diff --git a/src/lib/state/sandbox-manifest-publish.test.ts b/src/lib/state/sandbox-manifest-publish.test.ts
new file mode 100644
index 00000000000..4e085f0e5d7
--- /dev/null
+++ b/src/lib/state/sandbox-manifest-publish.test.ts
@@ -0,0 +1,82 @@
+// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+import { __test, type RebuildManifest } from "./sandbox.js";
+
+const tempDirs: string[] = [];
+
+function manifest(backupPath: string): RebuildManifest {
+  return {
+    version: 1,
+    sandboxName: "alpha",
+    timestamp: "2026-07-27T21-00-00-000Z",
+    agentType: "openclaw",
+    agentVersion: null,
+    expectedVersion: null,
+    stateDirs: [],
+    failedBackupDirs: [],
+    stateFiles: [],
+    dir: "/sandbox",
+    backupPath,
+    blueprintDigest: "digest",
+    policyPresets: [],
+    customPolicies: [],
+  };
+}
+
+afterEach(() => {
+  for (const dir of tempDirs.splice(0)) fs.rmSync(dir, { recursive: true, force: true });
+});
+
+describe("rebuild manifest publication", () => {
+  it("publishes a complete private manifest with no visible temporary file", () => {
+    const backupPath = fs.mkdtempSync(path.join(os.tmpdir(), "nemoclaw-manifest-"));
+    tempDirs.push(backupPath);
+
+    const expected = manifest(backupPath);
+    __test.writeManifest(backupPath, expected);
+
+    const manifestPath = path.join(backupPath, "rebuild-manifest.json");
+    expect(JSON.parse(fs.readFileSync(manifestPath, "utf8"))).toEqual(expected);
+    expect(fs.statSync(manifestPath).mode & 0o777).toBe(0o600);
+    expect(fs.readdirSync(backupPath)).toEqual(["rebuild-manifest.json"]);
+  });
+
+  it("removes the unpublished temporary manifest when rename fails", () => {
+    const remove = vi.fn();
+    const rename = vi.fn(() => {
+      throw new Error("rename failed");
+    });
+
+    expect(() =>
+      __test.writeManifest("/backup", manifest("/backup"), {
+        write: vi.fn(),
+        rename,
+        remove,
+      }),
+    ).toThrow("rename failed");
+
+    const tempPath = path.join("/backup", `.rebuild-manifest.json.tmp.${String(process.pid)}`);
+    expect(rename).toHaveBeenCalledWith(tempPath, path.join("/backup", "rebuild-manifest.json"));
+    expect(remove).toHaveBeenCalledWith(tempPath, { force: true });
+  });
+
+  it("preserves the publish failure when temporary cleanup also fails", () => {
+    expect(() =>
+      __test.writeManifest("/backup", manifest("/backup"), {
+        write: vi.fn(() => {
+          throw new Error("write failed");
+        }),
+        rename: vi.fn(),
+        remove: vi.fn(() => {
+          throw new Error("cleanup failed");
+        }),
+      }),
+    ).toThrow("write failed");
+  });
+});
diff --git a/src/lib/state/sandbox.ts b/src/lib/state/sandbox.ts
index af6040273a7..192c2268140 100644
--- a/src/lib/state/sandbox.ts
+++ b/src/lib/state/sandbox.ts
@@ -21,6 +21,7 @@ import {
   readdirSync,
   readFileSync,
   readlinkSync,
+  renameSync,
   rmSync,
   statSync,
   writeFileSync,
@@ -1787,12 +1788,45 @@ function restoreSandboxStateInternal(
 
 // ── Manifest ───────────────────────────────────────────────────────
 
-function writeManifest(backupPath: string, manifest: RebuildManifest): void {
+type ManifestPublishOps = {
+  write(filePath: string, contents: string, options: { mode: number; flag: "wx" }): void;
+  rename(source: string, destination: string): void;
+  remove(filePath: string, options: { force: true }): void;
+};
+
+const manifestPublishOps: ManifestPublishOps = {
+  write: (filePath, contents, options) => writeFileSync(filePath, contents, options),
+  rename: (source, destination) => renameSync(source, destination),
+  remove: (filePath, options) => rmSync(filePath, options),
+};
+
+function writeManifest(
+  backupPath: string,
+  manifest: RebuildManifest,
+  ops: ManifestPublishOps = manifestPublishOps,
+): void {
   const manifestPath = path.join(backupPath, "rebuild-manifest.json");
-  writeFileSync(manifestPath, JSON.stringify(manifest, null, 2));
-  chmodSync(manifestPath, 0o600);
+  const tempPath = path.join(backupPath, `.rebuild-manifest.json.tmp.${String(process.pid)}`);
+  let published = false;
+  try {
+    // A snapshot becomes recoverable only after its complete, private manifest
+    // is atomically renamed into place.
+    ops.write(tempPath, JSON.stringify(manifest, null, 2), { mode: 0o600, flag: "wx" });
+    ops.rename(tempPath, manifestPath);
+    published = true;
+  } finally {
+    if (!published) {
+      try {
+        ops.remove(tempPath, { force: true });
+      } catch {
+        // Preserve the publish failure; a same-directory temp file is never a snapshot.
+      }
+    }
+  }
 }
 
+export const __test = { writeManifest };
+
 function readManifestPayload(backupPath: string): unknown | null {
   const manifestPath = path.join(backupPath, "rebuild-manifest.json");
   if (!existsSync(manifestPath)) return null;