diff --git a/src/lib/onboard/runtime-provider/docker-operation-authority.test.ts b/src/lib/onboard/runtime-provider/docker-operation-authority.test.ts
index 0a3815cbc33..e84514543aa 100644
--- a/src/lib/onboard/runtime-provider/docker-operation-authority.test.ts
+++ b/src/lib/onboard/runtime-provider/docker-operation-authority.test.ts
@@ -343,6 +343,16 @@ describe("Docker operation authority", () => {
     );
   });
 
+  it("fails closed when the fixed PATH has no Docker executable", () => {
+    expect(() =>
+      createDockerOperationAuthority("sandbox-lifecycle", {
+        HOME: "/tmp/nemoclaw-home",
+        DOCKER_HOST: "unix:///tmp/nemoclaw-docker.sock",
+        PATH: fakeExecutableRoot(),
+      }),
+    ).toThrow("Docker operation could not resolve one absolute Docker executable");
+  });
+
   it("rejects plaintext remote TCP before issuing a daemon command", () => {
     const capture = contextCapture("unix:///var/run/docker.sock");
 
diff --git a/src/lib/onboard/runtime-provider/docker-state-mutation.test.ts b/src/lib/onboard/runtime-provider/docker-state-mutation.test.ts
index 540fd49319e..c4a1c8d55ef 100644
--- a/src/lib/onboard/runtime-provider/docker-state-mutation.test.ts
+++ b/src/lib/onboard/runtime-provider/docker-state-mutation.test.ts
@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 import fs from "node:fs";
+import path from "node:path";
 
 import { afterEach, describe, expect, it, vi } from "vitest";
 import {
@@ -51,6 +52,16 @@ afterEach(() => {
 });
 
 describe("Docker runtime-provider state mutation surface", () => {
+  it("uses one harness-owned absolute Docker executable", () => {
+    const runtime = harness();
+    runtime.authority.engine.capture(["version"]);
+    const executable = runtime.capture.mock.calls[0]?.[0] as string;
+
+    expect(path.isAbsolute(executable)).toBe(true);
+    expect(executable).toBe(fs.realpathSync(path.join(runtime.root, "bin", "docker")));
+    expect(runtime.context.environment).toMatchObject({ PATH: path.join(runtime.root, "bin") });
+  });
+
   it("resolves one full labeled runtime and records authority only on synchronous acquire", () => {
     const runtime = harness();
     const surface = createDockerStateMutationSurface({
diff --git a/test/helpers/docker-state-mutation-harness.ts b/test/helpers/docker-state-mutation-harness.ts
index 748ac6e04e3..be13ef0be52 100644
--- a/test/helpers/docker-state-mutation-harness.ts
+++ b/test/helpers/docker-state-mutation-harness.ts
@@ -32,6 +32,7 @@ export const DOCKER_STATE_MUTATION_PROJECTION_SHA256 = "b".repeat(64);
 export const DOCKER_STATE_MUTATION_STATE_ROOT = "/sandbox/.hermes";
 export const DOCKER_STATE_MUTATION_LIFECYCLE_GENERATION = "generation-7";
 const SANDBOX_ID = "sandbox-alpha-id";
+const DOCKER_EXECUTABLE_SOURCE = "#!/bin/sh\nexit 1\n";
 const PODMAN_EXECUTABLE_BYTES = Buffer.from("qualified-podman-state-mutation", "utf8");
 const PODMAN_SOCKET_AUTHORITY = {
   directoryChain: [],
@@ -82,6 +83,13 @@ function temporaryRoot(): string {
   return root;
 }
 
+function createDockerExecutableSearchPath(root: string): string {
+  const directory = path.join(root, "bin");
+  fs.mkdirSync(directory, { mode: 0o700 });
+  fs.writeFileSync(path.join(directory, "docker"), DOCKER_EXECUTABLE_SOURCE, { mode: 0o700 });
+  return directory;
+}
+
 export function cleanupDockerStateMutationRoots(): void {
   for (const root of roots.splice(0)) fs.rmSync(root, { force: true, recursive: true });
 }
@@ -375,6 +383,7 @@ function createContainerStateMutationHarness(
           HOME: "/tmp/nemoclaw-home",
           DOCKER_CONFIG: "/tmp/nemoclaw-docker",
           DOCKER_HOST: "unix:///tmp/nemoclaw-docker.sock",
+          PATH: createDockerExecutableSearchPath(root),
         }
       : { HOME: "/tmp/nemoclaw-home" };
   const dockerAuthority =