About NVIDIA NeMo RelayRelease Notes

Highlights

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This page summarizes the notable capabilities in the current release documentation set.

NeMo Relay 0.3

NeMo Relay 0.3 adds first-party guardrails, richer trajectory export, adaptive plugin workflows, and clearer integration support for agent runtimes.

Breaking Changes

  • The project was renamed to NeMo Relay across documentation, package guidance, and CLI-facing surfaces.
  • The core runtime registry surface was narrowed. Applications should use the documented middleware, intercept, subscriber, and plugin APIs instead of broad registry access.
  • Native subscriber delivery is now non-blocking. Event construction remains synchronous, but subscriber callbacks and exporter work are queued on a process-wide background dispatcher. Applications and tests that depend on subscriber side effects must call the subscriber flush API before reading captured events, files, or exported trace output.

Guardrails

  • Added the built-in nemo_guardrails plugin contract for installing NeMo Guardrails behavior through NeMo Relay plugin configuration.
  • Added a remote NeMo Guardrails backend for deployments that call an external guardrails service.
  • Added CLI editor support for guardrails plugin configuration.
  • Added guardrail scopes for conditional guardrails so trace output shows guardrail execution boundaries more clearly.
  • Integrated security guardrails around managed agent calls.

Observability

  • Exposed canonical ATOF event JSON across bindings so applications can consume the same event shape from Rust, Python, and Node.js.
  • Upgraded ATIF exporters to ATIF v1.7 with nested subagent support.
  • Added first-class S3-compatible storage export for ATIF traces.
  • Added streaming LLM chunk marks for more precise streaming trace inspection.
  • Fixed LLM start event ordering so managed LLM start events are emitted before execution intercepts.
  • Fixed ATIF tool-observation correlation.

Plugins And Adaptive Runtime

  • Enabled the adaptive plugin for the CLI and OpenClaw workflows.
  • Added CLI editor support for adaptive plugin configuration.
  • Added a Python context manager for plugin initialization and teardown.

Integrations

  • Improved LangChain serialization for wrapped requests and responses.
  • Preserved OpenClaw tool call replay visibility with the upgrade to OpenClaw 2026.5.26
  • Updated the launch banner to use NEMO RELAY.

Documentation And Tooling

  • Switched the documentation site to Fern and consolidated Fern publishing.
  • Added broken-link validation for Fern documentation.
  • Added agent runtime primer, trace incident runbook, plugin-building, migration, and adaptive tuning guidance.
  • Added built-in guardrails plugin documentation.
  • Added CI path filters, CLI draft release assets, dependency updates, and ATIF S3 storage test coverage.

The complete changelog and release artifacts can be viewed on GitHub Releases.