Concepts
Start here if Harn is new to you, or if you've been writing Harn long enough that the docs you actually want are the ones that explain why things are shaped the way they are.
These pages don't teach you syntax and don't list every function. They explain the model that the rest of the docs assume you already have.
Mental model
The containment diagram for a Harn conversation: how llm_call, agent_loop, workflow, pipeline, and session fit together.
Glossary
Every term Harn uses for a conversational unit, with one-line definitions and pointers to the page that owns each one.
Choosing an abstraction
When to reach for llm_call, agent_loop, agent_turn, workflow_execute, spawn_agent, and friends.
Steering seams
Where you can safely inject a user message into a running agent, and where you can't (yet).
Cross-session pattern knowledge
Why reusable agent pattern recall is a Harn memory primitive, not a host-side session-store extension.
Coming from elsewhere
Terminology cross-reference for readers arriving from OpenAI Agents SDK, Anthropic Claude Agent SDK, LangGraph, Inngest, Mastra, ACP, A2A, and MCP.
If you're here to ship code today
- Getting started — install and run your first program.
- Tutorials — guided walkthroughs.
- Cookbook — task-oriented recipes.
- Reference — every builtin function and option.