fix(build): stamp runtime postbuild artifacts

test/scripts/runtime-postbuild-stamp.test.ts

@@ -0,0 +1,29 @@
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+import { describe, expect, it } from "vitest";
+import { RUNTIME_POSTBUILD_STAMP_FILE } from "../../scripts/lib/local-build-metadata-paths.mjs";
+import { writeRuntimePostBuildStamp } from "../../scripts/runtime-postbuild-stamp.mjs";
+
+describe("runtime-postbuild-stamp script", () => {
+  it("writes dist/.runtime-postbuildstamp with the current git head", () => {
+    const rootDir = fs.mkdtempSync(path.join(os.tmpdir(), "openclaw-runtime-postbuild-stamp-"));
+    try {
+      const stampPath = writeRuntimePostBuildStamp({
+        cwd: rootDir,
+        now: () => 123,
+        spawnSync: () => ({ status: 0, stdout: "abc123\n" }),
+      });
+
+      expect(path.relative(rootDir, stampPath)).toBe(
+        path.join("dist", RUNTIME_POSTBUILD_STAMP_FILE),
+      );
+      expect(JSON.parse(fs.readFileSync(stampPath, "utf8"))).toEqual({
+        syncedAt: 123,
+        head: "abc123",
+      });
+    } finally {
+      fs.rmSync(rootDir, { recursive: true, force: true });
+    }
+  });
+});