diff --git a/extensions/lobster/src/lobster-tool.test.ts b/extensions/lobster/src/lobster-tool.test.ts
index 8aea32fc405..50971e48ba6 100644
--- a/extensions/lobster/src/lobster-tool.test.ts
+++ b/extensions/lobster/src/lobster-tool.test.ts
@@ -1,35 +1,21 @@
+import { EventEmitter } from "node:events";
 import fs from "node:fs/promises";
 import os from "node:os";
 import path from "node:path";
-import { describe, expect, it } from "vitest";
+import { PassThrough } from "node:stream";
+import { afterAll, beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
 import type { OpenClawPluginApi, OpenClawPluginToolContext } from "../../../src/plugins/types.js";
-import { createLobsterTool } from "./lobster-tool.js";
 
-async function writeFakeLobsterScript(scriptBody: string, prefix = "openclaw-lobster-plugin-") {
-  const dir = await fs.mkdtemp(path.join(os.tmpdir(), prefix));
-  const isWindows = process.platform === "win32";
+const spawnState = vi.hoisted(() => ({
+  queue: [] as Array<{ stdout: string; stderr?: string; exitCode?: number }>,
+  spawn: vi.fn(),
+}));
 
-  if (isWindows) {
-    const scriptPath = path.join(dir, "lobster.js");
-    const cmdPath = path.join(dir, "lobster.cmd");
-    await fs.writeFile(scriptPath, scriptBody, { encoding: "utf8" });
-    const cmd = `@echo off\r\n"${process.execPath}" "${scriptPath}" %*\r\n`;
-    await fs.writeFile(cmdPath, cmd, { encoding: "utf8" });
-    return { dir, binPath: cmdPath };
-  }
+vi.mock("node:child_process", () => ({
+  spawn: (...args: unknown[]) => spawnState.spawn(...args),
+}));
 
-  const binPath = path.join(dir, "lobster");
-  const file = `#!/usr/bin/env node\n${scriptBody}\n`;
-  await fs.writeFile(binPath, file, { encoding: "utf8", mode: 0o755 });
-  return { dir, binPath };
-}
-
-async function writeFakeLobster(params: { payload: unknown }) {
-  const scriptBody =
-    `const payload = ${JSON.stringify(params.payload)};\n` +
-    `process.stdout.write(JSON.stringify(payload));\n`;
-  return await writeFakeLobsterScript(scriptBody);
-}
+let createLobsterTool: typeof import("./lobster-tool.js").createLobsterTool;
 
 function fakeApi(overrides: Partial<OpenClawPluginApi> = {}): OpenClawPluginApi {
   return {
@@ -72,96 +58,115 @@ function fakeCtx(overrides: Partial<OpenClawPluginToolContext> = {}): OpenClawPl
 }
 
 describe("lobster plugin tool", () => {
-  it("runs lobster and returns parsed envelope in details", async () => {
-    const fake = await writeFakeLobster({
-      payload: { ok: true, status: "ok", output: [{ hello: "world" }], requiresApproval: null },
-    });
+  let tempDir = "";
+  let lobsterBinPath = "";
 
-    const originalPath = process.env.PATH;
-    process.env.PATH = `${fake.dir}${path.delimiter}${originalPath ?? ""}`;
+  beforeAll(async () => {
+    ({ createLobsterTool } = await import("./lobster-tool.js"));
 
-    try {
-      const tool = createLobsterTool(fakeApi());
-      const res = await tool.execute("call1", {
-        action: "run",
-        pipeline: "noop",
-        timeoutMs: 1000,
+    tempDir = await fs.mkdtemp(path.join(os.tmpdir(), "openclaw-lobster-plugin-"));
+    lobsterBinPath = path.join(tempDir, process.platform === "win32" ? "lobster.cmd" : "lobster");
+    await fs.writeFile(lobsterBinPath, "", { encoding: "utf8", mode: 0o755 });
+  });
+
+  afterAll(async () => {
+    if (!tempDir) {
+      return;
+    }
+    if (process.platform === "win32") {
+      await fs.rm(tempDir, { recursive: true, force: true, maxRetries: 10, retryDelay: 50 });
+    } else {
+      await fs.rm(tempDir, { recursive: true, force: true });
+    }
+  });
+
+  beforeEach(() => {
+    spawnState.queue.length = 0;
+    spawnState.spawn.mockReset();
+    spawnState.spawn.mockImplementation(() => {
+      const next = spawnState.queue.shift() ?? { stdout: "" };
+      const stdout = new PassThrough();
+      const stderr = new PassThrough();
+      const child = new EventEmitter() as EventEmitter & {
+        stdout: PassThrough;
+        stderr: PassThrough;
+        kill: (signal?: string) => boolean;
+      };
+      child.stdout = stdout;
+      child.stderr = stderr;
+      child.kill = () => true;
+
+      setImmediate(() => {
+        if (next.stderr) {
+          stderr.end(next.stderr);
+        } else {
+          stderr.end();
+        }
+        stdout.end(next.stdout);
+        child.emit("exit", next.exitCode ?? 0);
       });
 
-      expect(res.details).toMatchObject({ ok: true, status: "ok" });
-    } finally {
-      process.env.PATH = originalPath;
-    }
+      return child;
+    });
+  });
+
+  it("runs lobster and returns parsed envelope in details", async () => {
+    spawnState.queue.push({
+      stdout: JSON.stringify({
+        ok: true,
+        status: "ok",
+        output: [{ hello: "world" }],
+        requiresApproval: null,
+      }),
+    });
+
+    const tool = createLobsterTool(fakeApi());
+    const res = await tool.execute("call1", {
+      action: "run",
+      pipeline: "noop",
+      timeoutMs: 1000,
+    });
+
+    expect(spawnState.spawn).toHaveBeenCalled();
+    expect(res.details).toMatchObject({ ok: true, status: "ok" });
   });
 
   it("tolerates noisy stdout before the JSON envelope", async () => {
     const payload = { ok: true, status: "ok", output: [], requiresApproval: null };
-    const { dir } = await writeFakeLobsterScript(
-      `const payload = ${JSON.stringify(payload)};\n` +
-        `console.log("noise before json");\n` +
-        `process.stdout.write(JSON.stringify(payload));\n`,
-      "openclaw-lobster-plugin-noisy-",
-    );
+    spawnState.queue.push({
+      stdout: `noise before json\n${JSON.stringify(payload)}`,
+    });
 
-    const originalPath = process.env.PATH;
-    process.env.PATH = `${dir}${path.delimiter}${originalPath ?? ""}`;
+    const tool = createLobsterTool(fakeApi());
+    const res = await tool.execute("call-noisy", {
+      action: "run",
+      pipeline: "noop",
+      timeoutMs: 1000,
+    });
 
-    try {
-      const tool = createLobsterTool(fakeApi());
-      const res = await tool.execute("call-noisy", {
-        action: "run",
-        pipeline: "noop",
-        timeoutMs: 1000,
-      });
-
-      expect(res.details).toMatchObject({ ok: true, status: "ok" });
-    } finally {
-      process.env.PATH = originalPath;
-    }
+    expect(res.details).toMatchObject({ ok: true, status: "ok" });
   });
 
   it("requires absolute lobsterPath when provided (even though it is ignored)", async () => {
-    const fake = await writeFakeLobster({
-      payload: { ok: true, status: "ok", output: [{ hello: "world" }], requiresApproval: null },
-    });
-
-    const originalPath = process.env.PATH;
-    process.env.PATH = `${fake.dir}${path.delimiter}${originalPath ?? ""}`;
-
-    try {
-      const tool = createLobsterTool(fakeApi());
-      await expect(
-        tool.execute("call2", {
-          action: "run",
-          pipeline: "noop",
-          lobsterPath: "./lobster",
-        }),
-      ).rejects.toThrow(/absolute path/);
-    } finally {
-      process.env.PATH = originalPath;
-    }
+    const tool = createLobsterTool(fakeApi());
+    await expect(
+      tool.execute("call2", {
+        action: "run",
+        pipeline: "noop",
+        lobsterPath: "./lobster",
+      }),
+    ).rejects.toThrow(/absolute path/);
   });
 
   it("rejects lobsterPath (deprecated) when invalid", async () => {
-    const fake = await writeFakeLobster({
-      payload: { ok: true, status: "ok", output: [{ hello: "world" }], requiresApproval: null },
-    });
-
-    const originalPath = process.env.PATH;
-    process.env.PATH = `${fake.dir}${path.delimiter}${originalPath ?? ""}`;
-
-    try {
-      const tool = createLobsterTool(fakeApi());
-      await expect(
-        tool.execute("call2b", {
-          action: "run",
-          pipeline: "noop",
-          lobsterPath: "/bin/bash",
-        }),
-      ).rejects.toThrow(/lobster executable/);
-    } finally {
-      process.env.PATH = originalPath;
-    }
+    const tool = createLobsterTool(fakeApi());
+    await expect(
+      tool.execute("call2b", {
+        action: "run",
+        pipeline: "noop",
+        lobsterPath: "/bin/bash",
+      }),
+    ).rejects.toThrow(/lobster executable/);
   });
 
   it("rejects absolute cwd", async () => {
@@ -187,49 +192,38 @@ describe("lobster plugin tool", () => {
   });
 
   it("uses pluginConfig.lobsterPath when provided", async () => {
-    const fake = await writeFakeLobster({
-      payload: { ok: true, status: "ok", output: [{ hello: "world" }], requiresApproval: null },
+    spawnState.queue.push({
+      stdout: JSON.stringify({
+        ok: true,
+        status: "ok",
+        output: [{ hello: "world" }],
+        requiresApproval: null,
+      }),
     });
 
-    // Ensure `lobster` is NOT discoverable via PATH, while still allowing our
-    // fake lobster (a Node script with `#!/usr/bin/env node`) to run.
-    const originalPath = process.env.PATH;
-    process.env.PATH = path.dirname(process.execPath);
+    const tool = createLobsterTool(fakeApi({ pluginConfig: { lobsterPath: lobsterBinPath } }));
+    const res = await tool.execute("call-plugin-config", {
+      action: "run",
+      pipeline: "noop",
+      timeoutMs: 1000,
+    });
 
-    try {
-      const tool = createLobsterTool(fakeApi({ pluginConfig: { lobsterPath: fake.binPath } }));
-      const res = await tool.execute("call-plugin-config", {
-        action: "run",
-        pipeline: "noop",
-        timeoutMs: 1000,
-      });
-
-      expect(res.details).toMatchObject({ ok: true, status: "ok" });
-    } finally {
-      process.env.PATH = originalPath;
-    }
+    expect(spawnState.spawn).toHaveBeenCalled();
+    const [execPath] = spawnState.spawn.mock.calls[0] ?? [];
+    expect(execPath).toBe(lobsterBinPath);
+    expect(res.details).toMatchObject({ ok: true, status: "ok" });
   });
 
   it("rejects invalid JSON from lobster", async () => {
-    const { dir } = await writeFakeLobsterScript(
-      `process.stdout.write("nope");\n`,
-      "openclaw-lobster-plugin-bad-",
-    );
+    spawnState.queue.push({ stdout: "nope" });
 
-    const originalPath = process.env.PATH;
-    process.env.PATH = `${dir}${path.delimiter}${originalPath ?? ""}`;
-
-    try {
-      const tool = createLobsterTool(fakeApi());
-      await expect(
-        tool.execute("call3", {
-          action: "run",
-          pipeline: "noop",
-        }),
-      ).rejects.toThrow(/invalid JSON/);
-    } finally {
-      process.env.PATH = originalPath;
-    }
+    const tool = createLobsterTool(fakeApi());
+    await expect(
+      tool.execute("call3", {
+        action: "run",
+        pipeline: "noop",
+      }),
+    ).rejects.toThrow(/invalid JSON/);
   });
 
   it("can be gated off in sandboxed contexts", async () => {