TelemetryType

Process-wide switch for the message-flow narrative logs. Default: on.

Process-wide switch for including rendered message *payloads* in diagnostics. Default: on. Span *names* are always low-cardinality case names (e.g. "Command:Register") regardless of this switch — payload values never appear there, so per-operation tracing rules and trace-viewer grouping always work, and nothing sensitive leaks into the indexed span name. This switch governs the *detail*: the payload rendered into span tags (command.type / event.type) and into the message-flow log lines. Turn it off (Telemetry.IncludePayloads <- false, or FcqrsBuilder.WithPayloadDiagnostics(false)) for sensitive domains — tags and log lines then carry the case name only, matching the span name.

Saga state transitions.

Optional hook invoked right before FCQRS kills the process on a fatal error. FailFast skips finalizers and ProcessExit handlers, so without this everything still sitting in a batch exporter or buffered log sink is silently dropped — including the span and log entry of the fatal flow itself (every fatal site logs before invoking this hook). Flush your whole pipeline here, e.g. Telemetry.FatalFlush <- Action(fun () -> tracerProvider.ForceFlush(3000) |> ignore loggerProvider.ForceFlush(3000) |> ignore) // or Serilog's Log.CloseAndFlush() It runs on a background thread with a 5-second cap so a hung exporter cannot block the kill.

Logger category of the out-of-box message-flow narrative: which command reached which aggregate and what it yielded, saga state transitions, the commands sagas issue, and the events they pick up. Written at Information level — these lines describe the application's messages, not FCQRS internals, so they are ON by default. Silence them with Telemetry.MessageFlowLogging <- false (or FcqrsBuilder.WithMessageFlowLogging(false)), or filter this category in your logging configuration.

Commands and events flowing through aggregates.

Every FCQRS source, for one-call registration.

Read-side projection of journal events.

Metadata key carrying the W3C traceparent. Stamped automatically on commands created while an Activity is current; flows command -> events -> saga -> the saga's commands through the existing Metadata plumbing, so the CID stays a plain correlation id and tracing rides beside it.