ADR-0006: ILogger with Application Insights

Status

Accepted

Context

The system spans libraries and four hosts. Logging has to be complete and detailed across every tier and flow to Azure Application Insights, without coupling the libraries to a specific telemetry product.

Decision

Every tier logs through Microsoft.Extensions.Logging.ILogger. The libraries depend only on the logging abstractions. UniDataGen.Observability wires Application Insights at the host boundary through AppInsightsLogging.CreateFactory, and a DelegateLoggerProvider lets a host mirror logs into its own UI. Logs carry structured properties and a run-scoped correlation id.

Consequences

• The libraries stay free of a telemetry dependency and are testable with a null logger.
• Each host wires the destination once; Core, Configuration, Foundry, and the target adapters all flow through it.
• A single run is traceable end to end across hosts by its RunId.

Alternatives considered

• Reference the Application Insights SDK directly in each library. Couples the libraries to one product and complicates testing.
• A custom logging interface. Reinvents ILogger and loses the provider ecosystem.