chore: import upstream snapshot with attribution

scripts/aggregate-assert.mjs

@@ -0,0 +1,82 @@
+import nodeAssert from "node:assert/strict";
+import { mkdirSync, writeFileSync } from "node:fs";
+import { dirname } from "node:path";
+
+const methods = ["deepEqual", "doesNotMatch", "equal", "match", "notEqual", "ok"];
+
+function formatError(error) {
+  if (!(error instanceof Error)) return String(error);
+  return error.stack || error.message;
+}
+
+function formatFailure(failure, index) {
+  const header = `${index + 1}. ${failure.method}: ${failure.message}`;
+  return failure.stack ? `${header}\n${failure.stack}` : header;
+}
+
+export function createAggregateAssert(options = {}) {
+  const failFast = process.env.ZERO_VALIDATION_FAIL_FAST === "1" ||
+    process.env.ZERO_ASSERT_FAIL_FAST === "1" ||
+    options.failFast === true;
+  const failures = [];
+
+  function record(method, error) {
+    if (failFast) throw error;
+    failures.push({
+      method,
+      message: error instanceof Error ? error.message : String(error),
+      stack: error instanceof Error ? error.stack : "",
+    });
+  }
+
+  function aggregateAssert(value, message) {
+    try {
+      nodeAssert(value, message);
+    } catch (error) {
+      record("assert", error);
+    }
+  }
+
+  for (const method of methods) {
+    aggregateAssert[method] = (...args) => {
+      try {
+        nodeAssert[method](...args);
+      } catch (error) {
+        record(method, error);
+      }
+    };
+  }
+
+  aggregateAssert.fail = (...args) => {
+    try {
+      nodeAssert.fail(...args);
+    } catch (error) {
+      record("fail", error);
+    }
+  };
+
+  aggregateAssert.failures = failures;
+  return aggregateAssert;
+}
+
+export function finishAggregateAssert(assert, options = {}) {
+  const failures = assert?.failures ?? [];
+  if (failures.length === 0) return;
+
+  const suite = options.suite || "validation";
+  const reportPath = options.reportPath;
+  const summary = failures.map(formatFailure).join("\n\n");
+  const text = `${suite} collected ${failures.length} assertion failure(s):\n\n${summary}\n`;
+
+  if (reportPath) {
+    mkdirSync(dirname(reportPath), { recursive: true });
+    writeFileSync(reportPath, `${JSON.stringify({ suite, ok: false, failures }, null, 2)}\n`);
+  }
+
+  process.stderr.write(text);
+  process.exit(1);
+}
+
+export function describeFailure(error) {
+  return formatError(error);
+}