Add Windows debugging scripts for flaky stdio test

Add PowerShell scripts to help debug test_stdio_context_manager_exiting
flakiness on Windows with Python 3.11/3.12:

- check-tee-command.ps1: Verify tee command availability
- test-stdio-flakiness-200-runs.ps1: Run test 200 times for statistics
- test-stdio-flakiness-until-failure.ps1: Run until failure occurs
- test-stdio-verbose-debug.ps1: Single run with maximum debug output
- README.md: Documentation for using the scripts

Author: felixweinberger

scripts/windows-debug/README.md

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+# Windows Test Debugging Scripts
+
+This folder contains PowerShell scripts to help debug the flaky `test_stdio_context_manager_exiting` test on Windows with Python 3.11/3.12.
+
+## Prerequisites
+
+- Windows PowerShell or PowerShell Core
+- Python 3.11 or 3.12
+- `uv` installed and configured
+- Virtual environment activated
+
+## Scripts
+
+### 1. `check-tee-command.ps1`
+Checks if the `tee` command is available on your Windows system. The test requires `tee` to run.
+
+```powershell
+.\check-tee-command.ps1
+```
+
+### 2. `test-stdio-flakiness-200-runs.ps1`
+Runs the test 200 times and reports the failure rate.
+
+```powershell
+.\test-stdio-flakiness-200-runs.ps1
+```
+
+### 3. `test-stdio-flakiness-until-failure.ps1`
+Runs the test in a loop until it fails, useful for catching intermittent failures.
+
+```powershell
+.\test-stdio-flakiness-until-failure.ps1
+```
+
+### 4. `test-stdio-verbose-debug.ps1`
+Runs the test once with maximum debugging output enabled.
+
+```powershell
+.\test-stdio-verbose-debug.ps1
+```
+
+## Usage Notes
+
+1. Make sure your virtual environment is activated before running these scripts
+2. Run scripts from the repository root directory
+3. If scripts fail with execution policy errors, run:
+   ```powershell
+   Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser
+   ```
+
+## Interpreting Results
+
+- If `tee` is not available, the test will be skipped
+- Flaky failures typically show up as timeout errors or process cleanup issues
+- Look for patterns in failure output, especially around process termination timing

scripts/windows-debug/check-tee-command.ps1

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+#!/usr/bin/env pwsh
+# Script to check if tee command is available on Windows
+# Usage: .\check-tee-command.ps1
+
+Write-Host "Checking for 'tee' command availability on Windows..." -ForegroundColor Cyan
+Write-Host ""
+
+# Method 1: Using where.exe
+Write-Host "Method 1: Using where.exe" -ForegroundColor Yellow
+try {
+    $whereResult = where.exe tee 2>&1
+    if ($LASTEXITCODE -eq 0) {
+        Write-Host "  Found tee at: $whereResult" -ForegroundColor Green
+    } else {
+        Write-Host "  tee not found via where.exe" -ForegroundColor Red
+    }
+} catch {
+    Write-Host "  Error checking with where.exe: $_" -ForegroundColor Red
+}
+
+Write-Host ""
+
+# Method 2: Using Get-Command
+Write-Host "Method 2: Using Get-Command" -ForegroundColor Yellow
+try {
+    $getCommandResult = Get-Command tee -ErrorAction Stop
+    Write-Host "  Found tee:" -ForegroundColor Green
+    Write-Host "    Name: $($getCommandResult.Name)"
+    Write-Host "    CommandType: $($getCommandResult.CommandType)"
+    Write-Host "    Source: $($getCommandResult.Source)"
+    Write-Host "    Version: $($getCommandResult.Version)"
+} catch {
+    Write-Host "  tee not found via Get-Command" -ForegroundColor Red
+}
+
+Write-Host ""
+
+# Method 3: Check common locations
+Write-Host "Method 3: Checking common locations" -ForegroundColor Yellow
+$commonPaths = @(
+    "C:\Program Files\Git\usr\bin\tee.exe",
+    "C:\Program Files (x86)\Git\usr\bin\tee.exe",
+    "C:\tools\msys64\usr\bin\tee.exe",
+    "C:\msys64\usr\bin\tee.exe",
+    "C:\cygwin64\bin\tee.exe",
+    "C:\cygwin\bin\tee.exe"
+)
+
+$found = $false
+foreach ($path in $commonPaths) {
+    if (Test-Path $path) {
+        Write-Host "  Found at: $path" -ForegroundColor Green
+        $found = $true
+    }
+}
+
+if (-not $found) {
+    Write-Host "  tee not found in common locations" -ForegroundColor Red
+}
+
+Write-Host ""
+
+# Method 4: Check if it's a PowerShell alias
+Write-Host "Method 4: Checking PowerShell aliases" -ForegroundColor Yellow
+$alias = Get-Alias tee -ErrorAction SilentlyContinue
+if ($alias) {
+    Write-Host "  Found PowerShell alias:" -ForegroundColor Green
+    Write-Host "    Name: $($alias.Name)"
+    Write-Host "    Definition: $($alias.Definition)"
+} else {
+    Write-Host "  No PowerShell alias for tee" -ForegroundColor Yellow
+}
+
+Write-Host ""
+
+# Method 5: Python check (what the test uses)
+Write-Host "Method 5: Python shutil.which() check" -ForegroundColor Yellow
+$pythonCheck = python -c "import shutil; print(shutil.which('tee'))"
+if ($pythonCheck -and $pythonCheck -ne "None") {
+    Write-Host "  Python found tee at: $pythonCheck" -ForegroundColor Green
+} else {
+    Write-Host "  Python shutil.which() did not find tee" -ForegroundColor Red
+}
+
+Write-Host ""
+Write-Host "========== SUMMARY ==========" -ForegroundColor Cyan
+if ($whereResult -or $getCommandResult -or $found -or ($pythonCheck -and $pythonCheck -ne "None")) {
+    Write-Host "tee command is available" -ForegroundColor Green
+    Write-Host ""
+    Write-Host "The test_stdio_context_manager_exiting test should run." -ForegroundColor Green
+} else {
+    Write-Host "tee command is NOT available" -ForegroundColor Red
+    Write-Host ""
+    Write-Host "The test_stdio_context_manager_exiting test will be SKIPPED." -ForegroundColor Yellow
+    Write-Host ""
+    Write-Host "To install tee on Windows, you can:" -ForegroundColor Cyan
+    Write-Host "  1. Install Git for Windows (includes tee in Git Bash)"
+    Write-Host "  2. Install WSL (Windows Subsystem for Linux)"
+    Write-Host "  3. Install MSYS2 or Cygwin"
+    Write-Host "  4. Use PowerShell's Tee-Object cmdlet (different syntax)"
+}

scripts/windows-debug/test-stdio-flakiness-200-runs.ps1

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+#!/usr/bin/env pwsh
+# Script to run test_stdio_context_manager_exiting 200 times to detect flakiness
+# Usage: .\test-stdio-flakiness-200-runs.ps1
+
+Write-Host "Running test_stdio_context_manager_exiting 200 times to detect flakiness..." -ForegroundColor Cyan
+Write-Host "Test: tests/client/test_stdio.py::test_stdio_context_manager_exiting" -ForegroundColor Yellow
+Write-Host ""
+
+$startTime = Get-Date
+$count = 0
+$failures = 0
+$failedRuns = @()
+
+for ($i = 1; $i -le 200; $i++) {
+    Write-Host "Run $i of 200..." -NoNewline
+    
+    $output = uv run --frozen pytest tests/client/test_stdio.py::test_stdio_context_manager_exiting -xvs 2>&1
+    $exitCode = $LASTEXITCODE
+    
+    if ($exitCode -ne 0) {
+        $failures++
+        $failedRuns += $i
+        Write-Host " FAILED" -ForegroundColor Red
+        Write-Host "Failure output:" -ForegroundColor Red
+        Write-Host $output
+        Write-Host ""
+    } else {
+        Write-Host " PASSED" -ForegroundColor Green
+    }
+}
+
+$endTime = Get-Date
+$duration = $endTime - $startTime
+
+Write-Host ""
+Write-Host "========== SUMMARY ==========" -ForegroundColor Cyan
+Write-Host "Total runs: 200"
+Write-Host "Successful runs: $($count - $failures)" -ForegroundColor Green
+Write-Host "Failed runs: $failures" -ForegroundColor Red
+if ($failures -gt 0) {
+    Write-Host "Failed on runs: $($failedRuns -join ', ')" -ForegroundColor Red
+}
+Write-Host "Duration: $($duration.ToString())"
+Write-Host "Failure rate: $([math]::Round(($failures / 200) * 100, 2))%"

scripts/windows-debug/test-stdio-flakiness-until-failure.ps1

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+#!/usr/bin/env pwsh
+# Script to run test_stdio_context_manager_exiting until it fails
+# Usage: .\test-stdio-flakiness-until-failure.ps1
+
+Write-Host "Running test_stdio_context_manager_exiting until failure..." -ForegroundColor Cyan
+Write-Host "Test: tests/client/test_stdio.py::test_stdio_context_manager_exiting" -ForegroundColor Yellow
+Write-Host "Press Ctrl+C to stop" -ForegroundColor Gray
+Write-Host ""
+
+$startTime = Get-Date
+$i = 0
+
+while ($true) {
+    $i++
+    Write-Host "Run $i..." -NoNewline
+    
+    $output = uv run --frozen pytest tests/client/test_stdio.py::test_stdio_context_manager_exiting -xvs 2>&1
+    $exitCode = $LASTEXITCODE
+    
+    if ($exitCode -ne 0) {
+        $endTime = Get-Date
+        $duration = $endTime - $startTime
+        
+        Write-Host " FAILED!" -ForegroundColor Red
+        Write-Host ""
+        Write-Host "========== FAILURE DETECTED ==========" -ForegroundColor Red
+        Write-Host "Failed on run: $i" -ForegroundColor Red
+        Write-Host "Time until failure: $($duration.ToString())" -ForegroundColor Yellow
+        Write-Host ""
+        Write-Host "Failure output:" -ForegroundColor Red
+        Write-Host $output
+        break
+    } else {
+        Write-Host " PASSED" -ForegroundColor Green
+    }
+    
+    # Small delay to prevent overwhelming the system
+    Start-Sleep -Milliseconds 100
+}
+
+Write-Host ""
+Write-Host "Exiting after failure detection." -ForegroundColor Cyan

scripts/windows-debug/test-stdio-verbose-debug.ps1

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+#!/usr/bin/env pwsh
+# Script to run test_stdio_context_manager_exiting with maximum debugging output
+# Usage: .\test-stdio-verbose-debug.ps1
+
+Write-Host "Running test_stdio_context_manager_exiting with verbose debug output..." -ForegroundColor Cyan
+Write-Host ""
+
+# Set environment variables for debugging
+$env:PYTHONFAULTHANDLER = "1"
+$env:PYTEST_CURRENT_TEST = "1"
+
+Write-Host "Environment variables set:" -ForegroundColor Yellow
+Write-Host "  PYTHONFAULTHANDLER = 1 (enables Python fault handler)"
+Write-Host ""
+
+Write-Host "Running test with maximum verbosity..." -ForegroundColor Cyan
+Write-Host ""
+
+# Run the test with all debugging options
+uv run --frozen pytest `
+    tests/client/test_stdio.py::test_stdio_context_manager_exiting `
+    -xvs `
+    --log-cli-level=DEBUG `
+    --log-cli-format="%(asctime)s [%(levelname)s] %(name)s: %(message)s" `
+    --capture=no `
+    --tb=long `
+    --full-trace
+
+$exitCode = $LASTEXITCODE
+
+Write-Host ""
+if ($exitCode -eq 0) {
+    Write-Host "Test PASSED" -ForegroundColor Green
+} else {
+    Write-Host "Test FAILED with exit code: $exitCode" -ForegroundColor Red
+}
+
+# Clean up environment variables
+Remove-Item Env:PYTHONFAULTHANDLER -ErrorAction SilentlyContinue
+Remove-Item Env:PYTEST_CURRENT_TEST -ErrorAction SilentlyContinue