Skip S300 placeholders after raw receipt

lib/core/bluetooth/bt_poller.dart

@@ -87,12 +87,6 @@ class BtPoller {
       final Uint8List frame =
           Uint8List.fromList(_rxBuf.sublist(startIdx, startIdx + 128));
 
-      if (ecuType == EcuType.s300 && _isS300PlaceholderFrame(frame)) {
-        droppedFrames++;
-        _rxBuf.removeRange(0, startIdx + 128);
-        continue;
-      }
-
       final checksumOk = validateFrame(frame);
       final canUseFrame = checksumOk || ecuType == EcuType.s300;
 
@@ -125,31 +119,4 @@ class BtPoller {
     stop();
     _frameController.close();
   }
-
-  bool _isS300PlaceholderFrame(Uint8List frame) {
-    if (frame.length != 128) return false;
-
-    // The S300 Bluetooth stream can interleave a valid-checksum placeholder
-    // frame that is not the SManager live sensor frame. It has a fixed header
-    // and zero/overflow values for speed, TPS, injection and ignition, then it
-    // overwrites the dashboard with stale/empty values. Filter only this exact
-    // signature so true idle/stopped live frames can still pass.
-    return frame[0] == 0x1B &&
-        frame[1] == 0x00 &&
-        frame[2] == 0x14 &&
-        frame[3] == 0x00 &&
-        frame[4] == 0x00 &&
-        frame[5] == 0xFF &&
-        frame[6] == 0xFF &&
-        frame[7] == 0xF2 &&
-        frame[8] == 0x03 &&
-        frame[9] == 0x18 &&
-        frame[10] == 0x00 &&
-        frame[11] == 0x00 &&
-        frame[12] == 0x10 &&
-        frame[13] == 0x00 &&
-        frame[14] == 0x00 &&
-        frame[15] == 0x00 &&
-        frame[16] == 0xC4;
-  }
 }

lib/core/protocol/s300_parser.dart

@@ -3,6 +3,33 @@ import 'sensor_state.dart';
 import 'temp_table.dart';
 import 'neg8.dart';
 
+bool isS300PlaceholderFrame(Uint8List frame) {
+  if (frame.length != 128) return false;
+
+  // The S300 Bluetooth stream can interleave a valid-checksum placeholder
+  // frame that is not the SManager live sensor frame. It has a fixed header
+  // and zero/overflow values for speed, TPS, injection and ignition, then it
+  // overwrites the dashboard with stale/empty values. Keep this check near the
+  // parser so Bluetooth diagnostics can still receive and count raw frames.
+  return frame[0] == 0x1B &&
+      frame[1] == 0x00 &&
+      frame[2] == 0x14 &&
+      frame[3] == 0x00 &&
+      frame[4] == 0x00 &&
+      frame[5] == 0xFF &&
+      frame[6] == 0xFF &&
+      frame[7] == 0xF2 &&
+      frame[8] == 0x03 &&
+      frame[9] == 0x18 &&
+      frame[10] == 0x00 &&
+      frame[11] == 0x00 &&
+      frame[12] == 0x10 &&
+      frame[13] == 0x00 &&
+      frame[14] == 0x00 &&
+      frame[15] == 0x00 &&
+      frame[16] == 0xC4;
+}
+
 /// Parses a 128-byte S300 ECU response frame into a [SensorState].
 /// Throws [ArgumentError] if frame length is wrong, or if [validateChecksum]
 /// is true and the NEG8 checksum fails.

lib/core/providers/sensor_provider.dart

@@ -7,18 +7,22 @@ import '../protocol/sensor_state.dart';
 import 'bt_provider.dart';
 import 'settings_provider.dart';
 
-/// Emits a parsed [SensorState] for every valid frame received from the ECU.
+/// Emits a parsed [SensorState] for every live data frame received from the ECU.
 /// Automatically picks S300 or KPro parser based on [settingsProvider].
-final sensorStateProvider = StreamProvider<SensorState>((ref) {
+final sensorStateProvider = StreamProvider<SensorState>((ref) async* {
   final ecuType = ref.watch(settingsProvider).ecuType;
   final btNotifier = ref.watch(btProvider.notifier);
 
-  return btNotifier.frameStream.map((frame) {
+  await for (final frame in btNotifier.frameStream) {
     if (ecuType == EcuType.s300) {
-      return parseS300(frame, validateChecksum: false);
+      if (isS300PlaceholderFrame(frame)) {
+        continue;
+      }
+      yield parseS300(frame, validateChecksum: false);
+    } else {
+      yield parseKPro(frame);
     }
-    return parseKPro(frame);
-  });
+  }
 });
 
 /// Last successfully parsed sensor state (never null after first frame).

test/s300_parser_test.dart

@@ -1,5 +1,6 @@
 import 'dart:typed_data';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:hvbt_dash/core/protocol/neg8.dart';
 import 'package:hvbt_dash/core/protocol/s300_parser.dart';
 import 'package:hvbt_dash/core/protocol/temp_table.dart';
 
@@ -159,5 +160,34 @@ void main() {
       final state = parseS300(frame, validateChecksum: false);
       expect(state.rpm, equals(1000.0));
     });
+
+    test('detects known S300 placeholder frame', () {
+      final frame = Uint8List(128);
+      final signature = [
+        0x1B,
+        0x00,
+        0x14,
+        0x00,
+        0x00,
+        0xFF,
+        0xFF,
+        0xF2,
+        0x03,
+        0x18,
+        0x00,
+        0x00,
+        0x10,
+        0x00,
+        0x00,
+        0x00,
+        0xC4,
+      ];
+      for (var i = 0; i < signature.length; i++) {
+        frame[i] = signature[i];
+      }
+      frame[127] = calculateNeg8(frame.sublist(0, 127));
+
+      expect(isS300PlaceholderFrame(frame), isTrue);
+    });
   });
 }