Introduction

Core holds one canonical model: a single typed property graph shared by every product, standard, and agent in the estate (Core model fundamentals covers that graph directly). Holding the graph is only half the story - you also need one way to ask it something. That layer is Cogitave Query.

One query layer over the canonical graph. Same model, same retrieval for humans (API/UI) and agents (MCP). Retrieval is hybrid: lexical recall, semantic recall, and graph structure are three signals fused into one ranking - none alone is enough.

That single sentence from Cogitave Query is this module's whole subject. There is no separate "agent view" of the estate and a different "human view" - docs_search over MCP and the human-facing search box call the same pipeline and get the same ranking. This module teaches you to reason about what that pipeline actually does to a query, not to reimplement it.

Why fuse three signals instead of picking the best one

Lexical retrieval (BM25) and dense-vector retrieval each fail on inputs the other handles well: BM25 misses paraphrase and synonymy, dense retrieval misses the rare exact tokens - identifiers, error codes, API symbols, version strings - that dominate technical and agent queries. Cogitave adds a third signal neither text index can see at all: the graph itself, with its prerequisite edges, cross-references, and authority structure.

Read this as a Day 0 spec

Cogitave Core is a Day 0 design - the canonical model, its query layer, and its native MCP surface are specified and built against, not a black box you take on faith. This module follows that same posture: every mechanism it names - BM25 segments, HNSW vectors, Reciprocal Rank Fusion, the bounded query_graph profile - is stated exactly as Cogitave Query and ADR-0002 specify it, with a link back to the source.

What you will get from this module

By the end, you will be able to trace a query through the pipeline end to end, explain why rank-based fusion was chosen over a weighted score blend, and read the bounded graph-query contract that lets an agent call the graph directly without an unbounded write path opening underneath it.