fix(cli): hide windows console windows for runner/claude subprocesses (#242)

cli/src/utils/spawnHappyCLI.test.ts

@@ -0,0 +1,91 @@
+import { beforeAll, afterAll, beforeEach, describe, expect, it, vi } from 'vitest';
+import type { SpawnOptions } from 'child_process';
+
+const spawnMock = vi.fn((..._args: any[]) => ({ pid: 12345 } as any));
+
+vi.mock('child_process', async () => {
+  const actual = await vi.importActual<typeof import('child_process')>('child_process');
+  return {
+    ...actual,
+    spawn: spawnMock
+  };
+});
+
+const originalPlatformDescriptor = Object.getOwnPropertyDescriptor(process, 'platform');
+
+function setPlatform(value: string) {
+  Object.defineProperty(process, 'platform', {
+    value,
+    configurable: true
+  });
+}
+
+function getSpawnOptionsOrThrow(): SpawnOptions {
+  expect(spawnMock).toHaveBeenCalledTimes(1);
+  const firstCall = spawnMock.mock.calls[0] as unknown[] | undefined;
+  const options = firstCall?.[2] as SpawnOptions | undefined;
+  if (!options) {
+    throw new Error('Expected spawn options to be passed as third argument');
+  }
+  return options;
+}
+
+describe('spawnHappyCLI windowsHide behavior', () => {
+  beforeAll(() => {
+    if (!originalPlatformDescriptor?.configurable) {
+      throw new Error('process.platform is not configurable in this runtime');
+    }
+  });
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  afterAll(() => {
+    if (originalPlatformDescriptor) {
+      Object.defineProperty(process, 'platform', originalPlatformDescriptor);
+    }
+  });
+
+  it('sets windowsHide=true when platform is win32 and detached=true', async () => {
+    setPlatform('win32');
+    const { spawnHappyCLI } = await import('./spawnHappyCLI');
+
+    spawnHappyCLI(['runner', 'start-sync'], {
+      detached: true,
+      stdio: 'ignore'
+    });
+
+    const options = getSpawnOptionsOrThrow();
+    expect(options.detached).toBe(true);
+    expect(options.windowsHide).toBe(true);
+  });
+
+  it('does not set windowsHide when platform is win32 but detached is false', async () => {
+    setPlatform('win32');
+    const { spawnHappyCLI } = await import('./spawnHappyCLI');
+
+    spawnHappyCLI(['runner', 'start-sync'], {
+      detached: false,
+      stdio: 'ignore'
+    });
+
+    const options = getSpawnOptionsOrThrow();
+    expect(options.detached).toBe(false);
+    expect('windowsHide' in options).toBe(false);
+  });
+
+  it('does not set windowsHide on non-win32 even when detached=true', async () => {
+    setPlatform('linux');
+    const { spawnHappyCLI } = await import('./spawnHappyCLI');
+
+    spawnHappyCLI(['runner', 'start-sync'], {
+      detached: true,
+      stdio: 'ignore'
+    });
+
+    const options = getSpawnOptionsOrThrow();
+    expect(options.detached).toBe(true);
+    expect('windowsHide' in options).toBe(false);
+  });
+});

cli/src/utils/spawnHappyCLI.ts

@@ -105,5 +105,11 @@ export function spawnHappyCLI(args: string[], options: SpawnOptions = {}): Child
     }
   }
   
-  return spawn(spawnCommand, spawnArgs, options);
+  // On Windows, detached processes allocate a new console window by default.
+  // windowsHide: true suppresses this to prevent cmd windows from accumulating.
+  const finalOptions: SpawnOptions = { ...options };
+  if (process.platform === 'win32' && options.detached) {
+    finalOptions.windowsHide = true;
+  }
+  return spawn(spawnCommand, spawnArgs, finalOptions);
 }