feat(core-audit): MultiSinkAuditLog fan-out with settle-all + stderr fallback

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/core-audit/src/multi-sink-audit-log.test.ts

@@ -0,0 +1,65 @@
+import { describe, it, expect, vi } from "vitest";
+import { MultiSinkAuditLog } from "./multi-sink-audit-log";
+import type { AuditEntry } from "@repo/core-shared/audit";
+import type { IAuditLog } from "./audit-log.interface";
+
+const sample: AuditEntry = {
+  actorId: "user_1",
+  actorType: "user",
+  actorRoles: [],
+  action: "VIEW",
+  resource: { type: "articles" },
+  at: new Date(),
+  scope: { feature: "blog", environment: "test", tenant: "default" },
+  from: { ipTruncated: "10.0.0.0", userAgent: "test" },
+  containsPii: false,
+  outcome: "success",
+};
+
+function makeRecorder(): IAuditLog & { records: AuditEntry[]; erasures: string[] } {
+  const records: AuditEntry[] = [];
+  const erasures: string[] = [];
+  return {
+    records,
+    erasures,
+    async record(e) { records.push(e); },
+    async eraseSubject(actorId) { erasures.push(actorId); },
+  };
+}
+
+describe("MultiSinkAuditLog", () => {
+  it("record() fans out to every sink", async () => {
+    const a = makeRecorder();
+    const b = makeRecorder();
+    const m = new MultiSinkAuditLog([a, b]);
+    await m.record(sample);
+    expect(a.records).toHaveLength(1);
+    expect(b.records).toHaveLength(1);
+  });
+
+  it("settle-all: one sink failing does not skip others", async () => {
+    const errSpy = vi.spyOn(process.stderr, "write").mockImplementation(() => true);
+    const a: IAuditLog = { record: async () => { throw new Error("a-fail"); }, eraseSubject: async () => {} };
+    const b = makeRecorder();
+    const m = new MultiSinkAuditLog([a, b]);
+
+    await m.record(sample);
+
+    expect(b.records).toHaveLength(1);  // b still received the entry
+    expect(errSpy).toHaveBeenCalledOnce();
+    const written = errSpy.mock.calls[0]![0] as string;
+    const parsed = JSON.parse(written.trimEnd());
+    expect(parsed._type).toBe("audit-sink-error");
+    expect(parsed.error).toContain("a-fail");
+    errSpy.mockRestore();
+  });
+
+  it("eraseSubject() fans out to every sink", async () => {
+    const a = makeRecorder();
+    const b = makeRecorder();
+    const m = new MultiSinkAuditLog([a, b]);
+    await m.eraseSubject("user_1", "delete");
+    expect(a.erasures).toEqual(["user_1"]);
+    expect(b.erasures).toEqual(["user_1"]);
+  });
+});