diff --git a/src/daemon/service-env.test.ts b/src/daemon/service-env.test.ts
index be226a4f32..31a46c4990 100644
--- a/src/daemon/service-env.test.ts
+++ b/src/daemon/service-env.test.ts
@@ -1,5 +1,6 @@
+import os from "node:os";
 import path from "node:path";
-import { afterEach, describe, expect, it } from "vitest";
+import { describe, expect, it } from "vitest";
 import { resolveGatewayStateDir } from "./paths.js";
 import {
   buildMinimalServicePath,
@@ -9,16 +10,6 @@ import {
   getMinimalServicePathPartsFromEnv,
 } from "./service-env.js";
 
-const originalPlatform = process.platform;
-
-function setPlatform(platform: NodeJS.Platform): void {
-  Object.defineProperty(process, "platform", { value: platform, configurable: true });
-}
-
-afterEach(() => {
-  Object.defineProperty(process, "platform", { value: originalPlatform, configurable: true });
-});
-
 describe("getMinimalServicePathParts - Linux user directories", () => {
   it("includes user bin directories when HOME is set on Linux", () => {
     const result = getMinimalServicePathParts({
@@ -292,8 +283,7 @@ describe("buildServiceEnvironment", () => {
     }
   });
 
-  it("forwards TMPDIR from the host environment on macOS", () => {
-    setPlatform("darwin");
+  it("forwards TMPDIR from the host environment", () => {
     const env = buildServiceEnvironment({
       env: { HOME: "/home/user", TMPDIR: "/var/folders/xw/abc123/T/" },
       port: 18789,
@@ -301,21 +291,12 @@ describe("buildServiceEnvironment", () => {
     expect(env.TMPDIR).toBe("/var/folders/xw/abc123/T/");
   });
 
-  it("does not forward TMPDIR on non-macOS services", () => {
-    setPlatform("linux");
-    const env = buildServiceEnvironment({
-      env: { HOME: "/home/user", TMPDIR: "/tmp/custom" },
-      port: 18789,
-    });
-    expect(env.TMPDIR).toBeUndefined();
-  });
-
-  it("omits TMPDIR when not set in host environment", () => {
+  it("falls back to os.tmpdir when TMPDIR is not set", () => {
     const env = buildServiceEnvironment({
       env: { HOME: "/home/user" },
       port: 18789,
     });
-    expect(env.TMPDIR).toBeUndefined();
+    expect(env.TMPDIR).toBe(os.tmpdir());
   });
 
   it("uses profile-specific unit and label", () => {
@@ -338,20 +319,18 @@ describe("buildNodeServiceEnvironment", () => {
     expect(env.HOME).toBe("/home/user");
   });
 
-  it("forwards TMPDIR for node services on macOS", () => {
-    setPlatform("darwin");
+  it("forwards TMPDIR for node services", () => {
     const env = buildNodeServiceEnvironment({
       env: { HOME: "/home/user", TMPDIR: "/tmp/custom" },
     });
     expect(env.TMPDIR).toBe("/tmp/custom");
   });
 
-  it("does not forward TMPDIR for node services on non-macOS platforms", () => {
-    setPlatform("linux");
+  it("falls back to os.tmpdir for node services when TMPDIR is not set", () => {
     const env = buildNodeServiceEnvironment({
-      env: { HOME: "/home/user", TMPDIR: "/tmp/custom" },
+      env: { HOME: "/home/user" },
     });
-    expect(env.TMPDIR).toBeUndefined();
+    expect(env.TMPDIR).toBe(os.tmpdir());
   });
 });
 
diff --git a/src/daemon/service-env.ts b/src/daemon/service-env.ts
index b9590841c2..10fd4223c8 100644
--- a/src/daemon/service-env.ts
+++ b/src/daemon/service-env.ts
@@ -1,3 +1,4 @@
+import os from "node:os";
 import path from "node:path";
 import { VERSION } from "../version.js";
 import {
@@ -212,8 +213,8 @@ export function buildServiceEnvironment(params: {
   const systemdUnit = `${resolveGatewaySystemdServiceName(profile)}.service`;
   const stateDir = env.OPENCLAW_STATE_DIR;
   const configPath = env.OPENCLAW_CONFIG_PATH;
-  // launchd on macOS does not inherit shell TMPDIR by default; forward it explicitly there.
-  const tmpDir = process.platform === "darwin" ? env.TMPDIR : undefined;
+  // Keep a usable temp directory for supervised services even when the host env omits TMPDIR.
+  const tmpDir = env.TMPDIR?.trim() || os.tmpdir();
   return {
     HOME: env.HOME,
     TMPDIR: tmpDir,
@@ -237,8 +238,7 @@ export function buildNodeServiceEnvironment(params: {
   const { env } = params;
   const stateDir = env.OPENCLAW_STATE_DIR;
   const configPath = env.OPENCLAW_CONFIG_PATH;
-  // Keep TMPDIR propagation scoped to macOS launchd installs.
-  const tmpDir = process.platform === "darwin" ? env.TMPDIR : undefined;
+  const tmpDir = env.TMPDIR?.trim() || os.tmpdir();
   return {
     HOME: env.HOME,
     TMPDIR: tmpDir,