updated coding standards

tooling/coverage/Coverage.java

@@ -0,0 +1,30 @@
+import java.nio.file.Path;
+import javax.xml.parsers.DocumentBuilderFactory;
+import org.w3c.dom.Element;
+
+/** Exact module-wide line gate; consumes JaCoCo XML without rounding percentages. */
+public class Coverage {
+  public static void main(String[] args) throws Exception {
+    final var factory = DocumentBuilderFactory.newInstance();
+    factory.setFeature("http://xml.org/sax/features/external-general-entities", false);
+    factory.setFeature("http://xml.org/sax/features/external-parameter-entities", false);
+    factory.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
+    final Element report =
+        factory.newDocumentBuilder().parse(Path.of(args[0]).toFile()).getDocumentElement();
+    for (var child = report.getFirstChild(); child != null; child = child.getNextSibling()) {
+      if (child instanceof Element counter
+          && counter.getTagName().equals("counter")
+          && counter.getAttribute("type").equals("LINE")) {
+        final long covered = Long.parseLong(counter.getAttribute("covered"));
+        final long missed = Long.parseLong(counter.getAttribute("missed"));
+        final long total = covered + missed;
+        System.out.println("Backend line coverage: " + covered + "/" + total + " ("
+            + 100.0 * covered / total + "%)");
+        if (total == 0 || 5 * covered < 4 * total)
+          throw new IllegalStateException("Backend line coverage must reach 80%: " + args[0]);
+        return;
+      }
+    }
+    throw new IllegalStateException("Missing module LINE counter: " + args[0]);
+  }
+}