feat(update): add automatic update check on startup

- check cached update result synchronously on every command
- show warnBox notification if update available
- skip check for version/help/update commands
- refresh cache in background if stale (>24h)
- use proper UI components (warnBox) for notification

src/ccs.ts

@@ -1,12 +1,3 @@
-#!/usr/bin/env node
-/**
- * CCS (Claude Code Switch) - Entry Point
- *
- * Instant profile switching for Claude CLI.
- * Supports multiple accounts, alternative models (GLM, Kimi),
- * and cost-optimized delegation.
- */
-
 import { spawn, ChildProcess } from 'child_process';
 import * as path from 'path';
 import * as fs from 'fs';
@@ -33,6 +24,16 @@ import { handleUpdateCommand } from './commands/update-command';
 // Import extracted utility functions
 import { execClaude, escapeShellArg } from './utils/shell-executor';
 
+// Version and Update check utilities
+import { getVersion } from './utils/version';
+import {
+  checkForUpdates,
+  showUpdateNotification,
+  checkCachedUpdate,
+  isCacheStale,
+} from './utils/update-checker';
+import { detectInstallationMethod } from './utils/package-manager-detector';
+
 // ========== Profile Detection ==========
 
 interface DetectedProfile {
@@ -66,7 +67,8 @@ async function execClaudeWithProxy(
   // 1. Read settings to get API key
   const settingsPath = getSettingsPath(profileName);
   const settings = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
-  const apiKey = settings.env.ANTHROPIC_AUTH_TOKEN;
+  const envData = settings.env;
+  const apiKey = envData['ANTHROPIC_AUTH_TOKEN'];
 
   if (!apiKey || apiKey === 'YOUR_GLM_API_KEY_HERE') {
     console.error('[X] GLMT profile requires Z.AI API key');
@@ -87,7 +89,7 @@ async function execClaudeWithProxy(
     env: {
       ...process.env,
       ANTHROPIC_AUTH_TOKEN: apiKey,
-      ANTHROPIC_BASE_URL: settings.env.ANTHROPIC_BASE_URL,
+      ANTHROPIC_BASE_URL: envData['ANTHROPIC_BASE_URL'],
     },
   });
 
@@ -211,18 +213,73 @@ interface ProfileError extends Error {
   suggestions?: string[];
 }
 
+/**
+ * Perform background update check (refreshes cache, no notification)
+ */
+async function refreshUpdateCache(): Promise<void> {
+  try {
+    const currentVersion = getVersion();
+    const installMethod = detectInstallationMethod();
+    // Force=true to always fetch fresh data
+    await checkForUpdates(currentVersion, true, installMethod);
+  } catch (_e) {
+    // Silently fail - update check shouldn't crash main CLI
+  }
+}
+
+/**
+ * Show update notification if cached result indicates update available
+ * Returns true if notification was shown
+ */
+async function showCachedUpdateNotification(): Promise<boolean> {
+  try {
+    const currentVersion = getVersion();
+    const updateInfo = checkCachedUpdate(currentVersion);
+
+    if (updateInfo) {
+      await showUpdateNotification(updateInfo);
+      return true;
+    }
+  } catch (_e) {
+    // Silently fail
+  }
+  return false;
+}
+
 async function main(): Promise<void> {
   const args = process.argv.slice(2);
+  const firstArg = args[0];
+
+  // Trigger update check early for ALL commands except version/help/update
+  // Only if TTY and not CI to avoid noise in automated environments
+  const skipUpdateCheck = [
+    'version',
+    '--version',
+    '-v',
+    'help',
+    '--help',
+    '-h',
+    'update',
+    '--update',
+  ];
+  if (process.stdout.isTTY && !process.env['CI'] && !skipUpdateCheck.includes(firstArg)) {
+    // 1. Show cached update notification (async for proper UI)
+    await showCachedUpdateNotification();
+
+    // 2. Refresh cache in background if stale (non-blocking)
+    if (isCacheStale()) {
+      refreshUpdateCache();
+    }
+  }
 
   // Auto-migrate to unified config format (silent if already migrated)
   // Skip if user is explicitly running migrate command
-  if (args[0] !== 'migrate') {
+  if (firstArg !== 'migrate') {
     const { autoMigrate } = await import('./config/migration-manager');
     await autoMigrate();
   }
 
   // Special case: version command (check BEFORE profile detection)
-  const firstArg = args[0];
   if (firstArg === 'version' || firstArg === '--version' || firstArg === '-v') {
     handleVersionCommand();
   }