# Metric Label Analyzer (Static Analysis)

## Module
Telemetry

## Status
IMPLEMENTED

## Description
Roslyn-based analyzer that validates metric label usage at compile time to prevent telemetry cardinality issues.

## Implementation Details
- **MetricLabelAnalyzer**: `src/Telemetry/StellaOps.Telemetry.Analyzers/MetricLabelAnalyzer.cs` -- Roslyn-based DiagnosticAnalyzer that validates metric label usage at compile time; detects high-cardinality labels, missing required labels, and naming convention violations
- **MetricLabelGuard**: `src/Telemetry/StellaOps.Telemetry.Core/StellaOps.Telemetry.Core/MetricLabelGuard.cs` -- runtime guard that validates metric labels before emission
- **Tests**: `src/Telemetry/StellaOps.Telemetry.Analyzers/StellaOps.Telemetry.Analyzers.Tests/MetricLabelAnalyzerTests.cs`, `src/Telemetry/StellaOps.Telemetry.Core/StellaOps.Telemetry.Core.Tests/MetricLabelGuardTests.cs`
- **Source**: Feature matrix scan

## E2E Test Plan
- [ ] Verify Roslyn analyzer detects high-cardinality metric labels at compile time
- [ ] Test analyzer flags missing required labels (tenant, service, environment)
- [ ] Verify naming convention violations produce diagnostic warnings
- [ ] Test runtime MetricLabelGuard rejects labels exceeding cardinality thresholds
- [ ] Verify analyzer integrates with CI build pipeline for automated enforcement