+
+    test('get_goal_progress reflects active targets', () async {
+      await provider.createTarget(
+        exerciseId: 'bench_press',
+        type: 'weight',
+        targetValue: 100,
+      );
+
+      final result = await tools.handleCall(
+        FunctionCall('get_goal_progress', {'exercise_name': 'Bench Press'}),
+      );
+      final goals = result['goals'] as List;
+      expect(goals, hasLength(1));
+      expect((goals.first as Map)['type'], 'weight');
+      expect((goals.first as Map)['target_value'], 100);
+    });
+
+    test('get_muscle_recovery returns per-muscle status', () async {
+      final result = await tools.handleCall(
+        FunctionCall('get_muscle_recovery', {}),
+      );
+      final muscles = result['muscles'] as List;
+      expect(muscles, isNotEmpty);
+      final first = muscles.first as Map;
+      expect(first['muscle'], isA<String>());
+      expect(first['recovery_percent'], isA<int>());
+      expect(first['status'], isA<String>());
+    });
+  });
+}
diff --git a/workout-logger/test/conversation_manager_test.dart b/workout-logger/test/conversation_manager_test.dart
new file mode 100644
index 0000000..e533313
--- /dev/null
+++ b/workout-logger/test/conversation_manager_test.dart
@@ -0,0 +1,117 @@
+// Unit tests for ConversationManager — persistence + active-conversation logic.
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:repforge/models/models.dart';
+import 'package:repforge/services/managers/conversation_manager.dart';
+import 'test_utils/mock_storage_service.dart';
+
+void main() {
+  group('ConversationManager', () {
+    late MockStorageService storage;
+    late ConversationManager manager;
+
+    setUp(() {
+      storage = MockStorageService();
+      manager = ConversationManager(storage);
+    });
+
+    test('appendMessage creates a conversation and persists it', () async {
+      await manager.appendMessage(
+        ChatMessage(role: 'user', text: 'How is my bench press?'),
+      );
+
+      expect(manager.active, isNotNull);
+      expect(manager.activeMessages, hasLength(1));
+
+      // Persisted to storage.
+      final stored = await storage.getAllConversations();
+      expect(stored, hasLength(1));
+      expect(stored.first.messages.first.text, 'How is my bench press?');
+    });
+
+    test('title is derived from the first user message', () async {
+      await manager.appendMessage(
+        ChatMessage(role: 'user', text: 'Plan my next push day please'),
+      );
+      expect(manager.active!.title, 'Plan my next push day please');
+    });
+
+    test('long first message title is truncated', () async {
+      final long = 'a' * 80;
+      await manager.appendMessage(ChatMessage(role: 'user', text: long));
+      expect(manager.active!.title.length, lessThanOrEqualTo(41));
+      expect(manager.active!.title.endsWith('…'), isTrue);
+    });
+
+    test('multiple messages append to the same active conversation', () async {
+      await manager.appendMessage(ChatMessage(role: 'user', text: 'hi'));
+      await manager.appendMessage(ChatMessage(role: 'model', text: 'hello!'));
+
+      expect(manager.activeMessages, hasLength(2));
+      final stored = await storage.getAllConversations();
+      expect(stored, hasLength(1));
+      expect(stored.first.messages, hasLength(2));
+    });
+
+    test('reload restores conversations from storage', () async {
+      await manager.appendMessage(ChatMessage(role: 'user', text: 'first'));
+
+      final fresh = ConversationManager(storage);
+      await fresh.loadConversations();
+      expect(fresh.conversations, hasLength(1));
+      expect(fresh.conversations.first.messages.first.text, 'first');
+    });
+
+    test('conversations are sorted most-recently-updated first', () async {
+      // Small delays keep updatedAt timestamps distinct (millisecond clock).
+      await manager.appendMessage(ChatMessage(role: 'user', text: 'older'));
+      final olderId = manager.active!.id;
+
+      await Future<void>.delayed(const Duration(milliseconds: 5));
+      manager.startNewConversation();
+      await manager.appendMessage(ChatMessage(role: 'user', text: 'newer'));
+      final newerId = manager.active!.id;
+
+      expect(manager.conversations.first.id, newerId);
+
+      // Touching the older one bumps it to the front.
+      await Future<void>.delayed(const Duration(milliseconds: 5));
+      manager.selectConversation(olderId);
+      await manager.appendMessage(ChatMessage(role: 'model', text: 'reply'));
+      expect(manager.conversations.first.id, olderId);
+    });
+
+    test('startNewConversation clears the active conversation', () async {
+      await manager.appendMessage(ChatMessage(role: 'user', text: 'hi'));
+      expect(manager.active, isNotNull);
+
+      manager.startNewConversation();
+      expect(manager.active, isNull);
+      expect(manager.activeMessages, isEmpty);
+      // The prior conversation is still saved.
+      expect(manager.conversations, hasLength(1));
+    });
+
+    test('deleteConversation removes it and clears active when needed', () async {
+      await manager.appendMessage(ChatMessage(role: 'user', text: 'hi'));
+      final id = manager.active!.id;
+
+      await manager.deleteConversation(id);
+
+      expect(manager.active, isNull);
+      expect(manager.conversations, isEmpty);
+      expect(await storage.getAllConversations(), isEmpty);
+    });
+
+    test('renameConversation updates the title and persists', () async {
+      await manager.appendMessage(ChatMessage(role: 'user', text: 'hi'));
+      final id = manager.active!.id;
+
+      await manager.renameConversation(id, 'My chat');
+
+      expect(manager.active!.title, 'My chat');
+      final stored = await storage.getConversation(id);
+      expect(stored!.title, 'My chat');
+    });
+  });
+}
diff --git a/workout-logger/test/exercise_progress_view_test.dart b/workout-logger/test/exercise_progress_view_test.dart
index 2913cbe..f8f1ba4 100644
--- a/workout-logger/test/exercise_progress_view_test.dart
+++ b/workout-logger/test/exercise_progress_view_test.dart
@@ -17,7 +17,7 @@ import 'package:provider/provider.dart';
 import 'package:repforge/models/models.dart';
 import 'package:repforge/services/workout_provider.dart';
 import 'package:repforge/services/settings_provider.dart';
-import 'package:repforge/services/gemini_service.dart';
+import 'package:repforge/services/ai/gemini_ai_service.dart';
 import 'package:repforge/services/managers/program_manager.dart';
 import 'package:repforge/services/interfaces/ml_service_interface.dart';
 import 'package:repforge/screens/widgets/exercise_progress_view.dart';
@@ -38,7 +38,7 @@ Widget _wrap({
     providers: [
       ChangeNotifierProvider<WorkoutProvider>.value(value: provider),
       ChangeNotifierProvider<SettingsProvider>.value(value: sp),
-      ChangeNotifierProvider<GeminiService>.value(value: GeminiService()),
+      ChangeNotifierProvider<GeminiAiService>.value(value: GeminiAiService()),
       Provider<IMLService>.value(value: MockMLService()),
     ],
     child: MaterialApp(home: Scaffold(body: child)),
diff --git a/workout-logger/test/gemini_ai_service_usage_test.dart b/workout-logger/test/gemini_ai_service_usage_test.dart
new file mode 100644
index 0000000..046bdae
--- /dev/null
+++ b/workout-logger/test/gemini_ai_service_usage_test.dart
@@ -0,0 +1,59 @@
+// Unit tests for GeminiAiService token-usage tracking + persistence.
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:repforge/services/ai/gemini_ai_service.dart';
+import 'test_utils/mock_storage_service.dart';
+
+void main() {
+  group('GeminiAiService token usage', () {
+    late MockStorageService storage;
+    late GeminiAiService service;
+
+    setUp(() {
+      storage = MockStorageService();
+      service = GeminiAiService(storage: storage);
+    });
+
+    test('starts at zero', () {
+      expect(service.totalTokensUsed, 0);
+      expect(service.promptTokensUsed, 0);
+      expect(service.responseTokensUsed, 0);
+      expect(service.aiRequestCount, 0);
+    });
+
+    test('recordUsage accumulates across calls', () {
+      service.recordUsage(prompt: 10, response: 5, total: 15);
+      service.recordUsage(prompt: 20, response: 10, total: 30);
+
+      expect(service.promptTokensUsed, 30);
+      expect(service.responseTokensUsed, 15);
+      expect(service.totalTokensUsed, 45);
+      expect(service.aiRequestCount, 2);
+    });
+
+    test('usage is persisted and reloaded by a fresh instance', () async {
+      await service.recordUsage(prompt: 100, response: 40, total: 140);
+
+      final reloaded = GeminiAiService(storage: storage);
+      await reloaded.loadUsage();
+
+      expect(reloaded.promptTokensUsed, 100);
+      expect(reloaded.responseTokensUsed, 40);
+      expect(reloaded.totalTokensUsed, 140);
+      expect(reloaded.aiRequestCount, 1);
+    });
+
+    test('resetUsage zeros counters and persists', () async {
+      await service.recordUsage(prompt: 100, response: 40, total: 140);
+      await service.resetUsage();
+
+      expect(service.totalTokensUsed, 0);
+      expect(service.aiRequestCount, 0);
+
+      final reloaded = GeminiAiService(storage: storage);
+      await reloaded.loadUsage();
+      expect(reloaded.totalTokensUsed, 0);
+      expect(reloaded.aiRequestCount, 0);
+    });
+  });
+}
diff --git a/workout-logger/test/test_utils/mock_storage_service.dart b/workout-logger/test/test_utils/mock_storage_service.dart
index 9685c3b..2f0a9c3 100644
--- a/workout-logger/test/test_utils/mock_storage_service.dart
+++ b/workout-logger/test/test_utils/mock_storage_service.dart
@@ -21,6 +21,7 @@ class MockStorageService implements IStorageService {
   final Map<String, String> _settings = {};
   final List<TrainingProgram> _trainingPrograms = [];
   final Map<String, PersonalRecord> _personalRecords = {};
+  final Map<String, Conversation> _conversations = {};
 
   bool saveCustomExerciseCalled = false;
   Exercise? lastSavedExercise;
@@ -279,6 +280,26 @@ class MockStorageService implements IStorageService {
   Future<List<PersonalRecord>> getAllPersonalRecords() async =>
       List.from(_personalRecords.values);
 
+  @override
+  Future<void> saveConversation(Conversation conversation) async {
+    _conversations[conversation.id] = conversation;
+  }
+
+  @override
+  Future<List<Conversation>> getAllConversations() async {
+    final list = _conversations.values.toList()
+      ..sort((a, b) => b.updatedAt.compareTo(a.updatedAt));
+    return list;
+  }
+
+  @override
+  Future<Conversation?> getConversation(String id) async => _conversations[id];
+
+  @override
+  Future<void> deleteConversation(String id) async {
+    _conversations.remove(id);
+  }
+
   @override
   Future<String> exportAllData() async => '{}';