mev-beta/docs/planning/02_CRITICAL-002_Unhandled_Errors_Fix_Plan.md

CRITICAL-002: Unhandled Error Conditions - Detailed Fix Plan

Issue ID: CRITICAL-002
Category: Security
Priority: Critical
Status: Not Started
Generated: October 9, 2025
Estimate: 8-10 hours

Overview

This plan addresses multiple unhandled error conditions in critical system components, particularly in the lifecycle management and shutdown procedures. These unhandled errors could lead to improper resource cleanup, resource leaks, and potential security vulnerabilities during system shutdown or failure scenarios.

Affected Files and Lines

• pkg/lifecycle/shutdown_manager.go:460 - OnShutdownCompleted hook
• pkg/lifecycle/shutdown_manager.go:457 - OnShutdownFailed hook
• pkg/lifecycle/shutdown_manager.go:396 - ForceShutdown call
• pkg/lifecycle/shutdown_manager.go:388 - ForceShutdown in timeout
• pkg/lifecycle/shutdown_manager.go:192 - StopAll call
• pkg/lifecycle/module_registry.go:729-733 - Event publishing
• pkg/lifecycle/module_registry.go:646-653 - Module started event
• pkg/lifecycle/module_registry.go:641 - Health monitoring start
• pkg/lifecycle/health_monitor.go:550 - Health change notification
• pkg/lifecycle/health_monitor.go:444 - System health notification

Implementation Tasks

1. Add Proper Error Handling and Logging

Task ID: CRITICAL-002.1
Time Estimate: 3 hours
Dependencies: None

For each identified location, implement proper error handling:

• In pkg/lifecycle/shutdown_manager.go:460: Handle errors in OnShutdownCompleted hook callback
• In pkg/lifecycle/shutdown_manager.go:457: Handle errors in OnShutdownFailed hook callback
• In pkg/lifecycle/shutdown_manager.go:396: Check and handle ForceShutdown return errors
• In pkg/lifecycle/shutdown_manager.go:388: Handle ForceShutdown errors in timeout scenario
• In pkg/lifecycle/shutdown_manager.go:192: Handle errors from StopAll calls
• In pkg/lifecycle/module_registry.go:729-733: Check return values from event publishing
• In pkg/lifecycle/module_registry.go:646-653: Handle errors when publishing module started events
• In pkg/lifecycle/module_registry.go:641: Handle errors in health monitoring start
• In pkg/lifecycle/health_monitor.go:550: Handle errors in health change notifications
• In pkg/lifecycle/health_monitor.go:444: Handle errors in system health notifications

Implementation Strategy:

• Wrap all error-prone calls with error checking
• Use structured logging with error context
• Implement error aggregation for debugging

2. Implement Graceful Degradation

Task ID: CRITICAL-002.2
Time Estimate: 2 hours
Dependencies: CRITICAL-002.1

For non-critical failures, implement graceful degradation:

• Continue shutdown process even if some modules fail to stop
• Log failures but don't block critical shutdown procedures
• Implement timeout mechanisms for blocking operations
• Create fallback paths for failed operations

3. Add Retry Mechanisms

Task ID: CRITICAL-002.3
Time Estimate: 1.5 hours
Dependencies: CRITICAL-002.1

Implement retry logic for:

• Event publishing that may fail temporarily
• Module shutdown that might fail initially
• Health monitoring operations
• Use exponential backoff with maximum retry limits

4. Create Error Aggregation and Reporting System

Task ID: CRITICAL-002.4
Time Estimate: 1 hour
Dependencies: CRITICAL-002.1, CRITICAL-002.2, CRITICAL-002.3

Develop a centralized error reporting system:

• Aggregate shutdown-related errors
• Store errors with context and timing information
• Implement error reporting to monitoring systems
• Create error summary for debugging

5. Add Monitoring Alerts for Repeated Failures

Task ID: CRITICAL-002.5
Time Estimate: 0.5 hours
Dependencies: CRITICAL-002.4

Implement monitoring for:

• Repeated shutdown failures
• High error rates during lifecycle events
• Alerts for critical system state changes
• Metrics for error frequency and types

Detailed Implementation Steps

In pkg/lifecycle/shutdown_manager.go:

// Example for fixing line 460
func (sm *ShutdownManager) OnShutdownCompleted(callback func() error) {
    sm.mu.Lock()
    defer sm.mu.Unlock()
    
    sm.shutdownCompletedHook = func() error {
        err := callback()
        if err != nil {
            sm.logger.Error("Shutdown completed hook failed", "error", err)
            // Log error but don't prevent shutdown completion
        }
        return err
    }
}

// Example for fixing line 396
func (sm *ShutdownManager) forceShutdown() error {
    if err := sm.StopAll(); err != nil {
        sm.logger.Error("Force shutdown StopAll failed", "error", err)
        // Continue with force shutdown even if StopAll fails
    }
    
    // Additional cleanup logic
    // Ensure all resources are released
    return nil
}

In pkg/lifecycle/module_registry.go:

// Example for fixing event publishing
func (mr *ModuleRegistry) PublishEvent(event Event) error {
    mr.mu.RLock()
    defer mr.mu.RUnlock()
    
    var errCount int
    for _, listener := range mr.eventListeners[event.Type] {
        if err := listener(event); err != nil {
            mr.logger.Error("Event listener failed", "event", event.Type, "error", err)
            errCount++
            // Continue with other listeners even if one fails
        }
    }
    
    if errCount > 0 {
        return fmt.Errorf("failed to process %d event listeners", errCount)
    }
    return nil
}

Testing Strategy

• Unit tests for error handling paths
• Integration tests for shutdown scenarios
• Chaos testing to simulate failure conditions
• Load testing to verify performance under error conditions

Code Review Checklist

• All error return values are checked
• Proper logging implemented for errors
• Graceful degradation implemented for non-critical failures
• Retry mechanisms are appropriate and bounded
• Error aggregation system is functional
• Monitoring and alerting implemented for repeated failures

Rollback Strategy

If issues arise after deployment:

1. Revert error handling changes
2. Temporarily disable new error handling with feature flags
3. Monitor system stability and error rates

Success Metrics

• Zero unhandled errors in logs
• Proper error propagation and handling
• Graceful degradation during failures
• All shutdown procedures complete successfully
• No performance impact beyond acceptable thresholds