| Agent node | A node that runs an LLM in a loop, with tools. agentNode. |
| Approval request | A gated tool call waiting for a human, listed in the agent's approvalRequests. |
| Attestation | A signed record of an approval decision, chained to the previous one. |
| Catalog runner | runCatalogGraph / resumeCatalogGraph: runs a graph from its JSON definition and returns its state, so it can resume anywhere. |
| Channel | A named piece of run state, with a type label, a default and a reducer. |
| Checkpoint | The saved state of a run after a node. A run resumes from its last checkpoint. |
| Component | A ready-made node that runs inside the engine, such as a retriever or a prompt template. |
| Compiled graph | What compile() returns: a checked graph you can run many times. |
| Council | A graph where several agents answer, others rank the anonymized answers, and a chair decides. |
| Edge | A link from one node to the next. Plain, conditional (with a named predicate) or error. |
| Engine | The Rust runtime that executes graphs, shipped inside the npm package. |
| Fan-out | Running several branches at the same time, then joining. |
| Graph definition | A graph as plain JSON (app.definition), the same format YAML compiles to. |
| Human gate | A node that suspends the run until you resume it. |
| Offline mode | AILU_LLM_MOCK=1: agents without a key answer from a deterministic mock. |
| Reducer | How a channel combines updates: replace, append or merge. |
| Replay | Re-running a recorded run from its record, without calling a model. |
| Resolved by | The person who approved a tool call, recorded with the approval. |
| Run | One execution of a graph, with its own runId and state. |
| Subgraph | A graph used as one node of another graph. |
| Suspended | The status of a run waiting for a human, a date or a signal. |
| Tier | A capability level (fast, balanced, frontier, creative) mapped to a model per provider. |
| Tool | A function an agent can call. Gated tools need a human's approval. |