diff --git a/lib/core/datalog/datalog_db.dart b/lib/core/datalog/datalog_db.dart
new file mode 100644
index 0000000..1477600
--- /dev/null
+++ b/lib/core/datalog/datalog_db.dart
@@ -0,0 +1,140 @@
+import 'dart:typed_data';
+
+import 'package:path/path.dart' as p;
+import 'package:path_provider/path_provider.dart';
+import 'package:sqflite/sqflite.dart';
+
+import '../models/datalog_session.dart';
+
+/// SQLite database wrapper for sessions and raw ECU frames.
+class DatalogDb {
+  static const _dbName = 'hvbt_datalog.db';
+  static const _version = 1;
+
+  Database? _db;
+
+  Future<Database> get _database async {
+    _db ??= await _open();
+    return _db!;
+  }
+
+  Future<Database> _open() async {
+    final dir = await getApplicationDocumentsDirectory();
+    final path = p.join(dir.path, _dbName);
+    return openDatabase(
+      path,
+      version: _version,
+      onCreate: (db, _) async {
+        await db.execute('''
+          CREATE TABLE sessions (
+            id         INTEGER PRIMARY KEY AUTOINCREMENT,
+            ecu_type   TEXT    NOT NULL,
+            start_time INTEGER NOT NULL,
+            end_time   INTEGER,
+            frame_count INTEGER NOT NULL DEFAULT 0
+          )
+        ''');
+        await db.execute('''
+          CREATE TABLE frames (
+            id         INTEGER PRIMARY KEY AUTOINCREMENT,
+            session_id INTEGER NOT NULL,
+            timestamp  INTEGER NOT NULL,
+            data       BLOB    NOT NULL,
+            FOREIGN KEY(session_id) REFERENCES sessions(id) ON DELETE CASCADE
+          )
+        ''');
+        await db.execute(
+            'CREATE INDEX idx_frames_session ON frames(session_id)');
+      },
+    );
+  }
+
+  // ── Sessions ──────────────────────────────────────────────────────────────
+
+  /// Inserts a new session row. Returns the assigned id.
+  Future<int> insertSession(DatalogSession session) async {
+    final db = await _database;
+    return db.insert('sessions', session.toMap()..remove('id'));
+  }
+
+  /// Updates end_time and frame_count for an existing session.
+  Future<void> closeSession(int sessionId, DateTime endTime, int frameCount) async {
+    final db = await _database;
+    await db.update(
+      'sessions',
+      {
+        'end_time': endTime.millisecondsSinceEpoch,
+        'frame_count': frameCount,
+      },
+      where: 'id = ?',
+      whereArgs: [sessionId],
+    );
+  }
+
+  /// Returns all sessions ordered newest first.
+  Future<List<DatalogSession>> getSessions() async {
+    final db = await _database;
+    final rows = await db.query('sessions', orderBy: 'start_time DESC');
+    return rows.map(DatalogSession.fromMap).toList();
+  }
+
+  /// Deletes a session and all its frames (CASCADE).
+  Future<void> deleteSession(int sessionId) async {
+    final db = await _database;
+    await db.delete('sessions', where: 'id = ?', whereArgs: [sessionId]);
+  }
+
+  // ── Frames ────────────────────────────────────────────────────────────────
+
+  /// Batch-inserts multiple frames in a single transaction.
+  Future<void> insertFrames(
+      int sessionId, List<PendingFrame> frames) async {
+    if (frames.isEmpty) return;
+    final db = await _database;
+    await db.transaction((txn) async {
+      final batch = txn.batch();
+      for (final f in frames) {
+        batch.insert('frames', {
+          'session_id': sessionId,
+          'timestamp': f.timestamp.millisecondsSinceEpoch,
+          'data': f.data,
+        });
+      }
+      await batch.commit(noResult: true);
+    });
+  }
+
+  /// Returns all raw frames for a session, ordered by timestamp.
+  Future<List<StoredFrame>> getFrames(int sessionId) async {
+    final db = await _database;
+    final rows = await db.query(
+      'frames',
+      where: 'session_id = ?',
+      whereArgs: [sessionId],
+      orderBy: 'timestamp ASC',
+    );
+    return rows
+        .map((r) => StoredFrame(
+              timestamp: DateTime.fromMillisecondsSinceEpoch(
+                  r['timestamp'] as int),
+              data: r['data'] as Uint8List,
+            ))
+        .toList();
+  }
+
+  Future<void> close() async => _db?.close();
+}
+
+// ─── DTOs ─────────────────────────────────────────────────────────────────────
+
+class PendingFrame {
+  final DateTime timestamp;
+  final Uint8List data;
+  const PendingFrame(this.timestamp, this.data);
+}
+
+class StoredFrame {
+  final DateTime timestamp;
+  final Uint8List data;
+  const StoredFrame({required this.timestamp, required this.data});
+}
diff --git a/lib/core/datalog/datalog_player.dart b/lib/core/datalog/datalog_player.dart
new file mode 100644
index 0000000..5207236
--- /dev/null
+++ b/lib/core/datalog/datalog_player.dart
@@ -0,0 +1,119 @@
+import 'dart:async';
+import 'dart:typed_data';
+
+import 'datalog_db.dart';
+
+enum PlaybackStatus { idle, playing, paused }
+
+/// Loads stored frames from SQLite and replays them through a stream
+/// at configurable speed. Consumers watch [frameStream] exactly like
+/// the live BT stream — the parser layer is unaware of the difference.
+class DatalogPlayer {
+  final DatalogDb _db;
+
+  List<StoredFrame> _frames = [];
+  int _position = 0; // index into _frames
+  double _speed = 1.0; // 1.0 = real-time, 2.0 = 2× faster
+
+  PlaybackStatus _status = PlaybackStatus.idle;
+  PlaybackStatus get status => _status;
+  int get position => _position;
+  int get totalFrames => _frames.length;
+  double get speed => _speed;
+  set speed(double v) => _speed = v.clamp(0.25, 8.0);
+
+  final StreamController<Uint8List> _controller =
+      StreamController<Uint8List>.broadcast();
+
+  Stream<Uint8List> get frameStream => _controller.stream;
+
+  /// Callback fired on each tick — lets UI update a progress indicator.
+  void Function(int position, int total)? onProgress;
+
+  Timer? _timer;
+
+  DatalogPlayer(this._db);
+
+  /// Load all frames for [sessionId] into memory.
+  Future<void> load(int sessionId) async {
+    await stop();
+    _frames = await _db.getFrames(sessionId);
+    _position = 0;
+    _status = PlaybackStatus.idle;
+  }
+
+  /// Start or resume playback.
+  void play() {
+    if (_status == PlaybackStatus.playing) return;
+    if (_frames.isEmpty) return;
+    _status = PlaybackStatus.playing;
+    _scheduleNext();
+  }
+
+  void pause() {
+    _timer?.cancel();
+    _timer = null;
+    if (_status == PlaybackStatus.playing) {
+      _status = PlaybackStatus.paused;
+    }
+  }
+
+  Future<void> stop() async {
+    _timer?.cancel();
+    _timer = null;
+    _position = 0;
+    _status = PlaybackStatus.idle;
+  }
+
+  /// Jump to a specific frame index.
+  void seek(int index) {
+    _position = index.clamp(0, _frames.length - 1);
+    onProgress?.call(_position, _frames.length);
+  }
+
+  void _scheduleNext() {
+    if (_position >= _frames.length) {
+      _status = PlaybackStatus.idle;
+      onProgress?.call(_frames.length, _frames.length);
+      return;
+    }
+
+    // Calculate delay to next frame using original timestamps
+    Duration delay = const Duration(milliseconds: 100); // default 10 Hz
+    if (_position + 1 < _frames.length) {
+      final gap = _frames[_position + 1].timestamp
+          .difference(_frames[_position].timestamp);
+      delay = Duration(
+        microseconds: (gap.inMicroseconds / _speed).round(),
+      );
+      // Clamp to 10ms–2s to handle gaps from pauses/reconnects
+      delay = delay.clamp(
+        const Duration(milliseconds: 10),
+        const Duration(seconds: 2),
+      );
+    }
+
+    _timer = Timer(delay, () {
+      if (_status != PlaybackStatus.playing) return;
+      if (_position < _frames.length) {
+        _controller.add(_frames[_position].data);
+        onProgress?.call(_position, _frames.length);
+        _position++;
+      }
+      _scheduleNext();
+    });
+  }
+
+  void dispose() {
+    _timer?.cancel();
+    _controller.close();
+  }
+}
+
+extension on Duration {
+  Duration clamp(Duration min, Duration max) {
+    if (this < min) return min;
+    if (this > max) return max;
+    return this;
+  }
+}
diff --git a/lib/core/datalog/datalog_recorder.dart b/lib/core/datalog/datalog_recorder.dart
new file mode 100644
index 0000000..1d1f0d8
--- /dev/null
+++ b/lib/core/datalog/datalog_recorder.dart
@@ -0,0 +1,94 @@
+import 'dart:async';
+import 'dart:typed_data';
+
+import 'datalog_db.dart';
+import '../models/datalog_session.dart';
+
+/// Listens to a raw frame stream and batches writes to SQLite every 500ms.
+class DatalogRecorder {
+  final DatalogDb _db;
+
+  int? _sessionId;
+  String? _ecuType;
+  DateTime? _startTime;
+  int _frameCount = 0;
+
+  final List<PendingFrame> _batch = [];
+  Timer? _flushTimer;
+  StreamSubscription<Uint8List>? _frameSub;
+
+  bool get isRecording => _sessionId != null;
+  int get frameCount => _frameCount;
+  int? get sessionId => _sessionId;
+
+  DatalogRecorder(this._db);
+
+  /// Start a new recording session, listening to [frameStream].
+  Future<void> start(Stream<Uint8List> frameStream, String ecuType) async {
+    if (isRecording) await stop();
+
+    _ecuType = ecuType;
+    _startTime = DateTime.now();
+    _frameCount = 0;
+    _batch.clear();
+
+    final session = DatalogSession(
+      ecuType: ecuType,
+      startTime: _startTime!,
+    );
+    _sessionId = await _db.insertSession(session);
+
+    // Collect frames into batch buffer
+    _frameSub = frameStream.listen((Uint8List frame) {
+      _batch.add(PendingFrame(DateTime.now(), frame));
+      _frameCount++;
+    });
+
+    // Flush to DB every 500ms
+    _flushTimer = Timer.periodic(const Duration(milliseconds: 500), (_) {
+      _flush();
+    });
+  }
+
+  /// Stop recording and finalise the session row.
+  Future<DatalogSession?> stop() async {
+    if (!isRecording) return null;
+
+    _flushTimer?.cancel();
+    _flushTimer = null;
+    await _frameSub?.cancel();
+    _frameSub = null;
+
+    await _flush(); // write any remaining buffered frames
+
+    final endTime = DateTime.now();
+    await _db.closeSession(_sessionId!, endTime, _frameCount);
+
+    final finished = DatalogSession(
+      id: _sessionId,
+      ecuType: _ecuType!,
+      startTime: _startTime!,
+      endTime: endTime,
+      frameCount: _frameCount,
+    );
+
+    _sessionId = null;
+    _ecuType = null;
+    _startTime = null;
+    _frameCount = 0;
+
+    return finished;
+  }
+
+  Future<void> _flush() async {
+    if (_batch.isEmpty || _sessionId == null) return;
+    final toWrite = List<PendingFrame>.from(_batch);
+    _batch.clear();
+    await _db.insertFrames(_sessionId!, toWrite);
+  }
+
+  void dispose() {
+    _flushTimer?.cancel();
+    _frameSub?.cancel();
+  }
+}
diff --git a/lib/core/models/datalog_session.dart b/lib/core/models/datalog_session.dart
new file mode 100644
index 0000000..3da0c49
--- /dev/null
+++ b/lib/core/models/datalog_session.dart
@@ -0,0 +1,62 @@
+/// Metadata for a single recorded ECU datalog session.
+class DatalogSession {
+  final int? id;
+  final String ecuType;
+  final DateTime startTime;
+  final DateTime? endTime;
+  final int frameCount;
+
+  const DatalogSession({
+    this.id,
+    required this.ecuType,
+    required this.startTime,
+    this.endTime,
+    this.frameCount = 0,
+  });
+
+  Duration get duration {
+    final end = endTime ?? DateTime.now();
+    return end.difference(startTime);
+  }
+
+  String get durationLabel {
+    final d = duration;
+    final m = d.inMinutes.remainder(60).toString().padLeft(2, '0');
+    final s = d.inSeconds.remainder(60).toString().padLeft(2, '0');
+    return '$m:$s';
+  }
+
+  DatalogSession copyWith({
+    int? id,
+    String? ecuType,
+    DateTime? startTime,
+    DateTime? endTime,
+    int? frameCount,
+  }) =>
+      DatalogSession(
+        id: id ?? this.id,
+        ecuType: ecuType ?? this.ecuType,
+        startTime: startTime ?? this.startTime,
+        endTime: endTime ?? this.endTime,
+        frameCount: frameCount ?? this.frameCount,
+      );
+
+  Map<String, dynamic> toMap() => {
+        'id': id,
+        'ecu_type': ecuType,
+        'start_time': startTime.millisecondsSinceEpoch,
+        'end_time': endTime?.millisecondsSinceEpoch,
+        'frame_count': frameCount,
+      };
+
+  factory DatalogSession.fromMap(Map<String, dynamic> m) => DatalogSession(
+        id: m['id'] as int?,
+        ecuType: m['ecu_type'] as String,
+        startTime:
+            DateTime.fromMillisecondsSinceEpoch(m['start_time'] as int),
+        endTime: m['end_time'] == null
+            ? null
+            : DateTime.fromMillisecondsSinceEpoch(m['end_time'] as int),
+        frameCount: m['frame_count'] as int? ?? 0,
+      );
+}
diff --git a/lib/core/providers/datalog_provider.dart b/lib/core/providers/datalog_provider.dart
new file mode 100644
index 0000000..da9e592
--- /dev/null
+++ b/lib/core/providers/datalog_provider.dart
@@ -0,0 +1,206 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../datalog/datalog_db.dart';
+import '../datalog/datalog_player.dart';
+import '../datalog/datalog_recorder.dart';
+import '../models/datalog_session.dart';
+import 'bt_provider.dart';
+import 'settings_provider.dart';
+
+// ─── Singletons ───────────────────────────────────────────────────────────────
+
+final datalogDbProvider = Provider<DatalogDb>((ref) {
+  final db = DatalogDb();
+  ref.onDispose(db.close);
+  return db;
+});
+
+final datalogRecorderProvider = Provider<DatalogRecorder>((ref) {
+  final recorder = DatalogRecorder(ref.watch(datalogDbProvider));
+  ref.onDispose(recorder.dispose);
+  return recorder;
+});
+
+final datalogPlayerProvider = Provider<DatalogPlayer>((ref) {
+  final player = DatalogPlayer(ref.watch(datalogDbProvider));
+  ref.onDispose(player.dispose);
+  return player;
+});
+
+// ─── Recording state ──────────────────────────────────────────────────────────
+
+enum RecordingStatus { idle, recording }
+
+class RecordingState {
+  final RecordingStatus status;
+  final int frameCount;
+  final int? sessionId;
+
+  const RecordingState({
+    this.status = RecordingStatus.idle,
+    this.frameCount = 0,
+    this.sessionId,
+  });
+
+  bool get isRecording => status == RecordingStatus.recording;
+
+  RecordingState copyWith({
+    RecordingStatus? status,
+    int? frameCount,
+    int? sessionId,
+  }) =>
+      RecordingState(
+        status: status ?? this.status,
+        frameCount: frameCount ?? this.frameCount,
+        sessionId: sessionId ?? this.sessionId,
+      );
+}
+
+class RecordingNotifier extends StateNotifier<RecordingState> {
+  final Ref _ref;
+
+  RecordingNotifier(this._ref) : super(const RecordingState());
+
+  Future<void> startRecording() async {
+    if (state.isRecording) return;
+
+    final recorder = _ref.read(datalogRecorderProvider);
+    final btNotifier = _ref.read(btProvider.notifier);
+    final ecuType = _ref.read(settingsProvider).ecuType.name;
+
+    await recorder.start(btNotifier.frameStream, ecuType);
+
+    state = RecordingState(
+      status: RecordingStatus.recording,
+      sessionId: recorder.sessionId,
+    );
+  }
+
+  Future<DatalogSession?> stopRecording() async {
+    if (!state.isRecording) return null;
+
+    final recorder = _ref.read(datalogRecorderProvider);
+    final session = await recorder.stop();
+
+    state = const RecordingState();
+    // Refresh session list
+    _ref.invalidate(sessionListProvider);
+    return session;
+  }
+
+  /// Called periodically from UI to update live frame count display.
+  void syncFrameCount() {
+    if (!state.isRecording) return;
+    final count = _ref.read(datalogRecorderProvider).frameCount;
+    if (count != state.frameCount) {
+      state = state.copyWith(frameCount: count);
+    }
+  }
+}
+
+final recordingProvider =
+    StateNotifierProvider<RecordingNotifier, RecordingState>(
+  (ref) => RecordingNotifier(ref),
+);
+
+// ─── Session list ─────────────────────────────────────────────────────────────
+
+final sessionListProvider = FutureProvider<List<DatalogSession>>((ref) {
+  return ref.watch(datalogDbProvider).getSessions();
+});
+
+// ─── Playback state ───────────────────────────────────────────────────────────
+
+class PlaybackState {
+  final bool isActive;
+  final int? sessionId;
+  final int position;
+  final int total;
+  final double speed;
+  final PlaybackStatus status;
+
+  const PlaybackState({
+    this.isActive = false,
+    this.sessionId,
+    this.position = 0,
+    this.total = 0,
+    this.speed = 1.0,
+    this.status = PlaybackStatus.idle,
+  });
+
+  double get progress => total == 0 ? 0 : position / total;
+
+  PlaybackState copyWith({
+    bool? isActive,
+    int? sessionId,
+    int? position,
+    int? total,
+    double? speed,
+    PlaybackStatus? status,
+  }) =>
+      PlaybackState(
+        isActive: isActive ?? this.isActive,
+        sessionId: sessionId ?? this.sessionId,
+        position: position ?? this.position,
+        total: total ?? this.total,
+        speed: speed ?? this.speed,
+        status: status ?? this.status,
+      );
+}
+
+class PlaybackNotifier extends StateNotifier<PlaybackState> {
+  final Ref _ref;
+
+  PlaybackNotifier(this._ref) : super(const PlaybackState());
+
+  Future<void> loadSession(int sessionId) async {
+    final player = _ref.read(datalogPlayerProvider);
+    await player.load(sessionId);
+
+    player.onProgress = (pos, total) {
+      state = state.copyWith(
+        position: pos,
+        total: total,
+        status: player.status,
+      );
+    };
+
+    state = PlaybackState(
+      isActive: true,
+      sessionId: sessionId,
+      total: player.totalFrames,
+      speed: player.speed,
+      status: PlaybackStatus.idle,
+    );
+  }
+
+  void play() {
+    _ref.read(datalogPlayerProvider).play();
+    state = state.copyWith(status: PlaybackStatus.playing);
+  }
+
+  void pause() {
+    _ref.read(datalogPlayerProvider).pause();
+    state = state.copyWith(status: PlaybackStatus.paused);
+  }
+
+  Future<void> stop() async {
+    await _ref.read(datalogPlayerProvider).stop();
+    state = const PlaybackState();
+  }
+
+  void seek(int index) {
+    _ref.read(datalogPlayerProvider).seek(index);
+    state = state.copyWith(position: index);
+  }
+
+  void setSpeed(double speed) {
+    _ref.read(datalogPlayerProvider).speed = speed;
+    state = state.copyWith(speed: speed);
+  }
+}
+
+final playbackProvider =
+    StateNotifierProvider<PlaybackNotifier, PlaybackState>(
+  (ref) => PlaybackNotifier(ref),
+);
diff --git a/pubspec.lock b/pubspec.lock
index 89e2610..5b3c018 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -273,7 +273,7 @@ packages:
     source: hosted
     version: "2.2.0"
   path:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: path
       sha256: "75cca69d1490965be98c73ceaea117e8a04dd21217b37b292c9ddbec0d955bc5"
diff --git a/pubspec.yaml b/pubspec.yaml
index a8eda0d..806c1a2 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -3,7 +3,7 @@ description: HV BT Automotive ECU Dashboard
 
 publish_to: 'none'
 
-version: 1.2.0+3
+version: 1.3.0+4
 
 environment:
   sdk: '>=3.0.0 <4.0.0'
@@ -18,6 +18,7 @@ dependencies:
   shared_preferences: ^2.2.0
   path_provider: ^2.1.0
   intl: ^0.19.0
+  path: ^1.9.0
   permission_handler: ^11.0.0
 
 dev_dependencies: