# Bug Fix #9: Missing Error Handling in Status Rendering

## ⚠️ **HIGH SEVERITY BUG** - BROKEN UI STATE

**Location:** `core/io/terminal_renderer.py:186-194`
**Severity:** High
**Impact:** Broken UI state, inconsistent display

## 📋 **Bug Description**

The status rendering system lacks proper error handling, causing exceptions in status view rendering to break the entire UI display and leave the terminal in an inconsistent state.

### Current Problematic Code
```python
# core/io/terminal_renderer.py:186-194 (approximate)
class TerminalRenderer:
    def render_status_area(self):
        """Render the status area."""
        # ← PROBLEM: No error handling around status rendering
        for status_view in self.status_views:
            content = status_view.get_content()
            self.render_line(content, y_offset)
            y_offset += 1

    def render(self):
        """Main render method."""
        try:
            # Clear screen
            self.clear_screen()

            # Render main content
            self.render_main_content()

            # ← PROBLEM: Status rendering not wrapped in try/catch
            self.render_status_area()

            # Refresh display
            self.refresh()

        except Exception as e:
            # ← PROBLEM: Only outer exception handled, status errors crash UI
            logger.error(f"Render error: {e}")
            self.render_error_state()
```

### The Issue
- **No error handling** around individual status view rendering
- **Cascading failures** - one broken status view breaks entire UI
- **Inconsistent display state** when partial rendering fails
- **No recovery mechanism** for broken status views
- **UI freezes** when status rendering throws exceptions

## 🔧 **Fix Strategy**

### 1. Add Comprehensive Error Handling for Status Rendering
```python
import logging
import traceback
from typing import List, Optional, Dict, Any
from datetime import datetime

logger = logging.getLogger(__name__)

class TerminalRenderer:
    def __init__(self):
        # ... existing code ...
        self.status_view_errors: Dict[str, Dict] = {}
        self.max_status_errors = 5
        self.status_error_cooldown = 60  # seconds
        self.fallback_status_views = []

    def render_status_area(self):
        """Render status area with comprehensive error handling."""
        y_offset = self.status_area_start_y
        rendered_views = 0
        max_status_lines = self.get_max_status_lines()

        try:
            # Sort status views by priority
            sorted_views = self._sort_status_views_by_priority()

            for status_view in sorted_views:
                if rendered_views >= max_status_lines:
                    break

                # Check if this view has recent errors
                if self._is_view_error_limited(status_view.name):
                    self._render_error_placeholder(status_view, y_offset)
                    y_offset += 1
                    rendered_views += 1
                    continue

                # Try to render the status view
                try:
                    content = self._render_status_view_safe(status_view)
                    if content:
                        self.render_line(content, y_offset)
                        y_offset += 1
                        rendered_views += 1

                        # Clear any previous errors for this view
                        self._clear_status_view_errors(status_view.name)

                except Exception as e:
                    self._handle_status_view_error(status_view, e, y_offset)
                    y_offset += 1
                    rendered_views += 1

            # Fill remaining status area with fallback content
            if rendered_views < max_status_lines:
                self._render_fallback_status(rendered_views, y_offset, max_status_lines)

        except Exception as e:
            logger.error(f"Critical error in status area rendering: {e}")
            self._render_status_area_fallback(y_offset, max_status_lines)

    def _render_status_view_safe(self, status_view: 'StatusView') -> Optional[str]:
        """Safely render a single status view."""
        try:
            # Get content from view
            content = status_view.get_content()

            # Validate content
            if not isinstance(content, str):
                logger.warning(f"Status view {status_view.name} returned non-string content: {type(content)}")
                return f"[{status_view.name}: Invalid content type]"

            # Validate content length
            max_length = self.get_terminal_width() - 4  # Leave margin
            if len(content) > max_length:
                content = content[:max_length-3] + "..."

            # Validate content characters (prevent control characters)
            if not self._is_safe_content(content):
                logger.warning(f"Status view {status_view.name} returned unsafe content")
                return f"[{status_view.name}: Content validation failed]"

            return content

        except Exception as e:
            logger.error(f"Error rendering status view {status_view.name}: {e}")
            raise

    def _is_safe_content(self, content: str) -> bool:
        """Check if content is safe for terminal display."""
        # Check for dangerous control characters
        dangerous_chars = ['\x00', '\x01', '\x02', '\x03', '\x04', '\x05', '\x06', '\x07']
        return not any(char in content for char in dangerous_chars)

    def _sort_status_views_by_priority(self) -> List['StatusView']:
        """Sort status views by priority and health."""
        def view_priority(view):
            # Higher priority for views with no recent errors
            error_count = len(self.status_view_errors.get(view.name, {}).get('recent_errors', []))
            return (-view.priority, error_count)  # Lower error count = higher priority

        return sorted(self.status_views, key=view_priority)

    def _handle_status_view_error(self, status_view: 'StatusView', error: Exception, y_offset: int):
        """Handle errors in status view rendering."""
        error_info = {
            'timestamp': datetime.now(),
            'error': str(error),
            'traceback': traceback.format_exc(),
            'render_count': 0
        }

        # Record error
        if status_view.name not in self.status_view_errors:
            self.status_view_errors[status_view.name] = {
                'recent_errors': [],
                'total_errors': 0
            }

        self.status_view_errors[status_view.name]['recent_errors'].append(error_info)
        self.status_view_errors[status_view.name]['total_errors'] += 1

        # Keep only recent errors
        recent_errors = self.status_view_errors[status_view.name]['recent_errors']
        if len(recent_errors) > self.max_status_errors:
            self.status_view_errors[status_view.name]['recent_errors'] = recent_errors[-self.max_status_errors:]

        # Log error
        logger.error(f"Status view {status_view.name} failed to render: {error}")

        # Render error placeholder
        self._render_error_placeholder(status_view, y_offset)

    def _render_error_placeholder(self, status_view: 'StatusView', y_offset: int):
        """Render a placeholder for a failed status view."""
        error_text = f"[{status_view.name}: Error]"
        self.render_line(error_text, y_offset, style='error')

    def _is_view_error_limited(self, view_name: str) -> bool:
        """Check if a view is rate-limited due to errors."""
        if view_name not in self.status_view_errors:
            return False

        recent_errors = self.status_view_errors[view_name]['recent_errors']
        if not recent_errors:
            return False

        # Check if there are too many recent errors
        latest_error = recent_errors[-1]['timestamp']
        time_since_error = (datetime.now() - latest_error).total_seconds()

        if time_since_error < self.status_error_cooldown:
            if len(recent_errors) >= 3:  # Too many errors in cooldown period
                return True

        return False

    def _clear_status_view_errors(self, view_name: str):
        """Clear errors for a successfully rendered view."""
        if view_name in self.status_view_errors:
            self.status_view_errors[view_name]['recent_errors'] = []

    def _render_fallback_status(self, current_line: int, start_y: int, max_lines: int):
        """Render fallback status content."""
        fallback_content = [
            f"Time: {datetime.now().strftime('%H:%M:%S')}",
            f"Terminal: {self.get_terminal_width()}x{self.get_terminal_height()}",
            f"Views: {len(self.status_views)} active"
        ]

        for i, content in enumerate(fallback_content):
            if current_line + i < max_lines:
                self.render_line(content, start_y + current_line + i, style='fallback')

    def _render_status_area_fallback(self, start_y: int, max_lines: int):
        """Ultimate fallback for status area rendering."""
        try:
            fallback_content = [
                "Status rendering unavailable",
                f"Terminal size: {self.get_terminal_width()}x{self.get_terminal_height()}",
                f"Time: {datetime.now().strftime('%H:%M:%S')}",
                f"Active views: {len(self.status_views) if self.status_views else 0}"
            ]

            for i, content in enumerate(fallback_content[:max_lines]):
                self.render_line(content, start_y + i, style='error_fallback')

        except Exception as e:
            logger.error(f"Even fallback status rendering failed: {e}")
            # Last resort - just clear the area
            for i in range(max_lines):
                self.render_line("", start_y + i)
```

### 2. Add Status View Health Monitoring
```python
def get_status_view_health(self) -> Dict[str, Any]:
    """Get health status of all status views."""
    health_report = {
        'total_views': len(self.status_views),
        'healthy_views': 0,
        'error_views': 0,
        'rate_limited_views': 0,
        'view_details': {}
    }

    for view in self.status_views:
        view_health = {
            'name': view.name,
            'priority': view.priority,
            'status': 'healthy',
            'recent_errors': 0,
            'total_errors': 0,
            'last_error': None
        }

        if view.name in self.status_view_errors:
            error_data = self.status_view_errors[view.name]
            view_health.update({
                'recent_errors': len(error_data['recent_errors']),
                'total_errors': error_data['total_errors'],
                'last_error': error_data['recent_errors'][-1] if error_data['recent_errors'] else None
            })

            if self._is_view_error_limited(view.name):
                view_health['status'] = 'rate_limited'
                health_report['rate_limited_views'] += 1
            elif error_data['recent_errors']:
                view_health['status'] = 'error'
                health_report['error_views'] += 1
        else:
            health_report['healthy_views'] += 1

        health_report['view_details'][view.name] = view_health

    return health_report

def get_status_error_summary(self) -> str:
    """Get a summary of status view errors for logging."""
    total_errors = sum(
        data['total_errors']
        for data in self.status_view_errors.values()
    )

    if total_errors == 0:
        return "No status view errors"

    error_summary = f"Status view errors: {total_errors} total"
    for view_name, data in self.status_view_errors.items():
        if data['recent_errors']:
            error_summary += f", {view_name}: {len(data['recent_errors'])} recent"

    return error_summary
```

### 3. Add Enhanced Status View Interface
```python
class StatusView:
    """Enhanced status view with error handling capabilities."""

    def __init__(self, name: str, priority: int = 100):
        self.name = name
        self.priority = priority
        self.last_successful_render = None
        self.render_count = 0
        self.error_count = 0

    def get_content(self) -> str:
        """Get status content - must be implemented by subclasses."""
        raise NotImplementedError

    def is_healthy(self) -> bool:
        """Check if the status view is healthy."""
        if self.render_count == 0:
            return True  # New views are considered healthy

        error_rate = self.error_count / self.render_count
        return error_rate < 0.1  # Less than 10% error rate

    def get_health_status(self) -> Dict[str, Any]:
        """Get detailed health status."""
        return {
            'name': self.name,
            'priority': self.priority,
            'render_count': self.render_count,
            'error_count': self.error_count,
            'error_rate': self.error_count / max(self.render_count, 1),
            'last_successful_render': self.last_successful_render,
            'is_healthy': self.is_healthy()
        }

    def record_successful_render(self):
        """Record a successful render."""
        self.render_count += 1
        self.last_successful_render = datetime.now()

    def record_error(self):
        """Record a render error."""
        self.render_count += 1
        self.error_count += 1
```

### 4. Add Configuration for Error Handling
```python
# core/config/terminal_config.py
class TerminalConfig:
    status_rendering:
        max_status_errors: int = 5
        error_cooldown_seconds: int = 60
        enable_fallback_content: bool = True
        max_status_lines: int = 5
        content_validation: bool = True
        max_content_length: int = 200

    error_handling:
        log_status_errors: bool = True
        log_tracebacks: bool = False
        enable_health_monitoring: bool = True
        auto_disable_failing_views: bool = False
```

### 5. Add Recovery and Maintenance
```python
async def maintenance_cleanup(self):
    """Perform maintenance cleanup of status views."""
    try:
        # Clear old errors
        cutoff_time = datetime.now() - timedelta(hours=1)
        for view_name in self.status_view_errors:
            recent_errors = self.status_view_errors[view_name]['recent_errors']
            self.status_view_errors[view_name]['recent_errors'] = [
                error for error in recent_errors
                if error['timestamp'] > cutoff_time
            ]

        # Remove views with no recent errors
        views_to_remove = [
            name for name, data in self.status_view_errors.items()
            if not data['recent_errors']
        ]
        for view_name in views_to_remove:
            del self.status_view_errors[view_name]

        logger.info(f"Status view maintenance completed, removed {len(views_to_remove)} error records")

    except Exception as e:
        logger.error(f"Error during status view maintenance: {e}")

def reset_status_view_errors(self, view_name: Optional[str] = None):
    """Reset errors for a specific view or all views."""
    if view_name:
        if view_name in self.status_view_errors:
            del self.status_view_errors[view_name]
            logger.info(f"Reset errors for status view: {view_name}")
    else:
        self.status_view_errors.clear()
        logger.info("Reset all status view errors")
```

## ✅ **Implementation Steps**

1. **Add comprehensive error handling** around status view rendering
2. **Implement error tracking** and rate limiting for failing views
3. **Create fallback mechanisms** for broken status rendering
4. **Add content validation** to prevent unsafe content
5. **Implement health monitoring** for status views
6. **Add maintenance procedures** for error cleanup

## 🧪 **Testing Strategy**

1. **Test status view failures** - verify UI remains functional
2. **Test error rate limiting** - verify failing views are handled
3. **Test fallback rendering** - verify backup content works
4. **Test content validation** - verify unsafe content is blocked
5. **Test recovery procedures** - verify error cleanup works
6. **Test health monitoring** - verify reporting is accurate

## 🚀 **Files to Modify**

- `core/io/terminal_renderer.py` - Main fix location
- `core/io/status_view.py` - Enhance status view interface
- `core/config/terminal_config.py` - Add error handling configuration
- `tests/test_terminal_renderer.py` - Add error handling tests

## 📊 **Success Criteria**

- ✅ Status view failures don't break the entire UI
- ✅ Failing views are properly tracked and rate-limited
- ✅ Fallback content is displayed when views fail
- ✅ Content validation prevents unsafe display
- ✅ Health monitoring provides visibility into view status
- ✅ Maintenance procedures clean up old error data

## 💡 **Why This Fixes the Issue**

This fix eliminates UI breakdowns by:
- **Isolating status view errors** so they don't crash the entire interface
- **Implementing error tracking** to identify problematic views
- **Providing fallback content** when normal rendering fails
- **Adding content validation** to prevent display corruption
- **Enabling health monitoring** for proactive issue detection
- **Supporting automatic recovery** through maintenance procedures

The broken UI state issue is eliminated because every status view is wrapped in comprehensive error handling, and multiple layers of fallbacks ensure the terminal display remains functional even when individual components fail.