Engram

Self-hosted, governed long-term memory for your AI agents.

Engram is an open, self-hosted memory and knowledge-graph server for teams of AI agents. Agents store facts, decisions, and lessons; Engram indexes them by meaning (hybrid vector + keyword search), links them into a typed knowledge graph (supersedes / conflicts_with / depends_on / …), and governs who sees what (per-agent mTLS + roles; a personal → shared → trusted lifecycle). Connect any LLM agent over MCP and it gains durable, shared, access-controlled memory.

It runs entirely on your own hardware. It ships with no memory and no credentials — an empty brain that mints its own security material on first run.

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Contents

• Why · What you get · Core concepts
• What it looks like · Features · Architecture
• Security model · Install · Configuration
• Interfaces · Where Engram fits · FAQ
• Documentation map · Status · License

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Why

LLM agents forget everything between sessions. Bolting on a vector store gives you search but not governance — no identity, no access control, and no sense of which memory supersedes which. That breaks down the moment you have more than one agent:

• Whose memory is this? A flat store has no author, so you can't tell a verified fact from something a small local model hallucinated last Tuesday.
• Who's allowed to read it? One shared pool means your ops bot can read anything your personal assistant wrote.
• Which fact is current? Notes contradict each other over time, and plain similarity search happily returns the stale one.
• How does it stay clean? Without dedup, linking, and retention, the store rots.

Engram is the governed layer: every write is attributed to an authenticated agent, every read is filtered by role and sensitivity, and a typed graph keeps knowledge coherent as it grows.

What you get

• A memory server your agents talk to over MCP — 60+ tools, no client library needed (a manager sees the full set; workers see a governed subset).
• Hybrid retrieval that returns how notes connect, not just what matched — with optional on-demand LLM re-ranking and span-level body compression.
• Governance: per-agent identity, reader groups, a sensitivity ceiling, and a review queue.
• Autolearn: memories extracted from your sessions automatically, then gated.
• More than notes: tasks, projects, ideas, skills, sessions/transcripts, and agent-to-agent messages.
• A web dashboard for the graph, approvals, config, skills, and per-agent settings.
• Maintenance that runs itself: edge classification, verification, retention, re-embedding.

Core concepts

Memories

A memory is a named note with a body, a description, an author, a type (reference, feedback, project, decision, …), tags, and a sensitivity level. Agents write them with brain_remember (personal) or brain_propose (straight to the shared review queue).

The lifecycle: personal → ready_to_share → trusted

Capture is never blocked — anything an agent learns lands immediately as its own personal, untrusted note that only it can recall. Trust is earned later:

State	Who can read it	Meaning
personal	the author only	captured, not yet validated
ready_to_share	author + managers	proposed for sharing, in the review queue
trusted	per reader groups + sensitivity ceiling	validated and shared

Recall tells an agent when a note is untrusted and hands back the source session, so the agent can check it against the transcript and then brain_validate_memory it — or delete it. Sharing across agents always needs a manager. The effect: no agent silently inherits another agent's mistake.

The typed knowledge graph

Notes link to each other with typed edges — relates_to, supersedes, conflicts_with, depends_on, runs_on, accessed_via, uses. Edges come from three places:

1. Hand-typed at write time — put [[target|rel_type]] in a note body ([[target]] = relates_to).
2. Co-use links — new notes auto-link to their nearest semantic neighbours.
3. A classifier job that types untyped edges with a local LLM, precision-first: a relation is only promoted if it survives all gates, otherwise it stays relates_to. Uncertain types go to a review queue rather than being guessed into the graph.

The vocabulary lives in graph.yaml, not in code — add your domain's types (e.g. invoiced_to / archived_in) with a config edit and the classifier picks them up.

Identity and access

Every agent is a row in the agent table with a role (manager / worker / readonly), a lane, a sensitivity ceiling, and reader groups. Two factors are required on every call: an mTLS client certificate (CN = the agent's name) and a bearer token (only its hash is stored). Row-Level Security in Postgres is the backstop under the application's own checks.

It isn't only memories

The same governed store also holds tasks, projects (each with a living plan document), ideas, sessions (ingested transcripts, searchable), messages between agents, an infra model, and an audit log.

What it looks like

Once the MCP is wired, your agent just calls tools:

brain_remember(
  name="pg_upgrade_gotcha",
  body="Upgrading Postgres in place needs the pgvector extension rebuilt, "
       "or recall silently returns zero rows. See [[deploy_runbook|depends_on]].",
  mtype="reference", tags=["postgres","gotcha"]
)
→ saved: personal, usable immediately by you, invisible to everyone else.

brain_recall("why did recall return nothing after the db upgrade", k=5)
→ your note, plus the notes it links to, plus anything sharing a rare entity
  ("pgvector") with the query — each tagged trusted / untrusted.

brain_share(id)        → sends it to the review queue
brain_propose(...)     → skips personal, straight to review

Nothing here is bespoke: a manager approves it, it becomes trusted, and every other agent you run can now recall it — subject to reader groups and its sensitivity ceiling.

Features

Hybrid retrieval

Dense vectors (via a local embedding model) and keyword search (Postgres full-text) are fused with Reciprocal Rank Fusion, then expanded two ways:

• Graph expansion — pull in what the hits link to, so you see relationships, not isolated matches.
• Entity expansion — pull in notes sharing a rare entity with the query (task ids, hostnames, filenames), weighted by rarity; hub entities are skipped so common terms don't spray noise.

A trigram index catches typos and out-of-vocabulary terms that exact-token search misses.

Two optional refinements, both off by default (base hybrid recall is already at ceiling for a well-curated brain):

• On-demand re-ranking — pass rank=true to brain_recall and the content hits are reordered by the local LLM before returning; it fail-safes to the original order on any timeout, so recall never stalls.
• Span-level compression (RECALL_SPAN_COMPRESS) — trims each recalled body to its most query-relevant spans (cheap lexical scoring, no extra embed calls; the first span is always kept), ~85% smaller bodies on long notes for thinner injected context. The full body is always fetchable via brain_get.

Recall stays honest under strain: a transient embedder blip is ridden out with a bounded backoff-retry, and if the dense arm does stay down the degradation is surfaced (a recall_degraded audit event + a degraded field on the response) instead of silently returning weaker results.

Skills

Reusable how-to notes ("skills") are a first-class corpus: agents fetch them with brain_skill_recall / brain_skill_get, and the dashboard's Skills tab lists, filters, and opens them.

Autolearn

At session end, a transcript can be handed to Engram, which extracts durable candidate memories, scrubs secrets client-side first, runs a worthiness judge, checks for duplicates and conflicts, consults a lessons table (so it never re-learns something you already rejected), and lands what survives as personal/untrusted notes. Every step is configurable, and the whole thing can be turned off.

Sessions and transcripts

Transcripts are ingested (redacted), indexed for full-text and vector search, and become the source of truth an agent validates its own memories against. rebuild_session.py can re-derive memories and edges from a transcript after the fact.

Governance and review

A /needs-you queue surfaces only what genuinely needs a human — share requests and escalations — rather than every note. Managers approve, deny, or escalate. A manager may not graduate its own note (author ≠ validator). For retiring a stale trusted note there's a sanctioned, audited manager delete (brain_curate_delete, reason required, reversible soft-delete) — no raw SQL needed.

Dashboard

A small web UI ships under dashboard/: the knowledge graph, the approval queues, a memory explorer, a System tab (jobs, session rebuild), a Config tab, and an Agents tab with a per-agent session-start injection preview — exactly what a given agent will be told at boot.

Maintenance that runs itself

Eight systemd timers ship: edge classification, infra-edge derivation, queue drain, golden-set recall eval, memory verification, re-embedding, retention pruning, and the validation sweep. All are schedulable and runnable on demand from the dashboard.

Sensitivity routing

Extraction backends are pluggable and routed by sensitivity: content marked sensitive or secret never leaves your box for a cloud model, whatever the cloud setting says. test_pick_backend.py ships as a standalone proof you can run yourself.

Architecture

flowchart LR
    subgraph agents["your agents (any MCP runtime)"]
        A1["Claude Code"]
        A2["OpenClaw / Hermes"]
        A3["custom agent"]
    end
    A1 --> M["MCP server (brain_* tools)"]
    A2 --> M
    A3 --> M
    M -- "mTLS cert + bearer token" --> N["nginx (TLS + client-cert verify)"]
    N --> API["Flask API — auth, roles, RLS, governance"]
    API --> PG[("PostgreSQL + pgvector — memories, typed graph, tasks/projects/ideas, sessions, audit log")]
    API -- "embeddings + extraction" --> LLM["local LLM (Ollama)"]
    DASH["dashboard (web UI)"] --> API
    TIMERS["systemd timers — edge classify, memory verify, retention prune, ..."] --> PG

Loading

Every arrow into the API is authenticated (client cert and token); every read is filtered by row-level security (role, reader groups, sensitivity ceiling). The local LLM handles embeddings and session-end extraction.

Security model

• Two factors, always. mTLS client cert + bearer token on every call except open enrollment.
• The box mints its own CA. engram-init-pki.sh (plain openssl) creates a local CA and server cert at install. No external or cloud PKI, and no key material ships in this repo.
• Signing stays off the network service. sign-agent-cert.sh signs agent CSRs out-of-band, so compromising the API can never mint certs.
• Defence in depth. Application checks are backed by Postgres Row-Level Security; the app role's privileges are scoped (no DELETE on tables the app never hard-deletes).
• Tokens are hashed. Plaintext is shown once at enrollment and never stored.
• Enrollment is n-of-m. You choose how many managers must co-approve a new agent.

Reporting a vulnerability: see SECURITY.md.

Install

Requirements: PostgreSQL 15+ with pgvector, Python 3.11+, openssl, nginx, and a local LLM endpoint (Ollama or compatible) for embeddings and extraction. Install is systemd + venv; Docker packaging is planned but does not ship yet.

The fastest path is to point your LLM agent at AGENTS.md — it's a runbook written for an agent to execute: bring up the server, create your first (genesis) manager, wire the MCP.

Manually:

cp brain.env.example brain.env     # set your DB + Ollama endpoints
sudo ./install.sh                  # Postgres + pgvector, migrations, PKI, systemd + nginx
./engram-bootstrap-manager.py      # your first manager: you pick the name; prints cert + token ONCE
./smoke_test.sh                    # verifies the front door, mTLS, and a real recall

Then follow INSTALL.md to connect an agent, and ENROLL.md to add more. Upgrades are one command (./update.sh) and preserve your data, config, and PKI — see UPGRADING.md.

Configuration

Two layers:

• brain.env — connection-level settings, read at boot: PGDATABASE, OLLAMA_EMBED_URL, EMBED_MODEL, OLLAMA_GEN_URL, EXTRACT_MODEL, RERANK_MODEL.
• The live config table — ~21 tunables you can read and change at runtime via GET/PATCH /config or the dashboard's Config tab, with no restart. Highlights:

Knob	What it controls
RECALL_K, RECALL_POOL, RELATED_CAP	recall breadth and how much graph context comes back
ENTITY_EXPAND_WEIGHT, ENTITY_EXPAND_HUBCAP	entity-expansion strength; hub-entity cutoff
AUTOLEARN_LLM_JUDGE, AUTOLEARN_DEDUP_COSINE, AUTOLEARN_LINK_CAP	autolearn gating and linking
AUTOLEARN_LAND_SENSITIVE, AUTOLEARN_LAND_QUARANTINED	where autolearn output lands
RECALL_SPAN_COMPRESS, RECALL_SPAN_COUNT, RECALL_SPAN_MIN_CHARS	span-level body compression on recall (off by default)
PROVISIONAL_TTL_DAYS, VALIDATE_SWEEP_DELETE	lifecycle and the retention backstop
ENROLL_APPROVALS	how many managers must approve a new agent
ENTITY_IP_PREFIXES	optional site subnets to treat as entities (unset by default)

The relation vocabulary lives in graph.yaml; the embedding model is pinned in model-pin.json so a silent model swap is detectable.

Interfaces

• MCP — 60+ tools (a manager sees the full set; workers see a governed subset). Recall and search (brain_recall, brain_deep_search, brain_search_transcripts, brain_get, brain_schema, brain_docs_recall, brain_skill_recall, brain_skill_get); writing and governance (brain_remember, brain_propose, brain_share, brain_validate_memory, brain_curate_delete, brain_my_provisional, brain_get_session_turns); work tracking (brain_tasks, brain_add_task, brain_update_task, brain_projects, brain_add_project, brain_ideas, brain_add_idea); attachments, tags, infra, and agent-to-agent messaging (brain_send, brain_inbox). Full reference with worked examples: USAGE.md.
• HTTP — ~89 endpoints for everything the MCP exposes plus operator surfaces (/healthz, /whoami, /bootstrap, /config, /jobs, /agents, /graph, /audit, /needs-you, /session/ingest, /session/search, …). /healthz reports the running version.
• Dashboard — the web UI under dashboard/.

Where Engram fits

Engram is not an agent framework — it's the shared memory layer they plug into. Runtimes like OpenClaw and Hermes Agent run agents (chat channels, tool execution, one agent's own memory); Engram is a standalone, shared, governed memory server that any number of agents — on any framework — point at over MCP. Keep your runtime; add Engram so all your agents read and write one access-controlled long-term brain. In short: they run the agents; Engram is the shared brain you give them.

Compared with a plain vector store (pgvector, Qdrant, Chroma) or a hosted memory API: those give you similarity search. Engram adds identity, access control, a typed graph, a validation lifecycle, and the maintenance jobs that keep a store from rotting — and it runs on your hardware.

FAQ

Does any data leave my machine? No. Embeddings and extraction run against your local LLM endpoint. A cloud extraction backend is optional and sensitivity-routed — sensitive/secret content never routes to it.

Do I need Claude / a specific model? No. Any MCP-capable agent works. The local LLM is Ollama-or-compatible; the embedding model is your choice (pinned for reproducibility).

Does it ship with your data? No. The database starts empty and the box mints its own CA and tokens on first run.

Can I run one agent? Yes — governance stays out of your way (a single manager self-approves). The multi-agent machinery matters when you add a second.

What if the graph types are wrong for my domain? Edit graph.yaml. Types are config, not code, and there's a discovery script that proposes an ontology from your own notes.

Is it production-ready? It's v0.1.x and runs a real daily workload, but the API may still change between minor versions. Read CHANGELOG.md before upgrading.

Documentation map

Doc	What's in it
AGENTS.md	agent-executable setup runbook (the quickest install)
INSTALL.md	manual install + connecting an agent
ENROLL.md	adding more agents; the n-of-m approval flow
USAGE.md	day-to-day manual: every MCP tool, the memory model, a worked walkthrough
SECURITY.md	security model and vulnerability reporting
UPGRADING.md	what's preserved, one-command update, rollback
CHANGELOG.md	release notes
SCHEMA-SCAFFOLD-NOTES.md	schema scaffolding and dead-column guide
CONTRIBUTING.md	how to contribute (inbound = AGPL)

Status

v0.1.7. The engine, governance, graph, autolearn, and dashboard are in daily use. Known gaps: Docker packaging isn't shipped (systemd + venv only), and there's no built-in HA/failover — a single Postgres instance, so back it up.

License

GNU AGPL-3.0 — see LICENSE. You may run and modify Engram freely (including privately); if you distribute it or run a modified version as a network service, you must share your source under the AGPL. Founded and maintained by Aurelius (see NOTICE / AUTHORS); contributions welcome under CONTRIBUTING.md.