fix(dashboard): use fs.mkdir for cloudflared local-bin fallback on Windows

Replace execFileAsync("mkdir", ["-p", ...]) with fs.mkdir({ recursive: true })
in the cloudflared install fallback path. The -p flag is Unix-only and breaks
on Windows cmd.exe ("A subdirectory or file -p already exists"). Test mocks
updated to verify the fs.mkdir call instead of the shelled-out mkdir.

The original report covered both this site and packages/engine/src/worktree-hooks.ts;
the latter was already converted to fs.mkdir independently, so only the
dashboard route change is needed.

Co-Authored-By: kenlin8827 <kenlin8827@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.changeset/windows-mkdir-compatibility.md

@@ -0,0 +1,5 @@
+---
+"@runfusion/fusion": patch
+---
+
+Fix Windows compatibility in cloudflared install fallback by replacing `execFileAsync("mkdir", ["-p", ...])` with `fs.mkdir({ recursive: true })`. The shell-level `-p` flag is Unix-only and breaks installation on Windows cmd.exe with "A subdirectory or file -p already exists". The worktree-hooks fix from the original report was already landed independently.

packages/dashboard/src/__tests__/remote-access-routes.test.ts

@@ -4,8 +4,9 @@ import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import express from "express";
 import type { TaskStore } from "@fusion/core";
 
-const { mockExecFile } = vi.hoisted(() => ({
+const { mockExecFile, mockMkdir } = vi.hoisted(() => ({
   mockExecFile: vi.fn(),
+  mockMkdir: vi.fn(),
 }));
 vi.mock("node:child_process", async (importOriginal) => {
   const actual = await importOriginal<typeof import("node:child_process")>();
@@ -14,6 +15,13 @@ vi.mock("node:child_process", async (importOriginal) => {
     execFile: mockExecFile,
   };
 });
+vi.mock("node:fs/promises", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("node:fs/promises")>();
+  return {
+    ...actual,
+    mkdir: mockMkdir.mockImplementation(async () => undefined),
+  };
+});
 
 import { writeFileSync } from "node:fs";
 import { createHash } from "node:crypto";
@@ -123,6 +131,8 @@ afterEach(() => {
 
 beforeEach(() => {
   mockExecFile.mockReset();
+  mockMkdir.mockReset();
+  mockMkdir.mockImplementation(async () => undefined);
   mockExecFile.mockImplementation((command: string, _args: string[], optionsOrCallback: unknown, maybeCallback?: (error: Error | null, stdout?: string, stderr?: string) => void) => {
     const callback = typeof optionsOrCallback === "function"
       ? optionsOrCallback as (error: Error | null, stdout?: string, stderr?: string) => void
@@ -381,7 +391,7 @@ describe("remote access provider/lifecycle contracts", () => {
 
     expect(result.status).toBe(200);
     expect(result.body).toEqual(expect.objectContaining({ success: true }));
-    expect(mockExecFile.mock.calls.some(([command, args]) => command === "mkdir" && Array.isArray(args) && args[0] === "-p")).toBe(true);
+    expect(mockMkdir).toHaveBeenCalledWith(expect.stringContaining('/.local/bin'), { recursive: true });
     expect(mockExecFile.mock.calls.some(([command, args]) => command === "mv" && Array.isArray(args) && String(args[1]).includes("/.local/bin/cloudflared"))).toBe(true);
   });
 

packages/dashboard/src/routes/register-settings-memory-routes.ts

@@ -55,6 +55,7 @@ import crypto from "node:crypto";
 import { createReadStream } from "node:fs";
 import { execFile } from "node:child_process";
 import { homedir } from "node:os";
+import { mkdir } from "node:fs/promises";
 import { promisify } from "node:util";
 import { ApiError, badRequest } from "../api-error.js";
 import { resolveGithubTrackingAuth } from "../github-auth.js";
@@ -345,9 +346,9 @@ export function registerSettingsMemoryRoutes(ctx: ApiRoutesContext, deps: Settin
       } catch (error) {
         const localBinDir = `${homedir()}/.local/bin`;
         const localInstallPath = `${localBinDir}/cloudflared`;
-        attemptedCommands.push(`mkdir -p ${localBinDir}`);
+        attemptedCommands.push(`mkdir(${localBinDir}, { recursive: true })`);
         attemptedCommands.push(`mv ${tempPath} ${localInstallPath}`);
-        await execFileAsync("mkdir", ["-p", localBinDir], { timeout: 30_000 });
+        await mkdir(localBinDir, { recursive: true });
         try {
           await execFileAsync("mv", [tempPath, localInstallPath], { timeout: 30_000 });
         } catch (fallbackError) {