Test-AppInsightsAgentStatus

Comprehensive diagnostic tool for the Azure Application Insights on-premises agent
(also known as Status Monitor V2 or Redfield Agent). Validates all installation
artifacts created during the Enable-ApplicationInsightsMonitoring workflow and
inspects running processes to determine agent attachment status.

Currently supports Status Monitor V2 (Redfield) on IIS. Future versions will
support VM Extensions, App Service, and Functions auto-instrumentation.

QUICK START:
 .\Test-AppInsightsAgentStatus.ps1
 .\Test-AppInsightsAgentStatus.ps1 -IncludeInstrumentationEngine

WHAT IT CHECKS:
 - IIS service health (W3SVC and WAS)
 - applicationHost.config module registration (ManagedHttpModuleHelper)
 - GAC assembly registration
 - Registry environment variables (Classic AI and OpenTelemetry modes)
 - IIS application pool pipeline mode (Integrated vs Classic)
 - Application pool identity performance counter permissions
 - Redfield configuration files (ikey.config)
 - PowerShell module installation (Az.ApplicationMonitor)
 - ASP.NET Core startup hook and hosting startup files
 - Instrumentation Engine CLR profiler configuration (auto-detected or -IncludeInstrumentationEngine)

All checks are READ-ONLY. The script never modifies any configuration.

OUTPUT MODES:
- Default:  Full verbose output with educational explanations
- Compact:  Progress lines only with focused diagnosis at the end

WHAT TO EXPECT:
The script runs non-interactively in ~5-15 seconds. Results display as they
complete. Must be run as Administrator for full accuracy.

COMPANION TOOL:
If the agent status looks healthy but telemetry is still missing, run
Test-AppInsightsTelemetryFlow.ps1 to diagnose network path and backend issues.