Observability
Observability
Trace, log, audit, and cost-guard your agents end-to-end.
Loggers + tracers
consoleLogger— local dev.langsmith— LangSmith observer.opentelemetry— OTel observer.createTraceTracker— low-level span lifecycle.
Local trace viewer
createFileTraceSink+renderTraceViewerHtml— offline Jaeger-style HTML. Recipe.
Devtools server
createDevtoolsServer+toSseFrame— live feed for any devtools UI. Recipe.
Cost + tokens
costGuard— hard $ ceiling per run.approximateCounter,createProviderCounter— token accounting.
Audit
createSignedAuditLog— hash-chain + HMAC tamper-evident log. Recipe.
Per-observer deep dives land in step 6 of the docs IA rollout.