Axial.Telemetry Reference

Axial.Telemetry connects Flow execution and fiber lifecycle to .NET ActivitySource and Meter APIs. The host still chooses and configures its OpenTelemetry listeners, exporters, and sampling.

Surface	Members	Purpose
AttributeKey	string, boolean, int64, float, and list variants	Define a typed application attribute
Context	attribute, current, construction, scoping, inspection, and semantic helpers	Carry typed telemetry attributes through the ambient Flow runtime
ActivityTracer	create, .Trace	Capture an application-owned ActivitySource once and trace from it without repeating the source per call site
Activity	runtimeSource, traceOn, traceWithSource, withTracer, trace, traceWith	Wrap a workflow in an Activity and stamp its final Exit
FiberTelemetry	observer, observe, observerWithSpans, observeWithSpans	Report fiber defects or create one span per fiber
FiberMetrics	meter, observer, observe	Record fiber starts, live counts, settlement, duration, and unobserved defects
FiberDumpTelemetry	record	Add a live-fiber tree to the current trace or a standalone span

Start with Context.withAttributes and Activity.traceOn applicationActivitySource for searchable application workflow spans. Register that source name and "Axial" with OpenTelemetry. The application source owns user operation spans; Axial's runtimeSource owns automatic runtime and fiber spans — trace application workflows through your own source, not Axial's. When many call sites share one application source, capture it once with ActivityTracer.create and either call .Trace on the tracer directly, or install it ambiently for a whole workflow tree with Activity.withTracer and call the ambient Activity.trace/Activity.traceWith underneath it. Install FiberTelemetry.observe once at the application edge when unjoined child defects must be visible. Use the span-per-fiber observer only when that extra span volume is useful.

See Telemetry for setup and complete examples.