Activate coalescing in layouts for assoc scatter

esm/components/data_layer/scatter.js

@@ -13,11 +13,12 @@ const default_layout = {
     tooltip_positioning: 'horizontal',
     color: '#888888',
     coalesce: {
-        // Should we try to combine adjacent insignificant ("some region of interest") points
+        // Options to control whether and how to combine adjacent insignificant ("within region of interest") points
         //  to improve rendering performance?
-        active: true,
+        active: false,
         max_points: 800, // Many plots are 800-2400 px wide, so, more than 1 datum per pixel of average region width
-        // These are expressed in terms of data value and will be converted to pixels internally.
+        // Define the "region of interest", like "bottom half of plot"; any points outside this region are taken as is
+        //   Values are expressed in terms of data value and will be converted to pixels internally.
         x_min: '-Infinity',
         x_max: 'Infinity',
         y_min: 0,

esm/layouts/index.js

@@ -117,6 +117,9 @@ const association_pvalues_layer = {
     namespace: { 'assoc': 'assoc', 'ld': 'ld' },
     id: 'associationpvalues',
     type: 'scatter',
+    coalesce: {
+        active: true,
+    },
     point_shape: {
         scale_function: 'if',
         field: '{{namespace[ld]}}isrefvar',

test/unit/helpers/test_render.js

@@ -40,7 +40,7 @@ describe('Coordinate coalescing', function () {
     });
     describe('coalesce_scatter_points', function () {
         it('handles wide spans for any y within bounds', function () {
-            var actual = coalesce_scatter_points(
+            const actual = coalesce_scatter_points(
                 this.sample_data,
                 -Infinity, Infinity, 3,
                 0, 1, Infinity
@@ -116,5 +116,19 @@ describe('Coordinate coalescing', function () {
             assert.equal(actual.length, expected.length, 'Found correct number of items');
             assert.deepStrictEqual(actual, expected, 'Specified items are present');
         });
+
+        it('always adds points that are explicitly marked significant', function () {
+            const sample_data = _addSymbols([
+                { x: 0, y: 0.5, lz_highlight_match: true },
+                { x: 1, y: 0.9, lz_highlight_match: true },
+                { x: 2, y: 0.999, lz_highlight_match: true },
+            ]);
+            const actual = coalesce_scatter_points(
+                sample_data,
+                -Infinity, Infinity, 3,
+                0, 1, Infinity
+            );
+            assert.deepStrictEqual(actual, sample_data, 'Significant points do not coalesce');
+        });
     });
 });