fix(cache): use ~/.ccs/cache/ for usage and update-check files

- usage-disk-cache.ts: usage-cache.json → cache/usage.json
- update-checker.ts: update-check.json → cache/update-check.json
- Both ensure cache directory exists before writing
- Update tests to use new cache paths

src/utils/update-checker.ts

@@ -8,7 +8,8 @@ import * as os from 'os';
 import * as https from 'https';
 import { colored } from './helpers';
 
-const UPDATE_CHECK_FILE = path.join(os.homedir(), '.ccs', 'update-check.json');
+const CACHE_DIR = path.join(os.homedir(), '.ccs', 'cache');
+const UPDATE_CHECK_FILE = path.join(CACHE_DIR, 'update-check.json');
 const CHECK_INTERVAL = 24 * 60 * 60 * 1000; // 24 hours
 const GITHUB_API_URL = 'https://api.github.com/repos/kaitranntt/ccs/releases/latest';
 const NPM_REGISTRY_BASE = 'https://registry.npmjs.org/@kaitranntt/ccs';
@@ -208,9 +209,8 @@ export function readCache(): UpdateCache {
  */
 export function writeCache(cache: UpdateCache): void {
   try {
-    const ccsDir = path.join(os.homedir(), '.ccs');
-    if (!fs.existsSync(ccsDir)) {
-      fs.mkdirSync(ccsDir, { recursive: true, mode: 0o700 });
+    if (!fs.existsSync(CACHE_DIR)) {
+      fs.mkdirSync(CACHE_DIR, { recursive: true, mode: 0o700 });
     }
 
     fs.writeFileSync(UPDATE_CHECK_FILE, JSON.stringify(cache, null, 2), 'utf8');

src/web-server/usage-disk-cache.ts

@@ -4,7 +4,7 @@
  * Caches aggregated usage data to disk to avoid re-parsing 6000+ JSONL files
  * on every dashboard startup. Uses TTL-based invalidation with stale-while-revalidate.
  *
- * Cache location: ~/.ccs/usage-cache.json
+ * Cache location: ~/.ccs/cache/usage.json
  * Default TTL: 5 minutes (configurable)
  */
 
@@ -15,7 +15,8 @@ import type { DailyUsage, MonthlyUsage, SessionUsage } from './usage-types';
 
 // Cache configuration
 const CCS_DIR = path.join(os.homedir(), '.ccs');
-const CACHE_FILE = path.join(CCS_DIR, 'usage-cache.json');
+const CACHE_DIR = path.join(CCS_DIR, 'cache');
+const CACHE_FILE = path.join(CACHE_DIR, 'usage.json');
 const CACHE_TTL_MS = 5 * 60 * 1000; // 5 minutes
 const STALE_TTL_MS = 7 * 24 * 60 * 60 * 1000; // 7 days (max age for stale data)
 
@@ -33,11 +34,11 @@ export interface UsageDiskCache {
 const CACHE_VERSION = 2;
 
 /**
- * Ensure ~/.ccs directory exists
+ * Ensure ~/.ccs/cache directory exists
  */
-function ensureCcsDir(): void {
-  if (!fs.existsSync(CCS_DIR)) {
-    fs.mkdirSync(CCS_DIR, { recursive: true });
+function ensureCacheDir(): void {
+  if (!fs.existsSync(CACHE_DIR)) {
+    fs.mkdirSync(CACHE_DIR, { recursive: true });
   }
 }
 
@@ -97,7 +98,7 @@ export function writeDiskCache(
   session: SessionUsage[]
 ): void {
   try {
-    ensureCcsDir();
+    ensureCacheDir();
 
     const cache: UsageDiskCache = {
       version: CACHE_VERSION,

tests/unit/utils/update-checker-beta-channel.test.js

@@ -275,7 +275,7 @@ describe('Beta Channel Implementation (Phase 3)', function () {
         latest_version: null,
         dismissed_version: null
       };
-      mockFileSystem[path.join(os.homedir(), '.ccs', 'update-check.json')] = JSON.stringify(cacheData);
+      mockFileSystem[path.join(os.homedir(), '.ccs', 'cache', 'update-check.json')] = JSON.stringify(cacheData);
     });
 
     it('should use latest tag when targetTag is "latest"', async function () {
@@ -362,7 +362,7 @@ describe('Beta Channel Implementation (Phase 3)', function () {
       await updateCheckerModule.checkForUpdates('5.4.0', true, 'npm', 'dev');
 
       // Check cache was updated with dev version
-      const cachePath = path.join(os.homedir(), '.ccs', 'update-check.json');
+      const cachePath = path.join(os.homedir(), '.ccs', 'cache', 'update-check.json');
       const cacheData = JSON.parse(mockFileSystem[cachePath]);
 
       assert.strictEqual(cacheData.latest_version, '5.5.0');
@@ -376,7 +376,7 @@ describe('Beta Channel Implementation (Phase 3)', function () {
         latest_version: '5.5.0',
         dismissed_version: null
       };
-      mockFileSystem[path.join(os.homedir(), '.ccs', 'update-check.json')] = JSON.stringify(cacheData);
+      mockFileSystem[path.join(os.homedir(), '.ccs', 'cache', 'update-check.json')] = JSON.stringify(cacheData);
 
       // Call with force=false to use cache
       const result = await updateCheckerModule.checkForUpdates('5.4.0', false, 'npm', 'dev');
@@ -465,7 +465,7 @@ describe('Beta Channel Implementation (Phase 3)', function () {
   describe('Cache functionality', function () {
     it('should create cache directory if not exists', async function () {
       // Ensure no cache exists
-      const cacheDir = path.join(os.homedir(), '.ccs');
+      const cacheDir = path.join(os.homedir(), '.ccs', 'cache');
       delete mockFileSystem[cacheDir];
 
       await updateCheckerModule.checkForUpdates('5.4.0', true, 'npm', 'latest');
@@ -481,7 +481,7 @@ describe('Beta Channel Implementation (Phase 3)', function () {
         latest_version: '5.5.0',
         dismissed_version: '5.5.0'
       };
-      mockFileSystem[path.join(os.homedir(), '.ccs', 'update-check.json')] = JSON.stringify(cacheData);
+      mockFileSystem[path.join(os.homedir(), '.ccs', 'cache', 'update-check.json')] = JSON.stringify(cacheData);
 
       const result = await updateCheckerModule.checkForUpdates('5.4.1', false, 'npm', 'dev');
 
@@ -492,7 +492,7 @@ describe('Beta Channel Implementation (Phase 3)', function () {
 
     it('should handle corrupted cache gracefully', async function () {
       // Set up corrupted cache
-      mockFileSystem[path.join(os.homedir(), '.ccs', 'update-check.json')] = 'invalid json';
+      mockFileSystem[path.join(os.homedir(), '.ccs', 'cache', 'update-check.json')] = 'invalid json';
 
       // Should not throw error
       const result = await updateCheckerModule.checkForUpdates('5.4.0', true, 'npm', 'latest');