fix: clean up OAuth server when flow is abandoned or restarted

Cancel any existing OAuth flow before starting a new one to prevent
"Port 8080 is already in use" errors. Adds module-level tracking of
the active flow and a cancelActiveFlow() helper for proper cleanup.
Also reduces timeout from 5 minutes to 2 minutes.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/x/apps/main/src/oauth-handler.ts

@@ -1,4 +1,5 @@
 import { shell } from 'electron';
+import type { Server } from 'http';
 import { createAuthServer } from './auth-server.js';
 import * as oauthClient from '@x/core/dist/auth/oauth-client.js';
 import type { Configuration } from '@x/core/dist/auth/oauth-client.js';
@@ -14,12 +15,48 @@ import { emitOAuthEvent } from './ipc.js';
 const REDIRECT_URI = 'http://localhost:8080/oauth/callback';
 
 // Store active OAuth flows (state -> { codeVerifier, provider, config })
-const activeFlows = new Map<string, { 
-  codeVerifier: string; 
+const activeFlows = new Map<string, {
+  codeVerifier: string;
   provider: string;
   config: Configuration;
 }>();
 
+// Module-level state for tracking the active OAuth flow
+interface ActiveOAuthFlow {
+  provider: string;
+  state: string;
+  server: Server;
+  cleanupTimeout: NodeJS.Timeout;
+}
+
+let activeFlow: ActiveOAuthFlow | null = null;
+
+/**
+ * Cancel any active OAuth flow, cleaning up resources
+ */
+function cancelActiveFlow(reason: string = 'cancelled'): void {
+  if (!activeFlow) {
+    return;
+  }
+
+  console.log(`[OAuth] Cancelling active flow for ${activeFlow.provider}: ${reason}`);
+
+  clearTimeout(activeFlow.cleanupTimeout);
+  activeFlow.server.close();
+  activeFlows.delete(activeFlow.state);
+
+  // Only emit event for user-visible cancellations
+  if (reason !== 'new_flow_started') {
+    emitOAuthEvent({
+      provider: activeFlow.provider,
+      success: false,
+      error: `OAuth flow ${reason}`
+    });
+  }
+
+  activeFlow = null;
+}
+
 /**
  * Get OAuth repository from DI container
  */
@@ -98,6 +135,10 @@ async function getProviderConfiguration(provider: string): Promise<Configuration
 export async function connectProvider(provider: string): Promise<{ success: boolean; error?: string }> {
   try {
     console.log(`[OAuth] Starting connection flow for ${provider}...`);
+
+    // Cancel any existing flow before starting a new one
+    cancelActiveFlow('new_flow_started');
+
     const oauthRepo = getOAuthRepo();
     const providerConfig = getProviderConfig(provider);
 
@@ -122,9 +163,6 @@ export async function connectProvider(provider: string): Promise<{ success: bool
       state,
     });
 
-    // Declare timeout variable (will be set after server is created)
-    let cleanupTimeout: NodeJS.Timeout;
-
     // Create callback server
     const { server } = await createAuthServer(8080, async (code, receivedState) => {
       // Validate state
@@ -140,7 +178,7 @@ export async function connectProvider(provider: string): Promise<{ success: bool
       try {
         // Build callback URL for token exchange
         const callbackUrl = new URL(`${REDIRECT_URI}?code=${code}&state=${receivedState}`);
-        
+
         // Exchange code for tokens
         console.log(`[OAuth] Exchanging authorization code for tokens (${provider})...`);
         const tokens = await oauthClient.exchangeCodeForTokens(
@@ -172,21 +210,30 @@ export async function connectProvider(provider: string): Promise<{ success: bool
       } finally {
         // Clean up
         activeFlows.delete(state);
-        server.close();
-        clearTimeout(cleanupTimeout);
+        if (activeFlow && activeFlow.state === state) {
+          clearTimeout(activeFlow.cleanupTimeout);
+          activeFlow.server.close();
+          activeFlow = null;
+        }
       }
     });
 
-    // Set timeout to clean up abandoned flows (5 minutes)
+    // Set timeout to clean up abandoned flows (2 minutes)
     // This prevents memory leaks if user never completes the OAuth flow
-    cleanupTimeout = setTimeout(() => {
-      if (activeFlows.has(state)) {
+    const cleanupTimeout = setTimeout(() => {
+      if (activeFlow?.state === state) {
         console.log(`[OAuth] Cleaning up abandoned OAuth flow for ${provider} (timeout)`);
-        activeFlows.delete(state);
-        server.close();
-        emitOAuthEvent({ provider, success: false, error: 'OAuth flow timed out' });
+        cancelActiveFlow('timed_out');
       }
-    }, 5 * 60 * 1000); // 5 minutes
+    }, 2 * 60 * 1000); // 2 minutes
+
+    // Store complete flow state for cleanup
+    activeFlow = {
+      provider,
+      state,
+      server,
+      cleanupTimeout,
+    };
 
     // Open in system browser (shares cookies/sessions with user's regular browser)
     shell.openExternal(authUrl.toString());