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Terminology

This page defines the shared naming model used across the repository so runtime does not mean both “the execution system” and “the thing being executed.”

Short version:

Agent Engine runs an Agent Runtime and extends it with Agent Spec.

If you want the system map that shows how these concepts fit together, continue with:

Core Terms

Term Role Meaning
Agent Engine Execution system Loads, schedules, executes, recovers, audits, and exposes API / SSE.
Agent Runtime Primary runnable unit A runnable unit that carries agent / action / hook definitions. Formerly called blueprint.
Agent Spec User extension layer Extra user-authored inputs layered onto a runtime, mainly AGENTS.md, MEMORY.md, and extra loaded model / tool / skill.

Boundary Rule

  • Engine: how it runs
  • Runtime: what runs
  • Spec: what the user adds

What Belongs To Runtime

These concepts belong to Runtime and should not be renamed as another kind of spec:

  • agent definitions
  • action definitions
  • hook definitions
  • runtime-owned default behavior and capability composition
  • runnable units under runtimes/

Avoid:

  • agent spec
  • hook spec
  • runtime spec

What Belongs To Spec

Spec is not the whole runtime structure. It is the user-authored extension layer added on top of a runtime. It mainly includes:

  • project-root AGENTS.md
  • project-root MEMORY.md
  • extra loaded model
  • extra loaded tool
  • extra loaded skill

Naming Rules To Avoid Ambiguity

When the meaning is about execution flow rather than the primary runnable unit, prefer:

  • engine
  • run
  • session
  • execution
  • engine state

So use names like:

  • EngineLogger
  • engine.log
  • engine state paths