@@ -0,0 +1,87 @@
+// Smoke test for the vendored CSS Grid algorithm (Yoga PR #1894), pinned
+// against real Safari for the identical layout (see /tmp/gl/grid.html).
+//
+//   display: grid; width: 600px; gap: 10px;
+//   grid-template-columns: 100px 1fr 2fr;
+//   grid-template-rows: 50px auto;
+//   six children with fixed heights 20/30/25/40/15/35
+#include <yoga/Yoga.h>
+#include <cstdio>
+#include <cstdlib>
+
+struct Expected {
+  const char* name;
+  float x, y, w, h;
+};
+
+// Ground truth read out of Safari 26 via safaridriver.
+static const Expected kSafari[] = {
+    {"a", 0.0f, 0.0f, 100.0f, 20.0f},
+    {"b", 110.0f, 0.0f, 160.0f, 30.0f},
+    {"c", 280.0f, 0.0f, 320.0f, 25.0f},
+    {"d", 0.0f, 60.0f, 100.0f, 40.0f},
+    {"e", 110.0f, 60.0f, 160.0f, 15.0f},
+    {"f", 280.0f, 60.0f, 320.0f, 35.0f},
+};
+static const float kSafariContainerHeight = 100.0f;
+
+int main() {
+  const float heights[] = {20.0f, 30.0f, 25.0f, 40.0f, 15.0f, 35.0f};
+
+  YGNodeRef root = YGNodeNew();
+  YGNodeStyleSetDisplay(root, YGDisplayGrid);
+  YGNodeStyleSetWidth(root, 600.0f);
+  YGNodeStyleSetGap(root, YGGutterAll, 10.0f);
+
+  YGNodeStyleSetGridTemplateColumnsCount(root, 3);
+  YGNodeStyleSetGridTemplateColumn(root, 0, YGGridTrackTypePoints, 100.0f);
+  YGNodeStyleSetGridTemplateColumn(root, 1, YGGridTrackTypeFr, 1.0f);
+  YGNodeStyleSetGridTemplateColumn(root, 2, YGGridTrackTypeFr, 2.0f);
+
+  YGNodeStyleSetGridTemplateRowsCount(root, 2);
+  YGNodeStyleSetGridTemplateRow(root, 0, YGGridTrackTypePoints, 50.0f);
+  YGNodeStyleSetGridTemplateRow(root, 1, YGGridTrackTypeAuto, 0.0f);
+
+  for (size_t i = 0; i < 6; i++) {
+    YGNodeRef child = YGNodeNew();
+    YGNodeStyleSetHeight(child, heights[i]);
+    YGNodeInsertChild(root, child, i);
+  }
+
+  YGNodeCalculateLayout(root, YGUndefined, YGUndefined, YGDirectionLTR);
+
+  int failures = 0;
+  auto check = [&](const char* what, float actual, float expected) {
+    const bool ok = std::abs(actual - expected) < 0.01f;
+    if (!ok) {
+      failures++;
+    }
+    std::printf(
+        "  %-4s %-2s %7.2f %s %7.2f\n",
+        what,
+        ok ? "ok" : "XX",
+        actual,
+        ok ? "==" : "!=",
+        expected);
+  };
+
+  std::printf("container height:\n");
+  check("h", YGNodeLayoutGetHeight(root), kSafariContainerHeight);
+
+  for (size_t i = 0; i < 6; i++) {
+    const YGNodeRef child = YGNodeGetChild(root, i);
+    const Expected& e = kSafari[i];
+    std::printf("item %s:\n", e.name);
+    check("x", YGNodeLayoutGetLeft(child), e.x);
+    check("y", YGNodeLayoutGetTop(child), e.y);
+    check("w", YGNodeLayoutGetWidth(child), e.w);
+    check("h", YGNodeLayoutGetHeight(child), e.h);
+  }
+
+  YGNodeFreeRecursive(root);
+  std::printf(
+      "\n%s (%d mismatches vs Safari)\n",
+      failures == 0 ? "PASS" : "FAIL",
+      failures);
+  return failures == 0 ? 0 : 1;
+}
@@ -0,0 +1,36 @@
+<!DOCTYPE html>
+<html><head><meta charset="utf-8"><style>
+  * { margin: 0; padding: 0; box-sizing: border-box; }
+  body { margin: 0; }
+  #g {
+    display: grid;
+    width: 600px;
+    grid-template-columns: 100px 1fr 2fr;
+    grid-template-rows: 50px auto;
+    gap: 10px;
+  }
+  #g > div { background: #cde; }
+</style></head>
+<body>
+<div id="g">
+  <div id="a" style="height:20px"></div>
+  <div id="b" style="height:30px"></div>
+  <div id="c" style="height:25px"></div>
+  <div id="d" style="height:40px"></div>
+  <div id="e" style="height:15px"></div>
+  <div id="f" style="height:35px"></div>
+</div>
+<script>
+window.__rects = (function () {
+  const out = {};
+  const g = document.getElementById('g');
+  const gr = g.getBoundingClientRect();
+  out.container = {w: gr.width, h: gr.height};
+  for (const id of ['a','b','c','d','e','f']) {
+    const r = document.getElementById(id).getBoundingClientRect();
+    out[id] = {x: r.left - gr.left, y: r.top - gr.top, w: r.width, h: r.height};
+  }
+  return out;
+})();
+</script>
+</body></html>
@@ -20,7 +20,8 @@ include(${YOGA_ROOT}/cmake/project-defaults.cmake)
 
 file(GLOB SOURCES CONFIGURE_DEPENDS
     ${CMAKE_CURRENT_SOURCE_DIR}/*.cpp
-    ${CMAKE_CURRENT_SOURCE_DIR}/**/*.cpp)
+    ${CMAKE_CURRENT_SOURCE_DIR}/**/*.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/algorithm/grid/*.cpp)
 
 add_library(yogacore STATIC ${SOURCES})
 
 
@@ -29,6 +29,7 @@
 #include <yoga/algorithm/PixelGrid.h>
 #include <yoga/algorithm/SizingMode.h>
 #include <yoga/algorithm/TrailingPosition.h>
+#include <yoga/algorithm/grid/GridLayout.h>
 #include <yoga/debug/AssertFatal.h>
 #include <yoga/debug/Log.h>
 #include <yoga/event/event.h>
@@ -2826,6 +2827,27 @@ static void calculateLayoutImpl(
   // current node as they will not be traversed
   cleanupContentsNodesRecursively(node, performLayout);
 
+  // Grid formatting context: `display: grid` uses the dedicated grid layout
+  // path rather than the flex algorithm below. VENDORED — see
+  // algorithm/grid/README-VENDORED.md.
+  if (node->style().display() == Display::Grid) {
+    calculateGridLayoutInternal(
+        node,
+        availableWidth,
+        availableHeight,
+        ownerDirection,
+        widthSizingMode,
+        heightSizingMode,
+        ownerWidth,
+        ownerHeight,
+        performLayout,
+        reason,
+        layoutMarkerData,
+        depth,
+        generationCount);
+    return;
+  }
+
   // Block formatting context: `display: block` uses a dedicated block layout
   // path rather than the flex algorithm below (text-children-plan.md §3.A/§4.5).
   if (node->style().display() == Display::Block) {