fix: Windows: openclaw plugins install fails with spawn EINVAL

Fixes #7631

src/process/exec.test.ts

@@ -1,5 +1,6 @@
 import type { ChildProcess } from "node:child_process";
 import { EventEmitter } from "node:events";
+import fs from "node:fs";
 import process from "node:process";
 import { describe, expect, it, vi } from "vitest";
 import { attachChildProcessBridge } from "./child-process-bridge.js";
@@ -77,6 +78,20 @@ describe("runCommandWithTimeout", () => {
       expect(result.stdout.trim()).toMatch(/^\d+\.\d+\.\d+$/);
     },
   );
+
+  it.runIf(process.platform === "win32")(
+    "falls back to npm.cmd when npm-cli.js is unavailable",
+    async () => {
+      const existsSpy = vi.spyOn(fs, "existsSync").mockReturnValue(false);
+      try {
+        const result = await runCommandWithTimeout(["npm", "--version"], { timeoutMs: 10_000 });
+        expect(result.code).toBe(0);
+        expect(result.stdout.trim()).toMatch(/^\d+\.\d+\.\d+$/);
+      } finally {
+        existsSpy.mockRestore();
+      }
+    },
+  );
 });
 
 describe("attachChildProcessBridge", () => {

src/process/exec.ts

@@ -58,7 +58,13 @@ function resolveNpmArgvForWindows(argv: string[]): string[] | null {
   const nodeDir = path.dirname(process.execPath);
   const cliPath = path.join(nodeDir, "node_modules", "npm", "bin", cliName);
   if (!fs.existsSync(cliPath)) {
-    return null;
+    // Bun-based runs don't ship npm-cli.js next to process.execPath.
+    // Fall back to npm.cmd/npx.cmd so we still route through cmd wrapper
+    // (avoids direct .cmd spawn EINVAL on patched Node).
+    const command = argv[0] ?? "";
+    const ext = path.extname(command).toLowerCase();
+    const shimmedCommand = ext ? command : `${command}.cmd`;
+    return [shimmedCommand, ...argv.slice(1)];
   }
   return [process.execPath, cliPath, ...argv.slice(1)];
 }