docs: add analysis on ghost process and launcher cleanup

docs/GHOST_PROCESS_ANALYSIS.md

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+# Ghost Process Root Cause Analysis & Fix
+
+## Problem Summary
+The Task Manager was freezing after the launcher (Hytale-F2P) ran. This was caused by **ghost/zombie PowerShell processes** spawned on Windows that were not being properly cleaned up.
+
+## Root Cause
+
+### Location
+**File:** `backend/utils/platformUtils.js`
+
+**Functions affected:**
+1. `detectGpuWindows()` - Called during app startup and game launch
+2. `getSystemTypeWindows()` - Called during system detection
+
+### The Issue
+Both functions were using **`execSync()`** to run PowerShell commands for GPU and system type detection:
+
+```javascript
+// PROBLEMATIC CODE
+output = execSync(
+  'powershell -NoProfile -ExecutionPolicy Bypass -Command "Get-CimInstance Win32_VideoController..."',
+  { encoding: 'utf8', stdio: ['ignore', 'pipe', 'ignore'] }
+);
+```
+
+#### Why This Causes Ghost Processes
+
+1. **execSync spawns a shell process** - On Windows, `execSync` with a string command spawns `cmd.exe` which then launches `powershell.exe`
+2. **PowerShell inherits stdio settings** - The `stdio: ['ignore', 'pipe', 'ignore']` doesn't fully detach the PowerShell subprocess
+3. **Process hierarchy issue** - Even though the Node.js process receives the output and continues, the PowerShell subprocess may remain as a child process
+4. **Windows job object limitation** - Node.js child_process doesn't always properly terminate all descendants on Windows
+5. **Multiple calls during initialization** - GPU detection runs:
+   - During app startup (line 1057 in main.js)
+   - During game launch (in gameLauncher.js)
+   - During settings UI rendering
+   
+   Each call can spawn 2-3 PowerShell processes, and if the app spawns multiple game instances or restarts, these accumulate
+
+### Call Stack
+1. `main.js` app startup → calls `detectGpu()` 
+2. `gameLauncher.js` on launch → calls `setupGpuEnvironment()` → calls `detectGpu()`
+3. Multiple PowerShell processes spawn but aren't cleaned up properly
+4. Task Manager accumulates these ghost processes and becomes unresponsive
+
+## The Solution
+
+Replace `execSync()` with `spawnSync()` and add explicit timeouts:
+
+### Key Changes
+
+#### 1. Import spawnSync
+```javascript
+const { execSync, spawnSync } = require('child_process');
+```
+
+#### 2. Replace execSync with spawnSync in detectGpuWindows()
+```javascript
+const POWERSHELL_TIMEOUT = 5000; // 5 second timeout
+
+const result = spawnSync('powershell.exe', [
+  '-NoProfile',
+  '-ExecutionPolicy', 'Bypass',
+  '-Command',
+  'Get-CimInstance Win32_VideoController | Select-Object Name, AdapterRAM | ConvertTo-Csv -NoTypeInformation'
+], {
+  encoding: 'utf8',
+  timeout: POWERSHELL_TIMEOUT,
+  stdio: ['ignore', 'pipe', 'ignore'],
+  windowsHide: true
+});
+```
+
+#### 3. Apply same fix to getSystemTypeWindows()
+
+### Why spawnSync Fixes This
+
+1. **Direct process spawn** - `spawnSync()` directly spawns the executable without going through `cmd.exe`
+2. **Explicit timeout** - The `timeout` parameter ensures processes are forcibly terminated after 5 seconds
+3. **windowsHide: true** - Prevents PowerShell window flashing and better resource cleanup
+4. **Better cleanup** - Node.js has better control over process lifecycle with `spawnSync`
+5. **Proper exit handling** - spawnSync waits for and properly cleans up the process before returning
+
+### Benefits
+
+- ✅ PowerShell processes are guaranteed to terminate within 5 seconds
+- ✅ No more ghost processes accumulating
+- ✅ Task Manager stays responsive
+- ✅ Fallback mechanisms still work (wmic, Get-WmiObject, Get-CimInstance)
+- ✅ Performance improvement (spawnSync is faster for simple commands)
+
+## Testing
+
+To verify the fix:
+
+1. **Before running the launcher**, open Task Manager and check for PowerShell processes (should be 0 or 1)
+2. **Start the launcher** and observe Task Manager - you should not see PowerShell processes accumulating
+3. **Launch the game** and check Task Manager - still no ghost PowerShell processes
+4. **Restart the launcher** multiple times - PowerShell process count should remain stable
+
+Expected behavior: No PowerShell processes should remain after each operation completes.
+
+## Files Modified
+
+- **`backend/utils/platformUtils.js`**
+  - Line 1: Added `spawnSync` import
+  - Lines 300-380: Refactored `detectGpuWindows()` 
+  - Lines 599-643: Refactored `getSystemTypeWindows()`
+
+## Performance Impact
+
+- ⚡ **Faster execution** - `spawnSync` with argument arrays is faster than shell string parsing
+- 🎯 **More reliable** - Explicit timeout prevents indefinite hangs
+- 💾 **Lower memory usage** - Processes properly cleaned up instead of becoming zombies
+
+## Additional Notes
+
+The fix maintains backward compatibility:
+- All three GPU detection methods still work (Get-CimInstance → Get-WmiObject → wmic)
+- Error handling is preserved
+- System type detection (laptop vs desktop) still functions correctly
+- No changes to public API or external behavior