fix: normalise raw rotation angle to [-180, 180)

lib/src/gestures/map_interactive_viewer.dart

@@ -555,7 +555,10 @@ class MapInteractiveViewerState extends State<MapInteractiveViewer>
       return;
     }
 
-    final currentRotation = details.rotation * radians2Degrees;
+    // `details.rotation` is a raw difference of two `atan2` angles: two fingers
+    // side by side rotated by 4° may report -356°. Normalise to [-180, 180).
+    final currentRotation =
+        (details.rotation * radians2Degrees + 180) % 360 - 180;
     if (_dragMode) {
       _handleScaleDragUpdate(details);
     } else if (InteractiveFlag.hasMultiFinger(_interactionOptions.flags)) {

test/gestures/rotation_normalisation_test.dart

@@ -0,0 +1,67 @@
+import 'dart:math' as math;
+
+import 'package:flutter/widgets.dart';
+import 'package:flutter_map/flutter_map.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:latlong2/latlong.dart';
+
+/// Two fingers around [c], [scale] times their initial 100 px apart, the
+/// line between them rotated by [degrees]. At 0° the line runs along the x
+/// axis with the first finger to the left: `atan2` of the start line is 180°,
+/// so a small rotation crosses ±180°.
+List<Offset> _fingers(Offset c, double scale, double degrees) {
+  final a = degrees * math.pi / 180;
+  final v = Offset(math.cos(a), math.sin(a)) * 50 * scale;
+  return [c - v, c + v];
+}
+
+void main() {
+  testWidgets('a small rotation across ±180° does not win the gesture race',
+      (tester) async {
+    final controller = MapController();
+    await tester.pumpWidget(
+      Directionality(
+        textDirection: TextDirection.ltr,
+        child: Center(
+          child: SizedBox(
+            width: 400,
+            height: 400,
+            child: FlutterMap(
+              mapController: controller,
+              options: const MapOptions(
+                initialCenter: LatLng(46.5, 6.6),
+                initialZoom: 10,
+                interactionOptions: InteractionOptions(
+                  enableMultiFingerGestureRace: true,
+                ),
+              ),
+              children: const [],
+            ),
+          ),
+        ),
+      ),
+    );
+
+    final c = tester.getCenter(find.byType(FlutterMap));
+    final start = _fingers(c, 1, 0);
+    final g1 = await tester.startGesture(start[0], pointer: 1);
+    final g2 = await tester.startGesture(start[1], pointer: 2);
+    await tester.pump();
+    // Spread the fingers too, so the gesture passes the touch slop.
+    for (final (scale, degrees) in [(1.2, 2.0), (1.4, 4.0)]) {
+      final p = _fingers(c, scale, degrees);
+      await g1.moveTo(p[0]);
+      await g2.moveTo(p[1]);
+      await tester.pump();
+    }
+    await g1.up();
+    await g2.up();
+    await tester.pumpAndSettle();
+    // Let the double tap timer expire.
+    await tester.pump(const Duration(seconds: 1));
+
+    // 4° is below the default rotationThreshold (20°): rotation must not win
+    // the race, which the raw -356° value made it do.
+    expect(controller.camera.rotation, 0);
+  });
+}