> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.nvidia.com/nemo/relay/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.nvidia.com/nemo/relay/_mcp/server.

# Concepts

Use these pages to understand the NeMo Relay runtime model before applying it
in a use-case workflow.

NeMo Relay's shared runtime model has five parts:

* **Scopes** decide where work belongs and which scope-local behavior is visible.
* **Middleware** decides what can block, rewrite, sanitize, or wrap managed
  execution.
* **Plugins** install reusable runtime behavior from configuration.
* **Events** record what happened in the canonical lifecycle stream.
* **Subscribers and exporters** consume that stream in process, write raw ATOF
  events, or project events into downstream formats.

Managed tool and LLM helpers are the application-owned API path through scopes,
middleware, events, and subscribers. Codecs are boundary translators that
normalize typed application values or provider-native payloads when runtime
behavior needs stable data shapes.

Use the concepts pages for runtime semantics such as ownership, ordering,
cleanup, and support boundaries. Use the generated [API
Reference](/reference/api) for symbol lookup after you already know which
runtime concept or integration boundary you need.

Ownership boundaries for agent runs, requests, workflows, tools, LLM calls, and nested runtime work.

Guardrails and intercepts that sanitize, transform, block, or wrap tool and LLM execution.

Configuration-driven bundles that install reusable middleware, subscribers, and adaptive behavior.

Canonical lifecycle records for scopes, tool calls, LLM calls, marks, subscribers, and exporters.

Consumers for lifecycle events, including logs, traces, trajectories, analytics, and diagnostics.

Integration patterns for frameworks that own invocation boundaries, scheduling, retries, or provider payloads.

Normalization boundaries for typed application values, provider payloads, middleware, and exporters.