feat(core-audit): withAudit wraps and attaches runtime __audited marker

packages/core-audit/src/with-audit.test.ts

@@ -1,6 +1,7 @@
 import { describe, it, expect, expectTypeOf, vi } from "vitest";
 import { withAudit, type Audited } from "@/with-audit";
 import type { IAuditLog } from "@/audit-log.interface";
+import { isAudited } from "@repo/core-shared/conformance";
 
 function makeAuditLog(): IAuditLog {
   return {
@@ -17,6 +18,22 @@ describe("withAudit", () => {
     expectTypeOf(wrapped).toMatchTypeOf<Audited<typeof fn>>();
   });
 
+  it("attaches __audited as a non-enumerable property on the wrapped function", () => {
+    const auditLog = makeAuditLog();
+    const fn = async () => ({ ok: true });
+    const wrapped = withAudit(auditLog, fn);
+    expect(isAudited(wrapped)).toBe(true);
+    expect(Object.keys(wrapped)).not.toContain("__audited");
+  });
+
+  it("does NOT pollute the original input function with the brand", () => {
+    const auditLog = makeAuditLog();
+    const fn = async () => ({ ok: true });
+    const wrapped = withAudit(auditLog, fn);
+    expect(isAudited(fn)).toBe(false);
+    expect(wrapped).not.toBe(fn);
+  });
+
   it("passes input and output through unchanged", async () => {
     const auditLog = makeAuditLog();
     const fn = async (input: { id: string }) => ({ ok: true, id: input.id });