fix: set DISPLAY in worker process and configure tauri-driver connection

The DISPLAY environment variable was not available in the WDIO worker
process, causing ChromeDriver and diagnostic commands to fail when trying
to launch the Tauri binary with GTK.

This fix:
1. Sets DISPLAY in the worker process environment (onWorkerStart) so that
   ChromeDriver and all child processes have access to the X server
2. Configures WDIO to connect to tauri-driver's WebDriver endpoint instead
   of spawning a separate ChromeDriver instance
3. Keeps DISPLAY set when spawning tauri-driver for redundancy

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: goosewobbler

packages/tauri-service/src/launcher.ts

@@ -28,11 +28,17 @@ export default class TauriLaunchService {
    * Prepare the Tauri service
    */
   async onPrepare(
-    _config: Options.Testrunner,
+    config: Options.Testrunner,
     capabilities: TauriCapabilities[] | Record<string, { capabilities: TauriCapabilities }>,
   ): Promise<void> {
     log.debug('Preparing Tauri service...');
 
+    // Configure WDIO to connect to tauri-driver instead of spawning ChromeDriver
+    const tauriDriverPort = this.options.tauriDriverPort || 4444;
+    config.hostname = config.hostname || 'localhost';
+    config.port = config.port || tauriDriverPort;
+    log.info(`Configuring WDIO to connect to tauri-driver at ${config.hostname}:${config.port}`);
+
     // Check for unsupported platforms
     if (process.platform === 'darwin') {
       const errorMessage =
@@ -132,6 +138,13 @@ export default class TauriLaunchService {
   async onWorkerStart(cid: string, caps: TauriCapabilities): Promise<void> {
     log.debug(`Starting Tauri worker session: ${cid}`);
 
+    // On Linux, ensure DISPLAY is set in the worker process environment
+    // This is needed for ChromeDriver and any diagnostic commands
+    if (process.platform === 'linux' && !process.env.DISPLAY) {
+      process.env.DISPLAY = ':99';
+      log.info(`Set DISPLAY=${process.env.DISPLAY} in worker process for ChromeDriver and diagnostics`);
+    }
+
     // App binary path is already resolved in onPrepare
     const appPath = caps['tauri:options']?.application;
     if (!appPath) {
@@ -330,9 +343,17 @@ export default class TauriLaunchService {
     }
 
     return new Promise((resolve, reject) => {
+      // On Linux, explicitly set DISPLAY for xvfb compatibility
+      const env = { ...process.env };
+      if (process.platform === 'linux') {
+        env.DISPLAY = env.DISPLAY || ':99';
+        log.info(`Setting DISPLAY=${env.DISPLAY} for tauri-driver and children`);
+      }
+
       this.tauriDriverProcess = spawn(tauriDriverPath, args, {
         stdio: ['ignore', 'pipe', 'pipe'],
         detached: false,
+        env,
       });
 
       this.tauriDriverProcess.stdout?.on('data', (data: Buffer) => {