feat: version topology graph metadata

tests/metadata.test.ts

@@ -0,0 +1,45 @@
+import assert from "node:assert/strict";
+import { test } from "node:test";
+import { buildEmptyGraph } from "../src/metadata.js";
+
+const graphArgs = {
+  inputUrl: "./examples/simple.html",
+  entryUrl: "file:///examples/simple.html",
+  mode: "scan" as const,
+};
+
+test("input fingerprint is stable for the same input and mode", () => {
+  const first = buildEmptyGraph(graphArgs);
+  const second = buildEmptyGraph(graphArgs);
+
+  assert.equal(first.metadata.inputFingerprint, second.metadata.inputFingerprint);
+});
+
+test("crawl session id is unique for each generated graph", () => {
+  const first = withFixedDate(() => buildEmptyGraph(graphArgs));
+  const second = withFixedDate(() => buildEmptyGraph(graphArgs));
+
+  assert.notEqual(first.metadata.crawlSessionId, second.metadata.crawlSessionId);
+});
+
+function withFixedDate<T>(callback: () => T): T {
+  const RealDate = Date;
+  const fixedTime = new RealDate("2026-06-16T00:00:00.000Z").getTime();
+
+  class FixedDate extends RealDate {
+    constructor(value?: string | number | Date) {
+      super(value ?? fixedTime);
+    }
+
+    static now(): number {
+      return fixedTime;
+    }
+  }
+
+  globalThis.Date = FixedDate as DateConstructor;
+  try {
+    return callback();
+  } finally {
+    globalThis.Date = RealDate;
+  }
+}