# Container Health Fixes - Implementation Summary

## Overview
This PR addresses three critical issues that were causing container health failures and functionality problems.

## Issues Fixed

### 1. Tracking Error: "uniqueVisitors.add is not a function" ✅

**Problem:**
The application was logging repeated errors:
```
[2026-01-12T08:26:20.032Z] Tracking error {"error":"TypeError: trackingData.summary.dailyVisits[dateKey].uniqueVisitors.add is not a function"}
```

**Root Cause:**
When tracking data was persisted to JSON and loaded back, the `dailyVisits[dateKey].uniqueVisitors` Sets were serialized as arrays. On reload, they remained as arrays instead of being converted back to Sets, causing `.add()` method calls to fail.

**Solution:**
- Modified `loadTrackingData()` (lines 1055-1098) to iterate through `dailyVisits` and convert `uniqueVisitors` arrays back to Sets
- Modified `persistTrackingData()` (lines 1100-1124) to explicitly serialize Sets to arrays before JSON stringification
- Simplified conditional logic per code review feedback

**Files Changed:**
- `chat/server.js` (lines 1055-1124)

---

### 2. Invalid URL Error: "TypeError: Invalid URL" ✅

**Problem:**
The application was crashing with errors:
```
TypeError: Invalid URL
    at new URL (node:internal/url:806:29)
    at route (/opt/webchat/server.js:6853:15)
  code: 'ERR_INVALID_URL',
  input: '//?author=1',
```

**Root Cause:**
Malformed HTTP requests with URLs like `//?author=1` (double leading slashes) caused the native `URL` constructor to throw unhandled exceptions, crashing request handlers.

**Solution:**
- Created `sanitizeUrl()` utility function (lines 1136-1145) to detect and fix URLs starting with `//`
- Updated `route()` function (lines 6887-6910) to:
  - Use sanitizeUrl before URL parsing
  - Catch URL parsing errors and return 400 Bad Request
  - Log invalid URLs for monitoring
- Updated `trackVisit()` function (lines 1137-1153) to:
  - Use sanitizeUrl before URL parsing
  - Gracefully skip tracking on invalid URLs
  - Log skipped tracking attempts

**Files Changed:**
- `chat/server.js` (lines 1136-1145, 1147-1153, 6887-6910)

---

### 3. Model Dropdown Not Showing Up ✅

**Problem:**
Users reported that the model dropdown in the builder (`/builder`) was not displaying any options.

**Root Cause:**
The model dropdown functionality was working correctly, but the system only had 2 test models configured with outdated model identifiers. The dropdown requires properly configured models in `admin-models.json` to display options.

**Solution:**
Added comprehensive default model configurations with 5 modern, widely-available models:

1. **GPT-4o Mini** (free tier) - Fast, cost-effective OpenAI model
2. **GPT-4o** (plus tier) - Latest flagship OpenAI model
3. **Claude 3.5 Sonnet** (plus tier) - High-performance Anthropic model
4. **Claude 3.5 Haiku** (free tier) - Fast, efficient Anthropic model
5. **Gemini 2.0 Flash** (free tier) - Latest Google experimental model

Each model is properly configured with:
- Unique ID and name
- Display label
- CLI type (opencode)
- Provider mapping (openai, anthropic, google)
- Usage tier (free, plus, pro)

**Files Changed:**
- `.data/.opencode-chat/admin-models.json`

---

## Testing

### Manual Testing
Created `/tmp/test-fixes.js` script that validates:
- ✅ Tracking data serialization/deserialization
- ✅ Set operations after deserialization
- ✅ URL sanitization for various edge cases

All tests passed successfully.

### Syntax Validation
```bash
node -c chat/server.js  # ✅ Passed
```

### Code Review
- Addressed all code review feedback
- Extracted duplicated URL sanitization into shared utility function (DRY principle)
- Simplified conditional logic in loadTrackingData
- Improved documentation and comments

### Security Check
```bash
codeql_checker  # ✅ No alerts found
```

---

## Impact

### Before:
- Container health checks failing due to repeated tracking errors
- Application crashes on malformed URL requests
- Model dropdown showing no options for users
- Poor user experience and system instability

### After:
- ✅ Tracking system working correctly with proper Set serialization
- ✅ Robust URL handling preventing crashes from malformed requests
- ✅ Model dropdown populated with 5 modern, widely-available models
- ✅ Improved stability and user experience

---

## Code Quality Improvements

1. **DRY Principle**: Extracted duplicated URL sanitization logic into shared `sanitizeUrl()` utility
2. **Error Handling**: Added comprehensive try-catch blocks and graceful degradation
3. **Logging**: Enhanced logging for debugging and monitoring
4. **Documentation**: Added clear comments explaining the purpose of each fix
5. **Maintainability**: Simplified conditional logic and improved code readability

---

## Deployment Notes

### Configuration Requirements
- Models are configured in `.data/.opencode-chat/admin-models.json`
- File is loaded at server startup via `loadAdminModelStore()`
- No environment variables need to be changed

### Backward Compatibility
- ✅ All changes are backward compatible
- ✅ Existing tracking data will be properly migrated on load
- ✅ No breaking changes to API endpoints

### Monitoring
Watch for these log messages to confirm fixes are working:
- `Loaded tracking data` - Confirms tracking data loaded with Sets intact
- `Invalid URL` - Confirms malformed URLs are being handled gracefully
- `Tracking skipped - invalid URL` - Confirms tracking gracefully handles bad URLs
- `Models loaded successfully` - Confirms model dropdown will populate

---

## Related Documentation

- `BUILDER_MODEL_DROPDOWN_FIX.md` - Detailed investigation of dropdown functionality
- Model configuration schema documented in `BUILDER_MODEL_DROPDOWN_FIX.md`

---

## Security Summary

**Vulnerabilities Discovered:** 0
**Vulnerabilities Fixed:** 0
**Security Scan Results:** ✅ Clean (CodeQL found no alerts)

**Security Improvements:**
- Added input validation for URLs to prevent crashes
- Proper error handling prevents information leakage
- Sanitization applied before URL parsing

---

## Conclusion

All three issues have been successfully resolved with minimal, surgical changes to the codebase. The fixes improve system stability, enhance error handling, and provide a better user experience. No security vulnerabilities were introduced, and all code quality standards have been maintained.