Engraphy

An MCP server giving AI agents associative memory, modelled on the human mind.

Quickstart · Documentation · Tool reference · Design set · Contributing

The name comes from engraphy, an old term from memory science for the process of laying down an engram, the trace a memory leaves in the brain. Engraphy does that for agents: it checks each new memory against what it already knows before the write lands, merging restatements, linking genuinely new facts, and never silently overwriting. Nothing is deleted, so history stays walkable.

Engraphy is self-hosted. It stores what an agent learns as a typed knowledge graph on Postgres + pgvector: writes deduplicate themselves against existing memory, retrieval fuses semantic and lexical search, isolation between users is enforced by the database, and the whole shape of memory is declared per application as a pack.

It exists to replace the reference MCP memory server's flat-JSON, single-user, stdio model with something that survives concurrency, paraphrase, duplicates, and years of accumulated memory. It speaks the Model Context Protocol, so any MCP client (a VS Code extension, a desktop app, another agent) can use it over HTTP.

Source-available. Licensed under the Business Source License 1.1: read it, run it, build on it, and use it in production for your own product. Offering Engraphy itself as a hosted or managed service to third parties is reserved to the Licensor until the Change Date, when it converts to Apache-2.0. See License.

What it does

• A typed memory graph. Memories are typed nodes (fact, decision, person, event, …) joined by typed edges (involves, references, supersedes, …). The types, their attribute schemas, and the rules for which edges may connect which types are declared per space in a pack and enforced in Postgres.
• Writes that deduplicate themselves. Every write is embedded and banded against existing memory. A near-verbatim restatement auto-merges; a genuinely new but related fact is kept as its own searchable node and joined by an edge (nothing is silently absorbed); a borderline case parks as a pending duplicate-check verdict for the caller to resolve. Every write returns a resonance report of what it touched.
• Hybrid retrieval. search fuses a vector leg (cosine over embeddings) and a lexical leg (Postgres full-text) with Reciprocal Rank Fusion, and traverse walks the edges. Attribute values are folded into the searchable surface, so a fact stored only in a typed attribute is still findable.
• Isolation the database enforces. Multiple spaces, and multiple principals within a space, are separated by Postgres Row-Level Security running under a non-superuser role, not by application checks that can be forgotten. The server connects as a NOBYPASSRLS role.
• Scope routing built for LLMs. Every scope carries a description of what it governs; the read-only scope_guide tool returns that routing manifest so an agent can decide where a new memory belongs before it writes.
• An operator CLI and an MCP tool surface for everyt

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