Currently, MSBuild's BuildTelemetry class tracks general build success/failure via the BuildSuccess boolean property, but does not provide granularity on why a build failed. This makes it difficult to analyze failure patterns and improve the developer experience.

Add telemetry data to categorize build failure reasons when BuildSuccess = false. The failure categories should include at minimum:

Success Criteria

When a build fails, telemetry should report the primary failure category
Error counts by category should be included
The first error code encountered could optionally be included for debugging
Data should be available in both VS telemetry and SDK aggregated telemetry