Lower world effect thresholds to achievable levels; add water pollution to furnaces

The previous thresholds (grass=60, smoke=70) required pollutionScore > 60.
pollutionScore is a weighted average, so even if air pollution caps at 100
the score only reaches 40 from air alone — the thresholds were physically
unreachable from furnace burning.

New thresholds: grass degradation fires at pollutionScore > 15 (soilQuality
gate raised to 75 so it doesn't block — soil defaults to 60), smoke
particles fire at > 10. With 4 furnaces the score reaches ~15 in about
20 real simulation ticks (~2 minutes of play).

Also added acid-rain water pollution (0.1/furnace/scan) — coal burning
emits SO₂ which contributes to the weighted score alongside the existing
air and ground components.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/main/java/com/livingworld/LivingWorldMod.java

@@ -40,7 +40,8 @@ public class LivingWorldMod {
 
     private static final int    FURNACE_SCAN_INTERVAL         = 100;
     private static final double AIR_POLLUTION_PER_FURNACE    = 0.5;
-    private static final double SOIL_POLLUTION_PER_FURNACE = 0.1;
+    private static final double GROUND_POLLUTION_PER_FURNACE = 0.1;
+    private static final double WATER_POLLUTION_PER_FURNACE  = 0.1;
 
     private final LivingWorldBootstrap bootstrap;
     private MinecraftServer minecraftServer;
@@ -95,7 +96,8 @@ public class LivingWorldMod {
             if (litCount > 0) {
                 bootstrap.handleFurnaceActivity(region,
                         litCount * AIR_POLLUTION_PER_FURNACE,
-                        litCount * SOIL_POLLUTION_PER_FURNACE);
+                        litCount * GROUND_POLLUTION_PER_FURNACE,
+                        litCount * WATER_POLLUTION_PER_FURNACE);
             }
         }
     }

src/main/java/com/livingworld/bootstrap/LivingWorldBootstrap.java

@@ -206,13 +206,15 @@ public final class LivingWorldBootstrap {
     /**
      * Records pollution produced by burning activity (e.g. furnaces) in a region.
      * Called from the platform layer once per simulation interval.
+     *
+     * @param waterAmount acid-rain component — SO₂ from coal dissolves in atmospheric moisture
      */
-    public void handleFurnaceActivity(Region region, double airAmount, double groundAmount) {
+    public void handleFurnaceActivity(Region region, double airAmount, double groundAmount, double waterAmount) {
         if (!serverReady || region == null) return;
         PollutionRegionData data = region.getModuleData()
                 .get(PollutionModule.MODULE_ID, PollutionRegionData.class)
                 .orElseGet(PollutionRegionData::defaults);
-        data.addPollution(airAmount, groundAmount, 0.0);
+        data.addPollution(airAmount, groundAmount, waterAmount);
         region.getModuleData().put(PollutionModule.MODULE_ID, data);
         regionManager.markDirty(region);
     }

src/main/java/com/livingworld/modules/worldeffects/WorldEffectsModule.java

@@ -54,12 +54,15 @@ public final class WorldEffectsModule implements SimulationModule {
     public static final String MODULE_ID = "worldeffects";
 
     // Thresholds that trigger effect requests.
-    private static final double GRASS_DEGRADE_POLLUTION_MIN  = 60.0;
-    private static final double GRASS_DEGRADE_SOIL_MAX       = 30.0;
+    // Grass degradation: pollution score > 15 AND soil quality below the gate.
+    // Soil defaults to 60 so the gate is set at 75 to avoid blocking early effects.
+    private static final double GRASS_DEGRADE_POLLUTION_MIN  = 15.0;
+    private static final double GRASS_DEGRADE_SOIL_MAX       = 75.0;
     private static final double VEG_SPREAD_VEG_MIN           = 60.0;
     private static final double VEG_SPREAD_SOIL_MIN          = 50.0;
     private static final double SAPLING_SLOW_LOGGING_MIN     = 50.0;
-    private static final double POLLUTION_INDICATOR_MIN      = 70.0;
+    // Smoke particles appear as soon as any meaningful pollution exists.
+    private static final double POLLUTION_INDICATOR_MIN      = 10.0;
 
     private static final ModuleMetadata METADATA = new ModuleMetadata(
             MODULE_ID,

src/test/java/com/livingworld/modules/worldeffects/WorldEffectsModuleTest.java

@@ -97,7 +97,7 @@ class WorldEffectsModuleTest {
     @Test
     @DisplayName("GRASS_DEGRADES_TO_DIRT not emitted when pollution is low")
     void grassDegradeNotEmittedLowPollution() {
-        metrics.setPollutionScore(30.0);
+        metrics.setPollutionScore(10.0);
         metrics.setSoilQuality(15.0);
 
         module.updateRegion(new RegionUpdateContext(region));
@@ -204,7 +204,7 @@ class WorldEffectsModuleTest {
     @Test
     @DisplayName("POLLUTION_VISUAL_INDICATOR not emitted below threshold")
     void pollutionVisualNotEmitted() {
-        metrics.setPollutionScore(50.0);
+        metrics.setPollutionScore(5.0);
 
         module.updateRegion(new RegionUpdateContext(region));