Instruction file imported from kritikos-io/templates-dotnet (.github/instructions/observability.instructions.md). Copyright stays with the author.

Observability & Feature Flags

OpenTelemetry

• One ActivitySource per logical component, named Kritikos.<Project>.<Component>. Declare as static readonly on a dedicated Telemetry static class within the component (avoid scattering sources across every type).
• One Meter per component, alongside its ActivitySource. The names may match when both belong to the same component.
• Always wrap StartActivity(...) in a using — leaked activities skew downstream timings.
• Activity names:
  • When OpenTelemetry semantic conventions cover the operation (HTTP, DB, messaging, RPC), follow semconv exactly (HTTP GET, db.query, messaging.process).
  • For custom operations not covered by semconv: <Verb><Object> in PascalCase (ProcessOrder, LoadConfiguration). Avoid generic verbs like Handle or Execute.
• Tags / attributes: lowercase dotted, follow semantic conventions where they exist (http.request.method, db.system, messaging.destination.name). Project-specific tags use the kritikos.<area>.<name> namespace.
• Metric instruments: snake_case names with units in the suffix (orders_processed_total, request_duration_seconds). Always set unit and description at creation.
• Resource attributes: when a shared registration helper is added, it should populate service.name from AssemblyName and service.version from the GitVersion-computed InformationalVersion. Do not set them manually at call sites.
• Exporter: OTLP over gRPC, endpoint via OTEL_EXPORTER_OTLP_ENDPOINT. Do not register console exporters in Release builds.
• Sampling: parent-based with TraceIdRatioBased (1.0 in dev, configurable in prod). Do not set custom samplers without justification.

OpenFeature

• Resolve flags through the configured OpenFeature client (obtained via DI, or Api.Instance.GetClient() if no DI integration is wired). Never call provider SDKs directly.
• Flag keys: kebab-case, prefixed by domain (orders-allow-partial-fulfilment, auth-require-mfa). Keys are stable contracts — treat renames like API breaking changes.
• Always pass defaultValue: — client.GetBooleanValue("flag", defaultValue: false, context).
• Evaluation context is built once per request via the configured context provider — do not assemble ad-hoc contexts inline.
• Long-lived flags (kill switches, licensing) live in code; short-lived flags (rollouts, experiments) must have a removal date in their description and a tracking issue.