adding new features & layouts

1. Update suggestionGeneratorAgent.ts
- Match the suggestions to user's language

2. Add incognito mode
- Allow user to switch on / off incognito mode by webpage toggle or url parameter
- URL Parameter Control
 - Accessing `/?incognito=true` automatically enables incognito mode
 - Accessing `/?incognito=false` or without parameters will use normal mode

3. Add the history retention feature
- Allow users to set history retention days through config.toml or API endpoints, as well as on the settings page.

4. Add layout mode: Default / Tabs
- Allow users to change default layout mode through config.toml
- Allow users to customize layout mode for each browser through setting page

5. Allow users to change webpage theme by system detection

test-history-retention.md

@@ -0,0 +1,105 @@
+# History Retention Feature Test Guide
+
+This document outlines how to test the history retention feature that has been implemented.
+
+## Features Implemented
+
+1. **Config.toml Setting**: Added `RETENTION_DAYS` setting under `[HISTORY]` section
+2. **Settings Page**: Added UI control to set history retention days when incognito mode is off
+3. **API Endpoints**: 
+   - Updated `/api/config` to handle history retention settings
+   - Created `/api/cleanup-history` for manual cleanup
+4. **Automatic Cleanup**: History cleanup runs automatically when new chats are created (non-incognito mode)
+
+## Configuration
+
+### config.toml
+```toml
+[HISTORY]
+RETENTION_DAYS = 30 # Number of days to keep chat history when incognito mode is off (0 = keep forever)
+```
+
+### Settings Page
+- Navigate to Settings page
+- Find "History Settings" section
+- Set "History Retention (Days)" value
+- 0 = keep forever
+- Any positive number = days to retain history
+
+## How It Works
+
+1. **When Incognito Mode is OFF**:
+   - Chat history is saved to database
+   - History cleanup runs automatically when creating new chats
+   - Old chats (older than retention period) are automatically deleted
+
+2. **When Incognito Mode is ON**:
+   - Chat history is NOT saved to database
+   - No cleanup needed as nothing is stored
+
+3. **Cleanup Logic**:
+   - Runs automatically in background when new chats are created
+   - Deletes chats older than the configured retention period
+   - Also deletes all messages associated with old chats
+   - If retention is set to 0, keeps all history forever
+
+## Testing Steps
+
+1. **Set Retention Period**:
+   - Go to Settings page
+   - Set "History Retention (Days)" to a small number (e.g., 1 day for testing)
+   - Save the setting
+
+2. **Create Test Chats**:
+   - Make sure incognito mode is OFF
+   - Create several test chats
+   - Verify they appear in chat history
+
+3. **Test Manual Cleanup**:
+   - Call POST `/api/cleanup-history` endpoint
+   - Check response for cleanup results
+
+4. **Test Automatic Cleanup**:
+   - Wait for retention period to pass (or modify database dates for testing)
+   - Create a new chat (triggers automatic cleanup)
+   - Verify old chats are removed
+
+5. **Test Incognito Mode**:
+   - Turn ON incognito mode
+   - Create chats - they should not be saved to history
+   - Turn OFF incognito mode
+   - Create chats - they should be saved and cleanup should work
+
+## API Endpoints
+
+### GET /api/config
+Returns current configuration including `historyRetentionDays`
+
+### POST /api/config
+Updates configuration including `historyRetentionDays`
+
+### POST /api/cleanup-history
+Manually triggers history cleanup and returns results:
+```json
+{
+  "message": "Cleaned up X old chats and their messages",
+  "deletedChats": X
+}
+```
+
+## Files Modified
+
+1. `config.toml` - Added HISTORY section
+2. `src/lib/config.ts` - Added history retention getter/setter
+3. `src/app/api/config/route.ts` - Added history retention to API
+4. `src/app/settings/page.tsx` - Added UI control for history retention
+5. `src/app/api/cleanup-history/route.ts` - New cleanup endpoint
+6. `src/lib/utils/historyCleanup.ts` - Cleanup utility functions
+7. `src/app/api/chat/route.ts` - Integrated automatic cleanup
+
+## Notes
+
+- History retention only applies when incognito mode is OFF
+- Cleanup runs automatically in background to avoid blocking chat creation
+- Setting retention to 0 disables cleanup (keeps all history)
+- Cleanup is based on chat creation date (`createdAt` field)