2.2.0

Tracing and metrics

AnyMediator now emits OpenTelemetry-compatible spans and a duration histogram through .NET's own ActivitySource and Meter. No new dependency, no behavior change, and nothing is recorded until you subscribe:

builder.Services.AddOpenTelemetry()
    .WithTracing(t => t.AddSource(AnyMediatorDiagnostics.ActivitySourceName))
    .WithMetrics(m => m.AddMeter(AnyMediatorDiagnostics.MeterName));

• Spans: send {Request}, create_stream {Request} (open until the stream is read, fails or is abandoned), publish {Notification} with one handle {Notification} child per handler. Attributes anymediator.operation, anymediator.message.type, anymediator.handler.type; failures set Error status, error.type and an exception event.
• Metric: anymediator.operation.duration histogram, in seconds, by operation, message type and error.type.
• New: AnyMediatorDiagnostics.ActivitySourceName and AnyMediatorDiagnostics.MeterName.

Cost

	Not listening	Listening
Send (1 span)	87 ns, 96 B	564 ns, 704 B
Publish, 3 handlers (4 spans)	307 ns, 632 B	2,310 ns, 2,872 B

Guide: Tracing and metrics

What's Changed

• OpenTelemetry tracing and metrics for Send, CreateStream, Publish and handlers by @Adiakys in #19

Full Changelog: 2.1.1...2.2.0