diff --git a/src/infra/gateway-lock.ts b/src/infra/gateway-lock.ts
index eed65942a886..6454dbac0026 100644
--- a/src/infra/gateway-lock.ts
+++ b/src/infra/gateway-lock.ts
@@ -14,7 +14,8 @@ import { z } from "zod";
 import { resolveConfigPath, resolveGatewayLockDir, resolveStateDir } from "../config/paths.js";
 import { isPidAlive } from "../shared/pid-alive.js";
 import { safeParseJsonWithSchema } from "../utils/zod-parse.js";
-import { isGatewayArgv, parseProcCmdline, parseWindowsCmdline } from "./gateway-process-argv.js";
+import { isGatewayArgv, parseProcCmdline } from "./gateway-process-argv.js";
+import { readWindowsProcessArgsSync } from "./windows-port-pids.js";
 
 const DEFAULT_TIMEOUT_MS = 5000;
 const DEFAULT_POLL_INTERVAL_MS = 100;
@@ -79,32 +80,8 @@ function readLinuxCmdline(pid: number): string[] | null {
 
 const CMDLINE_EXEC_TIMEOUT_MS = 1000;
 
-/**
- * Read the command line of a Windows process via `wmic`.
- * Returns an argv-style array, or null when the lookup fails (process gone,
- * `wmic` missing/deprecated, timeout, etc.).
- */
 function readWindowsCmdline(pid: number): string[] | null {
-  try {
-    // Omit `encoding` so execFileSync returns a Buffer — wmic emits UTF-16LE
-    // (with BOM) on most Windows 10/11 builds, which would be garbled as UTF-8.
-    const buf = execFileSync(
-      "wmic",
-      ["process", "where", `processid=${pid}`, "get", "CommandLine", "/value"],
-      { timeout: CMDLINE_EXEC_TIMEOUT_MS, windowsHide: true, stdio: ["ignore", "pipe", "ignore"] },
-    ) as Buffer;
-    const raw =
-      buf.length >= 2 && buf[0] === 0xff && buf[1] === 0xfe
-        ? buf.toString("utf16le")
-        : buf.toString("utf8");
-    const match = raw.match(/CommandLine=(.+)/);
-    if (!match) {
-      return null;
-    }
-    return parseWindowsCmdline(match[1].trim());
-  } catch {
-    return null;
-  }
+  return readWindowsProcessArgsSync(pid, CMDLINE_EXEC_TIMEOUT_MS);
 }
 
 /**
diff --git a/src/infra/gateway-processes.test.ts b/src/infra/gateway-processes.test.ts
index c7fae9acad67..827622d4de8b 100644
--- a/src/infra/gateway-processes.test.ts
+++ b/src/infra/gateway-processes.test.ts
@@ -140,6 +140,26 @@ describe("gateway-processes", () => {
     expect(parseCmdScriptCommandLineMock).toHaveBeenCalledWith("node.exe gateway run");
   });
 
+  it("decodes UTF-16 WMIC output when reading windows process args", () => {
+    setPlatform("win32");
+    spawnSyncMock
+      .mockReturnValueOnce({
+        error: new Error("powershell missing"),
+        status: null,
+        stdout: "",
+      })
+      .mockReturnValueOnce({
+        error: null,
+        status: 0,
+        stdout: Buffer.from("\uFEFFCommandLine=node.exe gateway run\r\n", "utf16le"),
+      });
+    parseCmdScriptCommandLineMock.mockReturnValue(["node.exe", "gateway", "run"]);
+
+    expect(readGatewayProcessArgsSync(77)).toEqual(["node.exe", "gateway", "run"]);
+    expect(spawnSyncMock.mock.calls[1]?.[0]).toBe(getWindowsWmicExePath());
+    expect(parseCmdScriptCommandLineMock).toHaveBeenCalledWith("node.exe gateway run");
+  });
+
   it("signals only verified gateway processes", () => {
     setPlatform("linux");
     readFileSyncMock.mockReturnValue("node\0gateway\0");
diff --git a/src/infra/windows-port-pids.ts b/src/infra/windows-port-pids.ts
index bb1d0614f848..4712c8f3ad6a 100644
--- a/src/infra/windows-port-pids.ts
+++ b/src/infra/windows-port-pids.ts
@@ -95,8 +95,17 @@ export function readWindowsListeningPidsResultSync(
 // Windows process-args reading (PowerShell → WMIC fallback)
 // ---------------------------------------------------------------------------
 
-function extractWindowsCommandLine(raw: string): string | null {
-  const lines = normalizeStringEntries(raw.split(/\r?\n/));
+function decodeWindowsProcessOutput(output: Buffer | string): string {
+  if (!Buffer.isBuffer(output)) {
+    return output;
+  }
+  return output.length >= 2 && output[0] === 0xff && output[1] === 0xfe
+    ? output.toString("utf16le")
+    : output.toString("utf8");
+}
+
+function extractWindowsCommandLine(raw: Buffer | string): string | null {
+  const lines = normalizeStringEntries(decodeWindowsProcessOutput(raw).split(/\r?\n/));
   for (const line of lines) {
     if (!normalizeLowercaseStringOrEmpty(line).startsWith("commandline=")) {
       continue;
@@ -140,9 +149,9 @@ export function readWindowsProcessArgsResultSync(
     getWindowsWmicExePath(),
     ["process", "where", `ProcessId=${pid}`, "get", "CommandLine", "/value"],
     {
-      encoding: "utf8",
       timeout: timeoutMs,
       windowsHide: true,
+      stdio: ["ignore", "pipe", "ignore"],
     },
   );
   if (!wmic.error && wmic.status === 0) {