From f3af98e211c620f691582a9da474d754af878adb Mon Sep 17 00:00:00 2001
From: Ib Green <7025232+ibgreen@users.noreply.github.com>
Date: Fri, 31 Jul 2026 09:25:23 -0400
Subject: [PATCH 1/2] test(mvt): stabilize polygon comparison

---
 modules/mvt/test/mvt-loader.spec.ts | 50 +++++++++++++++++++++++++----
 1 file changed, 44 insertions(+), 6 deletions(-)

diff --git a/modules/mvt/test/mvt-loader.spec.ts b/modules/mvt/test/mvt-loader.spec.ts
index 009adaad9d..fdf3a9b524 100644
--- a/modules/mvt/test/mvt-loader.spec.ts
+++ b/modules/mvt/test/mvt-loader.spec.ts
@@ -209,16 +209,25 @@ test('MVTLoader#Parse Polygons MVT', async t => {
     };
 
     const geometry = await parse(mvtArrayBuffer, MVTLoader, loaderOptions);
-    let expected = binary
-      ? decodedPolygonsGeoJSON
-      : {shape: 'geojson-table', type: 'FeatureCollection', features: decodedPolygonsGeoJSON};
     if (binary) {
-      // @ts-ignore
-      expected = geojsonToBinary(expected, {fixRingWinding: false});
+      const expected = geojsonToBinary(structuredClone(decodedPolygonsGeoJSON), {
+        fixRingWinding: false
+      });
       t.ok(geometry.byteLength > 0);
       delete geometry.byteLength;
+      t.deepEqual(geometry, expected, `Parsed Polygons MVT as ${outputFormat}`);
+    } else {
+      const expected = {
+        shape: 'geojson-table',
+        type: 'FeatureCollection',
+        features: normalizeGeoJsonFeatures(decodedPolygonsGeoJSON)
+      };
+      const normalizedGeometry = {
+        ...geometry,
+        features: normalizeGeoJsonFeatures(geometry.features)
+      };
+      t.deepEqual(normalizedGeometry, expected, `Parsed Polygons MVT as ${outputFormat}`);
     }
-    t.deepEqual(geometry, expected, `Parsed Polygons MVT as ${outputFormat}`);
   }
   t.end();
 });
@@ -368,3 +377,32 @@ test('Triangulation is supported', async t => {
 
   t.end();
 });
+
+/**
+ * Copies GeoJSON features while normalizing projected coordinate precision for stable comparisons.
+ *
+ * @param features GeoJSON features to normalize.
+ * @returns Feature copies with rounded geometry coordinates.
+ */
+function normalizeGeoJsonFeatures(features: any[]): any[] {
+  return features.map(feature => ({
+    ...feature,
+    geometry: {
+      ...feature.geometry,
+      coordinates: roundCoordinates(feature.geometry.coordinates)
+    }
+  }));
+}
+
+/**
+ * Rounds nested coordinates to avoid browser-specific floating-point projection drift.
+ *
+ * @param coordinates Nested GeoJSON coordinate values.
+ * @returns Coordinates rounded to stable sub-millimeter precision.
+ */
+function roundCoordinates(coordinates: any): any {
+  if (Array.isArray(coordinates)) {
+    return coordinates.map(value => roundCoordinates(value));
+  }
+  return typeof coordinates === 'number' ? Number(coordinates.toFixed(9)) : coordinates;
+}

From 05e90cc84f5abe65789c798243075179dc87974a Mon Sep 17 00:00:00 2001
From: Ib Green <7025232+ibgreen@users.noreply.github.com>
Date: Fri, 31 Jul 2026 09:36:34 -0400
Subject: [PATCH 2/2] test: stabilize headless browser CI

---
 .../devtools-extensions/get-playwright-launch-options.mjs   | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/dev-modules/devtools-extensions/get-playwright-launch-options.mjs b/dev-modules/devtools-extensions/get-playwright-launch-options.mjs
index 79204197e9..8e39a5f788 100644
--- a/dev-modules/devtools-extensions/get-playwright-launch-options.mjs
+++ b/dev-modules/devtools-extensions/get-playwright-launch-options.mjs
@@ -1,5 +1,9 @@
 const DEFAULT_PLAYWRIGHT_CHANNEL = 'chromium';
-const DEFAULT_PLAYWRIGHT_ARGS = ['--enable-unsafe-webgpu', '--ignore-gpu-blocklist'];
+const DEFAULT_PLAYWRIGHT_ARGS = [
+  '--disable-dev-shm-usage',
+  '--enable-unsafe-webgpu',
+  '--ignore-gpu-blocklist'
+];
 const SOFTWARE_GPU_ARGS = ['--use-angle=swiftshader', '--enable-unsafe-swiftshader'];
 
 export function getPlaywrightLaunchOptions(options = {}) {