v2.3.9: Fix stalled processes and AOT cache crash

- Auto-kill stalled HytaleClient/java processes before launch and repair
  (cross-platform: Windows taskkill+PowerShell, macOS/Linux pkill)
- Remove HytaleServer.aot before launch to prevent incompatible AOT cache
  causing fastutil ClassNotFoundException on singleplayer
- safeRemoveDirectory auto-kills processes on EPERM/EBUSY before retry

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/managers/gameLauncher.js

@@ -27,6 +27,7 @@ const { ensureGameInstalled } = require('./differentialUpdateManager');
 const { syncModsForCurrentProfile } = require('./modManager');
 const { getUserDataPath } = require('../utils/userDataMigration');
 const { syncServerList } = require('../utils/serverListSync');
+const { killGameProcesses } = require('./gameManager');
 
 // Client patcher for custom auth server (sanasol.ws)
 let clientPatcher = null;
@@ -436,6 +437,22 @@ exec "$REAL_JAVA" "\${ARGS[@]}"
     }
   }
 
+  // Kill any stalled game processes from a previous launch to prevent file locks
+  // and "game already running" issues
+  await killGameProcesses();
+
+  // Remove AOT cache: generated by official Hytale JRE, incompatible with F2P JRE.
+  // Client adds -XX:AOTCache when this file exists, causing classloading failures.
+  const aotCache = path.join(gameLatest, 'Server', 'HytaleServer.aot');
+  if (fs.existsSync(aotCache)) {
+    try {
+      fs.unlinkSync(aotCache);
+      console.log('Removed incompatible AOT cache (HytaleServer.aot)');
+    } catch (aotErr) {
+      console.warn('Could not remove AOT cache:', aotErr.message);
+    }
+  }
+
   // DualAuth Agent: Set JAVA_TOOL_OPTIONS so java picks up -javaagent: flag
   // This enables runtime auth patching without modifying the server JAR
   const agentJar = path.join(gameLatest, 'Server', 'dualauth-agent.jar');

backend/managers/gameManager.js

@@ -39,6 +39,41 @@ async function isGameRunning() {
   }
 }
 
+// Force-kill stalled game processes to release file locks before repair/reinstall.
+// Cross-platform: Windows (taskkill/PowerShell), macOS (pkill), Linux (pkill).
+async function killGameProcesses() {
+  const killed = [];
+
+  async function tryKill(command, label) {
+    try {
+      await execAsync(command);
+      killed.push(label);
+    } catch (_) { /* process not found is expected */ }
+  }
+
+  if (process.platform === 'win32') {
+    // Kill client
+    await tryKill('taskkill /F /IM "HytaleClient.exe" /T', 'HytaleClient.exe');
+    // Kill java.exe instances running HytaleServer.jar via PowerShell
+    // (Get-CimInstance replaces deprecated wmic, works on Windows 10+)
+    await tryKill(
+      'powershell -NoProfile -Command "Get-CimInstance Win32_Process -Filter \\"name=\'java.exe\'\\" | Where-Object { $_.CommandLine -like \'*HytaleServer*\' } | ForEach-Object { Stop-Process -Id $_.ProcessId -Force }"',
+      'java.exe(HytaleServer)'
+    );
+  } else {
+    // macOS and Linux
+    await tryKill('pkill -9 -f HytaleClient', 'HytaleClient');
+    await tryKill('pkill -9 -f HytaleServer', 'HytaleServer');
+  }
+
+  if (killed.length > 0) {
+    console.log(`[GameManager] Force-killed stalled processes: ${killed.join(', ')}`);
+    // Wait for OS to release file handles
+    await new Promise(resolve => setTimeout(resolve, 2000));
+  }
+  return killed;
+}
+
 // Helper function to safely remove directory with retry logic
 async function safeRemoveDirectory(dirPath, maxRetries = 3) {
   for (let attempt = 1; attempt <= maxRetries; attempt++) {
@@ -50,8 +85,13 @@ async function safeRemoveDirectory(dirPath, maxRetries = 3) {
       return; // Success, exit the loop
     } catch (error) {
       console.warn(`Attempt ${attempt}/${maxRetries} failed to remove ${dirPath}: ${error.message}`);
-      
+
       if (attempt < maxRetries) {
+        // On EPERM/EBUSY, try killing stalled game processes that hold file locks
+        if (attempt === 1 && (error.code === 'EPERM' || error.code === 'EBUSY')) {
+          console.log('Permission error detected, killing stalled game processes...');
+          await killGameProcesses();
+        }
         // Wait before retrying (exponential backoff)
         const delay = Math.min(1000 * Math.pow(2, attempt - 1), 5000);
         console.log(`Waiting ${delay}ms before retry...`);
@@ -833,11 +873,14 @@ async function repairGame(progressCallback, branchOverride = null) {
     progressCallback('Removing old game files...', 30, null, null, null);
   }
 
-  // Check if game is running before attempting to delete files
+  // Kill stalled game processes before attempting to delete files
   const gameRunning = await isGameRunning();
   if (gameRunning) {
-    console.warn('[RepairGame] Game appears to be running. This may cause permission errors during repair.');
-    console.log('[RepairGame] Please close the game before repairing, or wait for the repair to complete.');
+    console.warn('[RepairGame] Game processes detected. Force-killing to release file locks...');
+    if (progressCallback) {
+      progressCallback('Stopping stalled game processes...', 20, null, null, null);
+    }
+    await killGameProcesses();
   }
 
   // Delete Game and Cache Directory with retry logic
@@ -964,5 +1007,6 @@ module.exports = {
   installGame,
   uninstallGame,
   checkExistingGameInstallation,
-  repairGame
+  repairGame,
+  killGameProcesses
 };