Add environment diagnostic script for Windows CI differences

This script collects detailed information about:
- Windows version and build
- Python version and subprocess configuration
- Job Objects support
- Security software
- Process creation timing
- Handle inheritance settings

This will help identify differences between local dev environments
(where the test passes) and CI environments (where it flakes).

Author: felixweinberger

scripts/windows-debug/diagnose-environment.ps1

@@ -0,0 +1,152 @@
+#!/usr/bin/env pwsh
+# Script to diagnose environment differences that might cause CI flakiness
+# Usage: .\diagnose-environment.ps1
+
+Write-Host "Diagnosing Windows environment for stdio test issues..." -ForegroundColor Cyan
+Write-Host ""
+
+# System Information
+Write-Host "=== SYSTEM INFORMATION ===" -ForegroundColor Yellow
+Write-Host "Windows Version:"
+(Get-CimInstance Win32_OperatingSystem).Version
+Write-Host "Windows Build:"
+(Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion").DisplayVersion
+Write-Host ""
+
+# Python Information
+Write-Host "=== PYTHON INFORMATION ===" -ForegroundColor Yellow
+Write-Host "Python Version:"
+python --version
+Write-Host ""
+Write-Host "Python Build Info:"
+python -c "import sys; print(f'Version: {sys.version}')"
+python -c "import sys; print(f'Platform: {sys.platform}')"
+python -c "import sys; print(f'Windows Version: {sys.getwindowsversion()}')"
+Write-Host ""
+
+# Check subprocess configuration
+Write-Host "=== SUBPROCESS CONFIGURATION ===" -ForegroundColor Yellow
+python -c @"
+import subprocess
+import sys
+print(f'CREATE_NO_WINDOW available: {hasattr(subprocess, "CREATE_NO_WINDOW")}')
+print(f'CREATE_NEW_PROCESS_GROUP available: {hasattr(subprocess, "CREATE_NEW_PROCESS_GROUP")}')
+print(f'Windows subprocess startup info: {hasattr(subprocess, "STARTUPINFO")}')
+
+# Check handle inheritance defaults
+import os
+print(f'\nHandle inheritance (os.O_NOINHERIT): {hasattr(os, "O_NOINHERIT")}')
+
+# Check asyncio event loop
+import asyncio
+try:
+    loop = asyncio.get_event_loop_policy()
+    print(f'Event loop policy: {type(loop).__name__}')
+except:
+    print('Event loop policy: Unable to determine')
+"@
+Write-Host ""
+
+# Check for Job Objects support
+Write-Host "=== JOB OBJECTS SUPPORT ===" -ForegroundColor Yellow
+python -c @"
+try:
+    import win32job
+    import win32api
+    print('pywin32 available: Yes')
+    print(f'win32job version: {win32job.__file__}')
+    
+    # Try to create a job object
+    try:
+        job = win32job.CreateJobObject(None, '')
+        win32api.CloseHandle(job)
+        print('Job Object creation: Success')
+    except Exception as e:
+        print(f'Job Object creation: Failed - {e}')
+except ImportError:
+    print('pywin32 available: No (Job Objects not available)')
+"@
+Write-Host ""
+
+# Check process limits
+Write-Host "=== PROCESS LIMITS ===" -ForegroundColor Yellow
+python -c @"
+import os
+import psutil
+proc = psutil.Process(os.getpid())
+print(f'Open handles: {proc.num_handles()}')
+print(f'Open files: {len(proc.open_files())}')
+
+# Check system-wide limits
+print(f'Total processes: {len(psutil.pids())}')
+"@
+Write-Host ""
+
+# Check security software
+Write-Host "=== SECURITY SOFTWARE ===" -ForegroundColor Yellow
+Get-CimInstance -Namespace "root\SecurityCenter2" -ClassName AntiVirusProduct -ErrorAction SilentlyContinue | 
+    Select-Object displayName, productState | Format-Table
+Write-Host ""
+
+# Test rapid process creation
+Write-Host "=== RAPID PROCESS CREATION TEST ===" -ForegroundColor Yellow
+Write-Host "Testing rapid tee process creation/destruction..."
+$testScript = @'
+import time
+import subprocess
+import sys
+
+failures = 0
+times = []
+
+for i in range(20):
+    start = time.time()
+    try:
+        # Create process with same flags as stdio client
+        proc = subprocess.Popen(
+            ['tee'],
+            stdin=subprocess.PIPE,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            creationflags=getattr(subprocess, 'CREATE_NO_WINDOW', 0)
+        )
+        proc.stdin.close()
+        proc.wait(timeout=0.5)
+        elapsed = time.time() - start
+        times.append(elapsed)
+    except Exception as e:
+        failures += 1
+        print(f"  Iteration {i+1}: FAILED - {e}")
+    
+    if (i+1) % 5 == 0:
+        avg_time = sum(times) / len(times) if times else 0
+        print(f"  Completed {i+1}/20 (avg: {avg_time*1000:.1f}ms)")
+
+print(f"\nFailures: {failures}/20")
+if times:
+    print(f"Average time: {sum(times)/len(times)*1000:.1f}ms")
+    print(f"Max time: {max(times)*1000:.1f}ms")
+'@
+
+python -c $testScript
+Write-Host ""
+
+# Environment variables that might affect subprocess
+Write-Host "=== RELEVANT ENVIRONMENT VARIABLES ===" -ForegroundColor Yellow
+@("COMSPEC", "PATH", "PYTHONPATH", "PYTHONASYNCIODEBUG") | ForEach-Object {
+    $value = [Environment]::GetEnvironmentVariable($_)
+    if ($value) {
+        Write-Host "$_`:"
+        Write-Host "  $value" -ForegroundColor Gray
+    }
+}
+Write-Host ""
+
+Write-Host "=== DIAGNOSIS COMPLETE ===" -ForegroundColor Cyan
+Write-Host ""
+Write-Host "Share this output when reporting the flakiness issue." -ForegroundColor Yellow
+Write-Host "Key differences to look for between local and CI:" -ForegroundColor Yellow
+Write-Host "  - Windows version/build" -ForegroundColor Gray
+Write-Host "  - Python build details" -ForegroundColor Gray
+Write-Host "  - Security software presence" -ForegroundColor Gray
+Write-Host "  - Process creation timing" -ForegroundColor Gray