# Glossary (https://brainapi.lumen-labs.ai/docs/v2/reference/glossary)

> For the complete BrainAPI documentation index, see [llms.txt](https://brainapi.lumen-labs.ai/docs/llms.txt). A markdown version of any docs page is available by appending `.md` to its URL (e.g. https://brainapi.lumen-labs.ai/docs/v2/reference/glossary.md).

Shared terminology for BrainAPI ingestion, graph, retrieval, Search, recommendations, and plugins

## Core data

**Brain**  
An authenticated knowledge boundary used to scope every application read and write.

**Resource**  
An ingested source such as text, a file, or structured data.

**Passage / text chunk**  
A retrievable portion of source text. Search uses passages by default.

**Entity / node**  
A stable graph object with identity, labels, description, and properties.

**Relationship / predicate**  
A typed directed connection between two nodes.

**Event hub**  
A first-class event node used when an action needs actor, target, time, or context. Static facts do not require one.

**Observation**  
An optional model-generated note stored alongside other knowledge representations.

## Retrieval

**Context**  
Evidence assembled for an LLM, including passages and graph/history fields. It is not a ranked Search response.

**Hit**  
One ranked Search result with an ID, score, optional component scores, snippet, labels, metadata, and catalog node mapping.

**Channel**  
A Search candidate source such as `passages`, `entities`, `events`, `communities`, or `plugin:<name>`.

**Candidate pool**  
The items retrieved before later filtering, reranking, personalization, and truncation.

**Fusion**  
Combining rankings or normalized scores from multiple candidate sources.

**Reranking**  
Reordering a bounded candidate head with a more expensive scoring function. It cannot recover missing candidates.

**Facet**  
Counts derived from metadata on returned Search hits.

**Personalization**  
A soft query-gated reordering signal applied to eligible catalog hits, not an authorization or hard filter.

**Recommendation**  
A ranking around a target user or node rather than a free-text query.

## Operations and extensions

**Task**  
An asynchronous ingest work record scoped to the same brain as the request.

**Plugin**  
Trusted Python code loaded into BrainAPI to add routes, tools, hooks, or ranking behavior.

**MCP**  
Model Context Protocol, used to expose BrainAPI or documentation tools to compatible agent runtimes.

**Shipped behavior**  
Implemented and test-backed behavior documented as part of the current contract.

**Idea to test**  
A hypothesis for application evaluation, not a BrainAPI quality or latency claim.