Ignore min_size when tile_post_process exists

planetiler-custommap/src/main/java/com/onthegomap/planetiler/custommap/ConfiguredFeature.java

@@ -21,6 +21,8 @@ import java.util.Objects;
 import java.util.Set;
 import java.util.function.BiConsumer;
 import java.util.function.Function;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * A map feature, configured from a YML configuration file.
@@ -29,6 +31,8 @@ import java.util.function.Function;
  * and {@link #processFeature(Contexts.FeaturePostMatch, FeatureCollector)} processes matching elements.
  */
 public class ConfiguredFeature {
+  private static final Logger LOGGER = LoggerFactory.getLogger(ConfiguredFeature.class);
+
   private static final double LOG4 = Math.log(4);
   private final Expression geometryTest;
   private final Function<FeatureCollector, Feature> geometryFactory;
@@ -91,8 +95,14 @@ public class ConfiguredFeature {
     }
     processors.add(makeFeatureProcessor(feature.minZoom(), Integer.class, Feature::setMinZoom));
     processors.add(makeFeatureProcessor(feature.maxZoom(), Integer.class, Feature::setMaxZoom));
-    processors.add(makeFeatureProcessor(feature.minSize(), Double.class, Feature::setMinPixelSize));
-    if (layer.postProcess() != null) {
+    if (layer.postProcess() == null) {
+      processors.add(makeFeatureProcessor(feature.minSize(), Double.class, Feature::setMinPixelSize));
+    } else {
+      processors.add(makeFeatureProcessor(0, Double.class, Feature::setMinPixelSize));
+      if (feature.minSize() != null ) {
+	LOGGER.info("Ignored min_size settings in layer {} in favour of its tile_post_process settings",
+	    layer.id());
+      }
       var merge = layer.postProcess().mergeLineStrings();
       if (merge != null) {
         var minLength = merge.minLength();

planetiler-custommap/src/test/java/com/onthegomap/planetiler/custommap/ConfiguredFeatureTest.java

@@ -226,6 +226,29 @@ class ConfiguredFeatureTest {
     assertEquals(List.of(feature), profile.postProcessLayerFeatures("testLayer", 0, List.of(feature)));
   }
 
+  @Test
+  void testMergeLineStringMinLengthSetsBufferPixels() {
+    testLinestring("""
+      sources:
+        osm:
+          type: osm
+          url: geofabrik:rhode-island
+          local_path: data/rhode-island.osm.pbf
+      layers:
+      - id: testLayer
+        features:
+        - source: osm
+          geometry: line
+        tile_post_process:
+          merge_line_strings:
+            min_length: 10
+            tolerance: 5
+            buffer: 4
+      """, Map.of(), f -> {
+      assertEquals(10, f.getBufferPixelsAtZoom(14));
+    }, 1);
+  }
+
   @Test
   void testFeaturePostProcessorMergePolygons() throws GeometryException {
     var config = """