fix(navigation): preserve disabled preference

src/test/java/games/dmg/spigotbase/BaseNavigationProgressionTest.java

@@ -1,6 +1,7 @@
 package games.dmg.spigotbase;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.Map;
@@ -21,4 +22,18 @@ final class BaseNavigationProgressionTest {
         assertTrue(update.player().navigationEnabled());
         assertTrue(update.unlockedBaseLevel());
     }
+
+    @Test
+    void laterProgressPreservesDisabledNavigationPreference() {
+        BaseProgressionService service =
+            new BaseProgressionService(PluginSettings.from(Map.of()));
+        PlayerState player = PlayerState.newPlayer(UUID.randomUUID(), "Alex")
+            .withGrassAndDirtProgress(500, 2)
+            .withNavigationEnabled(false);
+
+        ProgressionUpdate update = service.recordGrassOrDirtBreak(player);
+
+        assertFalse(update.player().navigationEnabled());
+        assertFalse(update.unlockedBaseLevel());
+    }
 }

src/test/java/games/dmg/spigotbase/NavigationPreferenceTest.java

@@ -0,0 +1,35 @@
+package games.dmg.spigotbase;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+final class NavigationPreferenceTest {
+    @Test
+    void noArgumentTogglesCurrentPreference() {
+        assertFalse(NavigationPreference.resolve(true, new String[0]));
+        assertTrue(NavigationPreference.resolve(false, new String[0]));
+    }
+
+    @Test
+    void explicitModesAreIdempotent() {
+        assertTrue(NavigationPreference.resolve(true, new String[] {"on"}));
+        assertTrue(NavigationPreference.resolve(false, new String[] {"on"}));
+        assertFalse(NavigationPreference.resolve(true, new String[] {"off"}));
+        assertFalse(NavigationPreference.resolve(false, new String[] {"off"}));
+    }
+
+    @Test
+    void rejectsUnknownOrExtraArguments() {
+        assertThrows(
+            IllegalArgumentException.class,
+            () -> NavigationPreference.resolve(false, new String[] {"maybe"})
+        );
+        assertThrows(
+            IllegalArgumentException.class,
+            () -> NavigationPreference.resolve(false, new String[] {"on", "off"})
+        );
+    }
+}